Modelagem de uma unidade de produção para caprinos leiteiros utilizando a dinâmica de sistemas

OpenAIRE

Guimarães, Vinicius Pereira

2007-01-01

O trabalho foi desenvolvido buscando abordar as características de dinâmica, complexidade e inter- relacionamento de um sistema de produção de caprinos. Buscou-se, através da metodologia de modelagem e simulação Dinâmica de Sistemas, identificar o impacto na dinâmica e rentabilidade econômica de rebanhos caprinos leiteiros provocados por modificações no manejo reprodutivo, mortalidade, qualidade do alimento e na idade para o início da vida reprodutiva em cabritas. Buscou-se também avaliar a u...

Modelagem fenomenológica do desempenho de torres de resfriamento de água acopladas e estudo de casos.

OpenAIRE

Rafael Candido de Lima Junior

2011-01-01

Neste trabalho foi realizada a modelagem fenomenológica do desempenho de uma torre de resfriamento de água e de um sistema de duas torres de resfriamento em série, com temperatura de água de entrada de até 65 ºC. Verificou-se a validade do modelo através de comparação dos resultados previstos com os obtidos em ensaios em uma unidade piloto. Em seguida, através de simulação matemática, a partir do modelo desenvolvido, foi feito o estudo de diversos casos de aplicação. Estudou-se a influência d...

Modelagem e Simulação no Âmbito da Hidrologia

Directory of Open Access Journals (Sweden)

Vassiliki Terezinha Galvão Boulomytis

2011-04-01

Full Text Available A modelagem hidrológica pode ser considerada como um conjunto de ferramentas destinadas ao cálculo e à representação de dados que possibilita a previsão de eventos, a realização de projetos, o gerenciamento dos recursos hídricos, além de outros tipos de aplicação. No entanto, devido à variabilidade na ocorrência dos processos hidrológicos, escassez e dificuldade na obtenção de dados levantados em campo, os modelos conceituais vêm sendo combinados com os físicos e empíricos, utilizando-se de novas técnicas, entre elas, o sensoriamento remoto e o geoprocessamento para a coleta, processamento, análise e geração de resultados. Neste trabalho será apresentada a base conceitual e a importância do conhecimento do tipo de ferramenta que se deseja utilizar para a implementação ou uso de um modelo hidrológico, para que deste modo seja possível verificar a possibilidade do mesmo ser de fato desenvolvido.

Modelagem e simulação virtual de pá para rotor eólico de pequeno porte

Directory of Open Access Journals (Sweden)

Julio Cesar Pires

2010-12-01

Full Text Available Este trabalho apresenta um estudo para aerogerador de pequeno porte projetado para uso residencial. A ênfase está na modelagem e simulação virtual da estrutura das pás em compósito de fibra de vidro. A modelagem foi feita com software para desenho assistido por computador (CAD 3D. Para o projeto, foi escolhido o perfil MH110 que apresenta boa relação entre coeficiente de sustentação e coeficiente de arrasto e facilidade de fabricação. Os parâmetros como o diâmetro do rotor, a corda e a torção da pá, as relações entre velocidades e a aplicação de cargas na estrutura do material utilizado foram definidos segundo bibliografia específica, software para análise de perfil aerodinâmico e simulações pelo método dos elementos finitos. Procurou-se buscar sempre a maior eficiência, segurança e economia. O material foi projetado para resistir às tensões decorrentes de operação em condições consideradas normais e para rajadas de vento. A simulação pelo método dos elementos finitos foi conduzida com ferramenta computacional e levou em conta os limites de falha do material utilizado. A geometria foi simulada sem reforço interno e apresentou baixo deslocamento quando submetida às cargas aerodinâmicas de empuxo e rotacional. Ao realizar simulação com critério de falha, foi possível determinar a espessura mais adequada para o material compósito e verificar seu comportamento de acordo com diferentes velocidades de vento.

ESTRATÉGIA PARA MODELAGEM NUMÉRICA DE SISTEMAS MISTOS CONSIDERANDO DIFERENTES MODELOS DE RUPTURA PARA OS MATERIAIS STRATEGY FOR NUMERIC MODELLING OF COMPOSITE SYSTEMS CONSIDERING DIFFERENT MODELS OF RUPTURE FOR THE MATERIALS

Directory of Open Access Journals (Sweden)

Julio Cesar Molina

2009-08-01

Full Text Available Este artigo apresenta a estratégia utilizada na modelagem numérica de um corpo-de-prova misto de madeira e concreto, com sistema de conexão metálico, sob carregamento. A modelagem do sistema foi efetuada a partir de um modelo tridimensional, que utiliza o software ANSYS, versão 10.0, que tem como base o Método dos Elementos Finitos, onde foram considerados diferentes modelos de ruptura para os materiais unidos, além de elementos de contato nas interfaces dos mesmos. Os elementos finitos, assim como os materiais utilizados, foram escolhidos em função de suas representatividades perante os comportamentos a serem simulados, para que, dessa forma, fosse possível a consideração de efeitos importantes como plasticidade e ortotropia para os materiais. Os resultados obtidos a partir da modelagem proposta foram comparados com os resultados experimentais de ensaios de cisalhamento, realizados em corpos-de-prova mistos com carregamento aplicado até a ruptura e o erro obtido, neste caso, foi de até 15%. A finalidade deste trabalho é servir de base para a modelagem de sistemas estruturais, presentes em diversas áreas da engenharia, dentre elas, mecânica e civil, onde são utilizados materiais com diferentes comportamentos estruturais. A modelagem proposta possibilita a análise global do modelo assim como a análise dos aspectos localizados de interesse como a concentração de tensões, efeito de difícil quantificação em uma análise experimental.This paper shows the strategy used in the numeric modeling of a composite specimen of wood and concrete, with metallic connection system, with applied cyclical load. The modeling of the system was made starting from a three-dimensional model, using the software ANSYS, version 10.0, that has as base the Method of the Finite Elements, in which different rupture models were considered for the materials, besides contact elements in the interfaces of the materials. The finite elements, as well as the

Modelagem do projeto da cadeia de suprimentos global: considerações teóricas e perspectivas futuras

Directory of Open Access Journals (Sweden)

Monize Sâmara Visentini

2014-06-01

Full Text Available Este artigo teórico objetiva apresentar e discutir características de modelos matemáticos de otimização do projeto da cadeia de suprimentos global, a fim de sugerir perspectivas de pesquisas futuras. A pesquisa bibliográfica foi realizada nos mais importantes periódicos internacionais de pesquisa operacional, compreendendo, predominantemente, artigos publicados entre 2000 e 2013. Dos 111 artigos selecionados, 22 foram analisados em profundidade, considerando aspectos referentes à modelagem da cadeia de suprimentos global e os fatores internacionais abordados. Através da discussão teórica, identificaram-se questões emergentes, indicando oportunidades e necessidades de desenvolvimento de novos modelos matemáticos e técnicas de solução.

Modelagem e simulação de um sistema solar de aquecimento e distribuição de água quente

OpenAIRE

Anderson Geraldo Alves de Oliveira

2014-01-01

O sistema solar de aquecimento de água é utilizado principalmente para aquecer água para o banho ou piscina nos setores residencial, industrial e de serviços. Atualmente, a crescente utilização desse sistema tem ajudado, principalmente, a redução do consumo da energia elétrica nas residências familiares e multifamiliares. Neste trabalho foram realizadas a modelagem matemática e a simulação numérica de um sistema solar de aquecimento e distribuição de água quente residencial de baixo custo. A ...

MODELAGEM DA PRODUÇÃO DE SEDIMENTOS NA SUB-BACIA HIDROGRÁFICA DO RIACHO JACARÉ - SE

Directory of Open Access Journals (Sweden)

Fabrício Lopes de MACEDO

2012-03-01

Full Text Available A produção de sedimentos nas bacias hidrográficas constitui um aspecto importante para o planejamento do uso e ocupação do solo. Modelos matemáticos são ferramentas úteis para a análise do problema fornecendo rapidez, praticidade e flexibilidade as simulações de condições atuais e futuras. Neste artigo foi avaliada uma metodologia para simular a produção de sedimentos em distintos cenários de uso e ocupação do solo utilizando de forma combinada a MUSLE, o modelo hidrológico ABC e um SIG. A modelagem utilizada apresentou bom desempenho para fins de planejamento do uso e ocupação do solo, bem como para o planejamento agrícola e ambiental.

MODELAGEM MATEMÁTICA NOS ANOS INICIAIS DO ENSINO FUNDAMENTAL: UMA INVESTIGAÇÃO IMPERATIVA. MATHEMATICAL MODELING IN THE EARLY ELEMENTARY SCHOOL: A REQUIRED INVESTIGATION

Directory of Open Access Journals (Sweden)

Vantielen da Silva Silva

2012-11-01

Full Text Available As pesquisas sobre Modelagem Matemática na Educação Matemática têm se ampliado no cenário educacional e apresentado contribuições relevantes para o ensino da matemática nas diferentes etapas da Educação. A partir disso, com o intuito de nos aproximarmos dessas pesquisas, pelo menos em parte, desenvolvemos esse artigo buscando responder ao questionamento: em que níveis de ensino estão focadas as pesquisas brasileiras sobre Modelagem Matemática na Educação Matemática e o que isso revela? Para responder a esse questionamento direcionamos nossa pesquisa aos resumos dos trabalhos stricto sensu disponíveis no Banco de Teses da CAPES. Nesse momento inicial, pudemos compreender que a Modelagem Matemática no âmbito da Educação Matemática apresenta-se como uma tendência que contribui com o desenvolvimento da aprendizagem significativa e com a melhoria da qualidade de Ensino em Matemática. Porém, a maior parte das investigações aponta a sua presença e contribuições para os Anos Finais e Ensino Médio, sendo incipientes as produções ou reflexões sobre a possibilidade de seu uso nos Anos Iniciais, ou seja, entre o 1º e 5º Ano do Ensino Fundamental.Researches on Mathematical Modeling in Mathematics Education have expanded the educational setting and presented relevant contributions to mathematics teaching in the different stages of education. Hence, in order to approach these surveys, we developed this work seeking for the answer to the question: Which education levels are Brazilian researches about Mathematical Modeling in Mathematics Education focused on and what does it reveal? To answer this question we directed our research to the abstracts of the post-graduation works that are available in CAPES Theses Database, Brazil. At this initial moment, we understood that Mathematical Modeling in Mathematics Education presents itself as a trend that contributes to the development of meaningful learning and improves the quality

MODELAGEM DE UM SISTEMA ESPECIALISTA PARA APRIMORAR PRODUTOS E PROCESSOS NA PRODUÇÃO DE LEITE UTILIZANDO A UML /MODELING AN EXPERT SYSTEM TO IMPROVE PRODUCTS AND PROCESSES IN THE MILK PRODUCTION USING THE UML

Directory of Open Access Journals (Sweden)

Mario Mollo Neto

2010-11-01

Full Text Available A zootecnia de precisão permite o desenvolvimento de ferramentas automatizadas que fornecem um acompanhamento detalhado do plantel, aumentando a rentabilidade, e protegendo os animais racionalmente. O setor agropecuário brasileiro, em decorrência das intempéries da economia mundial globalizada, vem, de maneira crescente, se adaptando à utilização destas ferramentas automatizadas para suporte à tomada de decisão. A laminite é a patologia de maior custo para o gado de leite confinado. Suas causas incluem condições climáticas, de alojamento, de alimentação e a presença de pisos mais abrasivos. Baseando-se nessas informações é possível, utilizando o algoritmo correto, construir um modelo que permita ao usuário estimar a possibilidade de incidência de laminite em gado leiteiro, a partir de dados históricos ou mesmo de outras variáveis que causam a patologia. Neste trabalho foi realizada a modelagem, utilizando a Universal Modelling Language (UML, de um sistema especialista com motor de inferência Fuzzy para o diagnóstico preventivo desta patologia que reduza os impactos na produção e no conforto animal. A partir da modelagem realizada ficam disponíveis novas bases para a futura codificação e construção do sistema especialista para mitigar a patologia de casco, reduzir os impactos de perdas de receita relacionados e ampliar o conforto animal. Palavras-chave: Laminite, Sistema Especialista, Suporte a Decisão, Lógica Fuzzy, Diagnóstico Preventivo, Bem-estar animal, Modelagem.

Utilização da função pearson tipo V, Weibull e hiperbólica para modelagem da distribuição de diâmetros

Directory of Open Access Journals (Sweden)

Daniel Henrique Breda Binoti

2013-09-01

Full Text Available Objetivou-se neste estudo avaliar a eficiência da função log-Pearson tipo V para a descrição da estrutura diamétrica de povoamentos equiâneos de eucaliptos, bem como propor um modelo de distribuição diamétrica utilizando essa função. A modelagem realizada pela função log-Pearson tipo V foi comparada com a modelagem realizada com a função Weibull e hiperbólica. Para isso utilizou-se dados de parcelas permanentes de eucalipto, localizadas na região centro oeste do estado de Minas Gerais. A função Pearson tipo V foi testada em três diferentes configurações, com três e dois parâmetros, e tendo o parâmetro de locação substituído pelo diâmetro mínimo da parcela. A aderência das funções aos dados foi comprovada pela aplicação do teste Kolmogorov-Sminorv (K-S. Todos os ajustes apresentaram aderência aos dados pelo teste KS. As funções Weibull e hiperbólica apresentaram desempenho superior ao demonstrado pela função Pearson tipo V.

Modelagem e simulação de reator de leito expandido aplicado ao hidroprocessamento de oleos pesados e residuos de destilação

OpenAIRE

João Capistrano Nobre de Abreu

1995-01-01

Resumo: O presente trabalho apresenta a modelagem e simulação de um reator de leito fluidizado trifásico aplicado ao hidroprocessamento de óleos pesados e resíduos de destilação. Duas reações principais foram consideradas no desenvolvimento do modelo, o hidrocraqueamento e a hidrodemetalização tendo sido a primeira considerada como exclusivamente térmica e a segunda como catalítica. O grau de mistura do reator foi representado de duas maneiras distintas. Inicialmente, considerou-se o sistem...

Modelagem numérica de vigas mistas aço-concreto

Directory of Open Access Journals (Sweden)

L. R. Marconcin

Full Text Available A utilização de estruturas mistas está cada vez mais presente nas obras de Engenharia Civil. As vigas mistas, em particular, são estruturas compostas por dois materiais, um perfil metálico, situado em região predominantemente tracionada, e uma seção de concreto, situada em região predominantemente comprimida, ligados entre si através de dispositivos metálicos denominados de conectores de cisalhamento. As funções prin- cipais dos conectores são: permitir o trabalho solidário da laje-viga, restringir o escorregamento longitudinal e o deslocamento vertical na interface dos elementos e, absorver forças de cisalhamento. Nesse contexto, apresentam-se neste trabalho, modelos numéricos tridimensionais de vigas mistas aço-concreto, com a finalidade de simular o seu comportamento estrutural, enfatizando a interface laje-viga. As simulações foram feitas através do software ANSYS versão 10.0, que tem como base o Método de Elementos Finitos. Os resultados obtidos foram comparados com os previstos por norma e com referências encontradas na revisão bibliográfica, verificando-se que a modelagem numérica é uma ferramenta válida para a análise de vigas mistas aço-concreto.

Modelagem hidrológica determinística e estocástica aplicada à região hidrográfica do Xingu- Pará

OpenAIRE

Lucas,Edmundo Wallace Monteiro; Sousa,Francisco de Assis Salviano de; Silva,Fabricio Daniel dos Santos; Lucio,Paulo Sergio

2009-01-01

A modelagem hidrológica é uma importante ferramenta no planejamento e gerenciamento de programas de recursos hídricos de bacias hidrográficas. Neste trabalho, foi aplicado o modelo hidrológico determinístico mensal de dois parâmetros e o modelo estocástico, ARIMA, para simular a vazão mensal das sub-bacias da região hidrográfica do Xingu no Estado do Pará. O objetivo principal foi simular a vazão mensal através dos modelos e comparar os seus resultados. O modelo hidrológico determinístico apl...

Modelagem e quantificação da incerteza espacial do potássio disponível no solo por simulações estocásticas

Directory of Open Access Journals (Sweden)

Ismênia Ribeiro de Oliveira

2014-09-01

Full Text Available O objetivo deste trabalho foi avaliar o desempenho da simulação sequencial gaussiana (SSG e da simulação sequencial indicatriz (SSI na modelagem da incerteza das predições do K disponível em área de cana-de-açúcar, e comparar as simulações com o método já consagrado de krigagem ordinária (KO. Uma malha amostral com 626 pontos foi instalada em área de 200 ha, no Município de Tabapuã, em São Paulo. As simulações reproduziram a variabilidade dos dados amostrais de K disponível, enquanto a KO superestimou os baixos teores de K e subestimou os altos. O mapa de desvio-padrão obtido a partir da KO mostrou menor variação ao longo da área de estudo, quando comparado aos mapas obtidos a partir das simulações. A SSI obteve acurácia 22% superior à obtida pela SSG, na modelagem da função de distribuição condicional do K. As simulações apresentam maior eficiência que a KO para modelar incerteza na distribuição espacial do K. A SSI apresenta melhor desempenho que a SSG na estimativa dos teores de K disponível, em área de cana-de-açúcar.

MODELAGEM SISTÊMICA DE PROJETOS DE AEC EM UML

Directory of Open Access Journals (Sweden)

Rita Cristina Ferreira

2007-11-01

Full Text Available O uso intensivo de Sistemas de Informação é uma possível solução para a integração das atividades de projeto em AEC, permitindo que decisões sejam tomadas ainda na fase de projeto e, conseqüentemente, evitando-se retrabalhos em obra. Neste sentido, esforços têm sido realizados para padronizar conceitos e terminologias de AEC, permitindo a troca e armazenagem de informações, como a norma ISO 12006-2 e os padrões estabelecidos pelo IFC. Ambas são baseadas na linguagem EXPRESS, assim como é o padrão industrial STEP. Entretanto, as representações de informação usadas na indústria de produtos não são as mais adequadas para a Engenharia de Software, responsável pelo desenvolvimento de Sistemas de Informação, onde as representações semânticas envolvem não somente a representação estrutural da informação, mas também a representação comportamental. Este artigo contribui com uma visão de implementação em UML da informação de um projeto de AEC e tornam explícitas, sob a ótica do desenvolvimento de software, as relações semânticas existentes. Os resultados desta pesquisa foram obtidos através da realização de um estudo de caso de projeto de produção em CAD 3D dos subsistemas alvenaria e revestimento para um edifício residencial. A partir das observações do estudo de caso foi feita a modelagem em UML dos objetos pertinentes. O principal resultado obtido foi a representação explícita das interfaces entre objetos AEC.

A indústria do petróleo como uma organização complexa: modelagem de negócios e processo decisório

OpenAIRE

Milani Júnior,Angelo; Bomtempo,José Vitor; Pinto Júnior,Helder Queiroz

2007-01-01

Este texto propõe a formulação de modelos de negócios para apoiar o processo decisório em organizações complexas. O processo decisório é estudado, explorando-se os temas da racionalidade limitada, da estruturação de problemas, dos modelos mentais, dos mundos virtuais e da modelagem como apoio à decisão. A dinâmica de sistemas é introduzida como um instrumento para a construção de modelos, a identificação de regras de decisão e sua comunicação. É desenvolvido um modelo de negócios para as ativ...

Método para projeto e planejamento de sistemas de produção na construção civil com uso da modelagem BIM 4D

OpenAIRE

Clarissa Notariano Biotto

2012-01-01

As atividades de projeto e planejamento de sistemas de produção na indústria da construção civil tendem a ser mais complexas em relação à manufatura pelo fato de que o produto (edificação) é fixo no espaço enquanto os recursos transformadores movimentam-se. Além disso, à medida que o empreendimento vai sendo construído, o leiaute é alterado, contribuindo para aumentar a complexidade destas atividades. O presente trabalho propõe o uso de modelagem 4D para a visualização espacial e temporal de ...

MODELAGEM DE UM SISTEMA MULTIAGENTE DE APOIO À PBL UTILIZANDO A METODOLOGIA MAS-COMMONKADS+

Directory of Open Access Journals (Sweden)

Laysa Mabel de Oliveira Fontes

2014-10-01

Full Text Available A aprendizagem baseada em problema (Problem-Based Learning - PBL é um método no qual os estudantes aprendem através da resolução de um problema que, em geral, não possui uma solução trivial e uma única solução correta. A PBL destaca o trabalho em equipe como um dos principais requisitos para o sucesso do processo de aprendizagem, ou seja, a colaboração é essencial. No entanto, a implantação de um método de ensino com base na PBL não é uma tarefa trivial. Em Ambientes Virtuais de Aprendizagem (AVAs, a complexidade de implantação deste método é ainda maior, pois o facilitador nem sempre pode detectar possíveis problemas na colaboração, nem possui todas as informações necessárias para aplicar as técnicas de aprendizagem deste método. Desta forma, este artigo apresenta o processo de modelagem de um Sistema Multiagente (SMA de apoio à PBL. O SMA proposto foi modelado utilizando a metodologia MAS-CommonKADS+, que consiste em uma extensão da metodologia MAS-CommonKADS.

Modelagem Integrada do Problema de Programação de Tripulantes de Aeronaves

Directory of Open Access Journals (Sweden)

Wagner de Paula Gomes

2011-09-01

Full Text Available

Este artigo trata o Problema de Programação de Tripulantes (PPT, de importância fundamental no planejamento operacional das empresas aéreas. O PPT é normalmente dividido na literatura em dois subproblemas, formulados e resolvidos sequencialmente: Problema de Determinação das Viagens (PDV e Problema de Atribuição de Escalas (PAE. Esta decomposição justifica-se pela sua natureza combinatória, porém deixa de proporcionar um tratamento global ao PPT, em termos de custo e qualidade da solução final. Portanto, o estado da arte envolve a solução integrada do PPT, em que ambos os subproblemas são resolvidos simultaneamente. O problema, no entanto, é NP-Difícil. Esta pesquisa apresenta uma metodologia para modelagem integrada do PPT, através de um Algoritmo Genético Híbrido (AGH associado a um procedimento de busca em profundidade, levando em conta as particularidades da legislação brasileira. A metodologia foi testada, com sucesso, para a solução de instâncias baseadas na malha real de uma empresa aérea brasileira.

Mathematical and numerical modeling of the turbulent dispersion of reactive pollutant plumes; Modelacion matematica y numerica de la dispersion turbulenta de plumas de contaminantes reactivos

Energy Technology Data Exchange (ETDEWEB)

Rodas Grapain, Arturo

1999-07-01

desarrolladas, por lo que poseen dos efectos secundarios inevitables: la inestabilidad del metodo numerico, es decir, su capacidad para lograr una convergencia rapida y aceptable del valor aproximado con relacion al valor real, el alto consumo de memoria de la maquina donde se ejecutan los calculos numericos y, paralelamente, el tiempo requerido para desarrollar dichos calculos. Otro problema innato a lo anterior es la estructura del modelo de calidad del aire, es decir, la base matematica donde descansan los calculos medulares de dicho modelo matematico. Generalmente los modelos simples realizan calculos rapidos pero poco precisos, contrapuesto a los modelos complejos y elaborados que realizan calculos mas precisos, pero que tardan mucho tiempo en llevarse a cabo, y por lo mismo tienen que ser ejecutados en potentes y rapidas computadoras, tales como las estaciones de trabajo o en super computadoras como una Cray. Por todo lo anterior, el modelo que aqui se propone, aunque posee una estructura teorica relativamente simple, produce resultados bastante aceptables con relacion al calculo puntual de concentraciones, mismos que son comparados por dos modelos matematicos de moderada complejidad teorica y numerica (modelos de Georgopoulos-Seinfeld y de Lipphardt). Este modelo propuesto, denominado MOTTQUIP (modelo de transporte turbulento y quimica de plumas), posee la caracteristica sobresaliente de que no involucra (al menos explicitamente) la solucion numerica de ecuaciones en diferenciales parciales y, por lo tanto, no presenta las dificultades tipicas de los metodos numericos de solucion para las ecuaciones de este tipo.

Techniques for contact and contact with friction problems; Tecnicas para problemas de contacto y contacto con friccion

Energy Technology Data Exchange (ETDEWEB)

Velandia Arana, Gonzalo [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1990-12-31

Different numerical techniques are presented based in the finite element method to obtain numerical solutions to contact and contact with friction problems between solid bodies, and compared between each other. [Espanol] Se presentan diferentes tecnicas numericas basadas en el metodo de elementos finitos para la obtencion de soluciones numericas de problemas de contacto y contacto con friccion entre cuerpos solidos, y se comparan entre si.

Techniques for contact and contact with friction problems; Tecnicas para problemas de contacto y contacto con friccion

Energy Technology Data Exchange (ETDEWEB)

Velandia Arana, Gonzalo [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1989-12-31

Different numerical techniques are presented based in the finite element method to obtain numerical solutions to contact and contact with friction problems between solid bodies, and compared between each other. [Espanol] Se presentan diferentes tecnicas numericas basadas en el metodo de elementos finitos para la obtencion de soluciones numericas de problemas de contacto y contacto con friccion entre cuerpos solidos, y se comparan entre si.

Discussão sobre algumas contribuições da modelagem multinível para a investigação de desempenho no trabalho Discussing some multilevel models contributions to investigate performance at work

Directory of Open Access Journals (Sweden)

Francisco Antonio Coelho Junior

2011-08-01

Full Text Available O investimento no capital intelectual tornou-se o pilar norteador das ações de gerenciamento de pessoas. A literatura em comportamento organizacional investigada enfatiza o efeito de variáveis de contexto no desempenho dos indivíduos. Faz-se mister compreender como se dá o impacto dessas variáveis segundo seus níveis de análise. O presente artigo discute contribuições potenciais da modelagem multinível na investigação de desempenho no trabalho. Discute, ainda, a aplicação dessa modelagem para compreensão de fenômenos comumente investigados em comportamento organizacional. Tais contribuições poderão favorecer a estruturação de modelos preditivos que poderão melhor capturar o significado da inclusão de variáveis típicas do contexto laboral.Investing on intellectual capital became the guiding pillar for personnel management actions. The organizational behavior literature highlights the effect of contextual variables on the performance of individuals. The impact of these variables, which belong to different levels of analysis, needs a better comprehension. This paper discusses the potential multilevel modeling contributions for investigating predictors of that performance. In addition, it also discusses the application of this modeling for understanding usually studied organizational behavior. These contributions may favor structuring predictive models which may better grasp the meaning of the inclusion of diverse and complex levels of variables from the labor context.

Modelagem Matemática: as discussões técnicas e as experiências prévias de um grupo de alunos

Directory of Open Access Journals (Sweden)

Jonson Ney Dias da Silva

2011-05-01

Full Text Available Este artigo tem o objetivo de analisar como as experiências prévias dos alunos influenciam a produção de discussões técnicas em um ambiente de modelagem matemática. Por discussão técnica, entendemos como toda tradução de um fenômeno eleito (oriundo do dia-a-dia, do campo das profissões ou de outras áreas da ciência em termos matemáticos. Esta pesquisa foi realizada com um grupo de alunos de um Curso de Licenciatura em Matemática, em uma sala de aula de uma universidade pública. A natureza da pesquisa é qualitativa e os dados foram coletados através da observação e entrevistas, a qual foi registrada através da filmagem. Os resultados sugerem que as discussões técnicas seguem uma lógica escolar, mobilizando conhecimentos matemáticos previamente estudados pelos alunos, porém com a incorporação de argumentos externos à sala de aula. Palavras-chave: Modelagem matemática. Interação aluno-aluno. Discussões técnicas. Alunos. Sala de aula. Mathematical Modeling: technical discussions and previous experiences of a group of students Abstract This paper aims to present an analysis of how students´ previous experiences may influence the production of technical discussions in an environment of mathematical modeling. By technical discussion, we mean “all translation of a selected phenomenon (from the daily routine, vocational settings or from other fields of science into mathematical terms. This research was carried out with a group of students of an undergraduate course in mathematics in a classroom of a public university. This research is a qualitative one, and the data were collected through observation and interviews, which have been registered through video recording. The results suggest that technical discussions follow the school logic, mobilizing students’ previous school mathematical experiences but also incorporating in some degree outside arguments into classroom. Keywords: Mathematical

Redução do impacto ambiental: uma abordagem no setor de modelagem em uma empresa calçadista

Directory of Open Access Journals (Sweden)

carlos Augusto Nascimento

2016-12-01

Full Text Available Este artigo apresenta os resultados de uma pesquisa quali-quantitativa de caráter exploratório e de natureza aplicada, realizada no setor de modelagem de uma empresa calçadista, com a finalidade de implantar um novo fluxo processual para gestão de resíduos e de materiais sobressalentes. Para a elaboração do projeto empregou-se metodologia DMAIC, ferramentas da qualidade, ecodesign e a ferramenta 3Rs, visando à redução da variação do processo de maneira a incorporar ações sustentáveis, que permitam a diminuição do custo industrial. Como resultado, obteve-se a redução de passivo ambiental do estoque em processo, da baixa eficiência produtiva, das perdas energéticas e maior desempenho econômico-financeiro, por meio da fabricação de calçados, com o uso de resíduos e materiais sobressalentes e de novo material reciclável para a utilização em gabaritos produtivos.

Depth migration and de-migration for 3-D migration velocity analysis; Migration profondeur et demigration pour l'analyse de vitesse de migration 3D

Energy Technology Data Exchange (ETDEWEB)

Assouline, F.

2001-07-01

3-D seismic imaging of complex geologic structures requires the use of pre-stack imaging techniques, the post-stack ones being unsuitable in that case. Indeed, pre-stack depth migration is a technique which allows to image accurately complex structures provided that we have at our disposal a subsurface velocity model accurate enough. The determination of this velocity model is thus a key element for seismic imaging, and to this end, migration velocity analysis methods have met considerable interest. The SMART method is a specific migration velocity analysis method: the singularity of this method is that it does not rely on any restrictive assumptions on the complexity of the velocity model to determine. The SMART method uses a detour through the pre-stack depth migrated domain for extracting multi-offset kinematic information hardly accessible in the time domain. Once achieved the interpretation of the pre-stack depth migrated seismic data, a kinematic de-migration technique of the interpreted events enables to obtain a consistent kinematic database (i.e. reflection travel-times). Then, the inversion of these travel-times, by means of reflection tomography, allows the determination of an accurate velocity model. To be able to really image geologic structures for which the 3-D feature is predominant, we have studied the implementation of migration velocity analysis in 3-D in the context of the SMART method, and more generally, we have developed techniques allowing to overcome the intrinsic difficulties in the 3-D aspects of seismic imaging. Indeed, although formally the SMART method can be directly applied to the case of 3-D complex structures, the feasibility of its implementation requires to choose well the imaging domain. Once this choice done, it is also necessary to conceive a method allowing, via the associated de-migration, to obtain the reflection travel-times. We first consider the offset domain which constitutes, still today, the strategy most usually used

Modelagem hidrodinâmica do canal do rio Paraná, trecho Porto São José - Porto 18. Parte II: Calibragem do modelo

Directory of Open Access Journals (Sweden)

Astrid Meira Martoni

1999-05-01

Full Text Available Neste artigo, apresenta-se a modelagem hidrodinâmica do trecho de canal entre Porto São José e Porto 18. Esta etapa compreendeu os trabalhos de obtenção de dados históricos, levantamentos de campo de níveis e vazões, obtenção dos parâmetros do modelo e análise da distribuição das vazões através dos canais principais. Para as seções internas da discretização foram feitas leituras de níveis nas seções e medidas de descarga usando o medidor ADCP, o que tornou possível estimar os coeficientes de rugosidade. O modelo calibrado constitui um instrumento eficiente para simular dados de níveis e vazões neste trecho do rio.

O uso das novas tecnologias da informação e comunicação no ensino de física : uma abordagem através da modelagem computacional

OpenAIRE

Marcelo Esteves de Andrade

2010-01-01

Neste projeto, utilizamos algumas tecnologias da informação e comunicação para desenvolver uma estratégia de ensino de Física para o Ensino Médio abordando o tópico da cinemática. A estratégia contou com a utilização de aulas e testes virtuais e também com atividades de modelagem computacional com o programa Modellus. Todas as atividades foram aplicadas no laboratório de informática e mediadas pelo computador. Esta estratégia foi aplicada em duas turmas do primeiro ano do Ensino Médio do Inst...

Modelagem em Vídeo para o Ensino de Habilidades de Comunicação a Indivíduos com Autismo: Revisão de Estudos

Directory of Open Access Journals (Sweden)

Viviane RODRIGUES

Full Text Available RESUMO as pessoas com transtorno do espectro autista (TEA apresentam limitações específicas nas habilidades de comunicação. A modelagem em vídeo (MV é considerada uma prática baseada em evidências para indivíduos com TEA pelo fato desta população preferir e responder melhor às estratégias de ensino por meio de pistas visuais. Neste sentido, o objetivo desta revisão foi discutir os resultados das intervenções que implementaram a MV para ensinar habilidades de comunicação para indivíduos com TEA. Para tanto, três critérios de inclusão foram estabelecidos, sendo eles: a os estudos deveriam utilizar como variável independente a modelagem em vídeo isoladamente, associada a outra intervenção ou como parte de um pacote de tratamentos; b as habilidades de comunicação deveriam fazer parte da variável dependente, mesmo que estivessem presentes outras habilidades; c todos os estudos deveriam ter participantes com Transtorno do Espectro Autista. Foi utilizado como banco de dados o Portal de Periódico da CAPES, com descritores específicos. O período determinado neste estudo foi de 2010 a 2016. Somente 11 artigos apresentaram os critérios de inclusão determinados neste estudo. Estes estudos enfatizaram os ganhos da pessoa com TEA em suas habilidades de comunicação por meio da MV. Dados os resultados positivos relatados nestes 11 estudos, há evidências suficientes para concluir que a MV é um procedimento indicado para ensinar uma variedade de habilidades comunicativas para crianças com TEA. Conclui-se que este estudo sumarizou intervenções que empregaram a MV para o ensino de habilidades de comunicação, proporcionando direções para pesquisas futuras.

Modelagem conceitual para identificação de áreas com potencial para geração de energia por fonte renovável

Directory of Open Access Journals (Sweden)

Vivian Celestino

2016-12-01

Full Text Available O mundo enfrenta um desafio na busca de alternativas para atender a demanda de energia elétrica de forma sustentável e diminuir os efeitos dos Gases de Efeito Estufa. Uma maneira de minimizar estes efeitos e expandir o parque gerador é incrementar a produção com recurso a fontes renováveis. Mas para que, no momento de instalar um novo empreendimento, seja tomada uma decisão assertiva é necessário realizar a compilação de variáveis que sejam pertinentes ao tema e ao espaço geográfico. O objetivo deste artigo é apresentar uma modelagem conceitual por objetos (de acordo com o padrão OMT-G de forma a identificar áreas potenciais para gerar energia elétrica por fontes renováveis.

Modelagem do vento e da fotosfera de AG Carinae

Science.gov (United States)

Groh, J. H.; Damineli, A.

2003-08-01

A trajetória evolutiva das estrelas de alta massa depende fortemente de suas taxas de perda de massa. Apesar do rápido progresso no estudo destas estrelas, a taxa de perda de massa e outros parâmetros físicos básicos, como a temperatura superficial e a velocidade terminal do vento ainda não estão bem determinados. Isto ocorre devido à presença de ventos irregulares, rápidos e fortes ao redor destas estrelas, tornando a interpretação dos seus espectros uma tarefa difícil. Assim, a modelagem do vento e da fotosfera dessas estrelas está sendo cada vez mais usada para obter tais parâmetros a partir dos espectros. O aumento da taxa de perda de massa durante a fase LBV (Variáveis Luminosas Azuis), comparado com outros tipos de estrelas, tem sido atribuído a instabilidades do tipo S Doradus. Dispomos de uma base de dados espectroscópicos cobrindo 22 anos de observações de AG Carinae, incluindo um ciclo S Doradus completo, com espectros CCD em alta resolução na faixa óptica e infravermelha. Utilizamos o programa desenvolvido por Schmutz (1997) para uma análise preliminar desse ciclo, obtendo a taxa de perda de massa a partir da linha do Ha. Não existe uma correlação clara da taxa de perda de massa com mudanças da temperatura efetiva, do raio da estrela e do fluxo na banda V. A estrela atingiu seu mínimo fotométrico (raio mínimo) em 1990 e o máximo fotométrico (raio máximo) em 1995, enquanto que o fluxo máximo da linha do Ha ocorreu em 1996. Além disso a taxa de perda de massa não segue esse ciclo, contrariamente às idéias correntes. Para fazer um modelo mais realista estamos usando o programa CMFGEN (Hillier & Miller), que trata a fotosfera e o vento estelar de forma consistente, considerando a radiação fora do equilíbrio termodinâmico (NLTE) e com blanketting total de linhas. Simulamos o espectro de AG Carinae em duas épocas extremas do ciclo S Dor para testar os resultados obtidos com o modelo mais simplificado.

Family migration and employment: the importance of migration history and gender.

Science.gov (United States)

Bailey, A J; Cooke, T J

1998-01-01

"This article uses event history data to specify a model of employment returns to initial migration, onward migration, and return migration among newly married persons in the U.S. Husbands are more likely to be full-time employed than wives, and being a parent reduces the employment odds among married women. Employment returns to repeated migration differ by gender, with more husbands full-time employed after onward migration and more wives full-time employed after return migration events. We interpret these empirical findings in the context of family migration theory, segmented labor market theory, and gender-based responsibilities." Data are from the National Longitudinal Survey of Youth from 1979 to 1991. excerpt

A preference for migration

OpenAIRE

Stark, Oded

2007-01-01

At least to some extent migration behavior is the outcome of a preference for migration. The pattern of migration as an outcome of a preference for migration depends on two key factors: imitation technology and migration feasibility. We show that these factors jointly determine the outcome of a preference for migration and we provide examples that illustrate how the prevalence and transmission of a migration-forming preference yield distinct migration patterns. In particular, the imitation of...

Critérios de projeto e benefícios esperados da implantação de técnicas compensatórias em drenagem urbana para controle de escoamentos na fonte, com base em modelagem computacional aplicada a um estudo de caso na zona oeste do Rio de Janeiro

Directory of Open Access Journals (Sweden)

Anaí Floriano Vasconcelos

Full Text Available RESUMO O processo de urbanização resulta em alterações no ciclo hidrológico prejudiciais à população. Para amenizar esses efeitos, as técnicas compensatórias em drenagem urbana visam à maior sustentabilidade hidrológica na expansão urbana. Nesse sentido, este artigo teve como objetivos avaliar, por meio de modelagem computacional, o efeito da adoção dessas técnicas na escala de lote e da bacia hidrográfica e avançar com diferentes possibilidades de concepção de projeto. A modelagem foi realizada para diversos cenários, considerando a implantação das técnicas de forma isolada e combinada. Os parâmetros utilizados na modelagem visaram verificar possibilidades extremas de aplicação, de modo a disponibilizar dados para balizamento de projetos reais. As chuvas avaliadas possuem variadas durações e intensidades, facilitando a extrapolação dos resultados deste trabalho para bacias hidrográficas de diferentes escalas. Os resultados das simulações indicam potenciais benefícios na drenagem urbana oriundos do uso dessas técnicas no lote, com mais efetividade para as menores chuvas de projeto. Esse foi o caso dos cenários que avaliaram os jardins rebaixados isoladamente ou combinados em série com um reservatório de lote e os cenários de pavimentos permeáveis na calçada que receberiam o escoamento superficial do lote adjacente. Também foi verificado que a combinação paralela de um reservatório de lote com as dimensões propostas pela legislação municipal e um jardim rebaixado em 0,07 m seria capaz de neutralizar, hidrologicamente, os impactos da ocupação do lote para todas as chuvas de projeto analisadas, entretanto o reservatório proposto pela legislação municipal, quando adotado isoladamente, quase não atuou na escala da bacia..

Japanese migration in contemporary Japan: economic segmentation and interprefectural migration.

Science.gov (United States)

Fukurai, H

1991-01-01

This paper examines the economic segmentation model in explaining 1985-86 Japanese interregional migration. The analysis takes advantage of statistical graphic techniques to illustrate the following substantive issues of interregional migration: (1) to examine whether economic segmentation significantly influences Japanese regional migration and (2) to explain socioeconomic characteristics of prefectures for both in- and out-migration. Analytic techniques include a latent structural equation (LISREL) methodology and statistical residual mapping. The residual dispersion patterns, for instance, suggest the extent to which socioeconomic and geopolitical variables explain migration differences by showing unique clusters of unexplained residuals. The analysis further points out that extraneous factors such as high residential land values, significant commuting populations, and regional-specific cultures and traditions need to be incorporated in the economic segmentation model in order to assess the extent of the model's reliability in explaining the pattern of interprefectural migration.

Modelagem matemática e difusividade efetiva do processo de secagem do miolo da macambira

Directory of Open Access Journals (Sweden)

Julianne Viana Freire Portela

2014-06-01

Full Text Available A macambira (Bromelia laciniosa M. é uma bromélia com grande potencialidade agrícola, energética, mas escasso embasamento científico. Assim, este trabalho objetivou avaliar as condições operacionais para a secagem convectiva do miolo da macambira, a fim de gerar um produto seco viável do ponto de vista tecnológico e com possibilidade de aplicação na alimentação humana. A matéria-prima com espessura de 2,5mm e umidade média inicial de 87,20% foi disposta em bandejas no secador de bandejas, utilizando como variáveis do processo a temperatura do ar (43, 49 e 560C e a variável fixa velocidade do ar igual a 1,0m.s-1. Após a execução dos experimentos realizou-se o estudo da cinética de secagem e a modelagem matemática (Fick, Page e empírico de dois parâmetros das curvas experimentais como forma de definir a melhor condição de processo. O aumento da temperatura refletia no incremento dos valores de difusividade efetiva de água, sendo estes com ordem de grandeza de 10-10 m2.s-1 e, tendo o modelo empírico exponencial de dois parâmetros como o que melhor se ajustou aos dados experimentais A temperatura de 560C resultou em secagem mais rápida e mais eficiente com umidade final de 12,61%.

The Globalisation of migration

OpenAIRE

Milan Mesić

2002-01-01

The paper demonstrates that contemporary international migration is a constitutive part of the globalisation process. After defining the concepts of globalisation and the globalisation of migration, the author discusses six key themes, linking globalisation and international migration (“global cities”, the scale of migration; diversification of migration flows; globalisation of science and education; international migration and citizenship; emigrant communities and new identities). First, in ...

Migration and Remittances : Recent Developments and Outlook - Transit Migration

OpenAIRE

World Bank Group

2018-01-01

This Migration and Development Brief reports global trends in migration and remittance flows, as well as developments related to the Global Compact on Migration (GCM), and the Sustainable Development Goal (SDG) indicators for volume of remittances as percentage of gross domestic product (GDP) (SDG indicator 17.3.2), reducing remittance costs (SDG indicator 10.c.1) and recruitment costs (SD...

Numerical modeling of oil spill in the Patos Lagoon estuary; Modelagem numerica de derrames de oleo no estuario da Lagoa dos Patos

Energy Technology Data Exchange (ETDEWEB)

Martinho, Vivian; Monteiro, Igor Oliveira; Janeiro, Joao; Fernandes, Elisa Helena Leao [Fundacao Universidade do Rio Grande (FURG), RS (Brazil)

2008-07-01

Navigation is responsible for the input of 555.000 tons of oil per year in the marine environment. The recovery of the system can take dozens of years, affecting economical, ecological and social areas. The Patos Lagoon estuary presents wide importance and high susceptibility to accidents of oil spill. Therefore, the objective of this study is to analyze the spread of oil spills using the MOHID model, which simulates both the hydrodynamics of the estuary and the oil dispersion considering the different processes involved. Wind and water level data from May 1 to August 18, 1999 were used to simulate a hypothetic accident of involving 2000 m3 of oil MF 380 during the passage of a cold front considering high and low river discharges. Results indicate that the oil dispersion is governed by the estuarine dynamic, which is controlled by the wind action and river discharge. Thus, during southwest wind the oil is retained within the estuary, and in situations of northeast wind the oil tends to leave the estuary and sometimes can reach the inner shallow bays. (author)

Population, migration and urbanization.

Science.gov (United States)

1982-06-01

Despite recent estimates that natural increase is becoming a more important component of urban growth than rural urban transfer (excess of inmigrants over outmigrants), the share of migration in the total population growth has been consistently increasing in both developed and developing countries. From a demographic perspective, the migration process involves 3 elements: an area of origin which the mover leaves and where he or she is considered an outmigrant; the destination or place of inmigration; and the period over which migration is measured. The 2 basic types of migration are internal and international. Internal migration consists of rural to urban migration, urban to urban migration, rural to rural migration, and urban to rural migration. Among these 4 types of migration various patterns or processes are followed. Migration may be direct when the migrant moves directly from the village to the city and stays there permanently. It can be circular migration, meaning that the migrant moves to the city when it is not planting season and returns to the village when he is needed on the farm. In stage migration the migrant makes a series of moves, each to a city closer to the largest or fastest growing city. Temporary migration may be 1 time or cyclical. The most dominant pattern of internal migration is rural urban. The contribution of migration to urbanization is evident. For example, the rapid urbanization and increase in urban growth from 1960-70 in the Republic of Korea can be attributed to net migration. In Asia the largest component of the population movement consists of individuals and groups moving from 1 rural location to another. Recently, because urban centers could no longer absorb the growing number of migrants from other places, there has been increased interest in the urban to rural population redistribution. This reverse migration also has come about due to slower rates of employment growth in the urban centers and improved economic opportunities

Radon depth migration

International Nuclear Information System (INIS)

Hildebrand, S.T.; Carroll, R.J.

1993-01-01

A depth migration method is presented that used Radon-transformed common-source seismograms as input. It is shown that the Radon depth migration method can be extended to spatially varying velocity depth models by using asymptotic ray theory (ART) to construct wavefield continuation operators. These operators downward continue an incident receiver-array plane wave and an assumed point-source wavefield into the subsurface. The migration velocity model is constrain to have longer characteristic wavelengths than the dominant source wavelength such that the ART approximations for the continuation operators are valid. This method is used successfully to migrate two synthetic data examples: (1) a point diffractor, and (2) a dipping layer and syncline interface model. It is shown that the Radon migration method has a computational advantage over the standard Kirchhoff migration method in that fewer rays are computed in a main memory implementation

Theoretical foundations of international migration process studies: analysis of key migration theories development

Directory of Open Access Journals (Sweden)

Shymanska K.V.

2017-03-01

Full Text Available The need for transformation of Ukraine's migration policy based on globalized world development trends and in response to the challenges of European integration transformations causes the need of researching the theoretical and methodological basis of migration studies, and the regulations of existing theories of international migration. The bibliometric analysis of scientific publications on international migration in cites indexes found that the recent researches on these problems acquire interdisciplinary character. It necessitates the transformation of migration study approaches basing on economic, social, institutional theories and concepts synthesis. The article is devoted to the study of theoretical regulations of existing international migration theories in the context of the evolution of scientists’ views on this phenomenon. The author found that the existing theories of international migration should be divided into three categories (microeconomic, macroeconomic, globalizational that contributes to their understanding in the context of implementation possibilities in migrational public administration practice. It allows to determine the theories which should be used for Ukrainian state migration policy constructing and eliminating or reducing the external migration negative effects.

Migration and risk: net migration in marginal ecosystems and hazardous areas

International Nuclear Information System (INIS)

De Sherbinin, Alex; Levy, Marc; Adamo, Susana; MacManus, Kytt; Yetman, Greg; Mara, Valentina; Razafindrazay, Liana; Aichele, Cody; Pistolesi, Linda; Goodrich, Benjamin; Srebotnjak, Tanja

2012-01-01

The potential for altered ecosystems and extreme weather events in the context of climate change has raised questions concerning the role that migration plays in either increasing or reducing risks to society. Using modeled data on net migration over three decades from 1970 to 2000, we identify sensitive ecosystems and regions at high risk of climate hazards that have seen high levels of net in-migration and out-migration over the time period. This paper provides a literature review on migration related to ecosystems, briefly describes the methodology used to develop the estimates of net migration, then uses those data to describe the patterns of net migration for various ecosystems and high risk regions. The study finds that negative net migration generally occurs over large areas, reflecting its largely rural character, whereas areas of positive net migration are typically smaller, reflecting its largely urban character. The countries with largest population such as China and India tend to drive global results for all the ecosystems found in those countries. Results suggest that from 1970 to 2000, migrants in developing countries have tended to move out of marginal dryland and mountain ecosystems and out of drought-prone areas, and have moved towards coastal ecosystems and areas that are prone to floods and cyclones. For North America results are reversed for dryland and mountain ecosystems, which saw large net influxes of population in the period of record. Uncertainties and potential sources of error in these estimates are addressed. (letter)

Neuronal Migration and Neuronal Migration Disorder in Cerebral Cortex

OpenAIRE

SUN, Xue-Zhi; TAKAHASHI, Sentaro; GUI, Chun; ZHANG, Rui; KOGA, Kazuo; NOUYE, Minoru; MURATA, Yoshiharu

2002-01-01

Neuronal cell migration is one of the most significant features during cortical development. After final mitosis, neurons migrate from the ventricular zone into the cortical plate, and then establish neuronal lamina and settle onto the outermost layer, forming an "inside-out" gradient of maturation. Neuronal migration is guided by radial glial fibers and also needs proper receptors, ligands, and other unknown extracellular factors, requests local signaling (e.g. some emitted by the Cajal-Retz...

Japanese Migration and the Americas: An Introduction to the Study of Migration.

Science.gov (United States)

Mukai, Gary; Brunette, Rachel

This curriculum module introduces students to the study of migration, including a brief overview of some categories of migration and reasons why people migrate. As a case study, the module uses the Japanese migration experience in the United States, Peru, Brazil, Canada, Mexico, Argentina, Bolivia, and Paraguay. The module introduces students to…

[Internal migration studies].

Science.gov (United States)

Stpiczynski, T

1986-10-01

Recent research on internal migration in Poland is reviewed. The basic sources of data, consisting of censuses or surveys, are first described. The author discusses the relationship between migration studies and other sectors of the national economy, and particularly the relationship between migration and income.

The apparent and effective chloride migration coefficients obtained in migration tests

NARCIS (Netherlands)

Spiesz, P.R.; Brouwers, H.J.H.

2013-01-01

The apparent (Dapp) and effective (Deff) migration coefficients obtained in chloride migration tests are investigated in this study. The presented Dapp profiles in concrete show that the apparent migration coefficient is strongly concentration-dependent. As demonstrated, the binding of chlorides is

Modelagem e análise de serviços de saúde baseados em Redes de Petri interpretadas

Directory of Open Access Journals (Sweden)

Marisa Mitie Miyagi

2001-12-01

Full Text Available Este trabalho introduz as Redes de Petri para modelagem e análise de sistemas de saúde que além da complexidade de suas atividades, envolve na sua concepção, implementação, operação e tomada de decisões, vários e diferentes profissionais. Os modelos são desenvolvidos em PFS (Production Flow Schema e MFG (Mark Flow Graph que são interpretações de redes de Petri, explicitando os recursos envolvidos e o fluxo de itens (pessoas, equipamentos, informações. Os serviços do Ambulatório do Hospital das Clínicas da Universidade de São Paulo são utilizados como estudo de caso para comprovar as vantagens da presente proposta.This paper introduces the Petri net for modelling and analysis of health systems where beyond the complexity of they activities, involves in its conception, implementation, operation and decision making several and differents professionals. The models are developed in PFS (Production Flow Schema and MFC (Mark Flow Graph that are interpretations of Peri nets aiming the explicit identification of resources and flow of itens (material and information. The services of the ambulatory of Clinic Hospital of University of São Paulo is considered in a case study to confirm the advantages of the proposal.

Reinventing US Internal Migration Studies in the Age of International Migration.

Science.gov (United States)

Ellis, Mark

2012-03-01

I argue that researchers have sidelined attention to issues raised by US internal migration as they shifted focus to the questions posed by the post-1960s rise in US immigration. In this paper, I offer some reasons about why immigration has garnered more attention and why there needs to be greater consideration of US internal migration and its significant and myriad social, economic, political, and cultural impacts. I offer three ideas for motivating more research into US internal geographic mobility that would foreground its empirical and conceptual connections to international migration. First, there should be more work on linked migration systems investigating the connections between internal and international flows. Second, the questions asked about immigrant social, cultural, and economic impacts and adaptations in host societies should also be asked about internal migrants. Third, and more generally, migration researchers should jettison the assumption that the national scale is the pre-eminent delimiter of migration types and processes. Some groups can move easily across borders; others are constrained in their moves within countries. These subnational scales and constraints will become more visible if migration research decentres the national from its theory and empirics.

MANAGING MIGRATION: TURKISH PERSPECTIVE

Directory of Open Access Journals (Sweden)

İhsan GÜLAY

2018-04-01

Full Text Available Conducting migration studies is of vital importance to Turkey, a country which has been experiencing migration throughout history due to its “open doors policy”. The objective of this study is to evaluate the strategic management of migration in Turkey in order to deal with the issue of migration. The main focus of the study is Syrian migrants who sought refuge in Turkey due to the civil war that broke out in their country in April 2011. This study demonstrates the policies and processes followed by Turkey for Syrian migration flow in terms of the social acceptance and harmonisation of the migrants within a democratic environment. The study addresses some statistical facts and issues related to Syrian migration as it has become an integral part of daily life in Turkey. The study also reviews how human rights are protected in the migration process. The study will provide insights for developing sound strategic management policies for the migration issue.

Migration chemistry

International Nuclear Information System (INIS)

Carlsen, L.

1992-05-01

Migration chemistry, the influence of chemical -, biochemical - and physico-chemical reactions on the migration behaviour of pollutants in the environment, is an interplay between the actual natur of the pollutant and the characteristics of the environment, such as pH, redox conditions and organic matter content. The wide selection of possible pollutants in combination with varying geological media, as well as the operation of different chemical -, biochemical - and physico-chemical reactions compleactes the prediction of the influence of these processes on the mobility of pollutants. The report summarizes a wide range of potential pollutants in the terrestrial environment as well as a variety of chemical -, biochemical - and physico-chemical reactions, which can be expected to influence the migration behaviour, comprising diffusion, dispersion, convection, sorption/desorption, precipitation/dissolution, transformations/degradations, biochemical reactions and complex formation. The latter comprises the complexation of metal ions as well as non-polar organics to naturally occurring organic macromolecules. The influence of the single types of processes on the migration process is elucidated based on theoretical studies. The influence of chemical -, biochemical - and physico-chemical reactions on the migration behaviour is unambiguous, as the processes apparently control the transport of pollutants in the terrestrial environment. As the simple, conventional K D concept breaks down, it is suggested that the migration process should be described in terms of the alternative concepts chemical dispersion, average-elution-time and effective retention. (AB) (134 refs.)

Countering inbreeding with migration 1. Migration from unrelated ...

African Journals Online (AJOL)

Ret:ieved 6 Octoher 1991; ut:cepted I8 Mur- 1995. The eff'ect of migration on inbreeding is moclelled fbr small populations with immigrants from a large unrelated population. Different migration rates and numbers fbr the two sexes are assumed, and a general recursion equation for inbreeding progress derived, which can ...

The Globalisation of migration

Directory of Open Access Journals (Sweden)

Milan Mesić

2002-04-01

Full Text Available The paper demonstrates that contemporary international migration is a constitutive part of the globalisation process. After defining the concepts of globalisation and the globalisation of migration, the author discusses six key themes, linking globalisation and international migration (“global cities”, the scale of migration; diversification of migration flows; globalisation of science and education; international migration and citizenship; emigrant communities and new identities. First, in accordance with Saskia Sassen’s analysis, the author rejects the wide-spread notion that unqualified migrants have lost an (important role in »global cities«, i.e. in the centres of the new (global economy. Namely, the post-modern service sector cannot function without the support of a wide range of auxiliary unqualified workers. Second, a critical comparison with traditional overseas mass migration to the USA at the turn of the 19th and 20th centuries indicates that present international migration is, perhaps, less extensive – however it is important to take into consideration various limitations that previously did not exist, and thus the present migration potential is in really greater. Third, globalisation is more evident in a diversification of the forms of migration: the source area of migrants to the New World and Europe has expanded to include new regions in the world; new immigration areas have arisen (the Middle East, new industrial countries of the Far East, South Europe; intra-regional migration has intensified. Forth, globalisation is linked to an increased migration of experts and the pessimistic notion of a brain drain has been replaced by the optimistic idea of a brain gain. Fifth, contemporary international migration has been associated with a crisis of the national model of citizenship. Sixth, the interlinking of (migrant cultural communities regardless of distance and the physical proximity of cultural centres (the

Migration and AIDS.

Science.gov (United States)

1998-01-01

This article presents the perspectives of UNAIDS and the International Organization for Migration (IOM) on migration and HIV/AIDS. It identifies research and action priorities and policy issues, and describes the current situation in major regions of the world. Migration is a process. Movement is enhanced by air transport, rising international trade, deregulation of trade practices, and opening of borders. Movements are restricted by laws and statutes. Denial to freely circulate and obtain asylum is associated with vulnerability to HIV infections. A UNAIDS policy paper in 1997 and IOM policy guidelines in 1988 affirm that refugees and asylum seekers should not be targeted for special measures due to HIV/AIDS. There is an urgent need to provide primary health services for migrants, voluntary counseling and testing, and more favorable conditions. Research is needed on the role of migration in the spread of HIV, the extent of migration, availability of health services, and options for HIV prevention. Research must be action-oriented and focused on vulnerability to HIV and risk taking behavior. There is substantial mobility in West and Central Africa, economic migration in South Africa, and nonvoluntary migration in Angola. Sex workers in southeast Asia contribute to the spread. The breakup of the USSR led to population shifts. Migrants in Central America and Mexico move north to the US where HIV prevalence is higher.

The role of migration-specific and migration-relevant policies in migrant decision-making in transit

NARCIS (Netherlands)

Kuschminder - de Guerre, Katie; Koser, Khalid

2017-01-01

This paper examines the role of migration-specific and migration-relevant policies in migrant decision-making factors for onwards migration or stay in Greece and Turkey. In this paper we distinguish migration-specific policies from migration-relevant policies in transit and destination countries,

Contribuição à obtenção do módulo de elasticidade do concreto utilizando modelagem micromecânica

Directory of Open Access Journals (Sweden)

A. H. Barbosa

Full Text Available Expressões presentes nas normas nacionais e internacionais relacionam o módulo de elasticidade do concreto com a resistência à compressão. O concreto, considerado como material compósito trifásico, tem suas propriedades elásticas diretamente influenciadas pela zona de transição (ITZ, a qual é caracterizada por sua maior porosidade em relação à pasta de cimento. Modelos de micromecânica como os de Mori-Tanaka e esfera de três fases podem ser aplicados com bons resultados quando utilizados para a análise do concreto. Este trabalho apresenta um estudo sobre o comportamento evolutivo do módulo de elasticidade do concreto, tal estudo é feito mediante a aplicação das expressões normativas e de modelos de micromecânica. Comparado-se com os valores experimentais produzidos percebe-se uma boa concordância quando a modelagem micromecânica leva em conta a ITZ. Também é confirmada a qualidade das expressões da NBR 6118:2003 e do CEB-90.

Partial diel migration: A facultative migration underpinned by long-term inter-individual variation.

Science.gov (United States)

Harrison, Philip M; Gutowsky, Lee F G; Martins, Eduardo G; Patterson, David A; Cooke, Steven J; Power, Michael

2017-09-01

The variations in migration that comprise partial diel migrations, putatively occur entirely as a consequence of behavioural flexibility. However, seasonal partial migrations are increasingly recognised to be mediated by a combination of reversible plasticity in response to environmental variation and individual variation due to genetic and environmental effects. Here, we test the hypothesis that while partial diel migration heterogeneity occurs primarily due to short-term within-individual flexibility in behaviour, long-term individual differences in migratory behaviour also underpin this migration variation. Specifically, we use a hierarchical behavioural reaction norm approach to partition within- and among-individual variation in depth use and diel plasticity in depth use, across short- and long-term time-scales, in a group of 47 burbot (Lota lota) tagged with depth-sensing acoustic telemetry transmitters. We found that within-individual variation at the among-dates-within-seasons and among-seasons scale, explained the dominant proportion of phenotypic variation. However, individuals also repeatedly differed in their expression of migration behaviour over the 2 year study duration. These results reveal that diel migration variation occurs primarily due to short-term within-individual flexibility in depth use and diel migration behaviour. However, repeatable individual differences also played a key role in mediating partial diel migration. These findings represent a significant advancement of our understanding of the mechanisms generating the important, yet poorly understood phenomena of partial diel migration. Moreover, given the pervasive occurrence of diel migrations across aquatic taxa, these findings indicate that individual differences have an important, yet previously unacknowledged role in structuring the temporal and vertical dynamics of aquatic ecosystems. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

Influences of environmental cues, migration history and habitat familiarity on partial migration

DEFF Research Database (Denmark)

Skov, Christian; Aarestrup, Kim; Baktoft, Henrik

2010-01-01

The factors that drive partial migration in organisms are not fully understood. Roach (Rutilus rutilus), a freshwater fish, engage in partial migration where parts of populations switch between summer habitats in lakes and winter habitats in connected streams. To test if the partial migration trait...

Conservation physiology of animal migration

Science.gov (United States)

Lennox, Robert J.; Chapman, Jacqueline M.; Souliere, Christopher M.; Tudorache, Christian; Wikelski, Martin; Metcalfe, Julian D.; Cooke, Steven J.

2016-01-01

Migration is a widespread phenomenon among many taxa. This complex behaviour enables animals to exploit many temporally productive and spatially discrete habitats to accrue various fitness benefits (e.g. growth, reproduction, predator avoidance). Human activities and global environmental change represent potential threats to migrating animals (from individuals to species), and research is underway to understand mechanisms that control migration and how migration responds to modern challenges. Focusing on behavioural and physiological aspects of migration can help to provide better understanding, management and conservation of migratory populations. Here, we highlight different physiological, behavioural and biomechanical aspects of animal migration that will help us to understand how migratory animals interact with current and future anthropogenic threats. We are in the early stages of a changing planet, and our understanding of how physiology is linked to the persistence of migratory animals is still developing; therefore, we regard the following questions as being central to the conservation physiology of animal migrations. Will climate change influence the energetic costs of migration? Will shifting temperatures change the annual clocks of migrating animals? Will anthropogenic influences have an effect on orientation during migration? Will increased anthropogenic alteration of migration stopover sites/migration corridors affect the stress physiology of migrating animals? Can physiological knowledge be used to identify strategies for facilitating the movement of animals? Our synthesis reveals that given the inherent challenges of migration, additional stressors derived from altered environments (e.g. climate change, physical habitat alteration, light pollution) or interaction with human infrastructure (e.g. wind or hydrokinetic turbines, dams) or activities (e.g. fisheries) could lead to long-term changes to migratory phenotypes. However, uncertainty remains

Recovery Migration After Hurricanes Katrina and Rita: Spatial Concentration and Intensification in the Migration System.

Science.gov (United States)

Curtis, Katherine J; Fussell, Elizabeth; DeWaard, Jack

2015-08-01

Changes in the human migration systems of the Gulf of Mexico coastline counties affected by Hurricanes Katrina and Rita provide an example of how climate change may affect coastal populations. Crude climate change models predict a mass migration of "climate refugees," but an emerging literature on environmental migration suggests that most migration will be short-distance and short-duration within existing migration systems, with implications for the population recovery of disaster-stricken places. In this research, we derive a series of hypotheses on recovery migration predicting how the migration system of hurricane-affected coastline counties in the Gulf of Mexico was likely to have changed between the pre-disaster and the recovery periods. We test these hypotheses using data from the Internal Revenue Service on annual county-level migration flows, comparing the recovery period migration system (2007-2009) with the pre-disaster period (1999-2004). By observing county-to-county ties and flows, we find that recovery migration was strong: the migration system of the disaster-affected coastline counties became more spatially concentrated, while flows within it intensified and became more urbanized. Our analysis demonstrates how migration systems are likely to be affected by the more intense and frequent storms anticipated by climate change scenarios, with implications for the population recovery of disaster-affected places.

Migration of cesium-137 through sandy soil layer effect of fine silt on migration

International Nuclear Information System (INIS)

Ohnuki, Toshihiko; Wadachi, Yoshiki

1983-01-01

The migration of 137 Cs through sandy soil layer was studied with consideration of the migration of fine silt by column method. It was found that a portion of fine silt migrated through the soil layer accompanying with 137 Cs. The mathematical migration model of 137 Cs involved the migration of fine silt through such soil layer was presented. This model gave a good accordance between calculated concentration distribution curve in sandy soil layer and effluent curve and observed those. So, this model seems to be advanced one for evaluating migration of 137 Cs in sandy soil layer with silt. (author)

Modelagem da eletro-oxidação de etanol sobre catalisador PtSn/C aplicada a células a combustível de etanol direto do tipo membrana trocadora de prótons (DEPEMFC)

OpenAIRE

Piña, Renzo Fabricio Figueroa

2014-01-01

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Mecânica, Florianópolis, 2014 Neste trabalho desenvolve-se a modelagem da reação eletroquímica de oxidação de etanol em células a combustível de etanol direto tipo PEM (DEPEMFC). O modelo da célula DEPEMFC considera a cinética de eletro-oxidação de etanol, o transporte de massa e a resistência elétrica dos diversos materiais que formam a célula a combustível. A reação elet...

South-South Migration and Remittances

OpenAIRE

Ratha, Dilip; Shaw, William

2007-01-01

South-South Migration and Remittances reports on preliminary results from an ongoing effort to improve data on bilateral migration stocks. It sets out some working hypotheses on the determinants and socioeconomic implications of South-South migration. Contrary to popular perception that migration is mostly a South-North phenomenon, South-South migration is large. Available data from nation...

Prestack depth migration

International Nuclear Information System (INIS)

Postma, R.W.

1991-01-01

Two lines form the southern North Sea, with known velocity inhomogeneities in the overburden, have been pre-stack depth migrated. The pre-stack depth migrations are compared with conventional processing, one with severe distortions and one with subtle distortions on the conventionally processed sections. The line with subtle distortions is also compared with post-stack depth migration. The results on both lines were very successful. Both have already influenced drilling decisions, and have caused a modification of structural interpretation in the respective areas. Wells have been drilled on each of the lines, and well tops confirm the results. In fact, conventional processing led to incorrect locations for the wells, both of which were dry holes. The depth migrated sections indicate the incorrect placement, and on one line reveals a much better drilling location. This paper reports that even though processing costs are high for pre-stack depth migration, appropriate use can save millions of dollars in dry-hole expense

Indonesia's migration transition.

Science.gov (United States)

Hugo, G

1995-01-01

This article describes population movements in Indonesia in the context of rapid and marked social and economic change. Foreign investment in Indonesia is increasing, and global mass media is available to many households. Agriculture is being commercialized, and structural shifts are occurring in the economy. Educational levels are increasing, and women's role and status are shifting. Population migration has increased over the decades, both short and long distance, permanent and temporary, legal and illegal, and migration to and between urban areas. This article focuses specifically on rural-to-urban migration and international migration. Population settlements are dense in the agriculturally rich inner areas of Java, Bali, and Madura. Although the rate of growth of the gross domestic product was 6.8% annually during 1969-94, the World Bank ranked Indonesia as a low-income economy in 1992 because of the large population size. Income per capita is US $670. Indonesia is becoming a large exporter of labor to the Middle East, particularly women. The predominance of women as overseas contract workers is changing women's role and status in the family and is controversial due to the cases of mistreatment. Malaysia's high economic growth rate of over 8% per year means an additional 1.3 million foreign workers and technicians are needed. During the 1980s urban growth increased at a very rapid rate. Urban growth tended to occur along corridors and major transportation routes around urban areas. It is posited that most of the urban growth is due to rural-to-urban migration. Data limitations prevent an exact determination of the extent of rural-to-urban migration. More women are estimated to be involved in movements to cities during the 1980s compared to the 1970s. Recruiters and middlemen have played an important role in rural-to-urban migration and international migration.

Recovery Migration after Hurricanes Katrina and Rita: Spatial Concentration and Intensification in the Migration System

Science.gov (United States)

Fussell, Elizabeth; DeWaard, Jack

2015-01-01

Changes in the human migration systems of Hurricane Katrina- and Rita-affected Gulf of Mexico coastline counties provide an example of how climate change may affect coastal populations. Crude climate change models predict a mass migration of “climate refugees,” but an emerging literature on environmental migration suggests most migration will be short-distance and short-duration within existing migration systems, with implications for the population recovery of disaster-struck places. In this research, we derive a series of hypotheses on recovery migration predicting how the migration system of hurricane-affected coastline counties in the Gulf of Mexico was likely to have changed between the pre-disaster and the recovery periods. We test these hypotheses using data from the Internal Revenue Service on annual county-level migration flows, comparing the recovery period migration system (2007–2009) to the pre-disaster period (1999–2004). By observing county-to-county ties and flows we find that recovery migration was strong, as the migration system of the disaster-affected coastline counties became more spatially concentrated while flows within it intensified and became more urbanized. Our analysis demonstrates how migration systems are likely to be affected by the more intense and frequent storms anticipated by climate change scenarios with implications for the population recovery of disaster-affected places. PMID:26084982

[Migration and urbanization in the Sahel. Consequences of the Sahelian migrations].

Science.gov (United States)

Traore, S

1997-10-01

The consequences of Sahelian migration are multiple and diverse. In rural areas there may be a loss of income in the short run and a reduced possibility of development in the long run. Apart from its implications for urban growth, Sahelian migration may have four series of consequences in the places of origin. In detaching peasants from their lands, migration may contribute to loss of appreciation and reverence for the lands. Attachment to the lands of the ancestors loses its meaning as soon as questions of survival or economic rationality are raised. Migration contributes to the restructuring of the societies of origin. Increasing monetarization of market relations and introduction of new needs create new norms that favor stronger integration into the world economy. Migration may cause a decline in production because of the loss of the most active population, and it changes the age and sex distribution of households and usually increases their dependency burden. The effects on fertility and mortality are less clear. The effects of migration on the zones of arrival in the Sahel depend on the type of area. Conflicts between natives and in-migrants are common in rural-rural migration. Degradation of land may result from the increased demands placed upon it. Migrants to cities in Africa, and especially in the Sahel, appear to conserve their cultural values and to transplant and reinterpret their village rules of solidarity.

Stereotactic core needle breast biopsy marker migration: An analysis of factors contributing to immediate marker migration.

Science.gov (United States)

Jain, Ashali; Khalid, Maria; Qureshi, Muhammad M; Georgian-Smith, Dianne; Kaplan, Jonah A; Buch, Karen; Grinstaff, Mark W; Hirsch, Ariel E; Hines, Neely L; Anderson, Stephan W; Gallagher, Katherine M; Bates, David D B; Bloch, B Nicolas

2017-11-01

To evaluate breast biopsy marker migration in stereotactic core needle biopsy procedures and identify contributing factors. This retrospective study analyzed 268 stereotactic biopsy markers placed in 263 consecutive patients undergoing stereotactic biopsies using 9G vacuum-assisted devices from August 2010-July 2013. Mammograms were reviewed and factors contributing to marker migration were evaluated. Basic descriptive statistics were calculated and comparisons were performed based on radiographically-confirmed marker migration. Of the 268 placed stereotactic biopsy markers, 35 (13.1%) migrated ≥1 cm from their biopsy cavity. Range: 1-6 cm; mean (± SD): 2.35 ± 1.22 cm. Of the 35 migrated biopsy markers, 9 (25.7%) migrated ≥3.5 cm. Patient age, biopsy pathology, number of cores, and left versus right breast were not associated with migration status (P> 0.10). Global fatty breast density (P= 0.025) and biopsy in the inner region of breast (P = 0.031) were associated with marker migration. Superior biopsy approach (P= 0.025), locally heterogeneous breast density, and t-shaped biopsy markers (P= 0.035) were significant for no marker migration. Multiple factors were found to influence marker migration. An overall migration rate of 13% supports endeavors of research groups actively developing new biopsy marker designs for improved resistance to migration. • Breast biopsy marker migration is documented in 13% of 268 procedures. • Marker migration is affected by physical, biological, and pathological factors. • Breast density, marker shape, needle approach etc. affect migration. • Study demonstrates marker migration prevalence; marker design improvements are needed.

Return migration as failure or success? : The determinants of return migration intentions among Moroccan migrants in Europe

NARCIS (Netherlands)

de Haas, H.; Fokkema, T.; Fihri, M.F.

2015-01-01

Different migration theories generate competing hypotheses with regard to determinants of return migration. While neoclassical migration theory associates migration to the failure to integrate at the destination, the new economics of labour migration sees return migration as the logical stage after

Migration and revolution

Directory of Open Access Journals (Sweden)

Nando Sigona

2012-06-01

Full Text Available The Arab Spring has not radically transformed migration patterns in the Mediterranean, and the label ‘migration crisis’ does not do justice to the composite and stratified reality.

Migration = cloning; aliasiing

DEFF Research Database (Denmark)

Hüttel, Hans; Kleist, Josva; Nestmann, Uwe

1999-01-01

In Obliq, a lexically scoped, distributed, object-oriented programming language, object migration was suggested as the creation of a copy of an object’s state at the target site, followed by turning the object itself into an alias, also called surrogate, for the remote copy. We consider the creat......In Obliq, a lexically scoped, distributed, object-oriented programming language, object migration was suggested as the creation of a copy of an object’s state at the target site, followed by turning the object itself into an alias, also called surrogate, for the remote copy. We consider...... the creation of object surrogates as an abstraction of the abovementioned style of migration. We introduce Øjeblik, a distribution-free subset of Obliq, and provide three different configuration-style semantics, which only differ in the respective aliasing model. We show that two of the semantics, one of which...... matches Obliq’s implementation, render migration unsafe, while our new proposal for a third semantics is provably safe. Our work suggests a straightforward repair of Obliq’s aliasing model such that it allows programs to safely migrate objects....

SiMA: A simplified migration assay for analyzing neutrophil migration.

Science.gov (United States)

Weckmann, Markus; Becker, Tim; Nissen, Gyde; Pech, Martin; Kopp, Matthias V

2017-07-01

In lung inflammation, neutrophils are the first leukocytes migrating to an inflammatory site, eliminating pathogens by multiple mechanisms. The term "migration" describes several stages of neutrophil movement to reach the site of inflammation, of which the passage of the interstitium and basal membrane of the airway are necessary to reach the site of bronchial inflammation. Currently, several methods exist (e.g., Boyden Chamber, under-agarose assay, or microfluidic systems) to assess neutrophil mobility. However, these methods do not allow for parameterization on single cell level, that is, the individual neutrophil pathway analysis is still considered challenging. This study sought to develop a simplified yet flexible method to monitor and quantify neutrophil chemotaxis by utilizing commercially available tissue culture hardware, simple video microscopic equipment and highly standardized tracking. A chemotaxis 3D µ-slide (IBIDI) was used with different chemoattractants [interleukin-8 (IL-8), fMLP, and Leukotriene B4 (LTB 4 )] to attract neutrophils in different matrices like Fibronectin (FN) or human placental matrix. Migration was recorded for 60 min using phase contrast microscopy with an EVOS ® FL Cell Imaging System. The images were normalized and texture based image segmentation was used to generate neutrophil trajectories. Based on these spatio-temporal information a comprehensive parameter set is extracted from each time series describing the neutrophils motility, including velocity and directness and neutrophil chemotaxis. To characterize the latter one, a sector analysis was employed enabling the quantification of the neutrophils response to the chemoattractant. Using this hard- and software framework we were able to identify typical migration profiles of the chemoattractants IL-8, fMLP, and LTB 4 , the effect of the matrices FN versus HEM as well as the response to different medications (Prednisolone). Additionally, a comparison of four asthmatic and

Usando splines cúbicas na modelagem matemática da evolução populacional de Pirapora/MG

Directory of Open Access Journals (Sweden)

José Sérgio Domingues

2014-08-01

Full Text Available O objetivo desse trabalho é obter um modelo matemático para a evolução populacional da cidade de Pirapora/MG, baseando-se apenas nos dados de censos e contagens populacionais do Instituto Brasileiro de Geografia e Estatística (IBGE. Para isso, é utilizada a interpolação por splines cúbicas, pois as técnicas de interpolação linear e polinomial, e também o modelo logístico, não se ajustam bem a essa população. Os dados analisados não são equidistantes, então, utiliza-se como amostra anos separados com passo h de 10 anos. Os valores descartados inicialmente e as estimativas populacionais para esse município, descritos pela Fundação João Pinheiro, serviram para validação do modelo construído, e para a estimativa das diferenças percentuais de previsão, que não ultrapassaram os 2,21%. Ao se considerar que o padrão de evolução populacional de 2000 a 2010 se manterá até 2020, estima-se as populações da cidade de 2011 a 2020, cuja diferença percentual média foi de apenas 0,49%. Conclui-se que o modelo se ajusta muito bem aos dados, e que estimativas populacionais em qualquer ano de 1970 e 2020 são confiáveis. Além disso, o modelo permite a visualização prática de uma aplicação dessa técnica na modelagem populacional, e, portanto, também pode ser utilizada para fins didáticos.Palavras-chave: Splines cúbicas. Interpolação. Modelagem matemática. Evolução populacional. Pirapora.Using cubic splines on mathematical modeling of the population evolution of Pirapora/MGThe main objective of this paper is to obtain a mathematical model for the evolution of the population in Pirapora/MG, based only on data from censuses and population counts from Brazilian Institute of Geography and Statistics (IBGE. For this, the cubic spline interpolation is used because the technique of linear and polynomial interpolation, and also the logistic model do not fit well with this population. The analyzed data are not equidistant

Migration into art

DEFF Research Database (Denmark)

Petersen, Anne Ring

This book addresses a topic of increasing importance to artists, art historians and scholars of cultural studies, migration studies and international relations: migration as a profoundly transforming force that has remodelled artistic and art institutional practices across the world. It explores...... contemporary art's critical engagement with migration and globalisation as a key source for improving our understanding of how these processes transform identities, cultures, institutions and geopolitics. The author explores three interwoven issues of enduring interest: identity and belonging, institutional...

What's driving migration?

Science.gov (United States)

Kane, H

1995-01-01

During the 1990s investment in prevention of international or internal migration declined, and crisis intervention increased. The budgets of the UN High Commissioner for Refugees and the UN Development Program remained about the same. The operating assumption is that war, persecution, famine, and environmental and social disintegration are inevitable. Future efforts should be directed to stabilizing populations through investment in sanitation, public health, preventive medicine, land tenure, environmental protection, and literacy. Forces pushing migration are likely to increase in the future. Forces include depletion of natural resources, income disparities, population pressure, and political disruption. The causes of migration are not constant. In the past, migration occurred during conquests, settlement, intermarriage, or religious conversion and was a collective movement. Current migration involves mass movement of individuals and the struggle to survive. There is new pressure to leave poor squatter settlements and the scarcities in land, water, and food. The slave trade between the 1500s and the 1800s linked continents, and only 2-3 million voluntarily crossed national borders. Involuntary migration began in the early 1800s when European feudal systems were in a decline, and people sought freedom. Official refugees, who satisfy the strict 1951 UN definition, increased from 15 million in 1980 to 23 million in 1990 but remained a small proportion of international migrants. Much of the mass movement occurs between developing countries. Migration to developed countries is accompanied by growing intolerance, which is misinformed. China practices a form of "population transfer" in Tibet in order to dilute Tibetan nationalism. Colonization of countries is a new less expensive form of control over territory. Eviction of minorities is another popular strategy in Iraq. Public works projects supported by foreign aid displace millions annually. War and civil conflicts

Parametrização do transporte dispersivo de solutos em solos estruturados: heterogeneidade do meio, percurso de transporte e modelagem

Directory of Open Access Journals (Sweden)

S. L. Schlindwein

1998-06-01

Full Text Available O transporte dispersivo de solutos no solo é parametrizado por meio de equações difusivas e de modelos que partem da existência de uma relação de causalidade entre as características físicas do meio poroso, da sua condição de umidade e da manifestação macroscópica do processo nele ocorrente. A validade dessa proposição, como critério na elaboração de modelos dos processos que governam o transporte de solutos no solo, é discutida heuristicamente. Com base em índices obtidos a partir de uma análise de momentos de curvas de avanço (BTCs, é possível avaliar objetivamente o vínculo que as características do sistema estabelecem com o atendimento do pressuposto do equilíbrio local e, assim, com o sucesso ou não da adoção de uma abordagem de modelagem. Assim, BTCs assimétricas nada mais são do que a manifestação macroscópica de um processo incompleto, e o alcance de uma distribuição simétrica da concentração de solutos só pode ser garantido com a adoção de um "comprimento mínimo de mistura".

MODELAGEM DE MISTURAS NA FABRICAÇÃO DE COMPÓSITOS POLÍMERO-FIBRA, UTILIZANDO POLIETILENO E SERRAGEM DE Pinus sp.

Directory of Open Access Journals (Sweden)

Karla Pocai

2006-07-01

Full Text Available Neste trabalho, foi estudado o efeito da composição de diferentes misturas de polietileno de alta densidade (HDPE virgem, HDPE reciclado e serragem de Pinus sp., nas propriedades físico-mecânicas de placas confeccionadas pelo processo de compressão. As misturas foram homogeneizadas em um misturador tipo Drais, sem controle de temperatura e moldadas por compressão em prensa hidráulica a 150oC. Partindo das placas, foram confeccionados corpos-de-prova para ensaios de tração, flexão, impacto e dureza, segundo normas ASTM, e também foram determinadas as densidades médias das placas. A modelagem estatística foi realizada segundo o planejamento centróide simplex, utilizando sete misturas dos três componentes e três repetições de cada mistura. Os resultados mostraram que a resistência à tração, a resistência à flexão, a dureza e a densidade das placas, são explicadas pelo modelo linear, enquanto a resistência ao impacto é explicada pelo modelo quadrático. Não houve diferença significativa nas propriedades físico-mecânicas dos compósitos confeccionados com HDPE virgem, daqueles confeccionados com HDPE reciclado, exceto para resistência ao impacto, no qual o HDPE virgem apresentou maiores valores.

Recovery Migration to the City of New Orleans after Hurricane Katrina: A Migration Systems Approach.

Science.gov (United States)

Fussell, Elizabeth; Curtis, Katherine J; Dewaard, Jack

2014-03-01

Hurricane Katrina's effect on the population of the City of New Orleans provides a model of how severe weather events, which are likely to increase in frequency and strength as the climate warms, might affect other large coastal cities. Our research focuses on changes in the migration system - defined as the system of ties between Orleans Parish and all other U.S. counties - between the pre-disaster (1999-2004) and recovery (2007-2009) periods. Using Internal Revenue Service county-to-county migration flow data, we find that in the recovery period Orleans Parish increased the number of migration ties with and received larger migration flows from nearby counties in the Gulf of Mexico coastal region, thereby spatially concentrating and intensifying the in-migration dimension of this predominantly urban system, while the out-migration dimension contracted and had smaller flows. We interpret these changes as the migration system relying on its strongest ties to nearby and less damaged counties to generate recovery in-migration.

Regional Redistribution and Migration

DEFF Research Database (Denmark)

Manasse, Paolo; Schultz, Christian

We study a model with free migration between a rich and a poor region. Since there is congestion, the rich region has an incentive to give the poor region a transfer in order to reduce immigration. Faced with free migration, the rich region voluntarily chooses a transfer, which turns out...... to be equal to that a social planner would choose. Provided migration occurs in equilibrium, this conclusion holds even in the presence of moderate mobility costs. However, large migration costs will lead to suboptimal transfers in the market solution...

Malaysia and forced migration

Directory of Open Access Journals (Sweden)

Arzura Idris

2012-06-01

Full Text Available This paper analyzes the phenomenon of “forced migration” in Malaysia. It examines the nature of forced migration, the challenges faced by Malaysia, the policy responses and their impact on the country and upon the forced migrants. It considers forced migration as an event hosting multifaceted issues related and relevant to forced migrants and suggests that Malaysia has been preoccupied with the issue of forced migration movements. This is largely seen in various responses invoked from Malaysia due to “south-south forced migration movements.” These responses are, however, inadequate in terms of commitment to the international refugee regime. While Malaysia did respond to economic and migration challenges, the paper asserts that such efforts are futile if she ignores issues critical to forced migrants.

Synthetic seismic monitoring using reverse-time migration and Kirchhoff migration for CO2 sequestration in Korea

Science.gov (United States)

Kim, W.; Kim, Y.; Min, D.; Oh, J.; Huh, C.; Kang, S.

2012-12-01

During last two decades, CO2 sequestration in the subsurface has been extensively studied and progressed as a direct tool to reduce CO2 emission. Commercial projects such as Sleipner, In Salah and Weyburn that inject more than one million tons of CO2 per year are operated actively as well as test projects such as Ketzin to study the behavior of CO2 and the monitoring techniques. Korea also began the CCS (CO2 capture and storage) project. One of the prospects for CO2 sequestration in Korea is the southwestern continental margin of Ulleung basin. To monitor the behavior of CO2 underground for the evaluation of stability and safety, several geophysical monitoring techniques should be applied. Among various geophysical monitoring techniques, seismic survey is considered as the most effective tool. To verify CO2 migration in the subsurface more effectively, seismic numerical simulation is an essential process. Furthermore, the efficiency of the seismic migration techniques should be investigated for various cases because numerical seismic simulation and migration test help us accurately interpret CO2 migration. In this study, we apply the reverse-time migration and Kirchhoff migration to synthetic seismic monitoring data generated for the simplified model based on the geological structures of Ulleung basin in Korea. Synthetic seismic monitoring data are generated for various cases of CO2 migration in the subsurface. From the seismic migration images, we can investigate CO2 diffusion patterns indirectly. From seismic monitoring simulation, it is noted that while the reverse-time migration generates clear subsurface images when subsurface structures are steeply dipping, Kirchhoff migration has an advantage in imaging horizontal-layered structures such as depositional sediments appearing in the continental shelf. The reverse-time migration and Kirchhoff migration present reliable subsurface images for the potential site characterized by stratigraphical traps. In case of

Managing migration: the Brazilian case

OpenAIRE

Eduardo L. G. Rios-Neto

2005-01-01

The objective of this paper is to present the Brazilian migration experience and its relationship with migration management. The article is divided into three parts. First, it reviews some basic facts regarding Brazilian immigration and emigration processes. Second, it focuses on some policy and legal issues related to migration. Finally, it addresses five issues regarding migration management in Brazil.

Migration og etnicitet

DEFF Research Database (Denmark)

Christiansen, Connie Carøe

2004-01-01

Migration og etnicitet er aktuelle og forbundne fænomener, idet migration øger berøringsfladerne mellem befolkningsgrupper. Etniciteter formes i takt med at grænser drages imellem disse grupper. Imod moderniserings-teoriernes forventning forsvandt etnicitet ikke som en traditionel eller oprindelig...... måde at skabe tilhørsforhold på; globalt set fremstår vor tid istedet som en "migrationens tidsalder", der tilsyneladende også er en tidsalder, hvor kulturelle særtræk, i form af etnicitet, udgør vigtige linjer, hvorefter grupper skilller sig ud fra hinanden. Både migration og etnicitet bringer fokus...... den finder sted i modtagerlandet, men nyere perspektiver på migration, som begreber om medborgerskab, transnationalisme og diaspora er eksponenter for, søger udover den nationalstatslige ramme og inddrager konsekvenserne af migrationen for afsenderlande....

Questions of migration and belonging: understandings of migration under neoliberalism in Ecuador.

Science.gov (United States)

Lawson, V

1999-01-01

This paper explores alternative understandings and experiences of migration under neoliberalism in Ecuador. Through the case study, the study examines migrants' multiple motivations for mobility and their ambivalence toward the process. Insights from the transnational migration literature were drawn in order to think through the implications of an increasingly contradictory context of economic modernization and its impact upon the sense of possibilities and belonging of migrants. In-depth interviews with urban-destined migrants in Ecuador were drawn to argue that mobility produces ambivalent development subjects. This argument is developed in three sections. First, the paper centers on the epistemological and theoretical basis for the relevance of migrant narratives in extending theorizations of migration. Second, in-depth interviews with migrants to Quito are drawn to explore migrants' sense of belonging and regional affiliation, identity formation through migration, and experiences of alienation and disruption in their lives. Lastly, this paper concludes with a retheorization of the role of migration places in the migrant identity construction.

The European Crisis and Migration to Germany: Expectations and the Diversion of Migration Flows

OpenAIRE

Brücker, Herbert; Bertoli, Simone; Fernández-Huertas Moraga, Jesús

2013-01-01

The European crisis has diverted migration flows away from countries affected by the recession towards Germany. The diversion process creates a challenge for traditional discrete-choice models that assume that only bilateral factors account for dyadic migration rates. This paper shows how taking into account the sequential nature of migration decisions leads to write the bilateral migration rate as a function of expectations about the evolution of economic conditions in alternative destinatio...

Income Inequality and Migration in Vietnam

OpenAIRE

NGUYEN, Tien Dung

2012-01-01

In this paper, we have analyzed the recent trends in income inequality, internal and international migrations and investigated the impact of migration on income distribution in Vietnam. Our analysis shows that the effects of migration on income inequality vary with different types of migration, depending on who migrate and where they migrate. Foreign remittances tend to flow toward more affluent households, and they increase income inequality. By contrast, domestic remittances accrue more to ...

Migration, Narration, Identity

DEFF Research Database (Denmark)

Leese, Peter

(co-editor with Carly McLaughlin and Wladyslaw Witalisz) This book presents articles resulting from joint research on the representations of migration conducted in connection with the Erasmus Intensive Programme entitled «Migration and Narration» taught to groups of international students over...

From migration to settlement: the pathways, migration modes and dynamics of neurons in the developing brain

Science.gov (United States)

HATANAKA, Yumiko; ZHU, Yan; TORIGOE, Makio; KITA, Yoshiaki; MURAKAMI, Fujio

2016-01-01

Neuronal migration is crucial for the construction of the nervous system. To reach their correct destination, migrating neurons choose pathways using physical substrates and chemical cues of either diffusible or non-diffusible nature. Migrating neurons extend a leading and a trailing process. The leading process, which extends in the direction of migration, determines navigation, in particular when a neuron changes its direction of migration. While most neurons simply migrate radially, certain neurons switch their mode of migration between radial and tangential, with the latter allowing migration to destinations far from the neurons’ site of generation. Consequently, neurons with distinct origins are intermingled, which results in intricate neuronal architectures and connectivities and provides an important basis for higher brain function. The trailing process, in contrast, contributes to the late stage of development by turning into the axon, thus contributing to the formation of neuronal circuits. PMID:26755396

Modelagem e simulação de reator trifasico aplicado a oleos pesados com reações de hidrocraqueamento termico e catalitico, desmetalização e deposição de coque na mistura e no catalisador

OpenAIRE

Letivan Gonçalves de Mendonça Filho

1998-01-01

Resumo: Esta dissertação apresenta a modelagem e simulação de um reator tipo ?slurry bubble column? que opera em leito fluidizado trifásico (gás-liquido-solido) com arraste de sólidos para promover a hidroconversão de resíduos de vácuo em condições severas de temperatura e pressão. Nosso objetivo foi reproduzir os fenômenos responsáveis pelas paradas típicas de reatores de hidroconversão de leito fluidizado trifásico, que são separação de fases devido a precipitação ds asfaltenos, a deposição...

Migrations in Slovenian geography textbooks

Directory of Open Access Journals (Sweden)

Jurij Senegačnik

2013-12-01

Full Text Available In Slovenia, the migrations are treated in almost all geographical textbooks for different levels of education. In the textbooks for the elementary school from the sixth to ninth grade, students acquire knowledge of the migrations by the inductive approach. Difficulty level of treatment and quantity of information are increasing by the age level. In the grammar school program a trail of gaining knowledge on migration is deductive. Most attention is dedicated to migrations in general geography textbooks. The textbooks for vocational and technical school programs deal with migrations to a lesser extent and with different approaches.

Palaearctic-African Bird Migration

DEFF Research Database (Denmark)

Iwajomo, Soladoye Babatola

Bird migration has attracted a lot of interests over past centuries and the methods used for studying this phenomenon has greatly improved in terms of availability, dimension, scale and precision. In spite of the advancements, relatively more is known about the spring migration of trans-Saharan m......Bird migration has attracted a lot of interests over past centuries and the methods used for studying this phenomenon has greatly improved in terms of availability, dimension, scale and precision. In spite of the advancements, relatively more is known about the spring migration of trans...... of birds from Europe to Africa and opens up the possibility of studying intra-African migration. I have used long-term, standardized autumn ringing data from southeast Sweden to investigate patterns in biometrics, phenology and population trends as inferred from annual trapping totals. In addition, I...... in the population of the species. The papers show that adult and juvenile birds can use different migration strategies depending on time of season and prevailing conditions. Also, the fuel loads of some individuals were theoretically sufficient for a direct flight to important goal area, but whether they do so...

Migration signatures across the decades: Net migration by age in U.S. counties, 1950-2010

Directory of Open Access Journals (Sweden)

Richelle L. Winkler

2015-05-01

Full Text Available Background: Migration is the primary population redistribution process in the United States. Selective migration by age, race/ethnic group, and spatial location governs population integration, affects community and economic development, contributes to land use change, and structures service needs. Objective: Delineate historical net migration patterns by age, race/ethnic, and rural-urban dimensions for United States counties. Methods: Net migration rates by age for all US counties are aggregated from 1950−2010, summarized by rural-urban location and compared to explore differential race/ethnic patterns of age-specific net migration over time. Results: We identify distinct age-specific net migration 'signatures' that are consistent over time within county types, but different by rural-urban location and race/ethnic group. There is evidence of moderate population deconcentration and diminished racial segregation between 1990 and 2010. This includes a net outflow of Blacks from large urban core counties to suburban and smaller metropolitan counties, continued Hispanic deconcentration, and a slowdown in White counterurbanization. Conclusions: This paper contributes to a fuller understanding of the complex patterns of migration that have redistributed the U.S. population over the past six decades. It documents the variability in county age-specific net migration patterns both temporally and spatially, as well as the longitudinal consistency in migration signatures among county types and race/ethnic groups.

The Great Migration.

Science.gov (United States)

Trotter, Joe William, Jr.

2002-01-01

Describes the migration of African Americans in the United States and the reasons why African Americans migrated from the south. Focuses on issues, such as the effect of World War I, the opportunities offered in the north, and the emergence of a black industrial working class. (CMK)

Migrating and herniating hydatid cysts

International Nuclear Information System (INIS)

Koc, Zafer; Ezer, Ali

2008-01-01

Objective: To present the prevalence and imaging findings of patients with hydatid disease (HD) showing features of migration or herniation of the hydatid cysts (HCs) and underline the clinical significance of this condition. Materials and methods: Between May 2003 and June 2006, 212 patients with HD were diagnosed by abdomen and/or thorax CT, searched for migrating or herniating HC. Imaging findings of 7 patients (5 women, 2 men with an age range of 19-63 years; mean ± S.D., 44 ± 19 years) with HD showing transdiaphragmatic migration (6 subjects) or femoral herniation (1 subject) were evaluated. Diagnosis of all the patients were established by pathologic examination and migration or herniation was confirmed by surgery in all patients. Results: Liver HD were identified in 169 (79.7%) of 212 patients with HD. Transdiaphragmatic migration of HCs were identified in 6 (3.5%) of the 169 patients with liver HD. In one patient, femoral herniation of the retroperitoneal HC into the proximal anterior thigh was identified. All of these seven patients exhibiting migration or herniation of HCs had active HCs including 'daughter cysts'. Two patients had previous surgery because of liver HD and any supradiaphragmatic lesion was not noted before operation. Findings of migration or herniation were confirmed by surgery. Conclusion: Active HCs may show migration or herniation due to pressure difference between the anatomic cavities, and in some of the patients, by contribution of gravity. Previous surgery may be a complementary factor for migration as seen in two of our patients. The possibility of migration or herniation in patients with HD should be considered before surgery

Migration in Asia-Europe Relations

DEFF Research Database (Denmark)

Juego, Bonn

2010-01-01

There is a remarkable difference between viewing migration as a 'social integration' issue, on the one hand, and migration as a 'social relation'. The idea of ‘social integration’ has unrealistic assumptions that see migration as a one-way process, that societies and human relations are static......, and that migrants are mechanical. Policies that are founded on unrealistic assumptions are most likely to generate tensions, conflicts, and contradictions. For a migration process to succeed in forging social harmony and development, it is therefore of decisive and crucial importance to regard migration...... as a ‘social relation’. This is simply because successful migration has to be a harmonious synergy between the migrants (and also the sending countries where they come from) and the receiving society (and its people). As indicated, migrants enter into the receiving society not merely as a passive commodity...

Migration Process Evolution in Europe

Directory of Open Access Journals (Sweden)

Carmen Tudorache

2006-08-01

Full Text Available The migration phenomenon has always existed, fluctuating by the historic context, the economic, political, social and demographic disparities between the Central and East European countries and the EU Member States, the interdependencies between the origin and receiving countries and the European integration process evolutions. In the European Union, an integrated and inclusive approach of the migration issue is necessary. But a common policy on migration rests an ambitious objective. A common approach of the economic migration management and the harmonization of the migration policies of the Member States represented a challenge for the European Union and will become urgent in the future, especially due to the demographic ageing.

[International migration in the Middle East].

Science.gov (United States)

Beauge, G

1985-01-01

This special issue contains a selection of 12 papers by various authors on aspects of international migration to the Middle East. Papers are included on the impact of migration on socioeconomic development, income distribution, and rural capitalization in Egypt; migration from rural Lebanon; the effect of emigration on Pakistan; Indian workers in Oman; inter-Arab migration and development; the role of the state in migration in the Arab peninsula; the dynamics of manpower in Kuwait; the Iraqi model and Arab unity; and the impact of this migration on the concept of the New Economic Order.

EMPIRICAL REFLECTIONS ON MIGRATION PHENOMENON. MAJOR EFFECTS OF MIGRATION ON THE HUMAN CAPITAL

Directory of Open Access Journals (Sweden)

Simona BUTA

2013-12-01

Full Text Available The paper Empirical reflections on migration phenomenon. Major effects of migration on the human capital analyzes the migration flows of the workforce (as part of the human capital globally/regionally, especially the highly qualified workforce migration. The qualified manpower processes of attracting on the work market have not been always well understood and, in some cases, have generated a series of difficulties. This is the reason why we will focus on the „waste of brains” phenomenon, which appears when highly qualified individuals are neither employed in the source-country nor in the target country; and, if they are, their job is below their qualifications.

International migration and the gender

OpenAIRE

Koropecká, Markéta

2010-01-01

My bachelor thesis explores the connection between international migration and gender. Gender, defined as a social, not a biological term, has a huge impact on the migration process. Statistics and expert studies that have been gender sensitive since 1970s demonstrate that women form half of the amount of the international migrants depending on the world region and representing a wide range of the kinds of international migration: family formation and reunification, labour migration, illegal ...

Cash seeking behaviour and migration: a place-to-place migration function for Cote d'Ivoire.

Science.gov (United States)

Velenchik, A D

1993-12-01

"This paper presents estimates of an aggregate place-to-place migration function for Cote d'Ivoire based on the premise that migration is motivated by rural residents' desire for cash income. The results indicate that migration from a region responds differently to changes in cash and food income, which supports the idea that it is the composition of rural income, and not just its level, that determines migration flows." excerpt

Samtidskunst og migration

DEFF Research Database (Denmark)

Petersen, Anne Ring

2010-01-01

"Samtidskunst og migration. En oversigt over faglitteraturen" er en forskningsoversigt der gør status over hvad der hidtil er skrevet inden for det kunsthistoriske område om vor tids billedkunst og migration som politisk, socialt og kulturelt fænomen, primært i forbindelse med immigration til...

RSA migration of total knee replacements.

Science.gov (United States)

Pijls, Bart G; Plevier, José W M; Nelissen, Rob G H H

2018-06-01

Purpose - We performed a systematic review and meta-analyses to evaluate the early and long-term migration patterns of tibial components of TKR of all known RSA studies. Methods - Migration pattern was defined as at least 2 postoperative RSA follow-up moments. Maximal total point motion (MTPM) at 6 weeks, 3 months, 6 months, 1 year, 2 years, 5 years, and 10 years were considered. Results - The literature search yielded 1,167 hits of which 53 studies were included, comprising 111 study groups and 2,470 knees. The majority of the early migration occurred in the first 6 months postoperatively followed by a period of stability, i.e., no or very little migration. Cemented and uncemented tibial components had different migration patterns. For cemented tibial components there was no difference in migration between all-poly and metal-backed components, between mobile bearing and fixed bearing, between cruciate retaining and posterior stabilized. Furthermore, no difference existed between TKR measured with model-based RSA or marker-based RSA methods. For uncemented TKR there was some variation in migration with the highest migration for uncoated TKR. Interpretation - The results from this meta-analysis on RSA migration of TKR are in line with both the survival analyses results from joint registries of these TKRs as well as revision rates results from meta-analyses, thus providing further proof for the association between early migration and late revision for loosening. The pooled migration patterns can be used both as benchmarks and for defining migration thresholds for future evaluation of new TKR.

Current Migration Movements in Europe

Directory of Open Access Journals (Sweden)

Jelena Zlatković Winter

2004-09-01

Full Text Available After a brief historical review of migrations in Europe, the paper focuses on current migration trends and their consequences. At the end of the 1950s, Western Europe began to recruit labour from several Mediterranean countries – Italy, Spain, Portugal and former Yugoslavia, and later from Morocco, Algeria, Tunisia and Turkey. Some countries, such as France, Great Britain and the Netherlands, recruited also workers from their former colonies. In 1970 Germany had the highest absolute number of foreigners, followed by France, and then Switzerland and Belgium. The total number of immigrants in Western Europe was twelve million. During the 1970s mass recruitment of foreign workers was abandoned, and only the arrival of their family members was permitted, which led to family reunification in the countries of employment. Europe closed its borders, with the result that clandestine migration increased. The year 1989 was a turning point in the history of international migrations. The political changes in Central and Eastern Europe brought about mass migration to the West, which culminated in the so-called “mass movement of 1989–1990”. The arrival of ethnic Germans in Germany, migration inside and outside of the territory of the former Soviet Union, an increase in the number of asylum seekers and displaced persons, due to armed conflicts, are – according to the author – the main traits of current migration. The main part of the paper discusses the causes and effects of this mass wave, as well as trends in labour migration, which is still present. The second part of the paper, after presenting a typology of migrations, deals with the complex processes that brought about the formation of new communities and led to the phenomenon of new ethnic minorities and to corresponding migration policies in Western European countries that had to address these issues.

The Transformative Forces of Migration: Refugees and the Re-Configuration of Migration Societies

Directory of Open Access Journals (Sweden)

Ulrike Hamann

2018-03-01

Full Text Available In this thematic issue, we attempt to show how migrations transform societies at the local and micro level by focusing on how migrants and refugees navigate within different migration regimes. We pay particular attention to the specific formation of the migration regimes that these countries adopt, which structure the conditions of the economic, racialised, gendered, and sexualized violence and exploitation during migration processes. This interactive process of social transformation shapes individual experiences while also being shaped by them. We aim to contribute to the most recent and challenging question of what kind of political and social changes can be observed and how to frame these changes theoretically if we look at local levels while focusing on struggles for recognition, rights, and urban space. We bring in a cross-country comparative perspective, ranging from Canada, Chile, Spain, Sweden, Turkey, and to Germany in order to lay out similarities and differences in each case, within which our authors analyse these transformative forces of migration.

Globalization, Migration and Development

Directory of Open Access Journals (Sweden)

George, Susan

2002-01-01

Full Text Available EnglishMigration may become the most important branch of demography in the earlydecades of the new millennium in a rapidly globalizing world. This paper discusses the causes, costsand benefits of international migration to countries of the South and North, and key issues of commonconcern. International migration is as old as national boundaries, though its nature, volume,direction, causes and consequences have changed. The causes of migration are rooted in the rate ofpopulation growth and the proportion of youth in the population, their education and training,employment opportunities, income differentials in society, communication and transportationfacilities, political freedom and human rights and level of urbanization. Migration benefits the Souththrough remittances of migrants, improves the economic welfare of the population (particularly womenof South countries generally, increases investment, and leads to structural changes in the economy.However, emigration from the South has costs too, be they social or caused by factors such as braindrain. The North also benefits by migration through enhancement of economic growth, development ofnatural resources, improved employment prospects, social development and through exposure toimmigrants' new cultures and lifestyles. Migration also has costs to the North such as of immigrantintegration, a certain amount of destabilization of the economy, illegal immigration, and socialproblems of discrimination and exploitation. Issues common to both North and South include impact onprivate investment, trade, international cooperation, and sustainable development. Both North andSouth face a dilemma in seeking an appropriate balance between importing South's labour or itsproducts and exporting capital and technology from the North.FrenchLa migration est sans doute devenue la partie la plus importante de la démographie des premières décennies du nouveau millénaire dans un monde qui change rapidement. Ce

How neurons migrate: a dynamic in-silico model of neuronal migration in the developing cortex

LENUS (Irish Health Repository)

Setty, Yaki

2011-09-30

Abstract Background Neuronal migration, the process by which neurons migrate from their place of origin to their final position in the brain, is a central process for normal brain development and function. Advances in experimental techniques have revealed much about many of the molecular components involved in this process. Notwithstanding these advances, how the molecular machinery works together to govern the migration process has yet to be fully understood. Here we present a computational model of neuronal migration, in which four key molecular entities, Lis1, DCX, Reelin and GABA, form a molecular program that mediates the migration process. Results The model simulated the dynamic migration process, consistent with in-vivo observations of morphological, cellular and population-level phenomena. Specifically, the model reproduced migration phases, cellular dynamics and population distributions that concur with experimental observations in normal neuronal development. We tested the model under reduced activity of Lis1 and DCX and found an aberrant development similar to observations in Lis1 and DCX silencing expression experiments. Analysis of the model gave rise to unforeseen insights that could guide future experimental study. Specifically: (1) the model revealed the possibility that under conditions of Lis1 reduced expression, neurons experience an oscillatory neuron-glial association prior to the multipolar stage; and (2) we hypothesized that observed morphology variations in rats and mice may be explained by a single difference in the way that Lis1 and DCX stimulate bipolar motility. From this we make the following predictions: (1) under reduced Lis1 and enhanced DCX expression, we predict a reduced bipolar migration in rats, and (2) under enhanced DCX expression in mice we predict a normal or a higher bipolar migration. Conclusions We present here a system-wide computational model of neuronal migration that integrates theory and data within a precise

How neurons migrate: a dynamic in-silico model of neuronal migration in the developing cortex

Directory of Open Access Journals (Sweden)

Skoblov Nikita

2011-09-01

Full Text Available Abstract Background Neuronal migration, the process by which neurons migrate from their place of origin to their final position in the brain, is a central process for normal brain development and function. Advances in experimental techniques have revealed much about many of the molecular components involved in this process. Notwithstanding these advances, how the molecular machinery works together to govern the migration process has yet to be fully understood. Here we present a computational model of neuronal migration, in which four key molecular entities, Lis1, DCX, Reelin and GABA, form a molecular program that mediates the migration process. Results The model simulated the dynamic migration process, consistent with in-vivo observations of morphological, cellular and population-level phenomena. Specifically, the model reproduced migration phases, cellular dynamics and population distributions that concur with experimental observations in normal neuronal development. We tested the model under reduced activity of Lis1 and DCX and found an aberrant development similar to observations in Lis1 and DCX silencing expression experiments. Analysis of the model gave rise to unforeseen insights that could guide future experimental study. Specifically: (1 the model revealed the possibility that under conditions of Lis1 reduced expression, neurons experience an oscillatory neuron-glial association prior to the multipolar stage; and (2 we hypothesized that observed morphology variations in rats and mice may be explained by a single difference in the way that Lis1 and DCX stimulate bipolar motility. From this we make the following predictions: (1 under reduced Lis1 and enhanced DCX expression, we predict a reduced bipolar migration in rats, and (2 under enhanced DCX expression in mice we predict a normal or a higher bipolar migration. Conclusions We present here a system-wide computational model of neuronal migration that integrates theory and data within a

MIGRATION IMPACT ON ECONOMICAL SITUATION

Directory of Open Access Journals (Sweden)

Virginia COJOCARU

2016-01-01

Full Text Available This paper presents recent trends and flows of labor migration and its impact on economic and social life. Main aim of this research sets up the influence of the migration on the European economics and its competitiveness. Methods of research are: method of comparison, analysis method, method of deduction, method of statistics, modeling method. The economic impact of migration has been intensively studied but is still often driven by ill-informed perceptions, which, in turn, can lead to public antagonism towards migration. These negative views risk jeopardising efforts to adapt migration policies to the new economic and demographic challenges facing many countries. Migration Policy looks at the evidence for how immigrants affect the economy in three main areas: The labour market, public purse and economic growth. In Europe, the scope of labour mobility greatly increased within the EU/EFTA zones following the EU enlargements of 2004, 2007 and 2014-2015. This added to labour markets’ adjustment capacity. Recent estimates suggest that as much as a quarter of the asymmetric labour market shock – that is occurring at different times and with different intensities across countries – may have been absorbed by migration within a year.

Migration processes in SCO member states

Directory of Open Access Journals (Sweden)

Valentina Sergeevna Antonyuk

2012-12-01

Full Text Available The article concerns modern state and development of migration processes in SCO member states. As a main method of research statistical analysis was applied. The article shows that migration streams between SCO member states are rather intensive, and the problem of labor migration becomes more and more urgent. The countries of consuming and supplying of labour force are clearly differentiated in the region. For some countries, labor export is the key sector of economy. At the same time, interstate relations between SCO member states sometimes are rather disputed. The most urgent factors causing the development of migration processes in the region were determined. Among them, thefactor of growing outflows from China isespecially noted. It is noted that migration processes are discussed by SCO member states nowadays in terms of illegal migration and international criminality connected with it. It means that the question of labor migration is a real problem. It is indicated that the creation of a specific joint commission on migration policy affiliated with the Council of Foreign Ministers of SCO member states is the necessary condition of effective interaction in migration questions within the framework of Shanghai Cooperation Organization.

Pre-migration persecution, post-migration stressors and resources, and post-migration mental health: A study of severely traumatized U.S. Arab immigrant women

Science.gov (United States)

Norris, Anne E.; Aroian, Karen J.; Nickerson, David

2015-01-01

Background Competing theories exist regarding the importance of pre-migration trauma as compared to post-migration stressors and resources with respect to the risk to immigrant mental health. Objective To examine how type of pre-migration trauma, post-migration stressors, and post-migration resources differentially predict PTSD and MDD symptomatology in Arab immigrant women who have been exposed to pre-migration trauma. Design Descriptive; using multinomial logistic regression to explain membership in one of four groups: (a) PTSD only (n = 14); (b) major depressive disorder (MDD) (n = 162), (c) Co-Morbid PTSD-MDD (n = 148), (d) Subclinical Symptoms (n = 209). Results Post-immigration related stressors (as measured by the Demands of Immigration (DI)) had the strongest effect: Parameter estimates indicated that a unit increase in DI scores was associated with a nearly 17 fold increase in the likelihood of being in the Co-morbid relative to the Subclinical group, and a nearly 2.5 increase in the likelihood of being in the Co-Morbid relative to the MDD only group (p Arab immigrant women for depression and PTSD is important given high levels observed in this community based sample. PMID:21835819

Migrations of theory, method and practice: a reflection on themes in migration studies (Review article)

OpenAIRE

Palmary, Ingrid

2009-01-01

In this review article, I offer some reflection on three themes in migration research, namely, the categorisation and quantification of migration, the role of trauma and distress in such categorisation, and the feminisation of migration. I was prompted to explore these three themes after reading a recent publication on migration in southern Africa (edited by Kok, Gelderblom, Oucho and Van Zyl, 2006). In this paper I raise these as three areas that appear to be determining the boundaries of th...

College Student Migration.

Science.gov (United States)

Fenske, Robert H.; And Others

This study examines the background characteristics of two large national samples of first-time enrolled freshmen who (a) attended college within their state of residence but away from their home community, (b) migrated to a college in an adjacent state, (c) migrated to a college in a distant state, and (d) attended college in their home community.…

Gamificação: modelagem de conteúdos para programas e aplicativos educativos no ambiente da TV digital interativa

Directory of Open Access Journals (Sweden)

Marcos Américo

2015-04-01

Full Text Available Com a implantação da TV Digital no Brasil, surge a necessidade de se fomentar a concepção e produção de conteúdos audiovisuais interativos de qualidade que apresentem mensagens educativas a partir do Edutretenimento. Este estudo propõe a aplicação da gamificação como elo comunicacional para incentivar e modificar o comportamento dos usuários, através de uma narrativa que incentive a motivação intrínseca para o entretenimento e o aprendizado nesses meios. Existem poucos modelos de roteiros para a produção de aplicativos, sobretudo educacionais, com aplicações interativas simultâneas para o fluxo televisivo ou para o conteúdo complementar da programação ofertada. Por essa razão, é atribuída uma atenção especial ao roteiro, em virtude de se inserir, em sua construção, os elementos que compõem a mecânica e a dinâmica dos jogos. Como resultado, é apresentado o verbete “Gamificação-TVDI”, bem como o desenvolvimento de uma metodologia de modelagem de conteúdo e de processo, apoiada em mapas conceituais, wireframes e roadmaps, fundamentando a concepção e a elaboração de um protótipo de roteiro com elementos de gamificação para programas educativos e seus aplicativos de interação.

National and international graduate migration flows.

Science.gov (United States)

Mosca, Irene; Wright, Robert E

2010-01-01

This article examines the nature of national and international graduate migration flows in the UK. Migration equations are estimated with microdata from a matched dataset of Students and Destinations of Leavers from Higher Education, information collected by the Higher Education Statistical Agency. The probability of migrating is related to a set of observable characteristics using multinomial logit regression. The analysis suggests that migration is a selective process with graduates with certain characteristics having considerably higher probabilities of migrating, both to other regions of the UK and abroad.

Nuss bar migrations: occurrence and classification

International Nuclear Information System (INIS)

Binkovitz, Lauren E.; Binkovitz, Larry A.; Zendejas, Benjamin; Moir, Christopher R.

2016-01-01

Pectus excavatum results from dorsal deviation of the sternum causing narrowing of the anterior-posterior diameter of the chest. It can result in significant cosmetic deformities and cardiopulmonary compromise if severe. The Nuss procedure is a minimally invasive technique that involves placing a thin horizontally oriented metal bar below the dorsal sternal apex for correction of the pectus deformity. To identify the frequency and types of Nuss bar migrations, to present a new categorization of bar migrations, and to present examples of true migrations and pseudomigrations. We retrospectively reviewed the electronic medical records and all pertinent radiologic studies of 311 pediatric patients who underwent a Nuss procedure. We evaluated the frequency and type of bar migrations. Bar migration was demonstrated in 23 of 311 patients (7%) and occurred within a mean period of 26 days after surgery. Bar migrations were subjectively defined as deviation of the bar from the position demonstrated on the immediate postoperative radiographs and categorized as superior, inferior, rotation, lateral or flipped using a new classification system. Sixteen of the 23 migrations required re-operation. Nuss bar migration can be diagnosed with careful evaluation of serial radiographs. Nuss bar migration has a wide variety of appearances and requires exclusion of pseudomigration resulting from changes in patient positioning between radiologic examinations. (orig.)

Nuss bar migrations: occurrence and classification

Energy Technology Data Exchange (ETDEWEB)

Binkovitz, Lauren E.; Binkovitz, Larry A. [Mayo Clinic, Department of Radiology, Rochester, MN (United States); Zendejas, Benjamin; Moir, Christopher R. [Mayo Clinic, Department of Surgery, Rochester, MN (United States)

2016-12-15

Pectus excavatum results from dorsal deviation of the sternum causing narrowing of the anterior-posterior diameter of the chest. It can result in significant cosmetic deformities and cardiopulmonary compromise if severe. The Nuss procedure is a minimally invasive technique that involves placing a thin horizontally oriented metal bar below the dorsal sternal apex for correction of the pectus deformity. To identify the frequency and types of Nuss bar migrations, to present a new categorization of bar migrations, and to present examples of true migrations and pseudomigrations. We retrospectively reviewed the electronic medical records and all pertinent radiologic studies of 311 pediatric patients who underwent a Nuss procedure. We evaluated the frequency and type of bar migrations. Bar migration was demonstrated in 23 of 311 patients (7%) and occurred within a mean period of 26 days after surgery. Bar migrations were subjectively defined as deviation of the bar from the position demonstrated on the immediate postoperative radiographs and categorized as superior, inferior, rotation, lateral or flipped using a new classification system. Sixteen of the 23 migrations required re-operation. Nuss bar migration can be diagnosed with careful evaluation of serial radiographs. Nuss bar migration has a wide variety of appearances and requires exclusion of pseudomigration resulting from changes in patient positioning between radiologic examinations. (orig.)

Climate change-related migration and infectious disease.

Science.gov (United States)

McMichael, Celia

2015-01-01

Anthropogenic climate change will have significant impacts on both human migration and population health, including infectious disease. It will amplify and alter migration pathways, and will contribute to the changing ecology and transmission dynamics of infectious disease. However there has been limited consideration of the intersections between migration and health in the context of a changing climate. This article argues that climate-change related migration - in conjunction with other drivers of migration - will contribute to changing profiles of infectious disease. It considers infectious disease risks for different climate-related migration pathways, including: forced displacement, slow-onset migration particularly to urban-poor areas, planned resettlement, and labor migration associated with climate change adaptation initiatives. Migration can reduce vulnerability to climate change, but it is critical to better understand and respond to health impacts - including infectious diseases - for migrant populations and host communities.

Family migration and relative earnings potentials

DEFF Research Database (Denmark)

Foged, Mette

2016-01-01

of husband centered migration. Couples are more likely to migrate if household earnings potential is disproportionally due to one partner, and families react equally strongly to a male and a female relative advantage in educational earnings potential. These results are driven by households with a strong......A unitarian model of family migration in which families may discount wives’ private gains is used to derive testable predictions regarding the type of couples that select into migrating. The empirical tests show that gender neutral family migration cannot be rejected against the alternative...

Migrating Art History

DEFF Research Database (Denmark)

Ørum, Tania

2012-01-01

Review of Hiroko Ikegami, The Great Migrator. Robert Rauschenberg and the Global Rise of American Art. Cambridge Mass., The MIT Press, 2010. 277 pages. ISBN 978-0-262-01425-0.......Review of Hiroko Ikegami, The Great Migrator. Robert Rauschenberg and the Global Rise of American Art. Cambridge Mass., The MIT Press, 2010. 277 pages. ISBN 978-0-262-01425-0....

Pre-migration Trauma Exposure and Psychological Distress for Asian American Immigrants: Linking the Pre- and Post-migration Contexts.

Science.gov (United States)

Li, Miao; Anderson, James G

2016-08-01

Drawing on the life course perspective and the assumptive world theory, this paper examines whether pre-migration trauma exposure is associated with psychological distress through post-migration perceived discrimination for Asian American immigrants. The study is based on cross-sectional data from the National Latino and Asian American Study (N = 1639). Structural equation model is used to estimate the relationship between pre-migration trauma, post-migration perceived discrimination, and psychological distress. Additional models are estimated to explore possible variations across ethnic groups as well as across different types of pre-migration trauma experience. Pre-migration trauma exposure is associated with higher levels of psychological distress, both directly and indirectly through higher level of perceived discrimination, even after controlling for demographic/acculturative factors and post-migration trauma exposure. This pattern holds for the following sub-types of pre-migration trauma: political trauma, crime victimization, physical violence, accidental trauma, and relational trauma. Multi-group analyses show that this pattern holds for all Asian immigrant subgroups except the Vietnamese. Studies of immigrant mental health primarily focus on post-migration stressors. Few studies have considered the link between pre- and post-migration contexts in assessing mental health outcomes. The study illustrates the usefulness of bridging the pre- and post-migration context in identifying the mental health risks along the immigrant life course.

Globalisation and international migration in Asia.

Science.gov (United States)

Hugo, G

1998-03-01

"The present paper attempts to summarise the major contemporary trends in international migration in Asia and how this is related to the rapid demographic transition occurring across most of the region. The diversity of types of mobility is one of the striking features of Asian international migration and developments in each major type [are] discussed in the paper. It is then argued that there are elements within the Asian migration system that give it a momentum which to some extent operates outside of the influence of economic and political trends. Finally some emerging issues in Asian international migration are briefly addressed. These include the scale and effects of remittances, the feminisation of migration, undocumented migration, increasing government involvement and brain drain issues." (EXCERPT)

Youth Labor Migration in Nepal

OpenAIRE

Bossavie, Laurent; Denisova, Anastasiya

2018-01-01

This descriptive study investigates internal and external labor migration by Nepalese youth. External labor migration is separated into the flow to India, which is unregulated, and the flow to other countries, which typically takes the form of temporary contract migration to countries with bilateral labor agreements with Nepal (referred to in Nepal as foreign employment). The study finds t...

Repeat migration and disappointment.

Science.gov (United States)

Grant, E K; Vanderkamp, J

1986-01-01

This article investigates the determinants of repeat migration among the 44 regions of Canada, using information from a large micro-database which spans the period 1968 to 1971. The explanation of repeat migration probabilities is a difficult task, and this attempt is only partly successful. May of the explanatory variables are not significant, and the overall explanatory power of the equations is not high. In the area of personal characteristics, the variables related to age, sex, and marital status are generally significant and with expected signs. The distance variable has a strongly positive effect on onward move probabilities. Variables related to prior migration experience have an important impact that differs between return and onward probabilities. In particular, the occurrence of prior moves has a striking effect on the probability of onward migration. The variable representing disappointment, or relative success of the initial move, plays a significant role in explaining repeat migration probabilities. The disappointment variable represents the ratio of actural versus expected wage income in the year after the initial move, and its effect on both repeat migration probabilities is always negative and almost always highly significant. The repeat probabilities diminish after a year's stay in the destination region, but disappointment in the most recent year still has a bearing on the delayed repeat probabilities. While the quantitative impact of the disappointment variable is not large, it is difficult to draw comparisons since similar estimates are not available elsewhere.

Probabilistic migration modelling focused on functional barrier efficiency and low migration concepts in support of risk assessment.

Science.gov (United States)

Brandsch, Rainer

2017-10-01

Migration modelling provides reliable migration estimates from food-contact materials (FCM) to food or food simulants based on mass-transfer parameters like diffusion and partition coefficients related to individual materials. In most cases, mass-transfer parameters are not readily available from the literature and for this reason are estimated with a given uncertainty. Historically, uncertainty was accounted for by introducing upper limit concepts first, turning out to be of limited applicability due to highly overestimated migration results. Probabilistic migration modelling gives the possibility to consider uncertainty of the mass-transfer parameters as well as other model inputs. With respect to a functional barrier, the most important parameters among others are the diffusion properties of the functional barrier and its thickness. A software tool that accepts distribution as inputs and is capable of applying Monte Carlo methods, i.e., random sampling from the input distributions of the relevant parameters (i.e., diffusion coefficient and layer thickness), predicts migration results with related uncertainty and confidence intervals. The capabilities of probabilistic migration modelling are presented in the view of three case studies (1) sensitivity analysis, (2) functional barrier efficiency and (3) validation by experimental testing. Based on the predicted migration by probabilistic migration modelling and related exposure estimates, safety evaluation of new materials in the context of existing or new packaging concepts is possible. Identifying associated migration risk and potential safety concerns in the early stage of packaging development is possible. Furthermore, dedicated material selection exhibiting required functional barrier efficiency under application conditions becomes feasible. Validation of the migration risk assessment by probabilistic migration modelling through a minimum of dedicated experimental testing is strongly recommended.

Socio-Economic Determinants of International Migration

Directory of Open Access Journals (Sweden)

Yaroslav PRYTULA

2012-05-01

Full Text Available Since economic factors cannot fully explain the determinants of bilateral migration, this study explores the social and cultural determinants that influence an individual’s decision to migrate. Values, norms and interests in a given culture, may determine whether an individual’s intention to move translates into actual migration. Work values inherent in different cultures could explain why people move or do not move under the condition of perceived economic advantages of migration. A gravity type migration model is used to incorporate variables related both to economic indicators and work values. It is perhaps the first migration study to use the World Value Survey (WVS and the European Value Survey (EVS. We use 2000 stock bilateral migration dataset collected by the World Bank. Our findings indicate that if more aspects of work are valued in a country, this country sends more migrants. Also we show that countries with higher extrinsic work value orientation tend to send more migrants, while countries with higher intrinsic work value orientation tend to send fewer migrants. Our finding shows that the value of work and the level of job security in a country may significantly change migration decision.

Wages, Welfare Benefits and Migration.

Science.gov (United States)

Kennan, John; Walker, James R

2010-05-01

Differences in economic opportunities give rise to strong migration incentives, across regions within countries, and across countries. In this paper we focus on responses to differences in welfare benefits across States. We apply the model developed in Kennan and Walker (2008), which emphasizes that migration decisions are often reversed, and that many alternative locations must be considered. We model individual decisions to migrate as a job search problem. A worker starts the life-cycle in some home location and must determine the optimal sequence of moves before settling down. The model is sparsely parameterized. We estimate the model using data from the National Longitudinal Survey of Youth (1979). Our main finding is that income differences do help explain the migration decisions of young welfare-eligible women, but large differences in benefit levels provide surprisingly weak migration incentives.

Measuring International Migration in Azerbaijan

Directory of Open Access Journals (Sweden)

Serhat Yüksel

2018-01-01

Full Text Available International migration significantly affects economic, social, cultural, and political factors of the country. Owing to this situation, it can be said that the reasons of international migration should be analyzed in order to control this problem. The purpose of this study is to determine the influencing factors of international migration in Azerbaijan. In this scope, annual data of 11 explanatory variables for the period of 1995–2015 was analyzed via Multivariate Adaptive Regression Splines (MARS method. According to the results of this analysis, it was identified that people prefer to move other countries in case of high unemployment rates. In addition, the results of the study show that population growth and high mortality rate increases the migration level. While considering these results, it was recommended that Azerbaijan should focus on these aspects to control international migration problem.

Labor migration in Asia.

Science.gov (United States)

Martin, P L

1991-01-01

"A recent conference sponsored by the United Nations Center for Regional Development (UNCRD) in Nagoya, Japan examined the growing importance of labor migration for four major Asian labor importers (Japan, Hong Kong, Malaysia, and Singapore) and five major labor exporters (Bangladesh, Korea, Pakistan, Philippines, and Thailand).... The conference concluded that international labor migration would increase within Asia because the tight labor markets and rising wages which have stimulated Japanese investment in other Asian nations, for example, have not been sufficient to eliminate migration push and pull forces...." excerpt

Dispersal and migration

Directory of Open Access Journals (Sweden)

Schwarz, C.

2004-06-01

Full Text Available Ringing of birds unveiled many aspects of avian migration and dispersal movements. However, there is even much more to be explored by the use of ringing and other marks. Dispersal is crucial in understanding the initial phase of migration in migrating birds as it is to understand patterns and processes of distribution and gene flow. So far, the analysis of migration was largely based on analysing spatial and temporal patters of recoveries of ringed birds. However, there are considerable biases and pitfalls in using recoveries due to spatial and temporal variation in reporting probabilities. Novel methods are required for future studies separating the confounding effects of spatial and temporal heterogeneity of recovery data and heterogeneity of the landscape as well. These novel approaches should aim a more intensive and novel use of the existing recovery data by taking advantage of, for instance, dynamic and multistate modeling, should elaborate schemes for future studies, and should also include other marks that allow a more rapid data collection, like telemetry, geolocation and global positioning systems, and chemical and molecular markers. The latter appear to be very useful in the delineating origin of birds and connectivity between breeding and non–breeding grounds. Many studies of migration are purely descriptive. However, King and Brooks (King & Brooks, 2004 examine if movement patterns of dolphins change after the introduction of a gillnet ban. Bayesian methods are an interesting approach to this problem as they provide a meaningful measure of the probability that such a change occurred rather than simple yes/no response that is often the result of classical statistical methods. However, the key difficulty of a general implementation of Bayesian methods is the complexity of the modelling —there is no general userfriendly package that is easily accessible to most scientists. Drake and Alisauskas (Drake & Alisauskas, 2004 examine the

IUSSP Committee on International Migration, Workshop on International Migration Systems and Networks.

Science.gov (United States)

Lim, Lin Lean

1987-01-01

This mini-workshop sought a framework for examining the dynamics of migration processes, especially the interlinkages between sending and receiving countries. These two focuses emerged as directions for further research: (1) a topology reflecting the concepts underlying international migration; and (2) empirical studies which attempt to apply the…

Determinants of the Egyptian labour migration.

Science.gov (United States)

Kandil, M; Metwally, M

1992-03-01

The objective is to summarize the pattern of Egyptian migration to Arab oil-producing countries (AOPC), to review some factors that are important determinants of labor movement based on theory, and to empirically model the migration rate to AOPC and to Saudi Arabia. Factors are differentiated as to their relative importance. Push factors are the low wages, high inflation rate, and high population density in Egypt; pull factors are higher wages. It is predicted that an increase in income from destination countries has a significant positive impact on the migration rate. An increase in population density stimulates migration. An increase in inflation acts to increase out-migration with a 2-year lag, which accommodates departure preparation. Egypt's experience with labor migration is described for the pre-oil boom, and the post-oil boom. Several estimates of labor migration are given. Government policy toward migration is positive. Theory postulates migration to be determined by differences in the availability of labor, labor rewards between destination and origin, and the cost of migration. In the empirical model, push factors are population density, the current inflation rate, and the ratio of income/capita in AOPC to Egypt. The results indicate that the ratio of income/capita had a strong pull impact and population density had a strong push impact. The inflation rate has a positive impact with a lag estimated at 2 years. Prior to the Camp David Accord, there was a significant decrease in the number of Egyptian migrants due to political tension. The findings support the classical theory of factor mobility. The consequences of migration on the Egyptian economy have been adverse. Future models should disaggregate data because chronic shortages exist in some parts of the labor market. Manpower needs assessment would be helpful for policy makers.

Transnational Solidarity—Not Aid: The Perspective of Migration on the Hype about Migration&Development

Directory of Open Access Journals (Sweden)

Maria Schwertl

2017-09-01

Full Text Available Migrants have organized transnational support for non-migrants, stay-at-homes, citizens and noncitizens, as well as for developmental or integrationist nation state projects for decades. These solidarities have been framed as “cultural programs,” “autochthone support of hometowns,” “development aid” or “diaspora politics.” Since the turn of the century especially those projects that could be framed as “development aid” have gained a lot of interest from official development aid and its agencies. More and more programs have been launched to coordinate and professionalize the transnational support labor of migrants under the aegis of development. This is what I call the hype about migration&development. In this article, I want to show why the notion of “migrant development aid” used in the hype falls short of what is at stake when it comes to transnational migrant solidarities. Thereby, I want to argue that looking at migration through its governance and through migration or development politics is short-sighted and insensitive towards the desires, ethics and politics of migration. This is the reason that a perspective of migration—such as that propagated by the autonomy of migration approach—needs to be brought into debates on migration&development.

Dynamic Migration Intentions and the Impact of Socio-Institutional Environments: A Transit Migration Hub in Turkey

NARCIS (Netherlands)

Wissink, M.J.; Düvell, F.; van Eerdewijk, A.

2013-01-01

Transit migration is generally defined by migrants having the intention to move onwards to a third country. Based on an empirical investigation in Izmir, a transit migration hub in Turkey, this paper critically discusses intentionality as a valid dimension in conceptualisations of transit migration.

Suture fixation of migrated septal occluder device to prevent further migration: a simple surgical technique

Directory of Open Access Journals (Sweden)

Mohite Prashant N

2013-01-01

Full Text Available Abstract As the use of percutaneous intervention is increasing for the closure of the atrial septal defect, the procedure related complications are also on rise, migration of the device being most common. The migrated devices with failed percutaneous retrieval must be removed surgically under cardiopulmonary bypass. During establishment of cardiopulmonary bypass, the handling of heart may cause further migration of the device into other chambers of heart which leads to difficulty in finding and retrieval of the device. The authors propose a simple and unique technique to prevent further migration of the septal occluder device.

Return Migration as Failure or Success?: The Determinants of Return Migration Intentions Among Moroccan Migrants in Europe.

Science.gov (United States)

de Haas, Hein; Fokkema, Tineke; Fihri, Mohamed Fassi

Different migration theories generate competing hypotheses with regard to determinants of return migration. While neoclassical migration theory associates migration to the failure to integrate at the destination, the new economics of labour migration sees return migration as the logical stage after migrants have earned sufficient assets and knowledge and to invest in their origin countries. The projected return is then likely to be postponed for sustained or indefinite periods if integration is unsuccessful. So, from an indication or result of integration failure return is rather seen as a measure of success. Drawing on recent survey data ( N  = 2,832), this article tests these hypotheses by examining the main determinants of return intention among Moroccan migrants across Europe. The results indicate that structural integration through labour market participation, education and the maintenance of economic and social ties with receiving countries do not significantly affect return intentions. At the same time, investments and social ties to Morocco are positively related, and socio-cultural integration in receiving countries is negatively related to return migration intentions. The mixed results corroborate the idea that there is no uniform process of (return) migration and that competing theories might therefore be partly complementary.

Mental health of newly arrived Burmese refugees in Australia: contributions of pre-migration and post-migration experience.

Science.gov (United States)

Schweitzer, Robert D; Brough, Mark; Vromans, Lyn; Asic-Kobe, Mary

2011-04-01

This study documents the mental health status of people from Burmese refugee backgrounds recently arrived in Australia, then examines the contributions of gender, pre-migration and post-migration factors in predicting mental health. Structured interviews, including a demographic questionnaire, the Harvard Trauma Questionnaire, the Post-migration Living Difficulties Checklist and Hopkins Symptom Checklist assessed pre-migration trauma, post-migration living difficulties, depression, anxiety, somatization and traumatization symptoms in a sample of 70 adults across five Burmese ethnic groups. Substantial proportions of participants reported psychological distress in symptomatic ranges including: post-traumatic stress disorder (9%), anxiety (20%) and depression (36%), as well as significant symptoms of somatization (37%). Participants reported multiple and severe pre-migration traumas. Post-migration living difficulties of greatest concern included communication problems and worry about family not in Australia. Gender did not predict mental health. Level of exposure to traumatic events and post-migration living difficulties each made unique and relatively equal contributions to traumatization symptoms. Post-migration living difficulties made unique contributions to depression, anxiety and somatization symptoms. While exposure to traumatic events impacted on participants' mental well-being, post-migration living difficulties had greater salience in predicting mental health outcomes of people from Burmese refugee backgrounds. Reported rates of post-traumatic stress disorder symptoms were consistent with a large review of adults across seven western countries. High levels of somatization point to a nuanced expression of distress. Findings have implications for service provision in terms of implementing appropriate interventions to effectively meet the needs of this newly arrived group in Australia.

The health impacts of climate-related migration.

Science.gov (United States)

Schwerdtle, Patricia; Bowen, Kathryn; McMichael, Celia

2017-12-11

Changes in climate, in conjunction with other drivers of mobility, shape human migration. While there is an increasing focus on the adaptive potential of migration, the health impacts of climate-related migration, including planned relocation and forced displacement, have not been thoroughly examined. The Intergovernmental Panel on Climate Change stated that migration is currently, and will increasingly be, influenced by environmental degradation and climate change, and that it needs to be addressed in a focused and coordinated manner. This paper examines the links between climate change, migration, and health, considering diverse migration responses, including immobility, forced displacement and planned migration, as well as the associated health risks and opportunities in different contexts. Using case studies, the paper illustrates strategies to reduce the health risks associated with climate change-related migration. While there is an increasing body of research examining the climate change-migration nexus, a dual approach is now required. This approach must include debate and further research regarding the health consequences and responses associated with climate migration as well as immediate strengthening of health systems to make them both climate resilient and migrant inclusive.

Migration in Burkina Faso

NARCIS (Netherlands)

Wouterse, F.S.

2007-01-01

Migration plays an important role in development and as a strategy for poverty reduction. A recent World Bank investigation finds a significant positive relationship between international migration and poverty reduction at the country level (Adams and Page 2003). Burkina Faso, whose conditions for

Investigation on nuclide migration behaviors

International Nuclear Information System (INIS)

Baik, Minhoon; Park, Chungkyun; Kim, Seungsoo

2012-04-01

In this study, we investigated the properties of geochemical reactions and sorption of high-level radionuclides and highly-mobile radionuclides in deep geological disposal environments. We also analyzed the dissolution properties of pyro wastes and constructed databases for the geochemical reactions and sorption for the safety assessment of HLW disposal. Technologies for measuring diffusion depths of radionuclides through fracture surfaces and rock matrix were developed in KURT conditions and their diffusion properties were analyzed and evaluated. The combined reactions of radionuclide/mineral/microbe in deep disposal environments were investigated and the effects of microbe on the radionuclide migration and disposal system behaviors were evaluated. In-situ solute migration system and on-line monitoring system were installed in KURT and the migration and retardation behaviors of various solutes and their interaction with fracture-filling materials were investigated. Basic properties of KURT groundwater colloids were analyzed using various methods. In addition, in-situ colloid migration experiments through a rock fracture were carried out and the developed migration model was verified. We have participated in Colloid Formation and Migration (CFM) international joint project in GTS and obtained reliability for our research results by comparing research results each other

Multiscale Cues Drive Collective Cell Migration

Science.gov (United States)

Nam, Ki-Hwan; Kim, Peter; Wood, David K.; Kwon, Sunghoon; Provenzano, Paolo P.; Kim, Deok-Ho

2016-07-01

To investigate complex biophysical relationships driving directed cell migration, we developed a biomimetic platform that allows perturbation of microscale geometric constraints with concomitant nanoscale contact guidance architectures. This permits us to elucidate the influence, and parse out the relative contribution, of multiscale features, and define how these physical inputs are jointly processed with oncogenic signaling. We demonstrate that collective cell migration is profoundly enhanced by the addition of contract guidance cues when not otherwise constrained. However, while nanoscale cues promoted migration in all cases, microscale directed migration cues are dominant as the geometric constraint narrows, a behavior that is well explained by stochastic diffusion anisotropy modeling. Further, oncogene activation (i.e. mutant PIK3CA) resulted in profoundly increased migration where extracellular multiscale directed migration cues and intrinsic signaling synergistically conspire to greatly outperform normal cells or any extracellular guidance cues in isolation.

Water and contaminant movement: migration barriers

International Nuclear Information System (INIS)

Lane, L.J.; Nyhan, J.W.

1984-11-01

Migration barriers are used in shallow land burial facilities to slow or stop the movement of water and contaminants and are discussed here as a single component embedded in a complex environmental system. Analytical solutions to solute transport equations are used to approximate the behavior of migration barriers and to derive design criteria for control of subsurface water and contaminant migration. Various types of migration barriers are compared and design recommendations are made for shallow land burial trench caps and liners. Needed improvements and suggested field experiments for future designs of migration barriers are then discussed relative to the management of low-level radioactive wastes

Migration, klima og sundhed

DEFF Research Database (Denmark)

Tellier, Siri; Carballo, Manuel

2009-01-01

Many tentative connections have been postulated between migration and climate. This article points to rural-urban migration, particularly into low elevation urban slums prone to flooding as an issue needing urgent attention by health professionals. It also notes the no-man's land in which environ...

Vulnerable to HIV / AIDS. Migration.

Science.gov (United States)

Fernandez, I

1998-01-01

This special report discusses the impact of globalization, patterns of migration in Southeast Asia, gender issues in migration, the links between migration and HIV/AIDS, and spatial mobility and social networks. Migrants are particularly marginalized in countries that blame migrants for transmission of infectious and communicable diseases and other social ills. Effective control of HIV/AIDS among migrant and native populations requires a multisectoral approach. Programs should critically review the privatization of health care services and challenge economic models that polarize the rich and the poor, men and women, North and South, and migrant and native. Programs should recognize the equality between locals and migrants in receipt of health services. Countermeasures should have input from migrants in order to reduce the conditions that increase vulnerability to HIV/AIDS. Gender-oriented research is needed to understand women's role in migration. Rapid assessment has obscured the human dimension of migrants' vulnerability to HIV. Condom promotion is not enough. Migration is a major consequence of globalization, which holds the promise, real or imagined, of prosperity for all. Mass migration can be fueled by explosive regional developments. In Southeast Asia, migration has been part of the process of economic development. The potential to emigrate increases with greater per capita income. "Tiger" economies have been labor importers. Safe sex is not practiced in many Asian countries because risk is not taken seriously. Migrants tend to be used as economic tools, without consideration of social adjustment and sex behavior among singles.

Migration Flows: Measurement, Analysis and Modeling

NARCIS (Netherlands)

Willekens, F.J.; White, Michael J.

2016-01-01

This chapter is an introduction to the study of migration flows. It starts with a review of major definition and measurement issues. Comparative studies of migration are particularly difficult because different countries define migration differently and measurement methods are not harmonized.

Individual versus Household Migration Decision Rules: Gender and Marital Status Differences in Intentions to Migrate in South Africa.

Science.gov (United States)

Gubhaju, Bina; De Jong, Gordon F

2009-03-01

This research tests the thesis that the neoclassical micro-economic and the new household economic theoretical assumptions on migration decision-making rules are segmented by gender, marital status, and time frame of intention to migrate. Comparative tests of both theories within the same study design are relatively rare. Utilizing data from the Causes of Migration in South Africa national migration survey, we analyze how individually held "own-future" versus alternative "household well-being" migration decision rules effect the intentions to migrate of male and female adults in South Africa. Results from the gender and marital status specific logistic regressions models show consistent support for the different gender-marital status decision rule thesis. Specifically, the "maximizing one's own future" neoclassical microeconomic theory proposition is more applicable for never married men and women, the "maximizing household income" proposition for married men with short-term migration intentions, and the "reduce household risk" proposition for longer time horizon migration intentions of married men and women. Results provide new evidence on the way household strategies and individual goals jointly affect intentions to move or stay.

Labour Force Migration Effects within European Union

Directory of Open Access Journals (Sweden)

Carmen Mihaela Tudorache

2006-10-01

Full Text Available Within the EU, there is no common policy on migration; there are common policies on certain aspects of migration. The Member States fear of migration, but their economies and societies will further need migrant workers. Labour force migration have positive, but also negative consequences for all parties involved: receiving countries, origin countries and migrant workers. Within this framework, a common approach of the migration management and the harmonization of the economic migration policies of the Member States represent already one of the most important challenges for the European Union and will be further emphasized.

Philippine migration policy: dilemmas of a crisis.

Science.gov (United States)

Battistella, G

1999-04-01

Philippine migration policy is traced from the early 1970s to the present. The main migration trends in the 1990s are described. An assessment is made of the efficacy and appropriateness of present migration policy in light of the economic crisis. A regional approach to migration policy is necessary in order to encourage placing migration as a greater priority on national agendas and in bilateral agreements. In the Philippines, migrants are considered better paid workers, which diminishes their importance as a legislative or program priority. Santo Tomas (1998) conducted an empirical assessment of migration policies in the Philippines, but refinement is needed. Although migration is a transnational experience, there is little dialogue and cooperation among countries. Philippine migration policy defines its role as an information resource for migrants. Policy shifted from labor export to migrant management in the public and private sectors. Predeparture information program studies are recommending a multi-stage process that would involve all appropriate parties. There is talk of including migration information in the education curriculum. There are a variety of agendas, competing interests, and information resources between migration networks and officiating agencies. The Asian financial crisis may have a mild impact, but there are still issues of reintegration, protection, and employment conditions

Effort Estimation in BPMS Migration

Directory of Open Access Journals (Sweden)

Christopher Drews

2018-04-01

Full Text Available Usually Business Process Management Systems (BPMS are highly integrated in the IT of organizations and are at the core of their business. Thus, migrating from one BPMS solution to another is not a common task. However, there are forces that are pushing organizations to perform this step, e.g. maintenance costs of legacy BPMS or the need for additional functionality. Before the actual migration, the risk and the effort must be evaluated. This work provides a framework for effort estimation regarding the technical aspects of BPMS migration. The framework provides questions for BPMS comparison and an effort evaluation schema. The applicability of the framework is evaluated based on a simplified BPMS migration scenario.

Individual Decisions to Migrate During Civil Conflict

Science.gov (United States)

Bohra-Mishra, Pratikshya; Massey, Douglas S.

2012-01-01

The existing literature on forced migration limits our understanding of how violence affects migration to competing destinations. This article adds to the literature on forced migration by studying how armed violence during a period of civil conflict in south-central Nepal influenced the likelihood of local, internal, and international migration. We find that violence has a nonlinear effect on migration, such that low to moderate levels of violence reduce the odds of movement, but when violence reaches high levels, the odds of movement increase. We also find that the effect of violence on mobility increases as the distance of the move increases. When we consider the influence of violence on microlevel decision-making, we find that the effects of individual and household-level determinants were mostly consistent with hypotheses derived from contemporary theories of voluntary migration and that no predictor of migration influenced the decision to migrate differently in the presence of violence. PMID:21541805

SHARPIN Regulates Uropod Detachment in Migrating Lymphocytes

Directory of Open Access Journals (Sweden)

Jeroen Pouwels

2013-11-01

Full Text Available SHARPIN-deficient mice display a multiorgan chronic inflammatory phenotype suggestive of altered leukocyte migration. We therefore studied the role of SHARPIN in lymphocyte adhesion, polarization, and migration. We found that SHARPIN localizes to the trailing edges (uropods of both mouse and human chemokine-activated lymphocytes migrating on intercellular adhesion molecule-1 (ICAM-1, which is one of the major endothelial ligands for migrating leukocytes. SHARPIN-deficient cells adhere better to ICAM-1 and show highly elongated tails when migrating. The increased tail lifetime in SHARPIN-deficient lymphocytes decreases the migration velocity. The adhesion, migration, and uropod defects in SHARPIN-deficient lymphocytes were rescued by reintroducing SHARPIN into the cells. Mechanistically, we show that SHARPIN interacts directly with lymphocyte-function-associated antigen-1 (LFA-1, a leukocyte counterreceptor for ICAM-1, and inhibits the expression of intermediate and high-affinity forms of LFA-1. Thus, SHARPIN controls lymphocyte migration by endogenously maintaining LFA-1 inactive to allow adjustable detachment of the uropods in polarized cells.

MIGRATION AND ITS ENVIROMENTAL EFFECTS

OpenAIRE

Rashid SAEED; Rana NADIR IDREES; Humna IJAZ; Marriam FURQANI; Raziya NADEEM

2012-01-01

Migration can be ongoing shifting of a particular person from one location to another. The reason of shifting depends on selected thought deficiency, shock, difficulties, hopes, enthusiasm. Case study ended up recognizing the extent to which in turn migration can be relying on the specifics especially natural environment. This particular document expects to research the actual linkages between the atmosphere as well as migration using secondary data. Lots of investigation may be completed wit...

Nordic Migration and Integration Research

OpenAIRE

Pyrhönen, Niko; Martikainen, Tuomas; Leinonen, Johanna

2017-01-01

EXECUTIVE SUMMARY Migration and integration are currently highly contentious topics in political, public and scientific arenas, and will remain so in the near future. However, many common migration-related prejudices and inefficien¬cies in the integration of the migrant population are due to the lack of sound, tested and accessible scientific research. Therefore, the study of migration – by developing basic research and by properly resourcing novel methodological approaches and interventions ...

MIGRATION OF PLANETS EMBEDDED IN A CIRCUMSTELLAR DISK

International Nuclear Information System (INIS)

Bromley, Benjamin C.; Kenyon, Scott J.

2011-01-01

Planetary migration poses a serious challenge to theories of planet formation. In gaseous and planetesimal disks, migration can remove planets as quickly as they form. To explore migration in a planetesimal disk, we combine analytic and numerical approaches. After deriving general analytic migration rates for isolated planets, we use N-body simulations to confirm these results for fast and slow migration modes. Migration rates scale as m -1 (for massive planets) and (1 + (e H /3) 3 ) -1 , where m is the mass of a planet and e H is the eccentricity of the background planetesimals in Hill units. When multiple planets stir the disk, our simulations yield the new result that large-scale migration ceases. Thus, growing planets do not migrate through planetesimal disks. To extend these results to migration in gaseous disks, we compare physical interactions and rates. Although migration through a gaseous disk is an important issue for the formation of gas giants, we conclude that migration has little impact on the formation of terrestrial planets.

Dinâmica da umidade de um solo da Caatinga em função de sua condutividade térmica

OpenAIRE

Silans, Alain M. B. P. de; Werlang, Lovania M.

2011-01-01

A elaboração de modelos SVATs (Soil Vegetation Atmosphere Transfer - Transporte no sistema solo-vegetação-atmosfera) apropriados, é de grande importância para a compreensão dos mecanismos de transferência de fluxos à superfície, com aplicações na modelagem da circulação atmosférica, na modelagem hidrológica e na modelagem ecodinâmica da vegetação. Neste trabalho se utiliza um modelo SVAT desenvolvido especificamente na região do Cariri, estado da Paraíba, para analisar o efeito dos gradientes...

Dinâmica da umidade de um solo da Caatinga em função de sua condutividade térmica Soil moisture dynamics of a soil in 'Caatinga' as a function of the thermal conductivity

OpenAIRE

Alain M. B. P. de Silans; Lovania M. Werlang

2011-01-01

A elaboração de modelos SVATs (Soil Vegetation Atmosphere Transfer - Transporte no sistema solo-vegetação-atmosfera) apropriados, é de grande importância para a compreensão dos mecanismos de transferência de fluxos à superfície, com aplicações na modelagem da circulação atmosférica, na modelagem hidrológica e na modelagem ecodinâmica da vegetação. Neste trabalho se utiliza um modelo SVAT desenvolvido especificamente na região do Cariri, estado da Paraíba, para analisar o efeito dos gradientes...

Soil moisture dynamics of a soil in 'Caatinga' as a function of the thermal conductivity

OpenAIRE

Silans, Alain M. B. P. de; Werlang, Lovania M.

2011-01-01

A elaboração de modelos SVATs (Soil Vegetation Atmosphere Transfer - Transporte no sistema solo-vegetação-atmosfera) apropriados, é de grande importância para a compreensão dos mecanismos de transferência de fluxos à superfície, com aplicações na modelagem da circulação atmosférica, na modelagem hidrológica e na modelagem ecodinâmica da vegetação. Neste trabalho se utiliza um modelo SVAT desenvolvido especificamente na região do Cariri, estado da Paraíba, para analisar o efeito dos gradientes...

Political motivations for intra-European migration.

Science.gov (United States)

Bygnes, Susanne; Flipo, Aurore

2017-08-01

Motivations for migrating within the European Union have mainly been attributed to economic, career and lifestyle choices. This article suggests that political dissatisfaction is also an important motivator of recent intra-European migration. In our analysis of in-depth interviews with Romanian migrants in Spain and with Spanish migrants in Norway, we found a common emphasis on the political dimensions of their decision to migrate. In the interviews, the economic component of migration was often related to bad governance and negative perceptions of the state. The similarities of Spanish and Romanian migration narratives are especially striking because Spain and Romania represent substantially different migratory, political and economic contexts. However, migration is more obviously intertwined with conventional acts of political protest in the Spanish case. We suggest that differences in democratic contexts are pivotal in people's reactions to and framing of their deep dissatisfaction with domestic politics, as found in many European countries today.

International Migration with Heterogeneous Agents: Theory and Evidence

DEFF Research Database (Denmark)

Schröder, Philipp J.H.; Brücker, Herbert

Temporary migration, though empirically relevant, is often ignored in formal models. This paper proposes a migration model with heterogeneous agents and persistent cross country income differentials that features temporary migration. In equilibrium there exists a positive relation between the stock...... of migrants and the income differential, while the net migration flow becomes zero. Consequently, existing empirical migration models, estimating net migration flows, instead of stocks, may be misspecified. This suspicion appears to be confirmed by our investigation of the cointegration relationships...... of German migration stocks and flows since 1967. We find that (i) panel-unit root tests reject the hypothesis that migration flows and the explanatory variables are integrated of the same order, while migration stocks and the explanatory variables are all I(1) variables, and (ii) the hypothesis...

Expectations, gender, and norms in migration decision-making.

Science.gov (United States)

DE Jong, Gordon F

2000-01-01

This paper argues that expectations - the process of evaluating the chances for future attainment of valued goals in the home community (stay decision) vs. alternative locations (move decision) - along with family norms about migration are major predictors of intention to move, which in turn is a proximate determinant of migration behaviour. Utilizing longitudinal data from the 1992 and 1994 waves of the Thailand National Migration Survey, logistic regression models show that a strikingly different set of expectations, household demographic indicators, and migrant capital factors were significant determinants of migration intentions for men and women; reflecting Thai gender roles. Migration intentions, in turn, predicted more permanent, but not temporary, survival strategy migration behaviour, while low household income predicted temporary but not more permanent migration behaviour. The measure of perceived family migration norms was a powerful determinant of migration behaviour, but the size of migrant networks was not a statistically significant determinant of either migration intentions or behaviour.

Regulators of Intestinal Epithelial Migration in Sepsis.

Science.gov (United States)

Meng, Mei; Klingensmith, Nathan J; Liang, Zhe; Lyons, John D; Fay, Katherine T; Chen, Ching-Wen; Ford, Mandy L; Coopersmith, Craig M

2018-02-08

The gut is a continuously renewing organ, with cell proliferation, migration and death occurring rapidly under basal conditions. Since the impact of critical illness on cell movement from crypt base to villus tip is poorly understood, the purpose of this study was to determine how sepsis alters enterocyte migration. Wild type, transgenic and knockout mice were injected with 5-bromo-2'deoxyuridine (BrdU) to label cells in S phase before and after the onset of cecal ligation and puncture and were sacrificed at pre-determined endpoints to determine distance proliferating cells migrated up the crypt-villus unit. Enterocyte migration rate was decreased from 24-96 hours following sepsis. BrdU was not detectable on villi 6 days after sham laparotomy, meaning all cells had migrated the length of the gut and been exfoliated into its lumen. However, BrdU positive cells were detectable on villi 10 days after sepsis. Multiple components of gut integrity altered enterocyte migration. Sepsis decreased crypt proliferation, which further slowed enterocyte transit as mice injected with BrdU after the onset of sepsis (decreased proliferation) had slower migration than mice injected with BrdU prior to the onset of sepsis (normal proliferation). Decreasing intestinal apoptosis via gut-specific overexpression of Bcl-2 prevented sepsis-induced slowing of enterocyte migration. In contrast, worsened intestinal hyperpermeability by genetic deletion of JAM-A increased enterocyte migration. Sepsis therefore significantly slows enterocyte migration, and intestinal proliferation, apoptosis and permeability all affect migration time, which can potentially be targeted both genetically and pharmacologically.

International migration desires related to subjective well-being

OpenAIRE

Cai, Ruohong; Esipova, Neli; Oppenheimer, Michael; Feng, Shuaizhang

2014-01-01

Previous research on the determinants of international migration has largely focused on objective factors, such as income. We instead use subjective well-being (SWB) to explain international migration desires, an expressed willingness to migrate. We find that individuals with higher SWB have lower international migration desires. At the individual level, the SWB-migration relationship appears to be more robust than the income-migration relationship. At the country level, national average SWB ...

The migration of uranium through sandstone

International Nuclear Information System (INIS)

Bennett, D.G.; Read, D.; Lawless, T.A.; Sims, R.J.

1992-01-01

Three column experiments are described in which the migration of uranium through Clashach Sandstone was studied. A priori predictions of uranium migration in the experiments were made using an equilibrium chemical transport model. The experimental results showed that, even under oxidising conditions, the migration of uranium is strongly retarded owing to the affinity of uranium for mineral surfaces. For the relatively simple chemical system investigated, the chemical transport model was successful in predicting the migration of uranium and its distribution along the column. (author)

The challenges of managing migration

Energy Technology Data Exchange (ETDEWEB)

Tacoli, Cecilia

2005-10-15

Migration and urbanisation are driven by economic growth and social change, but also by deepening inequalities. Managing migration should not be equated with curbing it, as this inevitably reduces migrants' rights. But managing population movement whilst respecting the rights of migrants and nonmigrants, supporting the contribution of migration to poverty reduction and economic growth in sending and receiving areas and reducing the human and material costs of movement means that fundamental challenges need to be addressed.

Migration Theories and Mental Health in Toni Morrison's Jazz

Directory of Open Access Journals (Sweden)

Leila Tafreshi Motalgh

2015-01-01

Full Text Available This article aims to elaborate the relationship between migration and mental health problems that are evident in migrant women in Toni Morrison's Jazz (1992. To this end, pre-migration, migration and post-migration stress factors are identified in the novel based on Danish Bhugra's theory of migration. It seems that pre-migration stress factors and traumas are associated with the push theory of migration, while post-migration stresses are associated with the pull theory of migration. Despite post-migration stresses, the main female characters who encounter pre-migration stress factors and traumas are more likely to develop mental health problems like Post-traumatic Stress Disorder (PTSD. Although there is extensive literary criticism of Jazz (1992, no theoretical criticism exists that simultaneously covers migration theories and the mental health problems evident in Toni Morrison's female characters. It is worth highlighting that gender is a variable that correlates positively with migration and mental health. This article attempts to fill a gap in literary criticism and contribute to the body of research on mental health problems associated with gender and migration. Keywords: Push-Pull Theory, Great Migration, Black Studies, Gender, Trauma, PTSD

Migration Studies and Academic Research on International Migration Policies in Argentina

Directory of Open Access Journals (Sweden)

Eduardo Domenech

2017-05-01

Full Text Available This article approaches the historical development of the field of migratory studies in Argentina and makes a review of the academic production around the so - called "migratory policies." The systematization of these studies, historically placed on migration policies, aims to highlight some of the most significant contributions of the research during the last 30 years, to understand or explain various aspects and dimensions of the Argentinean migration policy. To achieve this, texts were selected that derived from empirical research that explicitly assume the migratory policies as the object of study, or whose themes and research problems adopt as a framework for discussion the policies and practices aimed at regulating migration and mobility in Argentina. The organization and presentation of these selected texts consider issues related to the interests and thematic concerns, disciplinary and analytical approaches, distinct periods, scales of analysis and sources of information.

MIGRATE: A FOSS WEB MAPPING APPLICATION FOR EDUCATING AND RAISING AWARENESS ABOUT MIGRATION FLOWS IN EUROPE

Directory of Open Access Journals (Sweden)

M. A. Brovelli

2017-07-01

Full Text Available Recent years have seen a noticeable growth in migration flows from Africa and Middle East to Southern Europe, thus generating a remarkable increase of attention on media and public opinion, sometimes resulting in stereotypes and prejudices. Funded by the European Commission – Joint Research Centre through the MYGEOSS program, MIGRation pATtterns in Europe (MIGRATE aims at educating the citizens about migration fluxes in Europe using a gamification approach based on a trivia game. MIGRATE is completely developed with Free and Open Source Software. On the server-side Django is used to define the models that handle all the required data and tables are created in a PostgreSQL database. Questions and answers are sent in JSON format to the client, while the geospatial layers in GeoJSON format are rendered on the map interface using OpenLayers 3. Bootstrap, HTML5 and CSS3 are used for responsive design, while the jQuery library is used to ease the JavaScript programming. All the data sources used within MIGRATE are available as full and open access with no restrictions for reuse, except for the obligation to mention the source of the input data. Exploited data sources include OpenStreetMap for geospatial information, and UNHCR, IOM, Eurostat and The Migrant’s Files project for non-geospatial information. Overall, data shows how the users’ perceptions change while playing and that players’ awareness of migration-related problems increases with the number of games played. The source code of MIGRATE and the collected data are available respectively under the EU Public License (EUPL and the CC BY 4.0 license.

Morphological constraints on changing avian migration phenology.

Science.gov (United States)

Møller, A P; Rubolini, D; Saino, N

2017-06-01

Many organisms at northern latitudes have responded to climate warming by advancing their spring phenology. Birds are known to show earlier timing of spring migration and reproduction in response to warmer springs. However, species show heterogeneous phenological responses to climate warming, with those that have not advanced or have delayed migration phenology experiencing population declines. Although some traits (such as migration distance) partly explain heterogeneity in phenological responses, the factors affecting interspecies differences in the responsiveness to climate warming have yet to be fully explored. In this comparative study, we investigate whether variation in wing aspect ratio (reflecting relative wing narrowness), an ecomorphological trait that is strongly associated with flight efficiency and migratory behaviour, affects the ability to advance timing of spring migration during 1960-2006 in a set of 80 European migratory bird species. Species with larger aspect ratio (longer and narrower wings) showed smaller advancement of timing of spring migration compared to species with smaller aspect ratio (shorter and wider wings) while controlling for phylogeny, migration distance and other life-history traits. In turn, migration distance positively predicted aspect ratio across species. Hence, species that are better adapted to migration appear to be more constrained in responding phenologically to rapid climate warming by advancing timing of spring migration. Our findings corroborate the idea that aspect ratio is a major evolutionary correlate of migration, and suggest that selection for energetically efficient flights, as reflected by high aspect ratio, may hinder phenotypically plastic/microevolutionary adjustments of migration phenology to ongoing climatic changes. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Making the most out of least-squares migration

KAUST Repository

Huang, Yunsong

2014-09-01

Standard migration images can suffer from (1) migration artifacts caused by an undersampled acquisition geometry, (2) poor resolution resulting from a limited recording aperture, (3) ringing artifacts caused by ripples in the source wavelet, and (4) weak amplitudes resulting from geometric spreading, attenuation, and defocusing. These problems can be remedied in part by least-squares migration (LSM), also known as linearized seismic inversion or migration deconvolution (MD), which aims to linearly invert seismic data for the reflectivity distribution. Given a sufficiently accurate migration velocity model, LSM can mitigate many of the above problems and can produce more resolved migration images, sometimes with more than twice the spatial resolution of standard migration. However, LSM faces two challenges: The computational cost can be an order of magnitude higher than that of standard migration, and the resulting image quality can fail to improve for migration velocity errors of about 5% or more. It is possible to obtain the most from least-squares migration by reducing the cost and velocity sensitivity of LSM.

Effects of particles on macrophage migration

International Nuclear Information System (INIS)

Mueller, H.L.; Robinson, B.; Muggenburg, B.A.; Guilmette, R.A.

1988-01-01

Random and directed migration of cells lavaged from the lungs of rats and dogs were studied in vitro using formyl-methionyl-leucyl-phenylalanine (FMLP) as a chemo attractant. Rats and dogs were intratracheally instilled with either saline (controls) or about 10 9 fluorescent polystyrene microspheres, and lungs were lavaged after 1 or 7 days. More rat cells than dog cells migrated at 1 day after both particle and saline instillations; at 7 days, only cells lavaged from rats after particle instillations showed enhanced migration abilities. FMLP caused a 1.5 to 2-fold enhancement compared to random migration in cell numbers counted on the lower sides of chemotactic membranes. Cells with low particle numbers were more likely to migrate than those with high numbers of ingested particles. (author)

Rural migration in Nevada: Lincoln County

International Nuclear Information System (INIS)

Soden, D.L.; Carns, D.E.; Mosser, D.; Conary, J.S.; Ansell, J.P.

1993-01-01

The principal objective of this project was to develop insight into the scope of migration of working age Nevadans out of their county of birth; including the collection of data on their skill levels, desire to out or in-migrate, interactions between families of migratory persons, and the impact that the proposed high-level nuclear waste repository at Yucca mountain might have on their individual, and collective, decisions to migrate and return. The initial phase of this project reported here was conducted in 1992 and 1993 in Lincoln County, Nevada, one of the counties designated as ''affected'' by the proposed repository program. The findings suggest that a serious out-migration problem in Lincoln County, and that the Yucca mountain project will likely affect decisions relating to migration patterns in the future

75 FR 3479 - Mortgagee Review Board: Administrative Actions

Science.gov (United States)

2010-01-21

...-9763-MR] 5. All American Home Mortgages LLC, Henderson, NV [Docket No. 09-9764-MR] 6. American Capital...-MR] 29. Numerica Mortgage LLC, Virginia Beach, VA [Docket No. 09- 9510-MR] 30. Paladin Financial...

The accretion of migrating giant planets

Science.gov (United States)

Dürmann, Christoph; Kley, Wilhelm

2017-02-01

Aims: Most studies concerning the growth and evolution of massive planets focus either on their accretion or their migration only. In this work we study both processes concurrently to investigate how they might mutually affect one another. Methods: We modeled a two-dimensional disk with a steady accretion flow onto the central star and embedded a Jupiter mass planet at 5.2 au. The disk is locally isothermal and viscosity is modeled using a constant α. The planet is held on a fixed orbit for a few hundred orbits to allow the disk to adapt and carve a gap. After this period, the planet is released and free to move according to the gravitational interaction with the gas disk. The mass accretion onto the planet is modeled by removing a fraction of gas from the inner Hill sphere, and the removed mass and momentum can be added to the planet. Results: Our results show that a fast migrating planet is able to accrete more gas than a slower migrating planet. Utilizing a tracer fluid we analyzed the origin of the accreted gas originating predominantly from the inner disk for a fast migrating planet. In the case of slower migration, the fraction of gas from the outer disk increases. We also found that even for very high accretion rates, in some cases gas crosses the planetary gap from the inner to the outer disk. Our simulations show that the crossing of gas changes during the migration process as the migration rate slows down. Therefore, classical type II migration where the planet migrates with the viscous drift rate and no gas crosses the gap is no general process but may only occur for special parameters and at a certain time during the orbital evolution of the planet.

Circadian flight schedules in night-migrating birds caught on migration.

Science.gov (United States)

Coppack, Timothy; Becker, Simon F; Becker, Philipp J J

2008-12-23

Many species of migratory birds migrate in a series of solitary nocturnal flights. Between flights, they stop to rest and refuel for the next segment of their journey. The mechanism controlling this behaviour has long remained elusive. Here, we show that wild-caught migratory redstarts (Phoenicurus phoenicurus) are consistent in their flight scheduling. An advanced videographic system enabled us to determine the precise timing of flight activity in redstarts caught at a northern European stopover site during their return trip from Africa. Birds were held captive for three days in the absence of photoperiodic cues (constant dim light) and under permanent food availability. Despite the absence of external temporal cues, birds showed clear bimodal activity patterns: intense nocturnal activity alternating with diurnal foraging and resting periods. The onset of their migratory activity coincided with the time of local sunset and was individually consistent on consecutive nights. The data demonstrate that night-migrating birds are driven by autonomous circadian clocks entrained by sunset cues. This timekeeping system is probably the key factor in the overall control of nocturnal songbird migration.

An economic analysis of migration in Mexico.

Science.gov (United States)

Greenwood, M J; Ladman, J R

1978-07-01

This paper analyzes internal migration in Mexico over the 1960-70 period. A model of the determinants of migration is specified and estimated for aggregated interstate migration flows. Results show that distance serves as a significant deterrent to migration, that higher destination earning levels are attractive to migrants, and that regions with high unemployment rates experience lower rates of inmigration. An unanticipated finding is that regions with higher earning levels have greater rates of outmigration. The data are disaggregated to examine separate migration relationships for each state. The results are that distance is a lesser deterrent for those migrants with more accessible alternatives, that higher earning levels reduce the deterring effects of distance, and that regions with higher earning levels have lower associated elasticities of migration. It is concluded that economic factors have played a crucial role in internal migration and thus in the changing occupational and geographic structure of the Mexican labor force.

Plane-wave Least-squares Reverse Time Migration

KAUST Repository

Dai, Wei

2012-11-04

Least-squares reverse time migration is formulated with a new parameterization, where the migration image of each shot is updated separately and a prestack image is produced with common image gathers. The advantage is that it can offer stable convergence for least-squares migration even when the migration velocity is not completely accurate. To significantly reduce computation cost, linear phase shift encoding is applied to hundreds of shot gathers to produce dozens of planes waves. A regularization term which penalizes the image difference between nearby angles are used to keep the prestack image consistent through all the angles. Numerical tests on a marine dataset is performed to illustrate the advantages of least-squares reverse time migration in the plane-wave domain. Through iterations of least-squares migration, the migration artifacts are reduced and the image resolution is improved. Empirical results suggest that the LSRTM in plane wave domain is an efficient method to improve the image quality and produce common image gathers.

Elastic kirchhoff migration for vertical seismic profiles

International Nuclear Information System (INIS)

Keho, T.H.; Wu, R.S.

1987-01-01

Elastic Kirchhoff migration is implemented for the VSP recording geometry. The resulting migration formula requires measurement of the stress as well as the displacement. Since stress is not measured in a VSP, and in many cases the horizontal component of displacement is not measured, approximate migration formulas are given for these cases. The elastic migration formula for the case where only the vertical components are available, is the same as the acoustic migration formula, where the pressure data are replaced by the magnitudes of the elastic data as reconstructed from the vertical components, and the acoustic Green's functions are replaced with either the P or S wave elastic Green's functions. Two expressions for migration of two component displacement data are presented. In the first, the terms involving traction data are simply ignored. In the second, an improved backpropagation operator for the displacement field is obtained by replacing the traction data in the Kirchhoff integral by displacement data using Hooke's law. The migration expressions for the cases where two component data are available produce images which are less contaminated by artifacts than the migration images of one component data

Multi-source least-squares reverse time migration

KAUST Repository

Dai, Wei

2012-06-15

Least-squares migration has been shown to improve image quality compared to the conventional migration method, but its computational cost is often too high to be practical. In this paper, we develop two numerical schemes to implement least-squares migration with the reverse time migration method and the blended source processing technique to increase computation efficiency. By iterative migration of supergathers, which consist in a sum of many phase-encoded shots, the image quality is enhanced and the crosstalk noise associated with the encoded shots is reduced. Numerical tests on 2D HESS VTI data show that the multisource least-squares reverse time migration (LSRTM) algorithm suppresses migration artefacts, balances the amplitudes, improves image resolution and reduces crosstalk noise associated with the blended shot gathers. For this example, the multisource LSRTM is about three times faster than the conventional RTM method. For the 3D example of the SEG/EAGE salt model, with a comparable computational cost, multisource LSRTM produces images with more accurate amplitudes, better spatial resolution and fewer migration artefacts compared to conventional RTM. The empirical results suggest that multisource LSRTM can produce more accurate reflectivity images than conventional RTM does with a similar or less computational cost. The caveat is that the LSRTM image is sensitive to large errors in the migration velocity model. © 2012 European Association of Geoscientists & Engineers.

Multi-source least-squares reverse time migration

KAUST Repository

Dai, Wei; Fowler, Paul J.; Schuster, Gerard T.

2012-01-01

Least-squares migration has been shown to improve image quality compared to the conventional migration method, but its computational cost is often too high to be practical. In this paper, we develop two numerical schemes to implement least-squares migration with the reverse time migration method and the blended source processing technique to increase computation efficiency. By iterative migration of supergathers, which consist in a sum of many phase-encoded shots, the image quality is enhanced and the crosstalk noise associated with the encoded shots is reduced. Numerical tests on 2D HESS VTI data show that the multisource least-squares reverse time migration (LSRTM) algorithm suppresses migration artefacts, balances the amplitudes, improves image resolution and reduces crosstalk noise associated with the blended shot gathers. For this example, the multisource LSRTM is about three times faster than the conventional RTM method. For the 3D example of the SEG/EAGE salt model, with a comparable computational cost, multisource LSRTM produces images with more accurate amplitudes, better spatial resolution and fewer migration artefacts compared to conventional RTM. The empirical results suggest that multisource LSRTM can produce more accurate reflectivity images than conventional RTM does with a similar or less computational cost. The caveat is that the LSRTM image is sensitive to large errors in the migration velocity model. © 2012 European Association of Geoscientists & Engineers.

Migration and Literature

DEFF Research Database (Denmark)

Frank, Søren

We live in an age of migration and more and more authors have migrant backgrounds. Migration and Literature offers a thorough and thought provoking examination of the thematic and formal role of migration in four contemporary and canonized novelists, Günter Grass, Milan Kundera, Salman Rushdie, a......, and Jan Kjærstad. This book examines how these novelists reflect, problematize, and "resolve" the problems set by the migratory world and analyzes how the novels employ discursive strategies which emphasize their migratory and homeless form....

Demographic situation and population migration problems

International Nuclear Information System (INIS)

1993-01-01

Problem of the Chernobyl accident effect on the population migration in controlled areas of the Ukraine, Belarus and in Russian Federation. Comparison of the data on migration for 1990 and for 1995 has shown considerable growth of the intensity of efflux of rural population at most Ukrainian areas affected due to the Chernobyl accident. Negative migration growth in urban settlements of these regions is marked. Decrease in rural resident migration is observed. Migrant current in Russia is twice increased. Main regions of North-West, Central, North-Caucasus ones in Russia and Donetsk-Dnieper river in the Ukraine. 6 tabs

Anti-Aliasing filter for reverse-time migration

KAUST Repository

Zhan, Ge

2012-01-01

We develop an anti-aliasing filter for reverse-time migration (RTM). It is similar to the traditional anti-aliasing filter used for Kirchhoff migration in that it low-pass filters the migration operator so that the dominant wavelength in the operator is greater than two times the trace sampling interval, except it is applied to both primary and multiple reflection events. Instead of applying this filter to the data in the traditional RTM operation, we apply the anti-aliasing filter to the generalized diffraction-stack migration operator. This gives the same migration image as computed by anti-aliased RTM. Download

LHCb migration from Subversion to Git

Science.gov (United States)

Clemencic, M.; Couturier, B.; Closier, J.; Cattaneo, M.

2017-10-01

Due to user demand and to support new development workflows based on code review and multiple development streams, LHCb decided to port the source code management from Subversion to Git, using the CERN GitLab hosting service. Although tools exist for this kind of migration, LHCb specificities and development models required careful planning of the migration, development of migration tools, changes to the development model, and redefinition of the release procedures. Moreover we had to support a hybrid situation with some software projects hosted in Git and others still in Subversion, or even branches of one projects hosted in different systems. We present the way we addressed the special LHCb requirements, the technical details of migrating large non standard Subversion repositories, and how we managed to smoothly migrate the software projects following the schedule of each project manager.

Theories of international labor migration: an overview.

Science.gov (United States)

Stahl, C W

1995-01-01

"Emigration pressures are primarily the result of increasing inequalities between countries which, in turn, are the result of factors internal to less developed countries and their relations with developed countries. Both micro (neoclassical) and macrostructural theories of migration are reviewed. It is argued that the neoclassical theory of migration is often unjustly criticized and is sufficiently robust to incorporate those structural considerations which are at the core of macrostructural theories. Moreover, the neoclassical theory, with slight modification, can incorporate the ¿new economics of migration.' The major empirical problem confronting models of international labor migration is that migration flows are constrained by immigration policy. This policy, in turn, is influenced by various special interest groups. The direction and form of migration flows is conditioned by contemporary and historical relationships between source and destination countries." excerpt

International migration: a global challenge.

Science.gov (United States)

Martin, P; Widgren, J

1996-04-01

Trends in international migration are presented in this multiregional analysis. Seven of the world's wealthiest countries have about 33% of the world's migrant population, but under 16% of the total world population. Population growth in these countries is substantially affected by the migrant population. The migration challenge is external and internal. The external challenge is to balance the need for foreign labor and the commitment to human rights for those migrants seeking economic opportunity and political freedom. The internal challenge is to assure the social adjustment of immigrants and their children and to integrate them into society as citizens and future leaders. Why people cross national borders and how migration flows are likely to evolve over the next decades are explained. This report also presents some ways that countries can manage migration or reduce the pressures which force people to migrate. It is recommended that receiving nations control immigration by accelerating global economic growth and reducing wars and human rights violations. This report examines the impact of immigration on international trade, aid, and direct intervention policies. Although migration is one of the most important international economic issues, it is not coordinated by an international group. The European experience indicates that it is not easy to secure international cooperation on issues that affect national sovereignty. It is suggested that countries desiring control of their borders should remember that most people never cross national borders to live or work in another country, that 50% of the world's migrants move among developing countries, and that countries can shift from being emigration to immigration countries. The author suggests that sustained reductions in migration pressure are a better alternative than the "quick fixes" that may invite the very much feared mass and unpredictable movements.

Globalization of international migration: Social challenges and policy implication

Directory of Open Access Journals (Sweden)

I A Aleshkovski

2017-12-01

Full Text Available In the second half of the XX century, the humankind witnessed the insurmountable and irreversible power of globalization processes, which influence all spheres of social life and establish a global system of interdependency between countries and nations. Globalization within impetuous changes in global political, social and economic systems has determined dramatic shifts in the international migration processes that lead to the new stage of migration history. In nowadays globalized world, international migration has become a reality for almost all corners of the globe. The author considers features of the recent trends of international migration: the unprecedented growth of the international migration flows; the widening geography of international migration that involves nearly all countries of the world; qualitative changes in the structure of international migration flows; the key role of economic migration; the permanent growth and structural intricateness of irregular migration; the increasing scale and geographical widening of forced migration; the growing importance of international migration for the demographic development of the world, countries of both origin and destination. All these trends combined prove that the international migration patterns have become more complex. The author analyzes the legal framework of the international migration processes, and gives recommendations on the ways to improve the control and regulation of migration processes. Specific issues related to the social challenges of international migration are also discussed in the article.

Fluid migration studies in salt

International Nuclear Information System (INIS)

Shefelbine, H.C.; Raines, G.E.

1980-01-01

This discussion will be limited to the migration of water trapped in the rock salt under the influence of the heat field produced by nuclear waste. This is of concern because hypotheticl scenarios have been advanced in which this fluid movement allows radionuclides to escape to the biosphere. While portions of these scenarios are supported by observation, none of the complete scenarios has been demonstrated. The objectives of the present fluid migration studies are two-fold: 1. determine the character of the trapped fluid in terms of quantity, habitat and chemical constituents; and 2. define the mechanisms that cause the fluid to migrate toward heat sources. Based on the observations to date, fluid migration will not have a major impact on repository integrity. However, the above objectives will be pursued until the impacts, if any, can be quantified

Migration within China and from China to the USA: the effects of migration networks, selectivity, and the rural political economy in Fujian Province.

Science.gov (United States)

Liang, Zai; Chunyu, Miao David

2013-07-01

This paper tests a new strategy for simultaneously studying internal migration within, and international migration from, China. Our theoretical discussion draws on ideas from migration-networks theory and studies of the transition to a market-oriented economy. Data collection is modelled on the Mexican Migration Project. We find that education is more important in initiating internal migration than international migration. Second, although the role of migration networks at a community level seems similar to that for Mexico-USA migration, the networks at a family level show a different pattern. Third, there is evidence that internal and international migration are competing options. Finally, we find that individuals with cadres (public officials) in the family are less likely to undertake internal migration, but more likely to participate in international migration, a finding that highlights the continuing significance of the cadres in coastal rural China.

Migration in Deltas: An Integrated Analysis

Science.gov (United States)

Nicholls, Robert J.; Hutton, Craig W.; Lazar, Attila; Adger, W. Neil; Allan, Andrew; Arto, Inaki; Vincent, Katharine; Rahman, Munsur; Salehin, Mashfiqus; Sugata, Hazra; Ghosh, Tuhin; Codjoe, Sam; Appeaning-Addo, Kwasi

2017-04-01

Deltas and low-lying coastal regions have long been perceived as vulnerable to global sea-level rise, with the potential for mass displacement of exposed populations. The assumption of mass displacement of populations in deltas requires a comprehensive reassessment in the light of present and future migration in deltas, including the potential role of adaptation to influence these decisions. At present, deltas are subject to multiple drivers of environmental change and often have high population densities as they are accessible and productive ecosystems. Climate change, catchment management, subsidence and land cover change drive environmental change across all deltas. Populations in deltas are also highly mobile, with significant urbanization trends and the growth of large cities and mega-cities within or adjacent to deltas across Asia and Africa. Such migration is driven primarily by economic opportunity, yet environmental change in general, and climate change in particular, are likely to play an increasing direct and indirect role in future migration trends. The policy challenges centre on the role of migration within regional adaptation strategies to climate change; the protection of vulnerable populations; and the future of urban settlements within deltas. This paper reviews current knowledge on migration and adaptation to environmental change to discern specific issues pertinent to delta regions. It develops a new integrated methodology to assess present and future migration in deltas using the Volta delta in Ghana, Mahanadi delta in India and Ganges-Brahmaputra-Meghna delta across India and Bangladesh. The integrated method focuses on: biophysical changes and spatial distribution of vulnerability; demographic changes and migration decision-making using multiple methods and data; macro-economic trends and scenarios in the deltas; and the policies and governance structures that constrain and enable adaptation. The analysis is facilitated by a range of

Navigational Strategies of Migrating Monarch Butterflies

Science.gov (United States)

2014-11-10

AFRL-OSR-VA-TR-2014-0339 NAVIGATIONAL STRATEGIES OF MIGRATING MONARCH BUTTERFLIES Steven Reppert UNIVERSITY OF MASSACHUSETTS Final Report 11/10/2014...Final Progress Statement to (Dr. Patrick Bradshaw) Contract/Grant Title: Navigational Strategies of Migrating Monarch Butterflies Contract...Grant #: FA9550-10-1-0480 Reporting Period: 01-Sept-10 to 31-Aug-14 Overview of accomplishments: Migrating monarch butterflies (Danaus

[The productive structure and migration].

Science.gov (United States)

Fernandez, M

1980-01-01

The author discusses the possibility of determining the proper approach to the study of migration, with a focus on the importance of global, structural, and historical analysis of the phenomenon. A general theoretical outline is presented that tends to show migration as an integral part of the process of social change. The sociological focus on modernization as a theoretical guide influencing the study of migration in Latin America is evaluated. The concept of overpopulation is explained in relation to the migratory process, with reference to capitalist and non-capitalist forms of production.

Migration and Remittances Factbook 2016, Third Edition

OpenAIRE

World Bank Group

2016-01-01

The Migration and Remittances Factbook 2016 attempts to present numbers and facts behind the stories of international migration and remittances, drawing on authoritative, publicly available data. It provides a snapshot of statistics on immigration, emigration, skilled emigration, and remittance flows for 210 countries and 15 regional and income groups. The Migration and Remittances Factbook 2016 updates the 2011 edition of the Factbook with additional data on bilateral migration and remittanc...

Globalization and formal sector migration in Brazil

OpenAIRE

Aguayo-Tellez, Ernesto; Muendler, Marc-Andreas; Poole, Jennifer Pamela

2008-01-01

We use novel linked employer–employee data to study the relationship between globalization and formal sector interstate migration for Brazil. We estimate the worker’s multichoice migration problem and document that previously unobserved employer covariates are significant predictors associated with migration flows. Our results provide support for the idea that globalization acts on internal migration through the growth of employment opportunities at locations with a high concentration of fore...

THE ROMANIAN MIGRATIONAL EVOLUTION PHENOMENON

Directory of Open Access Journals (Sweden)

Cristian Raluca

2009-05-01

Full Text Available In our contemporary democratic society the migration phenomenon meets unknown valences in any previous societies. Free will and right to self-determination, much exploited by the XX century society., raised the possibility of interpretation of migration

"International Division of Labour and Migration as a Global Labour Supply---A Theoretical Perspective to Study International Migration---"

OpenAIRE

Masaki Takenouchi

2001-01-01

Why did not mass migration from the Third World to the highly-developed countries occur before the Second World War? This is a simple but important question, since the preponderance of the migration from the "South" to the "North" is a main characteristic of the contemporary international migration. The orthodox explanations of migration based on the concept of the national economy as a unit of analysis do not give us clues to answer this question. Neither do these by the world-system approac...

Migration: a concept analysis from a nursing perspective.

Science.gov (United States)

Freeman, Michelle; Baumann, Andrea; Blythe, Jennifer; Fisher, Anita; Akhtar-Danesh, Noori

2012-05-01

  This article is a report of a concept analysis of nurse migration.   International migration is increasing and nurse migrants are active participants in this movement. Migration is a complex term and can be examined from a range of perspectives. Analysis of nurse migration is needed to guide policy, practice and research.   A literature search was undertaken using electronic literature indexes, specific journals and websites, internet search engines and hand searches. No timeframe was placed on the search. Most literature found was published between 2001 and 2009. A sample of 80 documents met the inclusion criteria.   Walker and Avant's approach guided the analysis.   Nurse migration can be defined by five attributes: the motivation and decisions of individuals; external barriers and facilitators; freedom of choice to migrate; freedom to migrate as a human right, and dynamic movement. Antecedents of migration include the political, social, economic, legal, historical and educational forces that comprise the push and pull framework. The consequences of migration are positive or negative depending on the viewpoint and its affect on the individual and other stakeholders such as the source country, destination country, healthcare systems and the nursing profession.   This concept analysis clarified the complexities surrounding nurse migration. A nursing-specific middle-range theory was proposed to guide the understanding and study of nurse migration. © 2011 Blackwell Publishing Ltd.

Underground radionuclide migration at the Nevada Test Site

International Nuclear Information System (INIS)

Nimz, G.J.; Thompson, J.L.

1992-01-01

This document reviews results from a number of studies concerning underground migration of radionuclides from nuclear test cavities at the Nevada Test Site (NTS). Discussed are all cases known to the Department of Energy's Hydrology and Radionuclide Migration Program where radionuclides have been detected outside of the immediate vicinity of nuclear test cavities that are identifiable as the-source of the nuclides, as well as cases where radionuclides might have been expected and were intentionally sought but not fixed. There are nine locations where source-identifiable radionuclide migration has been detected, one where migration was purposely induced by pumping, and three where migration might be expected but was not found. In five of the nine cases of non-induced migration, the inferred migration mechanism is prompt fracture injection during detonation. In the other four cases, the inferred migration mechanism is water movement. In only a few of the reviewed cases can the actual migration mechanism be stated with confidence, and the attempt has been made to indicate the level of confidence for each case. References are cited where more information may be obtained. As an aid to future study, this document concludes with a brief discussion of the aspects of radionuclide migration that, as the present review indicates, are not yet understood. A course of action is suggested that would produce a better understanding of the phenomenon of radionuclide migration

Field tests on migration of TRU-nuclide, (2). Migration test for engineered barrier materials in aerated soil

International Nuclear Information System (INIS)

Maeda, Toshikatsu; Tanaka, Tadao; Mukai, Masayuki

2003-01-01

Field tests on migration of radionuclides for engineered barrier materials such as bentonite and cementitious materials were performed. The tests were run under both wet conditions with artificial rainfall and dry conditions with natural rainfall. Laboratory experiments such as batch adsorption tests were also conducted to analyze the result of field test. The results of field tests agreed with the predicted moisture conditions and the migration behaviors observed at the laboratory experiment that is reported so far. For bentonite material, the movements of the tracer were calculated using known information such as the results of batch sorption tests and migration mechanism. Comparing the result of field test and calculations, it is suggested that tracer migration behavior in bentonite material in field can be evaluated quantitatively by the known migration mechanism and the results of laboratory experiments such as batch sorption test. (author)

Migration stopover ecology of western avian populations: A southwestern migration workshop

Science.gov (United States)

Skagen, Susan K.; Melcher, Cynthia P.; Hazelwood, Rob

2004-01-01

The importance of migration stopover sites in ensuring that migratory birds successfully accomplish their journeys between breeding and non-breeding ranges has come to the forefront of avian research. Migratory birds that breed in western United States (US) and Canada and overwinter primarily in western Mexico migrate across the arid region of northern Mexico and southwestern US. Many of these migrants use lowland riparian stopover habitats, which comprise less than 0.1% of the western U.S. landscape. These habitats represent a significant conservation priority.

Radionuclide migration studies in soil

International Nuclear Information System (INIS)

Marumo, J.T.

1989-01-01

In this work a brief description about retention and migration parameters of radionuclides in soil, including main methods to determine the distribution coefficient (K) are given. Some of several factors that can act on the migration are also mentioned. (author) [pt

The Last Adventure: Retirement Migration, Climate and "Amenities"

Directory of Open Access Journals (Sweden)

Saša Božić

2001-12-01

Full Text Available The rising number of European retirement migrants on the Mediterranean coasts, especially in the EU countries shows that the practical and scientific relevance of the new forms of migration in Europe is on the rise. "Retirement migration" evolved from a descriptive term to a candidate for a scientific or a research concept, at least if the use of the term IRM (international retirement migration is considered. However, it is necessary to solve several problems before this term can really become a coherent concept, useful for the research and explanation of the "new" migration phenomena. The author claims that the studies usually do not distinguish clearly between the migration of the elderly and retirement migration. The naming of the concept in this case mixes the characteristics of the migrants with the reasons for migration. The author shows that the usually mentioned reasons for retirement migration cannot be clearly formulated as factors which explain retirement migration. Further on, retirement as such is not a pull, push or staying put factor. Migration rates of retired, although rising, are still lower than the migration rates of the working age population and the Mediterranean coasts are also a destination for professionals who have the means to detach the job from the working place. Only a combination of conditions that enable migration and migration decisions, as well as a combination of motives and perceptions of reasons for migration, can partially "explain" retirement migration. One of the problems that has to be solved before retirement migration is affirmed as a concept is the treatment of the temporal and spatial dimension of the mobility of the retirement migrants. The author shows that a clear positioning of retirement migration on the temporal scale of mobility is hardly possible. Retirement migration is too wide and too complex a phenomenon to be easily localised in the temporal continuum. A similar problem emerges when the

Multi-cellular logistics of collective cell migration.

Directory of Open Access Journals (Sweden)

Masataka Yamao

Full Text Available During development, the formation of biological networks (such as organs and neuronal networks is controlled by multicellular transportation phenomena based on cell migration. In multi-cellular systems, cellular locomotion is restricted by physical interactions with other cells in a crowded space, similar to passengers pushing others out of their way on a packed train. The motion of individual cells is intrinsically stochastic and may be viewed as a type of random walk. However, this walk takes place in a noisy environment because the cell interacts with its randomly moving neighbors. Despite this randomness and complexity, development is highly orchestrated and precisely regulated, following genetic (and even epigenetic blueprints. Although individual cell migration has long been studied, the manner in which stochasticity affects multi-cellular transportation within the precisely controlled process of development remains largely unknown. To explore the general principles underlying multicellular migration, we focus on the migration of neural crest cells, which migrate collectively and form streams. We introduce a mechanical model of multi-cellular migration. Simulations based on the model show that the migration mode depends on the relative strengths of the noise from migratory and non-migratory cells. Strong noise from migratory cells and weak noise from surrounding cells causes "collective migration," whereas strong noise from non-migratory cells causes "dispersive migration." Moreover, our theoretical analyses reveal that migratory cells attract each other over long distances, even without direct mechanical contacts. This effective interaction depends on the stochasticity of the migratory and non-migratory cells. On the basis of these findings, we propose that stochastic behavior at the single-cell level works effectively and precisely to achieve collective migration in multi-cellular systems.

Light pollution is greatest within migration passage areas for nocturnally-migrating birds around the world.

Science.gov (United States)

Cabrera-Cruz, Sergio A; Smolinsky, Jaclyn A; Buler, Jeffrey J

2018-02-19

Excessive or misdirected artificial light at night (ALAN) produces light pollution that influences several aspects of the biology and ecology of birds, including disruption of circadian rhythms and disorientation during flight. Many migrating birds traverse large expanses of land twice every year at night when ALAN illuminates the sky. Considering the extensive and increasing encroachment of light pollution around the world, we evaluated the association of the annual mean ALAN intensity over land within the geographic ranges of 298 nocturnally migrating bird species with five factors: phase of annual cycle, mean distance between breeding and non-breeding ranges, range size, global hemisphere of range, and IUCN category of conservation concern. Light pollution within geographic ranges was relatively greater during the migration season, for shorter-distance migrants, for species with smaller ranges, and for species in the western hemisphere. Our results suggest that migratory birds may be subject to the effects of light pollution particularly during migration, the most critical stage in their annual cycle. We hope these results will spur further research on how light pollution affects not only migrating birds, but also other highly mobile animals throughout their annual cycle.

Radiation-induced electron migration along DNA

International Nuclear Information System (INIS)

Fuciarelli, A.F.; Sisk, E.C.; Miller, J.H.; Zimbrick, J.D.

1994-04-01

Radiation-induced electron migration along DNA is a mechanism by which randomly produced stochastic energy deposition events can lead to nonrandom types of damage along DNA manifested distal to the sites of the initial energy deposition. Electron migration along DNA is significantly influenced by the DNA base sequence and DNA conformation. Migration along 7 base pairs in oligonucleotides containing guanine bases was observed for oligonucleotides irradiated in solution which compares to average migration distances of 6 to 10 bases for Escherichia coli DNA irradiated in solution and 5.5 base pairs for Escherichia coli DNA irradiated in cells. Evidence also suggests that electron migration can occur preferentially in the 5' to 3' direction along DNA. Our continued efforts will provide information regarding the contribution of electron transfer along DNA to formation of locally multiply damaged sites created in DNA by exposure to ionizing radiation

Collective cell migration during inflammatory response

Science.gov (United States)

Wu, Di; Stroka, Kimberly; Aranda-Espinoza, Helim

2012-02-01

Wound scratch healing assays of endothelial cell monolayers is a simple model to study collective cell migration as a function of biological signals. A signal of particular interest is the immune response, which after initial wounding in vivo causes the release of various inflammatory factors such as tumor necrosis alpha (TNF-α). TNF-α is an innate inflammatory cytokine that can induce cell growth, cell necrosis, and change cell morphology. We studied the effects of TNF-α on collective cell migration using the wound healing assays and measured several migration metrics, such as rate of scratch closure, velocities of leading edge and bulk cells, closure index, and velocity correlation functions between migrating cells. We observed that TNF-α alters all migratory metrics as a function of the size of the scratch and TNF-α content. The changes observed in migration correlate with actin reorganization upon TNF-α exposure.

Occupational change, employer change, internal migration, and earnings.

Science.gov (United States)

Krieg, R G

1997-02-01

"In this paper I use microdata from the [U.S.] Panel Study of Income Dynamics to measure the financial returns to intercounty and interstate migration for individuals in a temporal framework accounting for gains that accrue over time.... To account for the indirect effects of migration on earnings, explanatory variables are created by interacting migration status with: (1) occupational change, (2) employer change and (3) changes in both occupation and employer. These interaction terms are then included in the earnings functions. Earnings are estimated for three years subsequent to the migration decision to account for the financial returns to migration accruing over time. Results indicate that, when estimating earnings, the use of a simple migration dummy variable will mask the indirect effects of migration on earnings." excerpt

Why Migrate: For Study or for Work?

Directory of Open Access Journals (Sweden)

Elise S. Brezis

2016-08-01

Full Text Available Over the past decades, globalization has led to a huge increase in the migration of workers, as well as students. This paper develops a simple two-step model that describes the decisions of an individual vis-à-vis education and migration, and presents a unified model, wherein the two migration decisions are combined into a single, unique model. This paper shows that under the plausible assumption that costs of migration differ over the human life cycle, the usual brain drain strategy is sub-optimal. With an increase in globalization, the brain drain strategy will be replaced by the strategy of migration of students.

QUALIFIED VERSION OF MIGRATION: BRAIN DRAIN

Directory of Open Access Journals (Sweden)

Ayhan GENCLER

2009-07-01

Full Text Available Though globalization suggests an international exchange of people besides goods and capital, developed countries often tended to put forward some restrictions on the migration of workers from developed countries. However, there has been an increase in skilled international migration especially during the last two decades. Skilled international migration or brain drain points out the emigration of educated and highly skilled workers. It seems that, in general, developing or underdeveloped countries experience the negative consequences of the brain drain and suffer from the decreases in their human capital. The paper explains the phenomenon of skilled international migration, or brain drain, and summarizes the main global trends in this area.

Interntional Migration with Heterogeneous Agents: Theory and Evidence

DEFF Research Database (Denmark)

Schröder, Philipp J.H.; Brücker, Herbert

Two puzzling facts of international migration are that only a small share of a sending country's population emigrates and that net migration rates tend to cease over time. This paper addresses these issues in a migration model with heterogeneous agents that features temporary migration...

Variation of 137Cs migration parameters in soils

International Nuclear Information System (INIS)

Silant'ev, A.N.; Shkuratova, I.G.

1988-01-01

Quasidiffusion model accounting the oriented migration is used to describe the observed profiles of 137 Cs distribution in soil. A way of model use in case of real soil, the quasidiffusion migration factor being varied, is suggested. It is shown that in the upper thin soil layer the quasidiffusion migration factor and oriented migration rate values are constant. With further increase of depth the quasidiffusion coefficient grows, the oriented migration rate is unchanged. On the basis of location data characteristic values of migration parameters for different soils of the USSR European territory depending on the soil texture, vegetative cover and moistening are determined

Automation of Flexible Migration Workflows

Directory of Open Access Journals (Sweden)

Dirk von Suchodoletz

2011-03-01

Full Text Available Many digital preservation scenarios are based on the migration strategy, which itself is heavily tool-dependent. For popular, well-defined and often open file formats – e.g., digital images, such as PNG, GIF, JPEG – a wide range of tools exist. Migration workflows become more difficult with proprietary formats, as used by the several text processing applications becoming available in the last two decades. If a certain file format can not be rendered with actual software, emulation of the original environment remains a valid option. For instance, with the original Lotus AmiPro or Word Perfect, it is not a problem to save an object of this type in ASCII text or Rich Text Format. In specific environments, it is even possible to send the file to a virtual printer, thereby producing a PDF as a migration output. Such manual migration tasks typically involve human interaction, which may be feasible for a small number of objects, but not for larger batches of files.We propose a novel approach using a software-operated VNC abstraction layer in order to replace humans with machine interaction. Emulators or virtualization tools equipped with a VNC interface are very well suited for this approach. But screen, keyboard and mouse interaction is just part of the setup. Furthermore, digital objects need to be transferred into the original environment in order to be extracted after processing. Nevertheless, the complexity of the new generation of migration services is quickly rising; a preservation workflow is now comprised not only of the migration tool itself, but of a complete software and virtual hardware stack with recorded workflows linked to every supported migration scenario. Thus the requirements of OAIS management must include proper software archiving, emulator selection, system image and recording handling. The concept of view-paths could help either to automatically determine the proper pre-configured virtual environment or to set up system

Fault analysis in the very shallow seismic reflection method. Part 3. Migration; Gokusenso hanshaho ni okeru danso kaiseki. 3. Migration

Energy Technology Data Exchange (ETDEWEB)

Nagumo, S; Muraoka, S; Takahashi, T [OYO Corp., Tokyo (Japan)

1997-10-22

Concerning the analysis of data obtained by the seismic reflection method, migration in the very shallow layer is discussed. When the dip angle of the reflection plane involved is disclosed by DMO conversion, the amount of migration (travelling sideways) can be calculated by use of simple geometrical formulas though on the presumption that the sector velocity is constant. Categorized into this technique are such methods as DMO conversion migration, direct dip migration, F-K method, and finite difference method. This means that waveforms are not damaged by migration processing although elongation occurs due to time base conversion. When it is taken into account that waveform distortion is generally grave in the migration related methods widely in use, this feature has to be said valuable in holding information on faults. This is especially advantageous in the very shallow layer because the amount of migration is proportionally larger when the level is deeper and, in addition, migration processing is useful when it is necessary to know more accurately the character of the fault plane. 8 figs.

QUALIFIED VERSION OF MIGRATION: BRAIN DRAIN

OpenAIRE

Ayhan GENCLER

2009-01-01

Though globalization suggests an international exchange of people besides goods and capital, developed countries often tended to put forward some restrictions on the migration of workers from developed countries. However, there has been an increase in skilled international migration especially during the last two decades. Skilled international migration or brain drain points out the emigration of educated and highly skilled workers. It seems tha...

Low mass planet migration in magnetically torqued dead zones - II. Flow-locked and runaway migration, and a torque prescription

Science.gov (United States)

McNally, Colin P.; Nelson, Richard P.; Paardekooper, Sijme-Jan

2018-04-01

We examine the migration of low mass planets in laminar protoplanetary discs, threaded by large scale magnetic fields in the dead zone that drive radial gas flows. As shown in Paper I, a dynamical corotation torque arises due to the flow-induced asymmetric distortion of the corotation region and the evolving vortensity contrast between the librating horseshoe material and background disc flow. Using simulations of laminar torqued discs containing migrating planets, we demonstrate the existence of the four distinct migration regimes predicted in Paper I. In two regimes, the migration is approximately locked to the inward or outward radial gas flow, and in the other regimes the planet undergoes outward runaway migration that eventually settles to fast steady migration. In addition, we demonstrate torque and migration reversals induced by midplane magnetic stresses, with a bifurcation dependent on the disc surface density. We develop a model for fast migration, and show why the outward runaway saturates to a steady speed, and examine phenomenologically its termination due to changing local disc conditions. We also develop an analytical model for the corotation torque at late times that includes viscosity, for application to discs that sustain modest turbulence. Finally, we use the simulation results to develop torque prescriptions for inclusion in population synthesis models of planet formation.

Domestic and International Climate Migration from Rural Mexico

Science.gov (United States)

Nawrotzki, Raphael J.; Runfola, Daniel M.; Hunter, Lori M.; Riosmena, Fernando

2016-01-01

Evidence is increasing that climate change and variability may influence human migration patterns. However, there is less agreement regarding the type of migration streams most strongly impacted. This study tests whether climate change more strongly impacted international compared to domestic migration from rural Mexico during 1986-99. We employ eight temperature and precipitation-based climate change indices linked to detailed migration histories obtained from the Mexican Migration Project. Results from multilevel discrete-time event-history models challenge the assumption that climate-related migration will be predominantly short distance and domestic, but instead show that climate change more strongly impacted international moves from rural Mexico. The stronger climate impact on international migration may be explained by the self-insurance function of international migration, the presence of strong migrant networks, and climate-related changes in wage difference. While a warming in temperature increased international outmigration, higher levels of precipitation declined the odds of an international move. PMID:28439146

Domestic and International Climate Migration from Rural Mexico.

Science.gov (United States)

Nawrotzki, Raphael J; Runfola, Daniel M; Hunter, Lori M; Riosmena, Fernando

2016-12-01

Evidence is increasing that climate change and variability may influence human migration patterns. However, there is less agreement regarding the type of migration streams most strongly impacted. This study tests whether climate change more strongly impacted international compared to domestic migration from rural Mexico during 1986-99. We employ eight temperature and precipitation-based climate change indices linked to detailed migration histories obtained from the Mexican Migration Project. Results from multilevel discrete-time event-history models challenge the assumption that climate-related migration will be predominantly short distance and domestic, but instead show that climate change more strongly impacted international moves from rural Mexico. The stronger climate impact on international migration may be explained by the self-insurance function of international migration, the presence of strong migrant networks, and climate-related changes in wage difference. While a warming in temperature increased international outmigration, higher levels of precipitation declined the odds of an international move.

State policies and internal migration in Asia.

Science.gov (United States)

Oberai, A S

1981-01-01

The objective of this discussion is to identify policies and programs in Asia that are explicitly or implicitly designed to influence migration, to investigate why they were adopted and how far they have actually been implemented, and to assess their direct and indirect consequences. For study purposes, policies and programs are classified according to whether they prohibit or reverse migration, redirect or channel migration to specific rural or urban locations, reduce the total volume of migration, or encourage or discourage urban in-migration. Discussion of each type of policy is accompanied by a description of its rationale and implementation mechanism, examples of countries in Asia that have recourse to it, and its intended or actual effect on migration. Several countries in Asia have taken direct measures to reverse the flow of migration and to stop or discourage migration to urban areas. These measures have included administrative and legal controls, police registration, and direct "rustication" programs to remove urban inhabitants to the countryside. The availability of public land has prompted many Asian countries to adopt schemes that have been labeled resettlement, transmigration, colonization, or land development. These schemes have been designed to realize 1 or more of the following objectives: to provide land and income to the landless; increase agricultural production; correct spatial imbalances in the distribution of population; or exploit frontier lands for reasons of national security. 1 of the basic goals of decentralized industrialization and regional development policies has been the reduction of interregional disparities and the redirection of migrations from large metropolitan areas to smaller and medium sized towns. To encourage industry to move to small urban locations initial infrastructure investments, tax benefits, and other incentives have been offered. Policies to reduce the overall volume of migration have frequently included rural

Capitalist development and internal migration in Nigeria.

Science.gov (United States)

Akor, R I; Mou, D

1986-12-01

The authors analyze internal migration trends in Nigeria by examining individual household strategies and how they have adapted to structural changes brought about by colonial rule and capitalist development. The first section of this article describes the structural changes that started the process of labor migration. The second section deals with post-independence industrialization and the consequent rural-urban migration. The final section analyzes the consequences of these migration patterns for urban growth and rural productivity.

Labour migration and rural development in Egypt. A study of return migration in six villages.

Science.gov (United States)

Reichert, C

1993-01-01

An analysis of the impact of labor migration on social change in 6 rural villages (Shanawan and Kafr Shanawan north of Cairo, Kafr Yusuf and Tambul el Kubra near Simbalaween, and Abu Girg and Bani Walims in Minya governate) in Egypt was conducted in 1987-88. Since the 1991 Gulf war, the political environment, the labor markets, and the structure of migration opportunities have changed. An estimated 5% of rural households might have been directly affected by migrants' departure from Kuwait and Iraq. Data collection involved a household census survey of 8620 households, of which 2483 were migrants, including 1765 return migrants. A sample of return migrant (639) was interviewed about their migration experiences. Participant observation was also conducted among migrants and nonmigrants, and case studies were developed. Villages were demographically and socioeconomically very different; migration ranged from 18.5-434.2%. Structural change was measured on a scale of 1 to 6 in terms of population size, literacy of household heads, share of agricultural occupations, share of new red brick houses, and availability of infrastructural or institutional facilities. The probability of having a household with a migrant member increased with the rural character of the village. Landholdings or other major household variables were unrelated to migration. Rural outmigration was almost exclusively male, the average age was 29.6 years, and the average stay was 2.6 years. Migration destination was specific to individuals but affected by occupation and family or village resources. Professionals were overrepresented in Saudi Arabia, and farm and unskilled laborers or the unemployed were overrepresented in Iraq. Remittances from international migration have contributed along with the economic reforms of Sadat to new, private initiatives from all strata in rural society. 74.3% of returnees stated that improvement in income and living standards was the motivation for migration; many motives

Skeletonized Least Squares Wave Equation Migration

KAUST Repository

Zhan, Ge

2010-10-17

The theory for skeletonized least squares wave equation migration (LSM) is presented. The key idea is, for an assumed velocity model, the source‐side Green\\'s function and the geophone‐side Green\\'s function are computed by a numerical solution of the wave equation. Only the early‐arrivals of these Green\\'s functions are saved and skeletonized to form the migration Green\\'s function (MGF) by convolution. Then the migration image is obtained by a dot product between the recorded shot gathers and the MGF for every trial image point. The key to an efficient implementation of iterative LSM is that at each conjugate gradient iteration, the MGF is reused and no new finitedifference (FD) simulations are needed to get the updated migration image. It is believed that this procedure combined with phase‐encoded multi‐source technology will allow for the efficient computation of wave equation LSM images in less time than that of conventional reverse time migration (RTM).

Elastic least-squares reverse time migration

KAUST Repository

Feng, Zongcai

2017-03-08

We use elastic least-squares reverse time migration (LSRTM) to invert for the reflectivity images of P- and S-wave impedances. Elastic LSRTMsolves the linearized elastic-wave equations for forward modeling and the adjoint equations for backpropagating the residual wavefield at each iteration. Numerical tests on synthetic data and field data reveal the advantages of elastic LSRTM over elastic reverse time migration (RTM) and acoustic LSRTM. For our examples, the elastic LSRTM images have better resolution and amplitude balancing, fewer artifacts, and less crosstalk compared with the elastic RTM images. The images are also better focused and have better reflector continuity for steeply dipping events compared to the acoustic LSRTM images. Similar to conventional leastsquares migration, elastic LSRTM also requires an accurate estimation of the P- and S-wave migration velocity models. However, the problem remains that, when there are moderate errors in the velocity model and strong multiples, LSRTMwill produce migration noise stronger than that seen in the RTM images.

Elastic least-squares reverse time migration

KAUST Repository

Feng, Zongcai; Schuster, Gerard T.

2017-01-01

We use elastic least-squares reverse time migration (LSRTM) to invert for the reflectivity images of P- and S-wave impedances. Elastic LSRTMsolves the linearized elastic-wave equations for forward modeling and the adjoint equations for backpropagating the residual wavefield at each iteration. Numerical tests on synthetic data and field data reveal the advantages of elastic LSRTM over elastic reverse time migration (RTM) and acoustic LSRTM. For our examples, the elastic LSRTM images have better resolution and amplitude balancing, fewer artifacts, and less crosstalk compared with the elastic RTM images. The images are also better focused and have better reflector continuity for steeply dipping events compared to the acoustic LSRTM images. Similar to conventional leastsquares migration, elastic LSRTM also requires an accurate estimation of the P- and S-wave migration velocity models. However, the problem remains that, when there are moderate errors in the velocity model and strong multiples, LSRTMwill produce migration noise stronger than that seen in the RTM images.

Migration of accreting giant planets

Science.gov (United States)

Robert, C.; Crida, A.; Lega, E.; Méheut, H.

2017-09-01

Giant planets forming in protoplanetary disks migrate relative to their host star. By repelling the gas in their vicinity, they form gaps in the disk's structure. If they are effectively locked in their gap, it follows that their migration rate is governed by the accretion of the disk itself onto the star, in a so-called type II fashion. Recent results showed however that a locking mechanism was still lacking, and was required to understand how giant planets may survive their disk. We propose that planetary accretion may play this part, and help reach this slow migration regime.

MIGRATION – EFFECTS AND SOLUTIONS

Directory of Open Access Journals (Sweden)

Raluca Cruceru

2012-12-01

Full Text Available There are three main flows that influence workforce performance—worker migration, the dissemination of knowledge, and overseas development assistance. For the present paper we decided to deal with the analyses of these three, yet mainly migration. We considered it to be one of the most important phenomenon existent on the market at this hour and with the highest negative impact on the economic and social situation. We presented a case study regarding the situation of migration in Romania and the main candidates to Romanian intelligence imports, the main issues and possible solutions to the problems encountered.

Internal migration in the USSR: 1897-1926.

Science.gov (United States)

Leasure, J W; Lewis, R A

1967-06-01

The purpose of this study is to describe and to analyze internal migration in the USSR primarily by the use of data from the 1926 census of the USSR. The article is divided into two parts. The first is devoted to a description of the aggregate and regional migration patterns based on place-of-birth data. The second is an analysis of these migration patterns, primarily in terms of economic differentials by guberniya. Because only limited income data are available for the period around1926 and because other economic data are scarce or unusable owing to boundary changes, census data on labor force distribution, literacy, and urbanization are used as substitute variables to approximate income differences.Migrationis a complex phenomenon related to a host of factors. The present study does not presume fully to explain migration in the USSR, but it does attempt to isolate differences in income and to relate these to the internal migration that occurred during this period. As a result of processing and analyzing an extensive array of data, we have shown that differences in income, derived indirectly from a variety of data, are closely related to internal migration in the USSR in the period prior to the 1926 census. There were striking similarities in respect to internal migration between the period prior to the 1897 census and the period prior to the1926 census. The chief areas of out-migration and in-migration were roughly the same,and migrants in both periods moved primarily to areas of higher income.

International nurse migrations: Global trends

Directory of Open Access Journals (Sweden)

Ivković Marija

2011-01-01

Full Text Available This paper presents global trends of migration of nurses, as specific qualified personnel in high demand. In the last couple of decades, and especially in the last couple of years, many countries have faced the problem of insufficient healthcare workers, particularly nurses. Reasons for this occurrence might be found in the deficiencies of their education systems, as well as the population aging of northern and western countries. As a response to this deficiency, those countries have begun intensive recruitment of foreign qualified female healthcare workers, which has led to the point that nurse migration today presents a very intense, and by many accounts specific migration flow. Female migrating work force is often in pursuit of low-wage and lowqualified work. Nurse migration is actually an example of motion of qualified female migrants in pursuit for better employment opportunities. While such a way of filling up the vacant positions works for the “importing” countries as a temporary solution, departure of trained female personnel presents a significant loss for the originating countries. In this paper we pay special attention to the countries who are the main “importers”, but also to those who are “exporters” of nursing personnel, and to specific national strategies these countries have applied.

Elastic least-squares reverse time migration

KAUST Repository

Feng, Zongcai; Schuster, Gerard T.

2016-01-01

Elastic least-squares reverse time migration (LSRTM) is used to invert synthetic particle-velocity data and crosswell pressure field data. The migration images consist of both the P- and Svelocity perturbation images. Numerical tests on synthetic and field data illustrate the advantages of elastic LSRTM over elastic reverse time migration (RTM). In addition, elastic LSRTM images are better focused and have better reflector continuity than do the acoustic LSRTM images.

Cesium migration in LMFBR fuel pins

International Nuclear Information System (INIS)

Karnesky, R.A.; Jost, J.W.; Stone, I.Z.

1978-10-01

The factors affecting the axial migration of cesium in mixed oxide fuel pins and the effects of cesium migration on fuel pin performance are examined. The development and application of a correlated model which will predict the occurrence of cesium migration in a mixed oxide (75 w/o UO 2 + 25 w/o PuO 2 ) fuel pins over a wide range of fabrication and irradiation conditions are described

Elastic least-squares reverse time migration

KAUST Repository

Feng, Zongcai

2016-09-06

Elastic least-squares reverse time migration (LSRTM) is used to invert synthetic particle-velocity data and crosswell pressure field data. The migration images consist of both the P- and Svelocity perturbation images. Numerical tests on synthetic and field data illustrate the advantages of elastic LSRTM over elastic reverse time migration (RTM). In addition, elastic LSRTM images are better focused and have better reflector continuity than do the acoustic LSRTM images.

QUALIFIED VERSION OF MIGRATION: BRAIN DRAIN

OpenAIRE

Gencler, Ayhan

2009-01-01

Though globalization suggests an international exchange of people besides goods and capital, developed countries often tended to put forward some restrictions on the migration of workers from developed countries. However, there has been an increase in skilled international migration especially during the last two decades. Skilled international migration or brain drain points out the emigration of educated and highly skilled workers. It seems that, in general, developing or underdeveloped...

Study on the chloride migration coefficient obtained following different Rapid Chloride Migration (RCM) test guidelines

NARCIS (Netherlands)

Spiesz, P.R.; Brouwers, H.J.H.; Uzoegbo, H.C.; Schmidt, W.

2013-01-01

This work presents the differences in the available Rapid Chloride Migration (RCM) test guidelines, and their influence on the values of the chloride migration coefficients DRCM, obtained following these guidelines. It is shown that the differences between the guidelines are significant and concern

A note on migration with borrowing constraints.

Science.gov (United States)

Ghatak, S; Levine, P

1994-12-01

"This note examines an important conflict between the theory and evidence on migration in LDCs. While the Harris-Todaro class of models explain the phenomenon of migration mainly by expected income differential between the economically advanced and the backward regions, the actual evidence in some cases suggests that migration could actually rise following a rise in income in backward areas. We resolve this puzzle by analysing migration in the context of the existence of imperfect credit markets in LDCs. We show that under certain plausible conditions, the rate of migration from the rural to the urban areas may actually rise when rural wages rise, as they ease the constraints on borrowing by potential migrants." excerpt

Aspects of general linear modelling of migration.

Science.gov (United States)

Congdon, P

1992-01-01

"This paper investigates the application of general linear modelling principles to analysing migration flows between areas. Particular attention is paid to specifying the form of the regression and error components, and the nature of departures from Poisson randomness. Extensions to take account of spatial and temporal correlation are discussed as well as constrained estimation. The issue of specification bears on the testing of migration theories, and assessing the role migration plays in job and housing markets: the direction and significance of the effects of economic variates on migration depends on the specification of the statistical model. The application is in the context of migration in London and South East England in the 1970s and 1980s." excerpt

Internal migration: why do Filipinos move?

Science.gov (United States)

Jolipa, N

1980-01-01

The rapid movement of Filipinos from 1 part of the Philippines to another is not a new phenomenon, but mobility has been increasing. A study conducted by Peter C. Smith revealed that interprovincial lifetime mobility of the national population increased from 15.8% in 1960 to 17.6% in 1970, while interregional mobility increased from 12.7% to 13.4%. People still disagree as to whether the size and rate of growth of the population are excessive, but there seems to be total consensus as regards its spatial imbalance. Because internal migration appears to be an important factor in national development, a need exists to examine different aspects of internal migration, such as the directions taken by migration flows, the migrants' reasons for moving, the migrants' characteristics, the migrants' success or lack of success at their places of destination, the social problems accompanying internal migration, effforts to deal with the problems caused by internal migration, and the implications of migration trends for policy and for the country's development programs. The most dominant migration trend in the Philippines in recent years has been toward the urban, or more accurately the suburban, areas adjacent to Metropolitan Manila. The city of Manila itself suffered a net outflow, further pointing to the trend toward suburbanization. Migration flows are primarily caused by economic reasons. About one half the sample of a Filipinas Foundation Study moved to provinces other than the province of birth in the pursuit of employment and other economic opportunities. A study of the country's migrant population age 15 and older showed that 53% of migrants were female. For male migrants, age ranges from 20-40; it ranges from 15-35 for females. Where cash income is concerned, migrants in Pernia's study of rural urban migration were better off than nonmigrants. Migrants were, on the average, as well off as native urbanites or metropolitanites. Among the more significant points raised by

Individualisation of Migration from the East? Comparison of Different Socio-Demographic Groups and their Migration Intentions

Directory of Open Access Journals (Sweden)

Maarja Saar

2016-12-01

Full Text Available Recent studies on Eastern European migration argue that moving for self-development reasons is becoming increasingly common among this group. Furthermore, it is suggested that migration from the East is becoming individualised and less dependent on social surroundings. Nevertheless, most such results rely on interviews conducted among certain social groups, such as the young and highly skilled. Hence, the comparison between different social groups and their motivations is rarely provided and, therefore, the claims about increased individualisation might be premature. This article uses the Estonian Household Module Survey, including responses from 620 Estonians intending to migrate, to evaluate if migration flows are indeed becoming more individualised and less dependent on social surroundings. Using cluster analysis, three different groups — self-development, economic and life quality migrants — are formed, which are then tested using regression analysis to check for the influence of socio-demographic variables. The article concludes that socio-demographic variables such as gender, age, ethnicity, family status and socio-economic status are still relevant for migration intentions. Indeed, a new group of Eastern European migrants, mainly oriented towards self-development, is emerging; however, it is small and consists mostly of young, Estonian-speaking females. The results complicate the notions of free mobility and liquid migration from Eastern Europe and illustrate that there is a need to pay attention to the increasing group differences in these societies

Interregional migration in socialist countries: the case of China.

Science.gov (United States)

Wei, Y

1997-03-01

"This paper analyzes changing interregional migration in China and reveals that the recent eastward migration reverses patterns of migration under Mao. It finds that investment variables are more important than the conventional variables of income and job opportunities in determining China's recent interregional migration. It suggests that both state policy and the global force influence interregional migration, challenging the popular view that the socialist state is the only critical determinant. This paper also criticizes Mao's approach to interregional migration and discusses the impact of migration on development." excerpt

Theories on migration processes of Cd in Jiaozhou Bay

Science.gov (United States)

Yang, Dongfang; Li, Haixia; Wang, Qi; Ding, Jun; Zhang, Longlei

2018-03-01

Understanding the migration progress is essential to pollution control, while developing theories for the migration progress is the scientific basis. This paper further developed five key theories on migration processes of Cd including homogeneous theory, environmental dynamic theory, horizontal loss theory, migration trend theory and vertical migration theory, respectively. The performance and practical values of these theories were demonstrated in the application of these on analyzing the migration process of Cd in Jiaozhou Bay. Results these theory helpful to better understand the migration progress of pollutants in marine bay.

Social networks in the migration process: empirical evidence on chain migration in India.

Science.gov (United States)

Banerjee, B

1983-01-01

This study, based on interviews with 1615 migrant heads of household in Delhi, was concerned with interactions between labor migrants and their urban-based contacts. 86% of the rural migrants reported having relatives and/or covillagers living in Delhi at the time of their arrival, and virtually all received some form of assistance from their contacts. A preference for assistance from relatives rather than covillagers was noted, suggesting that migrants regarded kinship bonds as stronger than village and caste ties. However, covillagers tended to be contacted if relatives failed to secure a job for the new migrants within a reasonable time. The moves of only 17% of the sample could be classified under delayed family migration (relocation of family members in lagged stages). The tendency for traditional norms to be relaxed in an urban setting is reflected in the finding that the places of origin of migrants and their urban-based relatives differed in about half the cases that involved assistance from relatives. In addition, 13% of migrants violated traditional norms by seeking assistance from female agnates and kin affinally linked through these women. The most common pattern of assistance provided by both relatives and covillagers included room, food, and job search; however, new migrants tended to prefer to obtain board and lodging from relatives. Migrants helped by primary male agnates were twice as likely to receive money as those helped by other relatives. A consequence of chain migration is the concentration of persons from the same village or kinship network in particular occupations. 36% of the wage employees in the sample had relatives and/or covillagers working for the same employer. This suggests that migration induced by urban-based contacts (accounting for 42% of the migration in this sample) will be low if the sectors in which job opportunities are expanding are dominated by nonmigrants. Given the prevalence of chain migration, the contribution of

FOREIGN EXPERIENCE OF STATE REGULATION OF MIGRATION PROCESSES

Directory of Open Access Journals (Sweden)

Ekaterina Nikolaevna Tarasenko

2018-05-01

Full Text Available International migration of population has existed for centuries, as it has activated as a result of globalization. Share the non-economic causes of international migration (causes related to wars, political and religious persecution, the desire to explore new spaces, the desire for family reunification, natural disasters and economic problems (the search for a new job in the absence of the opportunity to find a job in their own country, the search for more paid or creative work, a higher quality of life. Recently, the main reason for migration is economic reasons, on the basis of which the popular migration corridors and the leading directions of migration of labor personnel are identified. Analyzed the main centers of attraction of migration, namely, the United States of America, Federal Republic of Germany and the Russian Federation. Noted that the means and methods of implementation of the State migration policy vary depending on the specific situation on the labor market. So, given the shortage of labor in some European countries, such as Germany, used methods of stimulating immigration. When there is a need to reduce the level of immigration, as in the case of the United States, government regulation sets barriers to a new influx of foreign workers. Revealed, the dynamics of migration primarily due to social phenomena. Adverse external conditions: the deterioration of the economic, environmental or political situation in the country of residence is becoming an important factor in the readiness of potential migrants for forced migration. However, migrants have different socio-economic characteristics, and so they choose the wrong country for migration that they will be closer to social and psychological features. However, migrants have different socio-economic characteristics, and so they choose the wrong country for migration that they will be closer to social and psychological features. The purpose is to study international experience of

Second-Generation Outcomes of the Great Migration.

Science.gov (United States)

Alexander, J Trent; Leibbrand, Christine; Massey, Catherine; Tolnay, Stewart

2017-12-01

The mass migration of African Americans out of the South during the first two-thirds of the twentieth century represents one of the most significant internal migration flows in U.S. Those undertaking the Great Migration left the South in search of a better life, and their move transformed the cultural, social, and political dynamics of African American life specifically and U.S. society more generally. Recent research offers conflicting evidence regarding the migrants' success in translating their geographic mobility into economic mobility. Due in part to the lack of a large body of longitudinal data, almost all studies of the Great Migration have focused on the migrants themselves, usually over short periods of their working lives. Using longitudinally linked census data, we take a broader view, investigating the long-term economic and social effects of the Great Migration on the migrants' children. Our results reveal modest but statistically significant advantages in education, income, and poverty status for the African American children of the Great Migration relative to the children of southerners who remained in the South. In contrast, second-generation white migrants experienced few benefits from migrating relative to southern or northern stayers.

Migration Adapter Development for SaaS Applications

OpenAIRE

Šemrov, Sandi

2013-01-01

This thesis presents methods and procedures for migration and applications integration, with the main focus on applications that are offered as a service – SaaS (Software-as-a-Service). At the level of data integration we analyze approaches for data migration between different types of SaaS applications. We design a framework for executing migration adapters and show an example of data migration between two SaaS applications. We then describe the development of adapters for two specific SaaS ...

Migration check tool: automatic plan verification following treatment management systems upgrade and database migration.

Science.gov (United States)

Hadley, Scott W; White, Dale; Chen, Xiaoping; Moran, Jean M; Keranen, Wayne M

2013-11-04

Software upgrades of the treatment management system (TMS) sometimes require that all data be migrated from one version of the database to another. It is necessary to verify that the data are correctly migrated to assure patient safety. It is impossible to verify by hand the thousands of parameters that go into each patient's radiation therapy treatment plan. Repeating pretreatment QA is costly, time-consuming, and may be inadequate in detecting errors that are introduced during the migration. In this work we investigate the use of an automatic Plan Comparison Tool to verify that plan data have been correctly migrated to a new version of a TMS database from an older version. We developed software to query and compare treatment plans between different versions of the TMS. The same plan in the two TMS systems are translated into an XML schema. A plan comparison module takes the two XML schemas as input and reports any differences in parameters between the two versions of the same plan by applying a schema mapping. A console application is used to query the database to obtain a list of active or in-preparation plans to be tested. It then runs in batch mode to compare all the plans, and a report of success or failure of the comparison is saved for review. This software tool was used as part of software upgrade and database migration from Varian's Aria 8.9 to Aria 11 TMS. Parameters were compared for 358 treatment plans in 89 minutes. This direct comparison of all plan parameters in the migrated TMS against the previous TMS surpasses current QA methods that relied on repeating pretreatment QA measurements or labor-intensive and fallible hand comparisons.

Entropy measures of collective cell migration

Science.gov (United States)

Whitby, Ariadne; Parrinello, Simona; Faisal, Aldo

2015-03-01

Collective cell migration is a critical process during tissue formation and repair. To this end there is a need to develop tools to quantitatively measure the dynamics of collective cell migration obtained from microscopy data. Drawing on statistical physics we use entropy of velocity fields derived from dense optic flow to quantitatively measure collective migration. Using peripheral nerve repair after injury as experimental system, we study how Schwann cells, guided by fibroblasts, migrate in cord-like structures across the cut, paving a highway for neurons. This process of emergence of organised behaviour is key for successful repair, yet the emergence of leader cells and transition from a random to ordered state is not understood. We find fibroblasts induce correlated directionality in migrating Schwann cells as measured by a decrease in the entropy of motion vector. We show our method is robust with respect to image resolution in time and space, giving a principled assessment of how various molecular mechanisms affect macroscopic features of collective cell migration. Finally, the generality of our method allows us to process both simulated cell movement and microscopic data, enabling principled fitting and comparison of in silico to in vitro. ICCS, Imperial College London & MRC Clinical Sciences Centre.

De‐blending reverse‐time migration

KAUST Repository

Fei, Tong W.; Luo, Yi; Schuster, Gerard T.

2010-01-01

Reverse‐time migration (RTM), based on the full two‐way wave equation, has gained interest and become a popular imaging tool for complex structures in the last few years. The method is well‐known for its ability to better image the steeply dipping and overturned structures than the migration methods based on the one‐way wave equation extrapolation. However, the RTM image often contains low frequency and back‐scattering noise, and the imaging quality is sensitive to the migration velocity. In order to improve the RTM imaging quality and make the RTM image less sensitive to the velocity model, we developed an RTM de‐blending technique which separates upgoing and downgoing source and receiver wavefields, and then use them to construct final RTM images. Test results show that decomposed images obtained from only the downgoing source and receiver wavefields are less sensitive to velocity. It removes unwanted noise and migration artifacts from conventional RTM, and the imaging quality is greatly improved compared with a conventional RTM image.

De‐blending reverse‐time migration

KAUST Repository

Fei, Tong W.

2010-10-17

Reverse‐time migration (RTM), based on the full two‐way wave equation, has gained interest and become a popular imaging tool for complex structures in the last few years. The method is well‐known for its ability to better image the steeply dipping and overturned structures than the migration methods based on the one‐way wave equation extrapolation. However, the RTM image often contains low frequency and back‐scattering noise, and the imaging quality is sensitive to the migration velocity. In order to improve the RTM imaging quality and make the RTM image less sensitive to the velocity model, we developed an RTM de‐blending technique which separates upgoing and downgoing source and receiver wavefields, and then use them to construct final RTM images. Test results show that decomposed images obtained from only the downgoing source and receiver wavefields are less sensitive to velocity. It removes unwanted noise and migration artifacts from conventional RTM, and the imaging quality is greatly improved compared with a conventional RTM image.

MRI of neuronal migration disorders

International Nuclear Information System (INIS)

Engelbrecht, V.

1996-01-01

Twenty-one MRI examinations of the brain were performed in 19 children with neuronal migration disorders. Multiplanar oriented spin-echo sequences were on a scanner with 1.5 T. In 8 children we performed an additional turbo-inversion recovery (TIR) sequence. Results of sonography or CT from five children were compared with MRI scans. Using the actual nomenclature, we found the following migration disorders: Lissencephaly (n=6), cobblestone lissencephaly with Walker-Warbung syndrome (WWS) (n=2), polymicrogyria and schizencephaly (n=2), focal heterotopia (n=5), diffuse heterotopie (n=2) and hemimegalencephaly (n=2). MRI was superior to CT and sonography in all children. Except for the two boys with WWS, the TIR sequence was the best to demonstrate the changes in migration disorder because of the high contrast between gray and white matter. We demonstrate the characteristic features of the different migration disorders and compare them with the existing literature. (orig.) [de

Eastern migrations vs western welfare states - (unbiased fears

Directory of Open Access Journals (Sweden)

Josifidis Kosta

2013-01-01

Full Text Available This inquiry considers some effects of migration on the labour markets and the welfare systems found in the EU-15, and from the perspectives of sustainability of the current welfare state regimes. Our inquiry aims to determine whether and to what extent different approaches in regulation of migration flows between the new and old member states are compatible with related economic and demographic findings. Within this context, our research considers regulations affecting migration flows. Our findings suggest that some effects of migration from the EU8+2 on the labour markets and social protection systems found in the EU-15, both with respect to level and structure, do indeed generate effects on migration, especially considering whether migration is based upon economic or welfare decisions. In addition, our inquiry considers perspectives upon restrictive versus liberal migration policies.

The effect of radial migration on galactic disks

International Nuclear Information System (INIS)

Vera-Ciro, Carlos; D'Onghia, Elena; Navarro, Julio; Abadi, Mario

2014-01-01

We study the radial migration of stars driven by recurring multi-arm spiral features in an exponential disk embedded in a dark matter halo. The spiral perturbations redistribute angular momentum within the disk and lead to substantial radial displacements of individual stars, in a manner that largely preserves the circularity of their orbits and that results, after 5 Gyr (∼40 full rotations at the disk scale length), in little radial heating and no appreciable changes to the vertical or radial structure of the disk. Our results clarify a number of issues related to the spatial distribution and kinematics of migrators. In particular, we find that migrators are a heavily biased subset of stars with preferentially low vertical velocity dispersions. This 'provenance bias' for migrators is not surprising in hindsight, for stars with small vertical excursions spend more time near the disk plane, and thus respond more readily to non-axisymmetric perturbations. We also find that the vertical velocity dispersion of outward migrators always decreases, whereas the opposite holds for inward migrators. To first order, newly arrived migrators simply replace stars that have migrated off to other radii, thus inheriting the vertical bias of the latter. Extreme migrators might therefore be recognized, if present, by the unexpectedly small amplitude of their vertical excursions. Our results show that migration, understood as changes in angular momentum that preserve circularity, can strongly affect the thin disk, but cast doubts on models that envision the Galactic thick disk as a relic of radial migration.

Effects of Migration on Women Mental Health

Directory of Open Access Journals (Sweden)

Ayla Tuzcu

2015-03-01

Full Text Available People leave their habitats and go to different regions of the world due to various reasons, which is defined as migration. One of the most important changes that have been experienced in migration in the last half century is the increase in women's migration. Women are among the risk groups that are affected by the process of migration at most. A particular attention is attracted to the special requirements of women among groups that are obliged to migrate due to the crisis in their countries. Different lifestyles in the migrated social environment, difficult economic and working conditions, language barrier and relevant adaptation problems all negatively affect the mental health of these women. In order to protect and develop the mental health of migrant women from different cultural groups, it is important to approach these groups as primary risk groups and start multi-directional interventions aimed at their areas required. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2015; 7(1: 56-67

Modelling collective cell migration of neural crest.

Science.gov (United States)

Szabó, András; Mayor, Roberto

2016-10-01

Collective cell migration has emerged in the recent decade as an important phenomenon in cell and developmental biology and can be defined as the coordinated and cooperative movement of groups of cells. Most studies concentrate on tightly connected epithelial tissues, even though collective migration does not require a constant physical contact. Movement of mesenchymal cells is more independent, making their emergent collective behaviour less intuitive and therefore lending importance to computational modelling. Here we focus on such modelling efforts that aim to understand the collective migration of neural crest cells, a mesenchymal embryonic population that migrates large distances as a group during early vertebrate development. By comparing different models of neural crest migration, we emphasize the similarity and complementary nature of these approaches and suggest a future direction for the field. The principles derived from neural crest modelling could aid understanding the collective migration of other mesenchymal cell types. Copyright © 2016 Elsevier Ltd. All rights reserved.

The metrics and correlates of physician migration from Africa

Directory of Open Access Journals (Sweden)

Arah Onyebuchi A

2007-05-01

Full Text Available Abstract Background Physician migration from poor to rich countries is considered an important contributor to the growing health workforce crisis in the developing world. This is particularly true for Africa. The perceived magnitude of such migration for each source country might, however, depend on the choice of metrics used in the analysis. This study examined the influence of choice of migration metrics on the rankings of African countries that suffered the most physician migration, and investigated the correlates of physician migration. Methods Ranking and correlational analyses were conducted on African physician migration data adjusted for bilateral net flows, and supplemented with developmental, economic and health system data. The setting was the 53 African birth countries of African-born physicians working in nine wealthier destination countries. Three metrics of physician migration were used: total number of physician émigrés; emigration fraction defined as the proportion of the potential physician pool working in destination countries; and physician migration density defined as the number of physician émigrés per 1000 population of the African source country. Results Rankings based on any of the migration metrics differed substantially from those based on the other two metrics. Although the emigration fraction and physician migration density metrics gave proportionality to the migration crisis, only the latter was consistently associated with source countries' workforce capacity, health, health spending, economic and development characteristics. As such, higher physician migration density was seen among African countries with relatively higher health workforce capacity (0.401 ≤ r ≤ 0.694, p ≤ 0.011, health status, health spending, and development. Conclusion The perceived magnitude of physician migration is sensitive to the choice of metrics. Complementing the emigration fraction, the physician migration density is a metric

A Student Migratory Process (Pre-Migration, Migration and Post-Migration: Moroccan Youngsters in the University of Granada

Directory of Open Access Journals (Sweden)

Eva María González Barea

2008-11-01

Full Text Available In this article we analyze a partircularly migratory process and, at the same time, we include a new and not studied notion of migration. It consists of the displacement of sutdents of different regions of Morocco to continue their academic formation in a foreign university, in this case, the University of Granada. We present the study as a new research topic, due to the practical inexistence of bibliography or studies in this matter. At the same time, we present it as the analysis of a new migratory process that we necessarily have to include in the global phenomenon of actual migrations. We also include the theoretical analysis that stands for the development of this study.

The mechanism for migration in Poland.

Science.gov (United States)

Rykiel, Z

1988-01-01

The author reviews neoclassical theories and models of migration. The mobility theory, which concerns the impact of local labor markets on migration, is discussed in the Polish context. A general model of the regional labor market and a multicausal model are developed to explain the patterns of internal migration. The period of a managed economy (1949-1980) is contrasted with the period since the implementation of a new economic system in 1983.

Exploring the Climate Change, Migration and Conflict Nexus

Science.gov (United States)

Burrows, Kate; Kinney, Patrick L.

2016-01-01

The potential link between climate change, migration, and conflict has been widely discussed and is increasingly viewed by policy makers as a security issue. However, considerable uncertainty remains regarding the role that climate variability and change play among the many drivers of migration and conflict. The overall objective of this paper is to explore the potential pathways linking climate change, migration and increased risk of conflict. We review the existing literature surrounding this issue and break the problem into two components: the links between climate change and migration, and those between migration and conflict. We found a large range of views regarding the importance of climate change as a driver for increasing rates of migration and subsequently of conflict. We argue that future research should focus not only on the climate-migration-conflict pathway but also work to understand the other pathways by which climate variability and change might exacerbate conflict. We conclude by proposing five questions to help guide future research on the link between climate change, migration, and conflict. PMID:27110806

Exploring the Climate Change, Migration and Conflict Nexus

Directory of Open Access Journals (Sweden)

Kate Burrows

2016-04-01

Full Text Available The potential link between climate change, migration, and conflict has been widely discussed and is increasingly viewed by policy makers as a security issue. However, considerable uncertainty remains regarding the role that climate variability and change play among the many drivers of migration and conflict. The overall objective of this paper is to explore the potential pathways linking climate change, migration and increased risk of conflict. We review the existing literature surrounding this issue and break the problem into two components: the links between climate change and migration, and those between migration and conflict. We found a large range of views regarding the importance of climate change as a driver for increasing rates of migration and subsequently of conflict. We argue that future research should focus not only on the climate-migration-conflict pathway but also work to understand the other pathways by which climate variability and change might exacerbate conflict. We conclude by proposing five questions to help guide future research on the link between climate change, migration, and conflict.

Exploring the Climate Change, Migration and Conflict Nexus.

Science.gov (United States)

Burrows, Kate; Kinney, Patrick L

2016-04-22

The potential link between climate change, migration, and conflict has been widely discussed and is increasingly viewed by policy makers as a security issue. However, considerable uncertainty remains regarding the role that climate variability and change play among the many drivers of migration and conflict. The overall objective of this paper is to explore the potential pathways linking climate change, migration and increased risk of conflict. We review the existing literature surrounding this issue and break the problem into two components: the links between climate change and migration, and those between migration and conflict. We found a large range of views regarding the importance of climate change as a driver for increasing rates of migration and subsequently of conflict. We argue that future research should focus not only on the climate-migration-conflict pathway but also work to understand the other pathways by which climate variability and change might exacerbate conflict. We conclude by proposing five questions to help guide future research on the link between climate change, migration, and conflict.

Challenged by migration: Europe's options

NARCIS (Netherlands)

Constant, Amelie F.; Zimmermann, Klaus F.

2017-01-01

This paper examines the migration and labour mobility in the European Union and elaborates on their importance for the existence of the EU. Against all measures of success, the current public debate seems to suggest that the political consensus that migration is beneficial is broken. This comes with

La migration féminine au Mali

OpenAIRE

KEITA, Modibo

2011-01-01

Euro-Mediterranean Consortium for Applied Research on International Migration (CARIM) Les données et les recherches au sujet de la migration féminine au Mali sont rares. Cet article, qui privilégie une approche qualitative, suggère d’approfondir la question de la relation entre migration féminine et promotion de la femme, autrement dit la connaissance des conséquences de la migration féminine aux plans individuel, social, économique et culturel. Cette question renvoie, plus largement, à la...

En fornemmelse for migration

DEFF Research Database (Denmark)

Schütze, Laura Maria

Afhandlingen undersøger, hvordan sted, museets rolle som aktør og religion er relevante for produktionen af migration på Immigrantmuseet (2012) og i Københavns Museums udstilling At blive københavner (2010). Afhandlingen er baseret på udstillingsanalyse samt interview med relevant museumsfagligt......, anvendes som virkemidler til at nuancere migration og distancere udstillingen fra den offentlige debat om indvandring. Afhandlingen peger på, at produktionen af den nyere danske historie på museum er præget af et fravær af religion. Det skyldes, at de museumsfaglige praksisser og traditioner afspejler en...... identiteter, som vi tager for givet: nationer, byer, kvinder - såvel som migration og religion. Afhandlingen argumenterer følgelig for, at museernes produktion af (materiel) religion er et særdeles relevant, men kun ringe udforsket, genstandsfelt for religionssociologien....

Internal migration in Mexico and its determinants

Directory of Open Access Journals (Sweden)

Rogelio Varela Llamas

2016-12-01

Full Text Available This paper presents an analysis of internal migration in Mexico. Using micro data from the National Survey on Occupation and Employment (enoe, we estimate a multinomial logit model for the case of intrastate and interstate migration. We also conduct estimations for municipalities of different sizes. The results suggest that the probability of migrating increases with the number of weeks spent searching for a job, regardless of whether the search is conducted while the individual is employed or unemployed. In addition, we find that as the number of hours of work per week increases, the probability of migrating rises. The search process does not increase the probability of migrating in rural communities as it does in urban centers.

Engendering climate change-induced migration

Science.gov (United States)

Caretta, Martina Angela; Miletto, Michela

2017-04-01

Climate change leads to increased climate variability, which is manifest in extreme weather events such as floods and droughts. These put at stake agricultural productivity, forestry, inland fisheries, aquaculture, water supply and sanitation which in turn hamper poorest householdś self-sufficiency and capability to cope with risks. Due to the risk of losing or the actual loss of livelihood, farmers in the Global South must look for alternative strategies to diversify risk. Migration is one of those strategies, which that can be seen either as an adaptive measure or an indicator of limits to adaptation to environmental stress. 60% of young migrants live in the Global South (UN, 2013). Many internally displaced people in the world are under the age of 18, some move with their families, other, mostly in South Asia and West Africa, migrate alone. Youth, as all migrants, are seeking better economic opportunities to support themselves and their families. Migration is a gendered process which plays out differently in diverse societies depending on local cultural norms that do not only affect and are affected by gender roles, but also by age, class and ethnicity. Threats to water availability, access and water hazards have diverse impacts on men and women. The link gender and climate-induced migration is still under investigation and few studies provide concrete country specific examples of this phenomenon. Our paper will present a state of the art literature review around climate-induced migration in the Global South from a gender perspective showing how meńs and womeńs migratory decisions, patterns and outcomes differ at the stage pre-during post migration.

Mitigation of artifacts in rtm with migration kernel decomposition

KAUST Repository

Zhan, Ge

2012-01-01

The migration kernel for reverse-time migration (RTM) can be decomposed into four component kernels using Born scattering and migration theory. Each component kernel has a unique physical interpretation and can be interpreted differently. In this paper, we present a generalized diffraction-stack migration approach for reducing RTM artifacts via decomposition of migration kernel. The decomposition leads to an improved understanding of migration artifacts and, therefore, presents us with opportunities for improving the quality of RTM images.

[Urban employment and internal migration in Peru].

Science.gov (United States)

Cotlear, D

1984-06-01

The relationship between internal migration and employment problems in Peru is examined. The author argues that regional differences in income distribution are the primary causes of migration, particularly to urban areas. A model of the migration process is developed and tested using data from official sources, surveys, and the published literature.

Migration and sorption phenomena in packaged foods.

Science.gov (United States)

Gnanasekharan, V; Floros, J D

1997-10-01

Rapidly developing analytical capabilities and continuously evolving stringent regulations have made food/package interactions a subject of intense research. This article focuses on: (1) the migration of package components such as oligomers and monomers, processing aids, additives, and residual reactants in to packaged foods, and (2) sorption of food components such as flavors, lipids, and moisture into packages. Principles of diffusion and thermodynamics are utilized to describe the mathematics of migration and sorption. Mathematical models are developed from first principles, and their applicability is illustrated using numerical simulations and published data. Simulations indicate that available models are system (polymer-penetrant) specific. Furthermore, some models best describe the early stages of migration/sorption, whereas others should be used for the late stages of these phenomena. Migration- and/or sorption-related problems with respect to glass, metal, paper-based and polymeric packaging materials are discussed, and their importance is illustrated using published examples. The effects of migrating and absorbed components on food safety, quality, and the environment are presented for various foods and packaging materials. The impact of currently popular packaging techniques such as microwavable, ovenable, and retortable packaging on migration and sorption are discussed with examples. Analytical techniques for investigating migration and sorption phenomena in food packaging are critically reviewed, with special emphasis on the use and characteristics of food-simulating liquids (FSLs). Finally, domestic and international regulations concerning migration in packaged foods, and their impact on food packaging is briefly presented.

Migration aspirations and migration cultures : A case study of Ukrainian migration towards the European Union

NARCIS (Netherlands)

Van Mol, C.; Snel, Erik; Hemmerechts, Kenneth; Timmerman, Christiane

2018-01-01

An abundant body of research focused on macrolevel, mesolevel, and microlevel factors explaining why individuals move across international borders. In this paper, we aim to complement the existing literature by exploring how, within a single country, mesolevel factors differently impact migration

The consequences of Ireland's culture of medical migration.

Science.gov (United States)

Humphries, Niamh; Crowe, Sophie; McDermott, Cian; McAleese, Sara; Brugha, Ruairi

2017-12-28

In recent years, Ireland has experienced a large-scale, outward migration of doctors. This presents a challenge for national policy makers and workforce planners seeking to build a self-sufficient medical workforce that trains and retains enough doctors to meet demand. Although, traditionally, medical migration has been considered beneficial to the Irish health system, austerity has brought a greater level of uncertainty to the health system and, with it, a need to reappraise the professional culture of migration and its impact on the Irish health system. This paper illustrates how a culture of migration informs career and migration plans. It draws on quantitative data-registration and migration data from source and destination countries-and qualitative data-in-depth interviews with 50 doctors who had undertaken postgraduate medical training in Ireland. Of 50 respondents, 42 highlighted the importance of migration. The culture of medical migration rests on two assumptions-that international training/experience is beneficial to all doctors and that those who emigrate will return to Ireland with additional skills and experience. This assumption of return is challenged by a new generation of doctors whose professional lives have been shaped by globalisation and by austerity. Global comparisons reveal the comparatively poor working conditions, training and career opportunities in Ireland and the relative attractiveness of a permanent career abroad. In light of these changes, there is a need to critically appraise the culture of medical migration to determine if and in what circumstances migration is appropriate to the needs of the Irish health system. The paper considers the need to reappraise the culture of medical migration and the widespread emigration that it promotes.

Migration, remittances and micro-finance in rural Mexico

Directory of Open Access Journals (Sweden)

Manuel G. Chávez Ángeles

2012-06-01

Full Text Available Using quantitative and qualitative techniques we gathered a 334 household basedata from three rural municipalities in Mexico to estimate through an instrumental variables model the impact of labor migration and remittances in household’s agricultural yield and financial constraints. We found a positive effect of migration on agriculture yield and a negative impact of migration on financial liquidity maybe due to the migration is often financed by their own savings or borrowing of the household because of lack of liquidity, raising a vicious circle of migration and lack of credit.

Self-selection and intermunicipal migration in Canada.

Science.gov (United States)

Islam, M N; Choudhury, S A

1991-02-01

"This paper investigates individual intermunicipal migration behaviour in Canada within the context of a human capital model that adjusts for the migrant's selectivity in computing expected income gains. In addition to the typical regional determinants of migration, housing and labour market characteristics are found to influence intermunicipal migration significantly, the effects differing with age. Structural coefficients remained more or less stable during the decade 1971-1981. It is shown that the failure to adjust income gains for selectivity bias results in an underestimation of the migration-impacts of income gains and municipal-specific factors." excerpt

Motorized Migrations: the Future or Mere Fantasy?

Science.gov (United States)

Ellis, D.H.; Sladen, William J. L.; Lishman, W.A.; Clegg, K.R.; Duff, J.W.; Gee, G.F.; Lewis, J.C.

2003-01-01

In 15 experiments from 1993-2002, we led cranes, geese, or swans on their first southward migration with either ultralight aircraft or vehicles on the ground. These experiments reveal that large birds can be readily trained to follow and most will return north (and south) in subsequent migrations unassisted. These techniques can now be used to teach birds new (or forgotten) migration paths. Although we are constantly improving our training techniques, we now have an operational program that can be broadly applied to those species where juveniles learn migration routes from their parents.

Final Report: Migration Mechanisms for Large-scale Parallel Applications

Energy Technology Data Exchange (ETDEWEB)

Jason Nieh

2009-10-30

Process migration is the ability to transfer a process from one machine to another. It is a useful facility in distributed computing environments, especially as computing devices become more pervasive and Internet access becomes more ubiquitous. The potential benefits of process migration, among others, are fault resilience by migrating processes off of faulty hosts, data access locality by migrating processes closer to the data, better system response time by migrating processes closer to users, dynamic load balancing by migrating processes to less loaded hosts, and improved service availability and administration by migrating processes before host maintenance so that applications can continue to run with minimal downtime. Although process migration provides substantial potential benefits and many approaches have been considered, achieving transparent process migration functionality has been difficult in practice. To address this problem, our work has designed, implemented, and evaluated new and powerful transparent process checkpoint-restart and migration mechanisms for desktop, server, and parallel applications that operate across heterogeneous cluster and mobile computing environments. A key aspect of this work has been to introduce lightweight operating system virtualization to provide processes with private, virtual namespaces that decouple and isolate processes from dependencies on the host operating system instance. This decoupling enables processes to be transparently checkpointed and migrated without modifying, recompiling, or relinking applications or the operating system. Building on this lightweight operating system virtualization approach, we have developed novel technologies that enable (1) coordinated, consistent checkpoint-restart and migration of multiple processes, (2) fast checkpointing of process and file system state to enable restart of multiple parallel execution environments and time travel, (3) process migration across heterogeneous

Plane-wave least-squares reverse-time migration

KAUST Repository

Dai, Wei

2013-06-03

A plane-wave least-squares reverse-time migration (LSRTM) is formulated with a new parameterization, where the migration image of each shot gather is updated separately and an ensemble of prestack images is produced along with common image gathers. The merits of plane-wave prestack LSRTM are the following: (1) plane-wave prestack LSRTM can sometimes offer stable convergence even when the migration velocity has bulk errors of up to 5%; (2) to significantly reduce computation cost, linear phase-shift encoding is applied to hundreds of shot gathers to produce dozens of plane waves. Unlike phase-shift encoding with random time shifts applied to each shot gather, plane-wave encoding can be effectively applied to data with a marine streamer geometry. (3) Plane-wave prestack LSRTM can provide higher-quality images than standard reverse-time migration. Numerical tests on the Marmousi2 model and a marine field data set are performed to illustrate the benefits of plane-wave LSRTM. Empirical results show that LSRTM in the plane-wave domain, compared to standard reversetime migration, produces images efficiently with fewer artifacts and better spatial resolution. Moreover, the prestack image ensemble accommodates more unknowns to makes it more robust than conventional least-squares migration in the presence of migration velocity errors. © 2013 Society of Exploration Geophysicists.

Data Migration between Document-Oriented and Relational Databases

OpenAIRE

Bogdan Walek; Cyril Klimes

2012-01-01

Current tools for data migration between documentoriented and relational databases have several disadvantages. We propose a new approach for data migration between documentoriented and relational databases. During data migration the relational schema of the target (relational database) is automatically created from collection of XML documents. Proposed approach is verified on data migration between document-oriented database IBM Lotus/ Notes Domino and relational database...

Lutein Inhibits the Migration of Retinal Pigment Epithelial Cells via Cytosolic and Mitochondrial Akt Pathways (Lutein Inhibits RPE Cells Migration

Directory of Open Access Journals (Sweden)

Ching-Chieh Su

2014-08-01

Full Text Available During the course of proliferative vitreoretinopathy (PVR, the retinal pigment epithelium (RPE cells will de-differentiate, proliferate, and migrate onto the surfaces of the sensory retina. Several studies have shown that platelet-derived growth factor (PDGF can induce migration of RPE cells via an Akt-related pathway. In this study, the effect of lutein on PDGF-BB-induced RPE cells migration was examined using transwell migration assays and Western blot analyses. We found that both phosphorylation of Akt and mitochondrial translocation of Akt in RPE cells induced by PDGF-BB stimulation were suppressed by lutein. Furthermore, the increased migration observed in RPE cells with overexpressed mitochondrial Akt could also be suppressed by lutein. Our results demonstrate that lutein can inhibit PDGF-BB induced RPE cells migration through the inhibition of both cytoplasmic and mitochondrial Akt activation.

The commercialization of migration.

Science.gov (United States)

Abrera-mangahas, M A

1989-01-01

International migration is not new to the Philippines. In the recent outflow of contract workers to the Middle East, there is a shift from individual and family initiated migrations to the more organized, highly commercial variety. While profit-taking intermediaries have played some role in the past, the increase in the number and influence of these intermediaries has altered the story of migration decision-making. In 1975, the signing of the bilateral labor agreement between the governments of Iran and the Philippines signalled the rising demand for Filipino contract workers. From 1970 to 1975, the number of Asian migrant workers in the Gulf countries rose from about 120,000 to 370,000. These figures rose dramatically to 3.3 million in 1985. The growing share of organized and commercialized migration has altered migration decision making. Primarily, intermediaries are able to broaden access to foreign job and high wage opportunities. Commercialization effectively raises the transaction costs for contract migration. Studies on recruitment costs and fees show that self-solicited foreign employment costs less than employment obtained through recruitment agents and intermediaries. The difference in the 2 prices is due, not only to overhead costs of intermediation, but more importantly to the rent exacted by agents from having job information and placement rights. In the Philippines in October 1987 the average placement fee was P8000, greatly exceeding the mandated maximum fee level of P5000. This average is understated because the computation includes the 17% who do not pay any fees. The widespread and popular view of recruitment intermediaries is negative, dominated by images of abuses and victims. Private intermediaries and the government bureaucracy need each other. Intermediaries need government; their consistent demand for incentives and protection is indicative. On the other hand, government expands its supervision of control of overseas employment via the

Modification of meander migration by bank failures

Science.gov (United States)

Motta, D.; Langendoen, E. J.; Abad, J. D.; García, M. H.

2014-05-01

Meander migration and planform evolution depend on the resistance to erosion of the floodplain materials. To date, research to quantify meandering river adjustment has largely focused on resistance to erosion properties that vary horizontally. This paper evaluates the combined effect of horizontal and vertical floodplain material heterogeneity on meander migration by simulating fluvial erosion and cantilever and planar bank mass failure processes responsible for bank retreat. The impact of stream bank failures on meander migration is conceptualized in our RVR Meander model through a bank armoring factor associated with the dynamics of slump blocks produced by cantilever and planar failures. Simulation periods smaller than the time to cutoff are considered, such that all planform complexity is caused by bank erosion processes and floodplain heterogeneity and not by cutoff dynamics. Cantilever failure continuously affects meander migration, because it is primarily controlled by the fluvial erosion at the bank toe. Hence, it impacts migration rates and meander shapes through the horizontal and vertical distribution of erodibility of floodplain materials. Planar failures are more episodic. However, in floodplain areas characterized by less cohesive materials, they can affect meander evolution in a sustained way and produce preferential migration patterns. Model results show that besides the hydrodynamics, bed morphology and horizontal floodplain heterogeneity, floodplain stratigraphy can significantly affect meander evolution, both in terms of migration rates and planform shapes. Specifically, downstream meander migration can either increase or decrease with respect to the case of a homogeneous floodplain; lateral migration generally decreases as result of bank protection due to slump blocks; and the effect on bend skewness depends on the location and volumes of failed bank material caused by cantilever and planar failures along the bends, with possible achievement of

DO GIANT PLANETS SURVIVE TYPE II MIGRATION?

International Nuclear Information System (INIS)

Hasegawa, Yasuhiro; Ida, Shigeru

2013-01-01

Planetary migration is one of the most serious problems to systematically understand the observations of exoplanets. We clarify that the theoretically predicted type II, migration (like type I migration) is too fast, by developing detailed analytical arguments in which the timescale of type II migration is compared with the disk lifetime. In the disk-dominated regime, the type II migration timescale is characterized by a local viscous diffusion timescale, while the disk lifetime is characterized by a global diffusion timescale that is much longer than the local one. Even in the planet-dominated regime where the inertia of the planet mass reduces the migration speed, the timescale is still shorter than the disk lifetime except in the final disk evolution stage where the total disk mass decays below the planet mass. This suggests that most giant planets plunge into the central stars within the disk lifetime, and it contradicts the exoplanet observations that gas giants are piled up at r ∼> 1 AU. We examine additional processes that may arise in protoplanetary disks: dead zones, photoevaporation of gas, and gas flow across a gap formed by a type II migrator. Although they make the type II migration timescale closer to the disk lifetime, we show that none of them can act as an effective barrier for rapid type II migration with the current knowledge of these processes. We point out that gas flow across a gap and the fraction of the flow accreted onto the planets are uncertain and they may have the potential to solve the problem. Much more detailed investigation for each process may be needed to explain the observed distribution of gas giants in extrasolar planetary systems

The gravity model of labor migration behavior

Science.gov (United States)

Alexandr, Tarasyev; Alexandr, Tarasyev

2017-07-01

In this article, we present a dynamic inter-regional model, that is based on the gravity approach to migration and describes in continuous time the labor force dynamics between a number of conjugate regions. Our modification of the gravity migration model allows to explain the migration processes and to display the impact of migration on the regional economic development both for regions of origin and attraction. The application of our model allows to trace the dependency between salaries levels, total workforce, the number of vacancies and the number unemployed people in simulated regions. Due to the gravity component in our model the accuracy of prediction for migration flows is limited by the distance range between analyzed regions, so this model is tested on a number of conjugate neighbor regions. Future studies will be aimed at development of a multi-level dynamic model, which allows to construct a forecast for unemployment and vacancies trends on the first modeling level and to use these identified parameters on the second level for describing dynamic trajectories of migration flows.

People's Republic of China's Contemporary Migration Processes

Directory of Open Access Journals (Sweden)

Martina Bofulin

2014-12-01

Full Text Available The last three decades of significant political, economic and social transformations in the People’s Republic of China have had a profound impact on the Chinese society. The article addresses selected topics of Chinese migration that give a more nuanced understanding of migration processes and their contextualization within the contemporary Chinese society: the internal migration, emigration from China and international immigration to China. Migration from rural area towards urban eastern coast is one of the largest spatial movements in the human history, as well as a key component of the economic rise and subsequent social change. Emigration from China has, despite its relatively small volume, profoundly transformed local places of origin, a process that is not independent from the current international geopolitical situation. Immigration of international migrants to China is a relatively new phenomenon that puts the country on the map of migration destination countries for the first time in sixty years. The author concludes that the prevalent research perspectives on Chinese migration offer only a limited insight and suggests some possible alternative ways of analyzing this phenomenon.

Prediction and Migration of Surface-related Resonant Multiples

KAUST Repository

Guo, Bowen; Schuster, Gerard T.; Huang, Yunsong

2015-01-01

Surface-related resonant multiples can be migrated to achieve better resolution than migrating primary reflections. We now derive the formula for migrating surface-related resonant multiples, and show its super-resolution characteristics. Moreover

Generalized diffraction-stack migration and filtering of coherent noise

KAUST Repository

Zhan, Ge

2014-01-27

We reformulate the equation of reverse-time migration so that it can be interpreted as summing data along a series of hyperbola-like curves, each one representing a different type of event such as a reflection or multiple. This is a generalization of the familiar diffraction-stack migration algorithm where the migration image at a point is computed by the sum of trace amplitudes along an appropriate hyperbola-like curve. Instead of summing along the curve associated with the primary reflection, the sum is over all scattering events and so this method is named generalized diffraction-stack migration. This formulation leads to filters that can be applied to the generalized diffraction-stack migration operator to mitigate coherent migration artefacts due to, e.g., crosstalk and aliasing. Results with both synthetic and field data show that generalized diffraction-stack migration images have fewer artefacts than those computed by the standard reverse-time migration algorithm. The main drawback is that generalized diffraction-stack migration is much more memory intensive and I/O limited than the standard reverse-time migration method. © 2014 European Association of Geoscientists & Engineers.

Assessing Hungary’s Stance on Migration and Asylum in Light of the European and Hungarian Migration Strategies

Directory of Open Access Journals (Sweden)

Juhász Krisztina

2017-06-01

Full Text Available The European Union and its member states are facing one of their biggest challenges in recent years due to the surge in migration. This crisis saw more than a million migrants and refugees cross into Europe in 2015. Solutions and policies have been advanced at both the European and national levels, keeping in mind that migration policy is an area of shared competence under Article 4 of the Treaty on the Functioning of the European Union (TFEU. On 13 May 2015, the EU adopted the European Agenda on Migration, which set out immediate and medium-term actions designed to tackle the crisis more effectively. Earlier, in October 2013, the Hungarian government adopted its own migration strategy. The first part of this study provides some insight into the aims and measures contained in the European and Hungarian migration strategies. In the second part, I focus on the steps taken by the Hungarian government regarding asylum policy and crisis management. I conclude that the actions and communications of the Hungarian government are contrary to both these strategic documents.

Migrating mule deer: effects of anthropogenically altered landscapes.

Directory of Open Access Journals (Sweden)

Patrick E Lendrum

Full Text Available Migration is an adaptive strategy that enables animals to enhance resource availability and reduce risk of predation at a broad geographic scale. Ungulate migrations generally occur along traditional routes, many of which have been disrupted by anthropogenic disturbances. Spring migration in ungulates is of particular importance for conservation planning, because it is closely coupled with timing of parturition. The degree to which oil and gas development affects migratory patterns, and whether ungulate migration is sufficiently plastic to compensate for such changes, warrants additional study to better understand this critical conservation issue.We studied timing and synchrony of departure from winter range and arrival to summer range of female mule deer (Odocoileus hemionus in northwestern Colorado, USA, which has one of the largest natural-gas reserves currently under development in North America. We hypothesized that in addition to local weather, plant phenology, and individual life-history characteristics, patterns of spring migration would be modified by disturbances associated with natural-gas extraction. We captured 205 adult female mule deer, equipped them with GPS collars, and observed patterns of spring migration during 2008-2010.Timing of spring migration was related to winter weather (particularly snow depth and access to emerging vegetation, which varied among years, but was highly synchronous across study areas within years. Additionally, timing of migration was influenced by the collective effects of anthropogenic disturbance, rate of travel, distance traveled, and body condition of adult females. Rates of travel were more rapid over shorter migration distances in areas of high natural-gas development resulting in the delayed departure, but early arrival for females migrating in areas with high development compared with less-developed areas. Such shifts in behavior could have consequences for timing of arrival on birthing areas

Families, children, migration and AIDS.

Science.gov (United States)

Haour-Knipe, Mary

2009-01-01

Migration is very often a family affair, and often involves children, directly or indirectly. It may give rise to better quality of life for an entire family, or to bitter disappointment, and may also increase vulnerability to HIV and AIDS. This review, carried out for the Joint Learning Initiative on Children and AIDS, links the literature on "migration", on "HIV and AIDS" and on "families". Three themes are sketched: (1) As both HIV prevalence and circular migration increase, former migrant workers affected by AIDS may return to their families for care and support, especially at the end of life, often under crisis conditions. Families thus lose promising members, as well as sources of support. However, very little is known about the children of such migrants. (2) Following patterns of migration established for far different reasons, children may have to relocate to different places, sometimes over long distances, if their AIDS-affected parents can no longer care for them. They face the same adaptation challenges as other children who move, but complicated by loss of parent(s), AIDS stigma, and often poverty. (3) The issue of migrant families living with HIV has been studied to some extent, but mainly in developed countries with a long history of migration, and with little attention paid to the children in such families. Difficulties include involuntary separation from family members, isolation and lack of support, disclosure and planning for children's care should the parent(s) die and differences in treatment access within the same family. Numerous research and policy gaps are defined regarding the three themes, and a call is made for thinking about migration, families and AIDS to go beyond description to include resilience theory, and to go beyond prevention to include care.

Globalising Chinese Migration: New Spaces, New Meanings

Directory of Open Access Journals (Sweden)

Pál Nyíri

2002-04-01

Full Text Available The paper reviews new trends in international migration from the People’s Republic of China in the last decade, focusing on two aspects: 1 The geographic expansion and merger of formerly distinct translocal migration flows into a global migration system. It includes the opening up of new migration spaces in Eastern Europe and Southeast Asia; increased mobility between destination countries; and increased interchange between different social strata of migrants, from students to illegal workers; 2 A shift in what the social and cultural meaning of migration is to the migrant, to non-migrants, and to elites, which can be described as “upgrading the migrant” (Wang,1998. Various discourses of migration have converged into a highly success-oriented discourse, which reduces the relevance of social background and path of migration. The People’s Republic of China imbues this discourse with tropes of patriotism and development. Concerning the first aspect, the paper problematises the distinction of flows of legal and illegal migrants, students, tourists, and workers, and calls for a holistic approach in studying the configuration of current migration from the PRC. Concerning the second aspect, the paper questions the persistent theory that the PRC as an entity supports emigration, and points out the conflicting interests of various levels and organisations within the state apparatus. At the same time, it recognises that the PRC, like other states, is currently enjoying a honeymoon with state-sanctioned transnationalism, in which migrants are often being more engaged into nation-building and enfranchised as political citizens than are rural non-migrants.

Multi-source least-squares migration of marine data

KAUST Repository

Wang, Xin

2012-11-04

Kirchhoff based multi-source least-squares migration (MSLSM) is applied to marine streamer data. To suppress the crosstalk noise from the excitation of multiple sources, a dynamic encoding function (including both time-shifts and polarity changes) is applied to the receiver side traces. Results show that the MSLSM images are of better quality than the standard Kirchhoff migration and reverse time migration images; moreover, the migration artifacts are reduced and image resolution is significantly improved. The computational cost of MSLSM is about the same as conventional least-squares migration, but its IO cost is significantly decreased.

Costs and benefits of the international labor migration

Directory of Open Access Journals (Sweden)

Alina Hagiu

2007-05-01

Full Text Available Migration has been an important part of the transition process and it's effects are complex including significant changes in attitudes and norms that are relevant for democratic processes. Migration changes the way of life, leads to social-economical and cultural modification, at a continuous readjustment of social organization and assimilation and rejection problems.The amplitude and intensity of migrating fluxes, its dynamic as well as the peculiarity of migrating persons (social level, professional preparation, age, sex is different according with the scope of migration ( work, obliged change of home, refugee, making or gathering the family.

Determinants of internal migration in Kazakhstan

OpenAIRE

Aldashev, Alisher; Dietz, Barbara

2011-01-01

In this paper we analyze the determinants of interregional migration in Kazakhstan using quarterly panel data on region to region migration in 2008–2010. To the best of our knowledge this is the first study on interregional population flows in Central Asia. We find that migration is determined by economic factors, first of all income: People are more likely to leave regions where incomes are low and more likely to move to regions with a higher income level. Furthermore, mobility is larger bet...

Migration of brine inclusions in salt

International Nuclear Information System (INIS)

Pigford, T.H.

1982-01-01

Theories of the migration of brine inclusions in salt are interpreted as simple physical processes, and theories by Russian and U.S. workers are shown to yield the same results. The migration theory is used to predict threshold temperature gradients below which migration of brine inclusions should not occur. The predicted threshold gradients are compared with the temperature gradients expected at the Waste Isolation Pilot Plant in New Mexico. The theory of a threshold gradient helps explain the existence of brine inclusions in natural salt deposits

The implications of migration theory for distributive justice

OpenAIRE

Sager, Alex

2012-01-01

This paper explores the implications of empirical theories of migration for normative accounts of migration and distributive justice. It examines neo-classical economics, world-systems theory, dual labor market theory, and feminist approaches to migration and contends that neo-classical economic theory in isolation provides an inadequate understanding of migration. Other theories provide a fuller account of how national and global economic, political, and social institutions cause and shape m...

ASIC proteins regulate smooth muscle cell migration.

Science.gov (United States)

Grifoni, Samira C; Jernigan, Nikki L; Hamilton, Gina; Drummond, Heather A

2008-03-01

The purpose of the present study was to investigate Acid Sensing Ion Channel (ASIC) protein expression and importance in cellular migration. We recently demonstrated that Epithelial Na(+)Channel (ENaC) proteins are required for vascular smooth muscle cell (VSMC) migration; however, the role of the closely related ASIC proteins has not been addressed. We used RT-PCR and immunolabeling to determine expression of ASIC1, ASIC2, ASIC3 and ASIC4 in A10 cells. We used small interference RNA to silence individual ASIC expression and determine the importance of ASIC proteins in wound healing and chemotaxis (PDGF-bb)-initiated migration. We found ASIC1, ASIC2, and ASIC3, but not ASIC4, expression in A10 cells. ASIC1, ASIC2, and ASIC3 siRNA molecules significantly suppressed expression of their respective proteins compared to non-targeting siRNA (RISC) transfected controls by 63%, 44%, and 55%, respectively. Wound healing was inhibited by 10, 20, and 26% compared to RISC controls following suppression of ASIC1, ASIC2, and ASIC3, respectively. Chemotactic migration was inhibited by 30% and 45%, respectively, following suppression of ASIC1 and ASIC3. ASIC2 suppression produced a small, but significant, increase in chemotactic migration (4%). Our data indicate that ASIC expression is required for normal migration and may suggest a novel role for ASIC proteins in cellular migration.

Radiation-induced electron migration in nucleic acids

International Nuclear Information System (INIS)

Fuciarelli, A.F.; Sisk, E.C.; Miller, J.H.; Zimbrick, J.D.

1994-01-01

Radiation-induced electron migration along DNA is a mechanism by which randomly produced stochastic energy deposition events can lead to non-random types of damage along DNA manifested distal to the sites of the initial energy deposition. Radiation-induced electron migration in nucleic acids has been examined using oligonucleotides containing 5-bromouracil (5-BrU). Interaction of 5-BrU with solvated electrons results in release of bromide ions and formation of uracil-5-yl radicals. Monitoring either bromide ion release or uracil formation provides an opportunity to study electron migration processes in model nucleic acid systems. Using this approach we have discovered that electron migration along oligonucleotides is significantly influenced by the base sequence and strandedness. Migration along 7 base pairs in oligonucleotides containing guanine bases was observed for oligonucleotides irradiated in solution, which compares with mean migration distances of 6-10 bp for Escherichia coli DNA irradiated in solution and 5.5 bp for E. coli DNA irradiated in cells. Evidence also suggests that electron migration can occur preferentially in the 5' to 3' direction along a double-stranded oligonucleotide containing a region of purine bases adjacent to the 5-BrU moiety. Our continued efforts will provide information regarding the contribution of electron transfer along DNA to formation of locally multiply damaged sites created in DNA by exposure to ionizing radiation. (Author)

Temperature-influenced energetics model for migrating waterfowl

Science.gov (United States)

Aagaard, Kevin; Thogmartin, Wayne E.; Lonsdorg, Eric V.

2018-01-01

Climate and weather affect avian migration by influencing when and where birds fly, the energy costs and risks of flight, and the ability to sense cues necessary for proper navigation. We review the literature of the physiology of avian migration and the influence of climate, specifically temperature, on avian migration dynamics. We use waterfowl as a model guild because of the ready availability of empirical physiological data and their enormous economic value, but our discussion and expectations are broadly generalizable to migratory birds in general. We detail potential consequences of an increasingly warm climate on avian migration, including the possibility of the cessation of migration by some populations and species. Our intent is to lay the groundwork for including temperature effects on energetic gains and losses of migratory birds with the expected consequences of increasing temperatures into a predictive modeling framework. To this end, we provide a simulation of migration progression exclusively focused on the influence of temperature on the physiological determinants of migration. This simulation produced comparable results to empirically derived and observed values for different migratory factors (e.g., body fat content, flight range, departure date). By merging knowledge from the arenas of avian physiology and migratory theory we have identified a clear need for research and have developed hypotheses for a path forward.

Do Social Casino Gamers Migrate to Online Gambling? An Assessment of Migration Rate and Potential Predictors.

Science.gov (United States)

Kim, Hyoun S; Wohl, Michael J A; Salmon, Melissa M; Gupta, Rina; Derevensky, Jeffrey

2015-12-01

Social casino games (i.e., free-to-play online gambling games) are enjoyed by millions of players worldwide on a daily basis. Despite being free to play, social casino games share many similarities to traditional casino games. As such, concerns have been raised as to whether social casino games influences the migration to online gambling among people who have not engaged in such activity (see Griffiths in World Online Gambl 9:12-13, 2010). To date, however, no empirical research has assessed this possibility. Thus, the purpose of the present research was to assess the extent to which social casino gamers migrate to online gambling and potential predictors (time spent on social casino games, skill building, enhancement and micro-transactions) of such migration. To this end, social casino gamers who never gambled online (N = 409) completed a questionnaire battery assessing our variables of interest and were re-contacted 6-months later to see if they had engaged in online gambling during the intervening months. Approximately 26% of social casino gamers reported having migrated to online gambling. Importantly, engagement in micro-transactions was the only unique predictor of migration from social casino gaming to online gambling. The implications for the potential harms associated with social casino gaming are discussed.

The Demographic Crisis and Global Migration - Selected Issues

Science.gov (United States)

Frątczak, Ewa Zofia

2016-01-01

Currently the world is undergoing a serious demographic shift, characterised by slowing population growth in developed countries. However, the population in certain less-developed regions of the world is still increasing. According to UN data, as of 2015, (World...2015), 244 million people (or 3.3% of the global population) lived outside their country of birth. While most of these migrants travel abroad looking for better economic and social conditions, there are also those forced to move by political crises, revolutions and war. Such migration is being experienced currently in Europe, a continent which is thus going through both a demographic crisis related to the low fertility rate and population ageing, and a migration crisis. Global migrations link up inseparably with demographic transformation processes taking place globally and resulting in the changing tempo of population growth. Attracting and discouraging migration factors are changing at the same time, as is the scale and range of global migration, and with these also the global consequences. The focus of work addressed in this paper is on global population, the demographic transformation and the role of global migrations, as well as the range and scale of international migration, and selected aspects of global migrations including participation in the global labour market, the scale of monetary transfers (remittances) and the place of global migration in the UN 2030 Agenda for Sustainable Development (Transforming...2015) and the Europe of two crises (Domeny 2016).

Health Selection, Migration, and HIV Infection in Malawi.

Science.gov (United States)

Anglewicz, Philip; VanLandingham, Mark; Manda-Taylor, Lucinda; Kohler, Hans-Peter

2018-04-27

Despite its importance in studies of migrant health, selectivity of migrants-also known as migration health selection-has seldom been examined in sub-Saharan Africa (SSA). This neglect is problematic because several features of the context in which migration occurs in SSA-very high levels of HIV, in particular-differ from contextual features in regions that have been studied more thoroughly. To address this important gap, we use longitudinal panel data from Malawi to examine whether migrants differ from nonmigrants in pre-migration health, assessed via SF-12 measures of mental and physical health. In addition to overall health selection, we focus on three more-specific factors that may affect the relationship between migration and health: (1) whether migration health selection differs by destination (rural-rural, rural-town, and rural-urban), (2) whether HIV infection moderates the relationship between migration and health, and (3) whether circular migrants differ in pre-migration health status. We find evidence of the healthy migrant phenomenon in Malawi, where physically healthier individuals are more likely to move. This relationship varies by migration destination, with healthier rural migrants moving to urban and other rural areas. We also find interactions between HIV-infected status and health: HIV-infected women moving to cities are physically healthier than their nonmigrant counterparts.

Integrating meteorology into research on migration.

Science.gov (United States)

Shamoun-Baranes, Judy; Bouten, Willem; van Loon, E Emiel

2010-09-01

Atmospheric dynamics strongly influence the migration of flying organisms. They affect, among others, the onset, duration and cost of migration, migratory routes, stop-over decisions, and flight speeds en-route. Animals move through a heterogeneous environment and have to react to atmospheric dynamics at different spatial and temporal scales. Integrating meteorology into research on migration is not only challenging but it is also important, especially when trying to understand the variability of the various aspects of migratory behavior observed in nature. In this article, we give an overview of some different modeling approaches and we show how these have been incorporated into migration research. We provide a more detailed description of the development and application of two dynamic, individual-based models, one for waders and one for soaring migrants, as examples of how and why to integrate meteorology into research on migration. We use these models to help understand underlying mechanisms of individual response to atmospheric conditions en-route and to explain emergent patterns. This type of models can be used to study the impact of variability in atmospheric dynamics on migration along a migratory trajectory, between seasons and between years. We conclude by providing some basic guidelines to help researchers towards finding the right modeling approach and the meteorological data needed to integrate meteorology into their own research. © The Author 2010. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved.

Comparative Political Economy and International Migration

NARCIS (Netherlands)

Afonso, A.; Devitt, C.

2016-01-01

This article provides an overview of the literature connecting comparative political economy and international migration in advanced industrialized countries with a focus on the relationship between labour migration, labour markets and welfare institutions. Immigration flows and policies are

Isotope migration and barrier in a VLLW site

International Nuclear Information System (INIS)

Kang Houjun; Zhang Dong; Yang Yong; Shi Zhengkun; Li Kuanliang; Zhang Peicong

2010-01-01

In this work, adsorption and migration of 238 U and 90 Sr in unsaturated soil at a VLLW (very low level waste) site was investigated, in an attempt to find geochemical features of the site. Migration of the isotopes in heterosphere was studied under instantaneous and sequential conditions of the sources. The migration barrier experiment was carried out in two steps on wall rock absorption of the isotopes and addictives to improve the barrier of the wall rock to 90 Sr. The results show that the migration speed of 238 U and 90 Sr in the soil is 0.365 and 0.385 mm/a, respectively. The heterosphere effects on the isotope migration not only alleviated the mainstream contamination, but also prolonged the time of contaminated affection. And false zeolite should be used as barrier additive material for 90 Sr migration. (authors)

Ventriculoperitoneal Shunt Migration

Directory of Open Access Journals (Sweden)

Justin P Puller

2017-01-01

Full Text Available History of present illness: A 40-year-old female presented to our ED with left upper abdominal pain and flank pain. The pain had begun suddenly 2 hours prior when she was reaching into a freezer to get a bag of frozen vegetables. She described the pain as sharp, constant, severe, and worse with movements and breathing. The pain radiated to the left shoulder. On review of systems, the patient had mild dyspnea and nausea. She denied fever, chills, headache, vision changes, vomiting, or urinary symptoms. Her medical history was notable for obstructive sleep apnea, gastroesophageal reflux disease, arthritis, fibromyalgia, depression, obesity, and idiopathic intracranial hypertension. For the latter, she had a VP (ventriculoperitoneal shunt placed 14 years prior to this visit. She had a history of 2 shunt revisions, the most recent 30 days before this ED visit. Significant findings: An immediate post-op abdominal x-ray performed after the patient’s VP shunt revision 30 days prior to this ED visit reveals the VP shunt tip in the mid abdomen. A CT of the abdomen performed on the day of the ED visit reveals the VP shunt tip interposed between the spleen and the diaphragm. Discussion: VP shunts have been reported to migrate to varied locations in the thorax and abdomen. Incidence of abdominal complications of VP shunt placement ranges from 10%-30%, and can include pseudocyst formation, migration, peritonitis, CSF ascites, infection, and viscus perforation. Incidence of distal shunt migration is reported as 10%, and most previously reported cases occurred in pediatric patients.1 A recent retrospective review cited BMI greater than thirty and previous shunt procedure as risk factors for distal shunt migration.2 The patient in the case presented had a BMI of 59 and 3 previous shunt procedures.

Forced migration and mental health: prolonged internal displacement, return migration and resilience.

Science.gov (United States)

Siriwardhana, Chesmal; Stewart, Robert

2013-03-01

Forced internal displacement has been rising steadily, mainly due to conflict. Many internally displaced people (IDP) experience prolonged displacement. Global research evidence suggests that many of these IDP are at high risk for developing mental disorders, adding weight to the global burden of disease. However, individual and community resilience may act as protective factors. Return migration may be an option for some IDP populations, especially when conflicts end, although return migration may itself be associated with worse mental health. Limited evidence is available on effects of resettlement or return migration following prolonged forced internal displacement on mental health. Also, the role of resilience factors remains to be clarified following situations of prolonged displacement. The public health impact of internal displacement is not clearly understood. Epidemiological and interventional research in IDP mental health needs to look beyond medicalised models and encompass broader social and cultural aspects. The resilience factor should be integrated and explored more in mental health research among IDP and a clearly focused multidisciplinary approach is advocated.

Transverse entanglement migration in Hilbert space

International Nuclear Information System (INIS)

Chan, K. W.; Torres, J. P.; Eberly, J. H.

2007-01-01

We show that, although the amount of mutual entanglement of photons propagating in free space is fixed, the type of correlations between the photons that determine the entanglement can dramatically change during propagation. We show that this amounts to a migration of entanglement in Hilbert space, rather than real space. For the case of spontaneous parametric down-conversion, the migration of entanglement in transverse coordinates takes place from modulus to phase of the biphoton state and back again. We propose an experiment to observe this migration in Hilbert space and to determine the full entanglement

Making the most out of the least (squares migration)

KAUST Repository

Dutta, Gaurav

2014-08-05

Standard migration images can suffer from migration artifacts due to 1) poor source-receiver sampling, 2) weak amplitudes caused by geometric spreading, 3) attenuation, 4) defocusing, 5) poor resolution due to limited source-receiver aperture, and 6) ringiness caused by a ringy source wavelet. To partly remedy these problems, least-squares migration (LSM), also known as linearized seismic inversion or migration deconvolution (MD), proposes to linearly invert seismic data for the reflectivity distribution. If the migration velocity model is sufficiently accurate, then LSM can mitigate many of the above problems and lead to a more resolved migration image, sometimes with twice the spatial resolution. However, there are two problems with LSM: the cost can be an order of magnitude more than standard migration and the quality of the LSM image is no better than the standard image for velocity errors of 5% or more. We now show how to get the most from least-squares migration by reducing the cost and velocity sensitivity of LSM.

Pre-migration trauma and HIV-risk behavior.

Science.gov (United States)

Steel, Jennifer; Herlitz, Claes; Matthews, Jesse; Snyder, Wendy; Mazzaferro, Kathryn; Baum, Andy; Theorell, Töres

2003-03-01

This study examined the relationship between pre-migration trauma and HIV-risk behavior in refugees from sub-Saharan Africa. The sample comprised 122 persons who had emigrated from sub-Saharan Africa and were currently residing in Sweden. Qualitative methods including individual interviews, focus groups, and interviews with key informants addressed questions regarding trauma experience and HIV-risk behavior. A history of pre-migration trauma was found to be associated with HIV-risk behavior. According to the participants, symptoms associated with post-traumatic stress disorder, depression, adjustment disorder, and substance use mediated the relationship between pre-migration trauma and sexual risk behavior. In contrast, a minority of the participants who reported pre-migration trauma but not psychological sequelae, or experienced post-traumatic growth, reported safer sexual practices. It appears that for some individuals, pre-migration trauma resulted in psychiatric sequelae, which may increase an individual's risk to be infected with HIV. Interventions targeted at individuals at increased risk (i.e. pre-migration trauma with unresolved psychiatric symptomatology) may facilitate the prevention of HIV and other sexually transmitted diseases in this population. Integration of multiple psychosocial and health issues is recommended for comprehensive treatment and prevention programs.

Pushing the pace of tree species migration.

Directory of Open Access Journals (Sweden)

Eli D Lazarus

Full Text Available Plants and animals have responded to past climate changes by migrating with habitable environments, sometimes shifting the boundaries of their geographic ranges by tens of kilometers per year or more. Species migrating in response to present climate conditions, however, must contend with landscapes fragmented by anthropogenic disturbance. We consider this problem in the context of wind-dispersed tree species. Mechanisms of long-distance seed dispersal make these species capable of rapid migration rates. Models of species-front migration suggest that even tree species with the capacity for long-distance dispersal will be unable to keep pace with future spatial changes in temperature gradients, exclusive of habitat fragmentation effects. Here we present a numerical model that captures the salient dynamics of migration by long-distance dispersal for a generic tree species. We then use the model to explore the possible effects of assisted colonization within a fragmented landscape under a simulated tree-planting scheme. Our results suggest that an assisted-colonization program could accelerate species-front migration rates enough to match the speed of climate change, but such a program would involve an environmental-sustainability intervention at a massive scale.

Development Education and the Psychosocial Dynamics of Migration

NARCIS (Netherlands)

Tarusarira, Joram

2017-01-01

A positive response to migration requires a joint effort from both the migrants and citizens of the host countries. Migration, especially forced migration, engenders negative personal and socio-psychological impacts on refugees, asylum seekers and economic migrants. The traumatic experiences they

Towards understanding international migration determinants today: Theoretical perspective

Directory of Open Access Journals (Sweden)

Predojević-Despić Jelena

2010-01-01

Full Text Available In times of global migration flows and ever increasing mobility of the workforce in the world, the necessity for constant deepening of theoretical knowledge is imposed as a basis for understanding main determinants of this phenomenon, and with an aim of directing the focus of migration researches towards more efficient overcoming of challenges and making use of the advantages which international migrations could bring both to origin, destination and transit countries. The main goal of this paper is to give a critical review on the development of the economic migrations theory, to state the main similarities and differences between various approaches and to point out to the main drawbacks and problems which the theoretical perspective is facing when studying the determinants of contemporary international labor migrations. The focus of the study refers to voluntary labor migrations with reference to migrations of the highly educated population, while the stress is on economic theories, although some of them are closely connected to sociological, geographical and anthropological theories. The development of the theory on international migrations has been started by micro theoretical models, namely, through the conceptualization of theories which place the individual in the focal point of research, who estimates the positive, namely negative sides of moving from one location to another. Economic models on the micro theoretical level cede more space to models of macro structure which research the social and economic structure within and between countries. There are many theoretical models which offer possible answers to the question on what are the main determinants of international migrations on the macro analytical level. Although every one of them tries to give an answer to the same question, they use different concepts, assumptions and frameworks of research. The reasons which bring about the initiation of international migrations can be

A critical survey of live virtual machine migration techniques

Directory of Open Access Journals (Sweden)

Anita Choudhary

2017-11-01

Full Text Available Abstract Virtualization techniques effectively handle the growing demand for computing, storage, and communication resources in large-scale Cloud Data Centers (CDC. It helps to achieve different resource management objectives like load balancing, online system maintenance, proactive fault tolerance, power management, and resource sharing through Virtual Machine (VM migration. VM migration is a resource-intensive procedure as VM’s continuously demand appropriate CPU cycles, cache memory, memory capacity, and communication bandwidth. Therefore, this process degrades the performance of running applications and adversely affects efficiency of the data centers, particularly when Service Level Agreements (SLA and critical business objectives are to be met. Live VM migration is frequently used because it allows the availability of application service, while migration is performed. In this paper, we make an exhaustive survey of the literature on live VM migration and analyze the various proposed mechanisms. We first classify the types of Live VM migration (single, multiple and hybrid. Next, we categorize VM migration techniques based on duplication mechanisms (replication, de-duplication, redundancy, and compression and awareness of context (dependency, soft page, dirty page, and page fault and evaluate the various Live VM migration techniques. We discuss various performance metrics like application service downtime, total migration time and amount of data transferred. CPU, memory and storage data is transferred during the process of VM migration and we identify the category of data that needs to be transferred in each case. We present a brief discussion on security threats in live VM migration and categories them in three different classes (control plane, data plane, and migration module. We also explain the security requirements and existing solutions to mitigate possible attacks. Specific gaps are identified and the research challenges in improving

Undocumented migration in response to climate change

Science.gov (United States)

Riosmena, Fernando; Hunter, Lori M.; Runfola, Daniel M.

2016-01-01

In the face of climate change induced economic uncertainty, households may employ migration as an adaptation strategy to diversify their livelihood portfolio through remittances. However, it is unclear whether such climate migration will be documented or undocumented. In this study we combine detailed migration histories with daily temperature and precipitation information for 214 weather stations to investigate whether climate change more strongly impacts undocumented or documented migration from 68 rural Mexican municipalities to the U.S. during the years 1986–1999. We employ two measures of climate change, the warm spell duration index (WSDI) and the precipitation during extremely wet days (R99PTOT). Results from multi-level event-history models demonstrate that climate-related international migration from rural Mexico was predominantly undocumented. We conclude that programs to facilitate climate change adaptation in rural Mexico may be more effective in reducing undocumented border crossings than increased border fortification. PMID:27570840

Undocumented migration in response to climate change.

Science.gov (United States)

Nawrotzki, Raphael J; Riosmena, Fernando; Hunter, Lori M; Runfola, Daniel M

In the face of climate change induced economic uncertainty, households may employ migration as an adaptation strategy to diversify their livelihood portfolio through remittances. However, it is unclear whether such climate migration will be documented or undocumented. In this study we combine detailed migration histories with daily temperature and precipitation information for 214 weather stations to investigate whether climate change more strongly impacts undocumented or documented migration from 68 rural Mexican municipalities to the U.S. during the years 1986-1999. We employ two measures of climate change, the warm spell duration index ( WSDI ) and the precipitation during extremely wet days ( R99PTOT ). Results from multi-level event-history models demonstrate that climate-related international migration from rural Mexico was predominantly undocumented. We conclude that programs to facilitate climate change adaptation in rural Mexico may be more effective in reducing undocumented border crossings than increased border fortification.

[Migration mobility and movement of the population].

Science.gov (United States)

Zaslavska, T; Ribakovski, L

1983-01-01

"The functions of migration are reviewed from the viewpoint of the demographic situation in the USSR (by regions, sex, age, education, profession, labour and social activity, nationality, rural-urban, etc.). Some effects of migration on fertility are shown. The authors investigate the role of the economic functions of migration for the process of professional mobility. The territorial mobility of the population is analysed on a wider scale as a part of the social mobility in the socialist society. In connection with this, some problems of the migration policy as an element of the demographic policy of the USSR are outlined." (summary in ENG, RUS) excerpt

Rural migration and health care

DEFF Research Database (Denmark)

Svendsen, Gunnar Lind Haase; Jensen, Marit Vatn

This literature study focuses on possible links between access to health services and migration in rural areas. Why do people move to or from rural areas or why do they stay? What determines where people settle? And, in this context, do local health care services play an important or minor role......, or no role at all? First, the paper reports on key findings from rural migration studies, in order to shed light on two migration trends: urbanization and counter-urbanization. Then we take a closer look on settlement preferences in rural areas, including the impact of health care facilities. Finally, we end...... up with a more deepgoing review of the relatively small number of studies, which explicitly deal with settlement preferences related to access to health care....

Lines of evidence for environmentally driven human migration

Science.gov (United States)

Davis, K. F.; D'Odorico, P.

2012-12-01

International human migration is an important mechanism that affects, and is affected by, various human and natural systems. With the number of people living outside their countries of origin currently estimated at 214 million people and projected to potentially reach more than 400 million people by mid-century, the topic of international human movements presents possible advantages and pitfalls for both sending and receiving countries on multiple fronts (e.g. economic, environmental, political and cultural). Understanding how human migration interacts with human and natural systems is therefore essential in realizing a sustainable and balanced future. While the study of international migration has historically been motivated largely by economic and political interests, the issue of environmentally induced migration has become increasingly important in light of a rapidly changing climate in conjunction with increasing population pressure on many important resources. Particularly in terms of theoretical and conceptual discussions, environmentally induced human migration has been receiving increased attention in the literature. To date, few studies - many of which focus on internal (intra-national) or regional migration - have attempted to quantify the interactions of human migration and the environment, with little attention paid to the global scale as a result of varying regional factors and lack of sufficient data. Recently available global bilateral migration datasets have been developed that allow for a more comprehensive understanding of human movements between all countries. With these datasets, we seek to elucidate environmental drivers of human migration over the past half-century using a multi-pronged approach. First, using a recently developed universal radiation model, we examine human movements based solely on global population distribution. Next, by comparison of migration movements with selected economic, environmental and human welfare indicators, we

Father's Labour Migration and Children's School Discontinuation in Rural Mozambique.

Science.gov (United States)

Yabiku, Scott T; Agadjanian, Victor

2017-08-01

We examine how the discontinuation of schooling among left-behind children is related to multiple dimensions of male labor migration: the accumulation of migration experience, the timing of these migration experiences in the child's life course, and the economic success of the migration. Our setting is rural southern Mozambique, an impoverished area with massive male labor out-migration. Results show that fathers' economically successful labor migration is more beneficial for children's schooling than unsuccessful migration or non-migration. There are large differences, however, by gender: compared to sons of non-migrants, sons of migrant fathers (regardless of migration success) have lower rates of school discontinuation, while daughters of migrant fathers have rates of school discontinuation no different than daughters of non-migrants. Furthermore, accumulated labor migration across the child's life course is beneficial for boys' schooling, but not girls'. Remittances sent in the past year reduce the rate of discontinuation for sons, but not daughters.

Why sub-Saharan African health workers migrate to European countries that do not actively recruit: a qualitative study post-migration.

Science.gov (United States)

Poppe, Annelien; Jirovsky, Elena; Blacklock, Claire; Laxmikanth, Pallavi; Moosa, Shabir; De Maeseneer, Jan; Kutalek, Ruth; Peersman, Wim

2014-01-01

Many studies have investigated the migration intentions of sub-Saharan African medical students and health professionals within the context of a legacy of active international recruitment by receiving countries. However, many health workers migrate outside of this recruitment paradigm. This paper aims to explore the reasons for migration of health workers from sub-Saharan Africa to Belgium and Austria; European countries without a history of active recruitment in sub-Saharan Africa. Data were collected using semistructured interviews. Twenty-seven health workers were interviewed about their migration experiences. Included participants were born in sub-Saharan Africa, had trained as health workers in sub-Saharan Africa, and were currently living in Belgium or Austria, though not necessarily currently working as a health professional. Both Austria and Belgium were shown not to be target countries for the health workers, who instead moved there by circumstance, rather than choice. Three principal reasons for migration were reported: 1) educational purposes; 2) political instability or insecurity in their country of origin; and 3) family reunification. In addition, two respondents mentioned medical reasons and, although less explicit, economic factors were also involved in several of the respondents' decision to migrate. These results highlight the importance of the broader economic, social, and political context within which migration decisions are made. Training opportunities proved to be an important factor for migration. A further development and upgrade of primary care might help to counter the common desire to specialize and improve domestic training opportunities.

The incomplete trajectory of Albanian migration in Greece

OpenAIRE

GEMI, Eda

2015-01-01

Proceedings from the conference "Governing Irregular Migration : States, Actors and Intermediaries", Athens 8-9 July 2015 The study addresses the irregular migration of Albanians to Greece. In particular, it analyses the key findings of the fieldwork with 87 Albanian migrants, the dynamic of irregular migration from Albania to Greece, the factors and the actors who affect them as well as the success or failure of the relevant migration policies. The report shows that the expanding possibil...

Adjusting the general growth balance method for migration

OpenAIRE

Hill, Kenneth; Queiroz, Bernardo

2010-01-01

Death distribution methods proposed for death registration coverage by comparison with census age distributions assume no net migration. This assumption makes it problematic to apply these methods to sub-national and national populations affected by substantial net migration. In this paper, we propose and explore a two-step process in which the Growth Balance Equation is first used to estimate net migration rates, using a model of age-specific migration, and then it is used to compare the obs...

Migration and depressive symptoms in migrant-sending areas: findings from the survey of internal migration and health in China.

Science.gov (United States)

Lu, Yao; Hu, Peifeng; Treiman, Donald J

2012-08-01

China has experienced large-scale internal migration and growing mental health disorders. Limited research has examined the relationship between the two processes. We examined the association between labor out-migration and depressive symptoms of family members left behind in migrant-sending areas. We conducted a multistage probability sample survey of Chinese adults in 2008 ("Internal Migration and Health in China"), including 787 people in rural migrant-sending areas. To study whether adults in out-migrant households were more likely to experience depressive symptoms (CES-D) than were adults in non-migrant households, we used multivariate regressions and adjusted for a wide range of confounding factors and for the complex sampling design. Adults in households with labor out-migrants were more likely to report depressive symptoms than those in households without out-migrants, presumably a result of the absence of family members. However, monetary remittances from labor migrants buffered the mental health costs of out-migration. Labor out-migration has important consequences for the mental health in migrant-sending communities. There is an urgent need to address the psychological costs of migration and to promote regular remittances.

On the interrelations between migration and commuting

Directory of Open Access Journals (Sweden)

Lukić Vesna

2013-01-01

Full Text Available In this paper, we emphasise the significance of studying the interrelations between commuting and migration. The aim of the paper is to point out the factors which affect these interrelations (demographic and socio-economic characteristics of migrants and commuters, labour market, real estate market, information, life style, etc., with the special emphasis on the role of commuting distance onto the chosen mobility type. Besides theorethical frameworks and results of the selected foreign researches up to date, the overview of research of interrelations between migration and commuting in Serbia has also been presented. While earlier studies conducted by Gawryszenski (1978, Termote (1980 and Reitsma&Vergoossen (1987 pointed to the replacement of migration types between each other within country, in recent literature the interaction between migration and commuting has been studied in a trans-boundary context of the contemporary EU. Modern trend of long distance commuting instead of migration and the concept of substitution/replacement regarding migration and commuting have also been discussed. In Serbia, there is a positive correlation between commuting outflows and immigration in rural settlements of Vojvodina province. Namely, commuting and migration are complement, which is the characteristic of both processes sub-urbanisation and ex-urbanisation (Lukić, 2012. In addition to ownership of real estate and previous migration experience, marital status influenced the chosen mobility type in Serbia as well. Adjustment to changes of Serbian labour market is mostly conducted via migration (Miletić, Lukić, Miljanović, 2011. Interrelations between migration and commuting are very significant due to the tendency of transformation of some commuters into migrants. This process has its consequences, both on demographic as well as the overall socio-economic development of the area of commuters’ origin and destination. However, even though the surveys

Croatia’s Migration Potential – Micro-Analytic Aspects

Directory of Open Access Journals (Sweden)

Saša Božić

2005-06-01

Full Text Available The authors set criteria for the selection of a model for measuring migration potential; they select and apply such a model to Croatia and determine the practical and scientific relevance of the Croatian case, especially its significance for the improvement of the chosen model. The authors concentrate on the application of Heinz Fassmann’s and Christiane Hintermann’s micro-analytic model for the estimation of East-Central Europe’s migration potential. After applying this model, they estimate Croatia’s total migration potential at 12.5%, i.e. 460,000 persons older than fourteen. The probable migration potential is estimated at 2.5%, i.e. 92,000 and the real migration potential at 0.4% of the population above fourteen, i.e. 14,700 persons. In Croatian case as well, the younger population (which can still utilise its labour capacity, as well as unemployed, unmarried and highly educated persons, are more likely to consider emigration. The data show also that the regions with the lowest share in GNP have the highest percentage of potential migrants and not the regions which are geographically the closest to potential immigration countries. The authors stress the necessity to integrate migration potential research models. The explanatory assumptions of migration potential research models, based on place utility and subjective expected utility, often overlap when used to interpret the data. Furthermore, the Croatian case shows that personal migration experience and the analytical mezzo level must be considered in order to gain an understanding of the creation of migration preferences.

Ecological advantages of partial migration as a conditional strategy.

Science.gov (United States)

Vélez-Espino, Luis A; McLaughlin, Robert L; Robillard, Melissa

2013-05-01

Partial migration is a widespread phenomenon characterized by migrant and resident forms from the same population. In phenotypically plastic taxa with indeterminate growth, resident and migrant ecophenotypes can differ in size and life history traits in ways expected to maximize fitness in the different habitats they exploit. Studies of partial migration in different taxa have advocated either density-dependence or environmental stochasticity as explanations for partial migration. We used a demographic approach for a virtual Brook Trout population to demonstrate the ecological consequences of partial migration under interacting density dependence and environmental stochasticity. The maintenance of partial migration as a conditional strategy in species/populations where resident and migrant forms exhibit life history asymmetries provides ecological advantages. We show that density-dependent migration is expected to increase population fitness under constant environmental conditions or low environmental variation, but decreases population fitness under high environmental variation. These conditions favor intermediate levels of migration as an advantageous tactic. However, there are threshold rates of return migration below which partial migration is no longer a viable tactic. Our modeling approach also allowed the exploration of the distribution of the population by life stage and habitat in response to the strength of density dependence, costs of migration, and return rates, and demonstrated the importance of the conservation of ecophenotypes in partially migratory populations. Copyright © 2013 Elsevier Inc. All rights reserved.

Skeletonized Least Squares Wave Equation Migration

KAUST Repository

Zhan, Ge; Schuster, Gerard T.

2010-01-01

of the wave equation. Only the early‐arrivals of these Green's functions are saved and skeletonized to form the migration Green's function (MGF) by convolution. Then the migration image is obtained by a dot product between the recorded shot gathers and the MGF

Integrating meteorology into research on migration

NARCIS (Netherlands)

Shamoun-Baranes, J.; Bouten, W.; van Loon, E.E.

2010-01-01

Atmospheric dynamics strongly influence the migration of flying organisms. They affect, among others, the onset, duration and cost of migration, migratory routes, stop-over decisions, and flight speeds en-route. Animals move through a heterogeneous environment and have to react to atmospheric

[Migration of dentists within Hungary].

Science.gov (United States)

Balázs, Péter

2010-09-01

Concerning the human resource management in the health care, Hungarian analysts focus mainly on cross-national migration, which was instigated considerably by joining the European Union in 2004. Contrasted to other health care professionals, dentists emphasized also the importance of in-country migration (mobility) indicating serious dangers of developing inequalities in the dental service. From the point of view of health system planning, the main problem is to balance the needs and the number of professionals in regions and areas with extremely different socio-economic conditions. Under dictatorial governments, this "balancing" (which was experienced also in Hungary) is a forced allocation of young professionals to the target regions. In political freedom and free market economy, these measures are unthinkable. The present domestic area distribution, concerning also the supply through vacancies by old age inactivity and cross-national migration, is ruled by personal decisions of actually graduated and immigrant professionals respectively. Therefore, it is unavoidable to investigate the interrelation of factors (dentists' births place, study migration and decisions for practice allocation) ruling the in-country geographic patterns of dental practices. This evidence-based knowledge can only explain the present situation and provide guidelines for health policy decision makers.

Migration pathways in soils

International Nuclear Information System (INIS)

Gronow, J.R.

1986-01-01

This study looked at diffusive migration through three types of deformation; the projectile pathways, hydraulic fractures of the sediments and faults, and was divided into three experimental areas: autoradiography, the determination of diffusion coefficients and electron microscopy of model projectile pathways in clay. For the autoradiography, unstressed samples were exposed to two separate isotopes, Pm-147 (a possible model for Am behaviour) and the poorly sorbed iodide-125. The results indicated that there was no enhanced migration through deformed kaolin samples nor through fractured Great Meteor East (GME) sediment, although some was evident through the projectile pathways in GME and possibly through the GME sheared samples. The scanning electron microscopy of projectile pathways in clay showed that emplacement of a projectile appeared to have no effect on the orientation of particles at distances greater than two projectile radii from the centre of a projectile pathway. It showed that the particles were not simply aligned with the direction of motion of the projectile but that, the closer to the surface of a particular pathway, the closer the particles lay to their original orientation. This finding was of interest from two points of view: i) the ease of migration of a pollutant along the pathway, and ii) possible mechanisms of hole closure. It was concluded that, provided that there is no advective migration, the transport of radionuclides through sediments containing these defects would not be significantly more rapid than in undeformed sediments. (author)

Networks and Selection in International Migration to Spain

DEFF Research Database (Denmark)

Neubecker, Nina; Smolka, Marcel; Steinbacher, Anne

This paper provides new evidence on migrant networks as determinants of the scale and skill structure of migration, using aggregate data from a recent migration boom to Spain. We develop a three-level nested multinomial logit migration model. Our model accommodates varying degrees of similarity...

Spatial-temporal migration laws of Cd in Jiaozhou Bay

Science.gov (United States)

Yang, Dongfang; Li, Haixia; Zhang, Xiaolong; Wang, Qi; Miao, Zhenqing

2018-02-01

Many marine bays have been polluted by various pollutants, and understanding the migration laws is essential to scientific research and pollution control. This paper analyzed the spatial and temporal migration laws of Cd in waters in Jiaozhou Bay during 1979—1983. Results showed that there were twenty spatial-temporal migration law for the migration processes of Cd. These laws were helpful for better understanding the migration of Cd in marine bay, providing basis for scientific research and pollution control.

Dateline Migration.

Science.gov (United States)

Tomasi, Lydio E., Ed.

1995-01-01

Presents data on international migration and its effects in and between various countries in North America, Europe, and Africa. Discussions include refugee, immigrant, and migrant worker flows; the legal, political, and social problems surrounding immigrants; alien terrorism and law enforcement problems; and migrant effects on education, social…

Skilled migration and health outcomes in developing countries.

Science.gov (United States)

Uprety, Dambar

2018-04-30

Many studies have found that health outcomes decline when health professionals leave the country, but do such results remain consistent in gender- and income-disaggregated skilled migration? To help uncover explanations for such a pro-migration nature of health outcomes, the present study revisits this topic but allows for associations of skilled migration with mortality and life expectancy to differ between male and female, and between low- and high-income countries. Using a panel of 133 developing countries as source and 20 OECD countries as destination from 1980 to 2010 allowing the coefficient on emigration across different education levels to differ, the study finds the negative effect of high-skilled emigration on health outcomes. Such effect is more pronounced for high-skilled female migration than those for male and for low-income countries than for middle-and high-income countries. Results also show that such adverse effect is larger for African countries than non-African ones. However, the low-skilled migration appears to be insignificant to affect health outcomes in developing countries. Thus, skilled migration is detrimental to longevity in developing countries but unskilled migration is not.

A Customizable Chamber for Measuring Cell Migration.

Science.gov (United States)

Chowdhury, Aniqa N; Vo, Huu Tri; Olang, Sharon; Mappus, Elliott; Peterson, Brian; Hlavac, Nora; Harvey, Tyler; Dean, Delphine

2017-03-12

Cell migration is a vital part of immune responses, growth, and wound healing. Cell migration is a complex process that involves interactions between cells, the extracellular matrix, and soluble and non-soluble chemical factors (e.g., chemoattractants). Standard methods for measuring the migration of cells, such as the Boyden chamber assay, work by counting cells on either side of a divider. These techniques are easy to use; however, they offer little geometric modification for different applications. In contrast, microfluidic devices can be used to observe cell migration with customizable concentration gradients of soluble factors 1 , 2 . However, methods for making microfluidics based assays can be difficult to learn. Here, we describe an easy method for creating cell culture chambers to measure cell migration in response to chemical concentration gradients. Our cell migration chamber method can create different linear concentration gradients in order to study cell migration for a variety of applications. This method is relatively easy to use and is typically performed by undergraduate students. The microchannel chamber was created by placing an acrylic insert in the shape of the final microchannel chamber well into a Petri dish. After this, poly(dimethylsiloxane) (PDMS) was poured on top of the insert. The PDMS was allowed to harden and then the insert was removed. This allowed for the creation of wells in any desired shape or size. Cells may be subsequently added to the microchannel chamber, and soluble agents can be added to one of the wells by soaking an agarose block in the desired agent. The agarose block is added to one of the wells, and time-lapse images can be taken of the microchannel chamber in order to quantify cell migration. Variations to this method can be made for a given application, making this method highly customizable.

Visualizing Human Migration Trhough Space and Time

Science.gov (United States)

Zambotti, G.; Guan, W.; Gest, J.

2015-07-01

Human migration has been an important activity in human societies since antiquity. Since 1890, approximately three percent of the world's population has lived outside of their country of origin. As globalization intensifies in the modern era, human migration persists even as governments seek to more stringently regulate flows. Understanding this phenomenon, its causes, processes and impacts often starts from measuring and visualizing its spatiotemporal patterns. This study builds a generic online platform for users to interactively visualize human migration through space and time. This entails quickly ingesting human migration data in plain text or tabular format; matching the records with pre-established geographic features such as administrative polygons; symbolizing the migration flow by circular arcs of varying color and weight based on the flow attributes; connecting the centroids of the origin and destination polygons; and allowing the user to select either an origin or a destination feature to display all flows in or out of that feature through time. The method was first developed using ArcGIS Server for world-wide cross-country migration, and later applied to visualizing domestic migration patterns within China between provinces, and between states in the United States, all through multiple years. The technical challenges of this study include simplifying the shapes of features to enhance user interaction, rendering performance and application scalability; enabling the temporal renderers to provide time-based rendering of features and the flow among them; and developing a responsive web design (RWD) application to provide an optimal viewing experience. The platform is available online for the public to use, and the methodology is easily adoptable to visualizing any flow, not only human migration but also the flow of goods, capital, disease, ideology, etc., between multiple origins and destinations across space and time.

Globalization and migration: A "unified brain drain" model

OpenAIRE

Brezis, Elise S.; Soueri, Ariel

2012-01-01

Globalization has led to a vast flow of migration of workers but also of students. The purpose of this paper is to analyze the migration of individuals encompassing decisions already at the level of education. We develop a unified brain drain model that incorporates the decisions of an individual vis - à - vis both education and migration. In the empirical part, this paper addresses international flows of migration within the EU and presents strong evidence of concentration of students in cou...

Unix Application Migration Guide

CERN Document Server

Microsoft. Redmond

2003-01-01

Drawing on the experience of Microsoft consultants working in the field, as well as external organizations that have migrated from UNIX to Microsoft® Windows®, this guide offers practical, prescriptive guidance on the issues you are likely to face when porting existing UNIX applications to the Windows operating system environment. Senior IT decision makers, network managers, and operations managers will get real-world guidance and best practices on planning and implementation issues to understand the different methods through which migration or co-existence can be accomplished. Also detailing

Double path-integral migration velocity analysis: a real data example

International Nuclear Information System (INIS)

Costa, Jessé C; Schleicher, Jörg

2011-01-01

Path-integral imaging forms an image with no knowledge of the velocity model by summing over the migrated images obtained for a set of migration velocity models. Double path-integral imaging migration extracts the stationary velocities, i.e. those velocities at which common-image gathers align horizontally, as a byproduct. An application of the technique to a real data set demonstrates that quantitative information about the time migration velocity model can be determined by double path-integral migration velocity analysis. Migrated images using interpolations with different regularizations of the extracted velocities prove the high quality of the resulting time-migration velocity information. The so-obtained velocity model can then be used as a starting model for subsequent velocity analysis tools like migration tomography or other tomographic methods

Children’s Migration to the United States from Mexico and Central America: Evidence from the Mexican and Latin American Migration Projects

Directory of Open Access Journals (Sweden)

Katharine M. Donato

2015-02-01

Full Text Available In light of rising numbers of unaccompanied minors at the Mexico-US border in 2014, this article examines child migration from Mexico, Guatemala, El Salvador, Costa Rica, and Nicaragua. Using data from the Mexican and Latin American Migration Projects that permit us to go beyond simple descriptive analysis about children apprehended at the border, we investigate the extent to which children from these countries: (1 enter without legal authorization to do so; (2 are more likely to cross the border now than in the past; and (3 are tied to their parents’ migration. In theory, if immigration and refugee protections worked well for children and offered them legal pathways to reunify with their families, then we would expect low levels of unauthorized entry and no dramatic shifts over time. However, our examination of child migration shows that it is strongly linked to unauthorized entry, period of entry, and parents’ US experience.The findings show that the migration of children is closely linked to their parents’ migration history. Although the overall likelihood of a Mexican child making a first US trip is quite low, it is practically non-existent for children whose parents have no US experience. Thus, the increase in child migration from Central America, and the continued high levels of child migration from Mexico result from widespread migration networks and the United States’ long-standing reliance on the children’s parents as immigrant workers. The findings suggest that these children need protection in the form of family reunification and permanent legal status.

Overall and specific migration from multilayer high barrier food contact materials - kinetic study of cyclic polyester oligomers migration.

Science.gov (United States)

Úbeda, Sara; Aznar, Margarita; Vera, Paula; Nerín, Cristina; Henríquez, Luis; Taborda, Laura; Restrepo, Claudia

2017-10-01

Most multilayer high barrier materials used in food packaging have a polyurethane adhesive layer in their structures. In order to assess the safety of these materials, it is important to determine the compounds intentionally added to the adhesives (IAS) as well as those non-intentionally added substances (NIAS). During the manufacture of polyurethane adhesives, some by-products can be formed, such as cyclic polyester oligomers coming from the reaction between dicarboxylic acids and glycols. Since these compounds are not listed in the Regulation 10/2011/EU, they should not be found in migration above 0.01 mg/kg of simulant. In this study two flexible multilayer packaging materials were used and migration was evaluated in simulant A (ethanol 10% v/v), simulant B (acetic acid 3% w/v) and simulant ethanol 95% v/v during 10 days at 60ºC. Identification and quantification of non-volatile compounds was carried out by UPLC-MS-QTOF. Most of migrants were oligomers such as cyclic polyesters and caprolactam oligomers. Overall migration and specific migration of adipic acid-diethylene glycol and phthalic acid-diethylene glycol were monitored over time and analysed by UPLC-MS-TQ. In most cases, ethanol 95% v/v was the simulant with the highest concentration values. Overall migration kinetics followed a similar pattern than specific migration kinetics.

A Chaos Theory Perspective on International Migration

Directory of Open Access Journals (Sweden)

Anca Tănasie

2017-12-01

Full Text Available This paper aims at providing a different approach to international migration analysis, beyond classical models previously proposed by specialized literature. Chaos theory is getting more and more applied into macroeconomics once traditional linear models or even previous dynamic analysis become less suitable. Modern science sees chaos as unpredictable evolution, maybe even disorder. Still, chaos has got its own rules and can describe many dynamic phenomena within our world. Thus, we test whether international migration data falls under the rules of chaos and whether recent developments within the “European migration crisis” (the total daily migration inflows towards the coasts of Italy, by sea, from January 2014 to April 2017 could be described as chaotic.

Substrate Curvature Regulates Cell Migration -A Computational Study

Science.gov (United States)

He, Xiuxiu; Jiang, Yi

Cell migration in host microenvironment is essential to cancer etiology, progression and metastasis. Cellular processes of adhesion, cytoskeletal polymerization, contraction, and matrix remodeling act in concert to regulate cell migration, while local extracellular matrix architecture modulate these processes. In this work we study how stromal microenvironment with native and cell-derived curvature at micron-meter scale regulate cell motility pattern. We developed a 3D model of single cell migration on a curved substrate. Mathematical analysis of cell morphological adaption to the cell-substrate interface shows that cell migration on convex surfaces deforms more than on concave surfaces. Both analytical and simulation results show that curved surfaces regulate the cell motile force for cell's protruding front through force balance with focal adhesion and cell contraction. We also found that cell migration on concave substrates is more persistent. These results offer a novel biomechanical explanation to substrate curvature regulation of cell migration. NIH 1U01CA143069.

Energetic and biomechanical constraints on animal migration distance.

Science.gov (United States)

Hein, Andrew M; Hou, Chen; Gillooly, James F

2012-02-01

Animal migration is one of the great wonders of nature, but the factors that determine how far migrants travel remain poorly understood. We present a new quantitative model of animal migration and use it to describe the maximum migration distance of walking, swimming and flying migrants. The model combines biomechanics and metabolic scaling to show how maximum migration distance is constrained by body size for each mode of travel. The model also indicates that the number of body lengths travelled by walking and swimming migrants should be approximately invariant of body size. Data from over 200 species of migratory birds, mammals, fish, and invertebrates support the central conclusion of the model - that body size drives variation in maximum migration distance among species through its effects on metabolism and the cost of locomotion. The model provides a new tool to enhance general understanding of the ecology and evolution of migration. © 2011 Blackwell Publishing Ltd/CNRS.

Internal migration and household living conditions in Ethiopia

Directory of Open Access Journals (Sweden)

Blessing Uchenna Mberu

2006-06-01

Full Text Available Using the 1998 Migration, Gender and Health Survey in Five Regions of Ethiopia, and multivariate regression techniques, this paper examines the relationship between internal migration and household living conditions. The analysis finds significant living condition advantage of permanent and temporary migrants over non-migrants. These advantages are primarily linked to migration selectivity by education and non-agricultural income. Once the independent effects of these variables are controlled, no statistical significant independent association exists between migration status and living conditions. Government policies of resettlement in the 1980s and ethnic federalism of the 1990s may have engendered stress migration and exacerbated poor living outcomes for return migrants. The resort to migration and/or resettlement as an individual or government policy response to periodic unfavorable conditions in places of origin is not strongly supported by this analysis as the key to improved living conditions. Promoting higher education and opportunities for employment outside the agricultural sector are more likely to yield improved living conditions in Ethiopia.

Metropolitan migration and population growth in selected developing countries.

Science.gov (United States)

1983-01-01

The purpose of this article is to estimate the components of metropolitan population growth in selected developing countries during 1960-1970 period. The study examines population growth in 26 cities: 5 are in Africa, 8 in Asia, and 13 in Latin America, using data from national census publications. These cities in general are the political capitals of their countries, but some additional large cities were selected in Brazil, Mexico, and South Africa. All cities, at the beginning of the 1960-1970 decade had over 500,000 population; Accra, the only exception, reached this population level during the 1960s. Some cities had over 4 million residents in 1970. Net migration contributed about 37% to total metropolitan population growth; the remainder of the growth is attributable to natural increase. Migration has a much stronger impact on metropolitan growth than suggested by the above figure: 1) Several metropolitan areas, for various reasons, are unlikely to receive many migrants; without those cities, the share of metropolitan growth from net migration is 44%. 2) Estimates of the natural increase of migrants after their arrival in the metropolitan areas, when added to migration itself, changes the total contribution of migration to 49% in some metropolitan areas. 3) Even where net migration contributes a smaller proportion to metropolitan growth than natural increase, the rates of net migration are generally high and should be viewed in the context of rapid metropolitan population growth from natural increase alone. Finally, the paper also compares the components of metropolitan growth with the components of growth in the remaining urban areas. The results show that the metropolitan areas, in general, grow faster than the remaining urban areas, and that this more rapid growth is mostly due to a higher rate of net migration. Given the significance of migration for metropolitan growth, further investigations of the effects of these migration streams, particularly with

Is there a connection between weather at departure sites, onset of migration and timing of soaring-bird autumn migration in Israel?

NARCIS (Netherlands)

Shamoun-Baranes, J.; van Loon, E.E.; Alon, D.; Alpert, P.; Yom-Tov, Y.; Leshem, Y.

2006-01-01

Aims Different aspects of soaring-bird migration are influenced by weather. However, the relationship between weather and the onset of soaring-bird migration, particularly in autumn, is not clear. Although long-term migration counts are often unavailable near the breeding areas of many soaring birds

Migration: a core public health ethics issue.

Science.gov (United States)

Wild, V; Dawson, A

2018-05-01

In this article, we outline the link between migration, public health and ethics. Discussing relevant arguments about migration from the perspective of public health and public health ethics. Critical review of theories and frameworks, case-based analysis and systematic identification and discussion of challenges. Migration is a core issue of public health ethics and must take a case-based approach: seeking to identify the specific ethical dimensions and vulnerabilities in each particular context. Public health as a practice, built upon the core value of justice, requires the protection and promotion of migrants' well-being (even if this produces tension with immigration services). Ethical analysis should take all phases of migration into account: before, during and after transit. We argue that migration policies, at least as they relate to migrants' well-being, should be founded upon a shared humanity, respect for human rights and on the idea that effective public health cannot and should not be confined within the borders and to the citizens of any host country. We make the case for migration to be seen as a core issue of public health ethics. Copyright © 2018 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Kinetic evolutionary behavior of catalysis-select migration

International Nuclear Information System (INIS)

Wu Yuan-Gang; Lin Zhen-Quan; Ke Jian-Hong

2012-01-01

We propose a catalysis-select migration driven evolution model of two-species (A- and B-species) aggregates, where one unit of species A migrates to species B under the catalysts of species C, while under the catalysts of species D the reaction will become one unit of species B migrating to species A. Meanwhile the catalyst aggregates of species C perform self-coagulation, as do the species D aggregates. We study this catalysis-select migration driven kinetic aggregation phenomena using the generalized Smoluchowski rate equation approach with C species catalysis-select migration rate kernel K(k;i,j) = Kkij and D species catalysis-select migration rate kernel J(k;i,j)= Jkij. The kinetic evolution behaviour is found to be dominated by the competition between the catalysis-select immigration and emigration, in which the competition is between JD 0 and KC 0 (D 0 and C 0 are the initial numbers of the monomers of species D and C, respectively). When JD 0 −KC 0 > 0, the aggregate size distribution of species A satisfies the conventional scaling form and that of species B satisfies a modified scaling form. And in the case of JD 0 −KC 0 0 −KC 0 > 0 case. (interdisciplinary physics and related areas of science and technology)

Gender and rural-urban migration in China.

Science.gov (United States)

Davin, D

1996-02-01

Many men and women in China are migrating in search of better economic opportunities. Young women who migrate to urban centers in search of opportunity may stay away from their home villages for several years. At some point, however, they are likely to return home. This article considers the effect which such circular migration is having upon gender relations in China. The author's argument is presented in sections on China's 1990 census, migration and the sexual division of labor, migration and child care, the influence of returning migrants, the influence of young female returnees, and the fertility of returnees. She speculates that the demands and expectations of young women who return to their villages after spending some time earning high wages in urban areas will be affected by urban norms. While their return may lead to initial conflict, it is likely that the women will retain greater personal autonomy from their urban experience. Their return is also likely to lead to a higher degree of material consumption in the rural areas. Present circular migration in China has the potential to return human and financial resources to the villages, thereby helping to prevent the urban-rural gap between economic, social, cultural, and educational factors from growing even wider.

Focus: Asian migration to Canada.

Science.gov (United States)

Kobayashi, A

1988-01-01

This collection of 5 short essays on Asian migration to Canada focuses on the relationships between individual migrants and their social contexts, both Asian and Canadian. Papers by Anderson and Kobayashi adopt research perspectives of outsider and insider, respectively. Vibert provides a historical overview against which the substantive issues introduced in the other 3 papers can be understood, and he illustrates the links between circumstances of migration and the larger issues by which the course of Canadian social progress has been steered. Mercer provides an introduction to issues that dominate the agenda of contemporary research, to show that Canadian communities of Asian heritage continue to grow in size, diversity, and complexity, as they become more established on the Canadian landscape. This collection is as much about the geography of racism as it is about migration.

Evolution of mammalian migrations for refuge, breeding, and food.

Science.gov (United States)

Gnanadesikan, Gitanjali E; Pearse, William D; Shaw, Allison K

2017-08-01

Many organisms migrate between distinct habitats, exploiting variable resources while profoundly affecting ecosystem services, disease spread, and human welfare. However, the very characteristics that make migration captivating and significant also make it difficult to study, and we lack a comprehensive understanding of which species migrate and why. Here we show that, among mammals, migration is concentrated within Cetacea and Artiodactyla but also diffusely spread throughout the class (found in 12 of 27 orders). We synthesize the many ecological drivers of round-trip migration into three types of movement-between breeding and foraging sites, between breeding and refuge sites, and continuous tracking of forage/prey-each associated with different traits (body mass, diet, locomotion, and conservation status). Our results provide only partial support for the hypothesis that migration occurs without phylogenetic constraint. Furthermore, our findings suggest that categorizing migration into these three types may aid predictions of migrants' responses to environmental changes.

Outward migration may alter population dynamics and income inequality

Science.gov (United States)

Shayegh, Soheil

2017-11-01

Climate change impacts may drive affected populations to migrate. However, migration decisions in response to climate change could have broader effects on population dynamics in affected regions. Here, I model the effect of climate change on fertility rates, income inequality, and human capital accumulation in developing countries, focusing on the instrumental role of migration as a key adaptation mechanism. In particular, I investigate how climate-induced migration in developing countries will affect those who do not migrate. I find that holding all else constant, climate change raises the return on acquiring skills, because skilled individuals have greater migration opportunities than unskilled individuals. In response to this change in incentives, parents may choose to invest more in education and have fewer children. This may ultimately reduce local income inequality, partially offsetting some of the damages of climate change for low-income individuals who do not migrate.

The benefits and caveats of international nurse migration

Directory of Open Access Journals (Sweden)

Hongyan Li

2014-09-01

Full Text Available Worldwide, there is a dramatic shortage of nurses. An increase in the migration of nurses from their home countries to recipient countries is having a global effect on the healthcare system. This global phenomenon stems from historical, economical, social, and political factors. Migration has a significant impact on both the individual and national level. This article summarizes the factors that contribute to nurse migration form the perspective of the source and recipient countries. Additionally, the impacts and issues surrounding nurse migration were also analyzed.

Data and methods in the environment-migration nexus

DEFF Research Database (Denmark)

Eklund, Lina; Romankiewicz, Clemens; Brandt, Martin Stefan

2016-01-01

The relationship between environment and migration has gained increased attention since the 1990s when the Intergovernmental Panel on Climate Change projected climate change to become a major driver of human migration. Evaluations of this relationship include both quantitative and qualitative ass....... Several case studies base their results on data at very coarse resolutions that have undergone strong modifications and generalizations. We argue that scale-related shortcomings must be considered in all stages of environment-migration research....... assessments. This review article introduces the concept of scale to environment-migration research as an important methodological issue for the reliability of conclusions drawn. The review of case studies shows that scale issues are highly present in environment-migration research but rarely discussed...

Migrating Worker

DEFF Research Database (Denmark)

Hansen, Hans

This is the preliminary report on the results obtained in the Migrating Worker-project. This project was initiated by the Danish Ministry of Finance with the aim of illustrating the effects of the 1408/71 agreement and the bilateral double taxation agreements Denmark has with the countries included...

Migrating to learn and learning to migrate: a study of the experiences and intentions of international student migrants.

Science.gov (United States)

Li, F L; Findlay, A M; Jowett, A J; Skeldon, R

1996-03-01

"The research reported here evaluates whether students come to the UK mainly for educational reasons, and therefore perceive their stay as temporary, or whether emigration for study is being used as part of a conscious strategy by people intending to become future labour migrants.... The simplest interpretation of the results appears to be that migration, experienced as a result of international moves for study purposes, does not influence planning of further migration moves. But the research also indicates that migration for education is closely tied to other types of population redistribution and should be treated by population geographers as an integral part of international migration systems." Data were collected by questionnaire survey from 349 engineering students at Hong Kong universities and 82 Hong Kong students studying engineering in the UK. excerpt

Internal migration and income of immigrant families

OpenAIRE

Rashid, Saman

2004-01-01

Using a longitudinal dataset from the years 1995 and 2000, respectively, this study examines whether migration within the host country of Sweden generates higher total annual income for (two-earner) immigrant families. The empirical findings indicate that internal migration generates a positive outcome in terms of higher family income for newly arrived refugee-immigrant families. Further, with the length of residence in the host country, the monetary gain accruing from internal migration decr...

Mechanism of constitution liquid film migration

Energy Technology Data Exchange (ETDEWEB)

Zuo, Hongjun [Univ. of Alabama, Birmingham, AL (United States)

1999-06-01

Liquid film migration (LFM) in liquid phase sintering classically involves a large metastable liquid volume adjacent to solid, and migration occurs at an isolated solid-liquid (S-L) interface. Constitutional liquid film migration (CLFM), discovered in alloy 718, has major characteristics similar to those of LFM, except that the metastable liquid is from the constitutional liquation of precipitates on the grain boundary. The similarity between LFM and CLFM has led to the theory that coherency lattice strain responsible for LFM is also responsible for CLFM. The coherency strain hypothesis was tested in this study by evaluating whether the Hillert model of LFM would also apply for CLFM. Experimental results of CLFM in alloy 718 showed that migration velocity followed the trend predicted by the Hillert model. This indicates that the coherency strain hypothesis of LFM also applies for CLFM and that the coherency lattice strain responsible for LFM is also the driving force for CLFM.

Re-thinking the politics of migration. On the uses and challenges of regime perspectives for migration research

NARCIS (Netherlands)

Horvath, Kenneth; Amelinaz, Anna; Peters, Karin

2017-01-01

The aim of this special issue is to critically assess the potential of regime theory for migration research. Against the background of contemporary political dynamics, regime terminology has become rather popular in migration studies. There has, however, been little debate on the foundations and

Defective neuronal migration and inhibition of bipolar to multipolar transition of migrating neural cells by Mesoderm-Specific Transcript, Mest, in the developing mouse neocortex.

Science.gov (United States)

Ji, Liting; Bishayee, Kausik; Sadra, Ali; Choi, Seunghyuk; Choi, Wooyul; Moon, Sungho; Jho, Eek-Hoon; Huh, Sung-Oh

2017-07-04

Brain developmental disorders such as lissencephaly can result from faulty neuronal migration and differentiation during the formation of the mammalian neocortex. The cerebral cortex is a modular structure, where developmentally, newborn neurons are generated as a neuro-epithelial sheet and subsequently differentiate, migrate and organize into their final positions in the cerebral cortical plate via a process involving both tangential and radial migration. The specific role of Mest, an imprinted gene, in neuronal migration has not been previously studied. In this work, we reduced expression of Mest with in utero electroporation of neuronal progenitors in the developing embryonic mouse neocortex. Reduction of Mest levels by shRNA significantly reduced the number of neurons migrating to the cortical plate. Also, Mest-knockdown disrupted the transition of bipolar neurons into multipolar neurons migrating out of the sub-ventricular zone region. The migrating neurons also adopted a more tangential migration pattern upon knockdown of the Mest message, losing their potential to attach to radial glia cells, required for radial migration. The differentiation and migration properties of neurons via Wnt-Akt signaling were affected by Mest changes. In addition, miR-335, encoded in a Mest gene intron, was identified as being responsible for blocking the default tangential migration of the neurons. Our results suggest that Mest and its intron product, miR-335, play important roles in neuronal migration with Mest regulating the morphological transition of primary neurons required in the formation of the mammalian neocortex. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Climate Vulnerability and Human Migration in Global Perspective

Science.gov (United States)

Grecequet, Martina; DeWaard, Jack; Hellmann, Jessica J.; Abel, Guy J.

2018-01-01

The relationship between climate change and human migration is not homogenous and depends critically on the differential vulnerability of population and places. If places and populations are not vulnerable, or susceptible, to climate change, then the climate–migration relationship may not materialize. The key to understanding and, from a policy perspective, planning for whether and how climate change will impact future migration patterns is therefore knowledge of the link between climate vulnerability and migration. However, beyond specific case studies, little is known about this association in global perspective. We therefore provide a descriptive, country-level portrait of this relationship. We show that the negative association between climate vulnerability and international migration holds only for countries least vulnerable to climate change, which suggests the potential for trapped populations in more vulnerable countries. However, when analyzed separately by life supporting sector (food, water, health, ecosystem services, human habitat, and infrastructure) and vulnerability dimension (exposure, sensitivity, and adaptive capacity), we detect evidence of a relationship among more, but not the most, vulnerable countries. The bilateral (i.e., country-to-country) migration show that, on average, people move from countries of higher vulnerability to lower vulnerability, reducing global risk by 15%. This finding is consistent with the idea that migration is a climate adaptation strategy. Still, ~6% of bilateral migration is maladaptive with respect to climate change, with some movement toward countries with greater climate change vulnerability. PMID:29707262

DISCERNING EXOPLANET MIGRATION MODELS USING SPIN-ORBIT MEASUREMENTS

International Nuclear Information System (INIS)

Morton, Timothy D.; Johnson, John Asher

2011-01-01

We investigate the current sample of exoplanet spin-orbit measurements to determine whether a dominant planet migration channel can be identified, and at what confidence. We use the predictions of Kozai migration plus tidal friction and planet-planet scattering as our misalignment models, and we allow for a fraction of intrinsically aligned systems, explainable by disk migration. Bayesian model comparison demonstrates that the current sample of 32 spin-orbit measurements strongly favors a two-mode migration scenario combining planet-planet scattering and disk migration over a single-mode Kozai migration scenario. Our analysis indicates that between 34% and 76% of close-in planets (95% confidence) migrated via planet-planet scattering. Separately analyzing the subsample of 12 stars with T eff >6250 K-which Winn et al. predict to be the only type of stars to maintain their primordial misalignments-we find that the data favor a single-mode scattering model over Kozai with 85% confidence. We also assess the number of additional hot star spin-orbit measurements that will likely be necessary to provide a more confident model selection, finding that an additional 20-30 measurement has a >50% chance of resulting in a 95% confident model selection, if the current model selection is correct. While we test only the predictions of particular Kozai and scattering migration models in this work, our methods may be used to test the predictions of any other spin-orbit misaligning mechanism.

Climate Vulnerability and Human Migration in Global Perspective.

Science.gov (United States)

Grecequet, Martina; DeWaard, Jack; Hellmann, Jessica J; Abel, Guy J

2017-05-01

The relationship between climate change and human migration is not homogenous and depends critically on the differential vulnerability of population and places. If places and populations are not vulnerable, or susceptible, to climate change, then the climate-migration relationship may not materialize. The key to understanding and, from a policy perspective, planning for whether and how climate change will impact future migration patterns is therefore knowledge of the link between climate vulnerability and migration. However, beyond specific case studies, little is known about this association in global perspective. We therefore provide a descriptive, country-level portrait of this relationship. We show that the negative association between climate vulnerability and international migration holds only for countries least vulnerable to climate change, which suggests the potential for trapped populations in more vulnerable countries. However, when analyzed separately by life supporting sector (food, water, health, ecosystem services, human habitat, and infrastructure) and vulnerability dimension (exposure, sensitivity, and adaptive capacity), we detect evidence of a relationship among more, but not the most, vulnerable countries. The bilateral (i.e., country-to-country) migration show that, on average, people move from countries of higher vulnerability to lower vulnerability, reducing global risk by 15%. This finding is consistent with the idea that migration is a climate adaptation strategy. Still, ~6% of bilateral migration is maladaptive with respect to climate change, with some movement toward countries with greater climate change vulnerability.

Nanoparticles migration in fractured rocks and affects on contaminant migration

Science.gov (United States)

Missana, Tiziana; Garcia-Gutierrez, Miguel; Alonso, Ursula

2014-05-01

In previous studies, the transport behavior of artificial (gold and latex) and natural (smectite clay) colloids, within a planar fracture in crystalline rock, was analyzed. In order to better understand the effects of colloid size, shape and surface charge on nanoparticle migration and especially on filtration processes on natural rock surfaces, different clay colloids and oxide nanoparticles were selected and their transport studied as a function of the residence time. In all the cases, (a fraction of) the nanoparticles travelled in the fracture as fast as or faster than water (with a retardation factor, Rf ≤ 1) and the observed Rf, was related to the Taylor dispersion coefficient, accounting for colloid size, water velocity and fracture width. However, under most of the cases, in contrast to the behavior of a conservative tracer, colloids recovery was much lower than 100 %. Differences in recovery between different nanoparticles, under similar residence times, were analyzed. In order to evaluate the possible consequences, on contaminant migration, of the presence of nanoparticles in the system, transport tests were carried out with both colloids and sorbing radionuclides. The overall capacity for colloids of enhancing radionuclide migration in crystalline rock fractures is discussed. Acknowledgments: The research leading to these results received funding from EU FP7/2007-2011 grant agreement Nº 295487 (BELBAR, Bentonite Erosion: effects on the Long term performance of the engineered Barrier and Radionuclide Transport) and by the Spanish Government under the project NANOBAG (CTM2011-2797).

OECD migration, welfare and skill selectivity

DEFF Research Database (Denmark)

Pedersen, Peder; Pytlikova, Mariola; Smith, Nina

into 27 OECD countries over the period of 12 years, 1989-2000. Using a fixed effects panel data model, we analyze the determinants of the migration flows during the latest decade. We study whether there are significant selectivity effects in international migration flows, i.e. whether the countries...

Migration control, documentation, and state transformation

NARCIS (Netherlands)

Vigneswaran, D.; Segatti, A.; Landau, L.B.

2011-01-01

Examines undocumented migration, one of the main outcomes of the transition from formal labor migration to a mixed system, gauges the long-term impacts of the bureaucratic stasis on governance in South Africa, and explores how an ongoing state of crisis in this policy sphere is shaping the everyday

Ethical issues in irregular migration research

NARCIS (Netherlands)

Duvell, F.; Triandafyllidou, A.; Vollmer, B.

2008-01-01

This paper is concerned with the ethical issues arising for researchers engaged in the study of irregular migration. Irregular migration is by definition an elusive phenomenon as it takes place in violation of the law and at the margins of society. This very nature of the phenomenon raises important

Transnational nurse migration: future directions for medical anthropological research.

Science.gov (United States)

Prescott, Megan; Nichter, Mark

2014-04-01

Transnational nurse migration is a serious global health issue in which inequitably distributed shortages hinder health and development goals. This article selectively reviews the literature on nurse migration that has emerged from nursing, health planning, and the social sciences and offers productive directions for future anthropological research. The literature on global nurse migration has largely focused on push/pull economic logic and the concept of brain drain to understand the causes and effects of nurse migration. These concepts obscure political-economic, historical, and cultural factors that pattern nurse migration and influence the complex effects of nurse migration. Global nurse care chain analysis helps illuminate the numerous nodes in the production and migration of nurses, and management of this transnational process. Examples are provided from the Philippines and India to illustrate ways in which this analysis may be deepened, refined and rendered more critical by anthropological research. Copyright © 2014 Elsevier Ltd. All rights reserved.

Migration of Cells in a Social Context

DEFF Research Database (Denmark)

Vedel, Søren; Tay, Savas; Johnston, Darius M.

2013-01-01

In multicellular organisms and complex ecosystems, cells migrate in a social context. While this is essential for the basic processes of life such as embryonic development, wound healing and unregulated migration furthermore is implicated in diseases such as cancer, the influence of neighboring...... cells on the individual remains poorly understood. Previous work on isolated cells has revealed a stereotypical migratory behavior, however many aspects of the migration characteristics of cells in populations remained unknown exactly because of this lack of characterization of neighbour-cell influence....... We quantified1 the migration of thousands of individual cells in their population context using time-lapse microscopy, microfluidic cell culture and automated image analysis, and discovered a much richer dynamics in the social context, with significant variations in directionality, displacement...

Migration and Well-being: Beyond the Macrosystem

Directory of Open Access Journals (Sweden)

Dina Birman

2011-11-01

Full Text Available This commentary reviews the contributions of the 6 papers to the emerging focus on migration within community psychology. This collection of articles on migration and community represents a growing interest in the field in immigration issues in general, and a community psychology focus on these issues in particular. The papers span a range of issues raised by migration in a variety of different contexts. The papers reflect principles of community psychology by articulating a perspective on migration and its outcomes within national and global contexts. Taken together, these articles demonstrate the increasing mutual enrichment of immigration and community research. The articles suggest the need to continue to articulate psychological constructs as transactional and contextual across multiple levels of analysis.

Virtual machine migration in an over-committed cloud

KAUST Repository

Zhang, Xiangliang

2012-04-01

While early emphasis of Infrastructure as a Service (IaaS) clouds was on providing resource elasticity to end users, providers are increasingly interested in over-committing their resources to maximize the utilization and returns of their capital investments. In principle, over-committing resources hedges that users - on average - only need a small portion of their leased resources. When such hedge fails (i.e., resource demand far exceeds available physical capacity), providers must mitigate this provider-induced overload, typically by migrating virtual machines (VMs) to underutilized physical machines. Recent works on VM placement and migration assume the availability of target physical machines [1], [2]. However, in an over-committed cloud data center, this is not the case. VM migration can even trigger cascading overloads if performed haphazardly. In this paper, we design a new VM migration algorithm (called Scattered) that minimizes VM migrations in over-committed data centers. Compared to a traditional implementation, our algorithm can balance host utilization across all time epochs. Using real-world data traces from an enterprise cloud, we show that our migration algorithm reduces the risk of overload, minimizes the number of needed migrations, and has minimal impact on communication cost between VMs. © 2012 IEEE.

Women Moving Within Borders: Gender and Internal Migration ...

African Journals Online (AJOL)

Internal migration is an inherent part of the processes of development and structural transformation in any region. In Africa, while the focus is often on international migration, internal migration is far more significant for development in terms of the numbers of people moving and their poverty reduction potential and well-being ...

Does Migration Make You Happy? A Longitudinal Study of Internal Migration and Subjective Well-Being (discussion paper)

NARCIS (Netherlands)

Nowok, B.; Van Ham, M.; Findlay, A.; Gayle, V.

2011-01-01

The majority of modelling studies on consequences of internal migration focus almost exclusively on the labour market outcomes and the material well-being of migrants. We investigate whether individuals who migrate within the UK become happier after the move than they were before it and whether the

Toward predictive scenarios of planetary migration

International Nuclear Information System (INIS)

Baruteau, Clement

2008-01-01

The recent detection of extra-solar planets has provided an exciting opportunity to test our theories of planet formation and evolution. An impressive result is the significant proportion of giant planets located much closer to their star than Mercury is from our own Sun. These planets should have formed further out in the protoplanetary disc, thus one needs to explain how they could move closer to their host star. Remarkably enough, such an explanation was proposed well before the discovery of the first exo-planet. It considered the interaction between a planet and the protoplanetary disc, which leads to a decrease of the planet's semi-major axis. This is known as planetary migration. Many studies have shown that the migration timescale of low-mass planets is much shorter than the lifetime of the disc. All planets should therefore have migrated to the vicinity of their host star. This is at least in contradiction with the locations of the planets in our Solar System. In order to elaborate predictive scenarios of planet formation and evolution, it is of primary interest to refine our understanding of disc-planet interactions. The inclusion of the disc self-gravity is an illustration of this. With analytical and numerical arguments, I show that discarding the self-gravity leads to a significant overestimate of the differential Lindblad torque for migrating low-mass planets. Another aspect explored in this thesis is the impact of the gas thermodynamics on migration. I show that the thermodynamic evolution of the disc induces an additional contribution to the corotation torque, which may dramatically slow down or even reverse the migration of low-mass planets. (author) [fr

Supplemental feeding alters migration of a temperate ungulate.

Science.gov (United States)

Jones, Jennifer D; Kauffman, Matthew J; Monteith, Kevin L; Scurlock, Brandon M; Albeke, Shannon E; Cross, Paul C

Conservation of migration requires information on behavior and environmental determinants. The spatial distribution of forage resources, which migration exploits, often are altered and may have subtle, unintended consequences. Supplemental feeding is a common management practice, particularly for ungulates in North America and Europe, and carryover effects on behavior of this anthropogenic manipulation of forage are expected in theory, but have received limited empirical evaluation, particularly regarding effects on migration. We used global positioning system (GPS) data to evaluate the influence of winter feeding on migration behavior of 219 adult female elk (Cervus elaphus) from 18 fed ranges and 4 unfed ranges in western Wyoming. Principal component analysis revealed that the migratory behavior of fed and unfed elk differed in distance migrated, and the timing of arrival to, duration on, and departure from summer range. Fed elk migrated 19.2 km less, spent 11 more days on stopover sites, arrived to summer range 5 days later, resided on summer range 26 fewer days, and departed in the autumn 10 days earlier than unfed elk. Time-to-event models indicated that differences in migratory behavior between fed and unfed elk were caused by altered sensitivity to the environmental drivers of migration. In spring, unfed elk migrated following plant green-up closely, whereas fed elk departed the feedground but lingered on transitional range, thereby delaying their arrival to summer range. In autumn, fed elk were more responsive to low temperatures and precipitation events, causing earlier departure from summer range than unfed elk. Overall, supplemental feeding disconnected migration by fed elk from spring green-up and decreased time spent on summer range, thereby reducing access to quality forage. Our findings suggest that ungulate migration can be substantially altered by changes to the spatial distribution of resources, including those of anthropogenic origin, and that

Supplemental feeding alters migration of a temperate ungulate

Science.gov (United States)

Jones, Jennifer D; Kauffman, Matthew J.; Monteith, Kevin L.; Scurlock, Brandon M.; Albeke, Shannon E.; Cross, Paul C.

2014-01-01

Conservation of migration requires information on behavior and environmental determinants. The spatial distribution of forage resources, which migration exploits, often are altered and may have subtle, unintended consequences. Supplemental feeding is a common management practice, particularly for ungulates in North America and Europe, and carryover effects on behavior of this anthropogenic manipulation of forage are expected in theory, but have received limited empirical evaluation, particularly regarding effects on migration. We used global positioning system (GPS) data to evaluate the influence of winter feeding on migration behavior of 219 adult female elk (Cervus elaphus) from 18 fed ranges and 4 unfed ranges in western Wyoming. Principal component analysis revealed that the migratory behavior of fed and unfed elk differed in distance migrated, and the timing of arrival to, duration on, and departure from summer range. Fed elk migrated 19.2 km less, spent 11 more days on stopover sites, arrived to summer range 5 days later, resided on summer range 26 fewer days, and departed in the autumn 10 days earlier than unfed elk. Time-to-event models indicated that differences in migratory behavior between fed and unfed elk were caused by altered sensitivity to the environmental drivers of migration. In spring, unfed elk migrated following plant green-up closely, whereas fed elk departed the feedground but lingered on transitional range, thereby delaying their arrival to summer range. In autumn, fed elk were more responsive to low temperatures and precipitation events, causing earlier departure from summer range than unfed elk. Overall, supplemental feeding disconnected migration by fed elk from spring green-up and decreased time spent on summer range, thereby reducing access to quality forage. Our findings suggest that ungulate migration can be substantially altered by changes to the spatial distribution of resources, including those of anthropogenic origin, and that

Climate Variability and Migration: Evidence from Tanzania

OpenAIRE

Mathilde MAUREL; Zaneta KUBIK

2014-01-01

We analyze whether Tanzanian households engage in internal migration as a response to weather-related shocks. Our findings confirm that climate shocks lead to a higher probability of migration by reducing agricultural yields, which in turn induces households to send their members away in order to spatially diversify their income. This effect is, however, low, since a 1% reduction in agricultural income induced by weather shock increases the probability of migration by 3% for an average househ...

Hydrogen migration in Lu at low temperatures

International Nuclear Information System (INIS)

Yamakawa, K.

1997-01-01

The migration of hydrogen in Lu is determined by electrical resistance measurements in temperature range of 140-170 K. Disordered hydrogen atoms, which are formed by quenching, migrate to order during annealing in the above temperature range. The rate of the resistance decrease depends on the ordering rate of hydrogen. From the resistance decrease during isothermal annealings, the activation energy of hydrogen migration is determined as 0.43 eV (41.5 kJ mol -1 ). (orig.)

Migration and Well-being: Beyond the Macrosystem

OpenAIRE

Birman, Dina

2011-01-01

This commentary reviews the contributions of the 6 papers to the emerging focus on migration within community psychology. This collection of articles on migration and community represents a growing interest in the field in immigration issues in general, and a community psychology focus on these issues in particular. The papers span a range of issues raised by migration in a variety of different contexts. The papers reflect principles of community psychology by articulating a perspective on mi...

KIN NETWORKS AND MIGRATION IN SAGBAMA LOCAL ...

African Journals Online (AJOL)

CIU

Historically, migration process has been characterized and continues to be .... Mexican migration to the U.S (Massey, Arango, Hugo, Kouaouci, Pellegrino and .... the study destination (Sagbama) according to Independent National Electoral.

[Migration patterns of health professionals].

Science.gov (United States)

Kingma, Mireille

2005-01-01

The past three decades have seen the number of international migrants double, to reach the unprecedented total of 175 million people in 2003. National health systems are often the biggest national employer, responsible for an estimated 35 million workers worldwide. Health professionals are part of the expanding global labour market. Today, foreign-educated health professionals represent more than a quarter of the medical and nursing workforces of Australia, Canada, the United Kingdom and the United States. Destination countries, however, are not limited to industrialised nations. For example, 50 per cent of physicians in the Namibia public services are expatriates and South Africa continues to recruit close to 80% of its rural physicians from other countries. International migration often imitates patterns of internal migration. The exodus from rural to urban areas, from lower to higher income urban neighbourhoods and from lower-income to higher-income sectors contributes challenges to the universal coverage of the population. International migration is often blamed for the dramatic health professional shortages witnessed in the developing countries. A recent OECD study, however, concludes that many registered nurses in South Africa (far exceeding the number that emigrate) are either inactive or unemployed. These dire situations constitute a modern paradox which is for the most part ignored. Shared language, promises of a better quality of life and globalization all support the continued existence of health professionals' international migration. The ethical dimension o this mobility is a sensitive issue that needs to be addressed. A major paradigm shift, however, is required in order to lessen the need to migrate rather than artificially curb the flows.

Spontaneous neutrophil migration patterns during sepsis after major burns.

Science.gov (United States)

Jones, Caroline N; Moore, Molly; Dimisko, Laurie; Alexander, Andrew; Ibrahim, Amir; Hassell, Bryan A; Warren, H Shaw; Tompkins, Ronald G; Fagan, Shawn P; Irimia, Daniel

2014-01-01

Finely tuned to respond quickly to infections, neutrophils have amazing abilities to migrate fast and efficiently towards sites of infection and inflammation. Although neutrophils ability to migrate is perturbed in patients after major burns, no correlations have yet been demonstrated between altered migration and higher rate of infections and sepsis in these patients when compared to healthy individuals. To probe if such correlations exist, we designed microfluidic devices to quantify the neutrophil migration phenotype with high precision. Inside these devices, moving neutrophils are confined in channels smaller than the neutrophils and forced to make directional decisions at bifurcations and around posts. We employed these devices to quantify neutrophil migration across 18 independent parameters in 74 blood samples from 13 patients with major burns and 3 healthy subjects. Blinded, retrospective analysis of clinical data and neutrophil migration parameters revealed that neutrophils isolated from blood samples collected during sepsis migrate spontaneously inside the microfluidic channels. The spontaneous neutrophil migration is a unique phenotype, typical for patients with major burns during sepsis and often observed one or two days before the diagnosis of sepsis is confirmed. The spontaneous neutrophil migration phenotype is rare in patients with major burns in the absence of sepsis, and is not encountered in healthy individuals. Our findings warrant further studies of neutrophils and their utility for early diagnosing and monitoring sepsis in patients after major burns.

Eu Enlargement and Migration: Scenarios of Croatian Accession

Directory of Open Access Journals (Sweden)

Wadim Strielkowski

2013-09-01

Full Text Available This paper analyzes possible incidence of pending Croatian EU accession that is to take place on the 1st of July 2013, on the labour migration from Croatia to the European Union. We apply panel data estimators using the data on emigration from 18 EU countries into Germany (which is the EU country with the largest share of ex-Yugoslav and Croatian migrants in order to construct possible scenarios of Croatian migration to the EU.Three scenarios of migration - pessimistic, realistic and optimistic - are drawn and the sensitivity of estimated coefficients on migration from Croatia into Germany during next 25 years is further discussed in detail. We conclude that, similarly to hypothetical Turkish accession, Croatian EU accession is not going to cause massive migration inflows.

Divergent migration within lake sturgeon (Acipenser fulvescens) populations: Multiple distinct patterns exist across an unrestricted migration corridor.

Science.gov (United States)

Kessel, Steven T; Hondorp, Darryl W; Holbrook, Christopher M; Boase, James C; Chiotti, Justin A; Thomas, Michael V; Wills, Todd C; Roseman, Edward F; Drouin, Richard; Krueger, Charles C

2018-01-01

Population structure, distribution, abundance and dispersal arguably underpin the entire field of animal ecology, with consequences for regional species persistence, and provision of ecosystem services. Divergent migration behaviours among individuals or among populations are an important aspect of the ecology of highly mobile animals, allowing populations to exploit spatially or temporally distributed food and space resources. This study investigated the spatial ecology of lake sturgeon (Acipenser fulvescens) within the barrier free Huron-Erie Corridor (HEC), which connects Lake Huron and Lake Erie of the North American Laurentian Great Lakes. Over 6 years (2011-2016), movements of 268 lake sturgeon in the HEC were continuously monitored across the Great Lakes using acoustic telemetry (10 years battery life acoustic transmitters). Five distinct migration behaviours were identified with hierarchical cluster analysis, based on the phenology and duration of river and lake use. Lake sturgeon in the HEC were found to contain a high level of intraspecific divergent migration, including partial migration with the existence of residents. Specific behaviours included year-round river residency and multiple lake-migrant behaviours that involved movements between lakes and rivers. Over 85% of individuals were assigned to migration behaviours as movements were consistently repeated over the study, which suggested migration behaviours were consistent and persistent in lake sturgeon. Differential use of specific rivers or lakes by acoustic-tagged lake sturgeon further subdivided individuals into 14 "contingents" (spatiotemporally segregated subgroups). Contingents associated with one river (Detroit or St. Clair) were rarely detected in the other river, which confirmed that lake sturgeon in the Detroit and St. Clair represent two semi-independent populations that could require separate management consideration for their conservation. The distribution of migration behaviours

Divergent migration within lake sturgeon (Acipenser fulvescens) populations: Multiple distinct patterns exist across an unrestricted migration corridor

Science.gov (United States)

Kessel, Steven T.; Hondorp, Darryl W.; Holbrook, Christopher; Boase, James C.; Chiotti, Justin A.; Thomas, Michael V.; Wills, Todd C.; Roseman, Edward; Drouin, Richard; Krueger, Charles C.

2018-01-01

Population structure, distribution, abundance, and dispersal arguably underpin the entire field of animal ecology, with consequences for regional species persistence, and provision of ecosystem services. Divergent migration behaviours among individuals or among populations is an important aspect of the ecology of highly-mobile animals, allowing populations to exploit spatially- or temporally-distributed food and space resources.This study investigated the spatial ecology of lake sturgeon (Acipenser fulvescens) within the barrier free Huron-Erie Corridor (HEC), which connects Lake Huron and Lake Erie of the North American Laurentian Great Lakes.Over six years (2011 – 2016), movements of 268 lake sturgeon in the HEC were continuously monitored across the Great Lakes using acoustic telemetry (10 yr battery life acoustic transmitters). Five distinct migration behaviours were identified with hierarchical cluster analysis, based on the phenology and duration of river and lake use.Lake sturgeon in the HEC were found to contain a high level of intraspecific divergent migration, including partial migration with the existence of residents. Specific behaviours included year-round river residency and multiple lake-migrant behaviours that involved movements between lakes and rivers. Over 85% of individuals were assign to migration behaviours as movements were consistently repeated over the study, which suggested migration behaviours were consistent and persistent in lake sturgeon. Differential use of specific rivers or lakes by acoustic-tagged lake sturgeon further subdivided individuals into 14 “contingents” (spatiotemporally segregated subgroups).Contingents associated with one river (Detroit or St. Clair) were rarely detected in the other river, which confirmed that lake sturgeon in the Detroit and St. Clair represent two semi-independent populations that could require separate management consideration for their conservation. The distribution of migration behaviours

Migration of accreting giant planets

Science.gov (United States)

Crida, A.; Bitsch, B.; Raibaldi, A.

2016-12-01

We present the results of 2D hydro simulations of giant planets in proto-planetary discs, which accrete gas at a more or less high rate. First, starting from a solid core of 20 Earth masses, we show that as soon as the runaway accretion of gas turns on, the planet is saved from type I migration : the gap opening mass is reached before the planet is lost into its host star. Furthermore, gas accretion helps opening the gap in low mass discs. Consequently, if the accretion rate is limited to the disc supply, then the planet is already inside a gap and in type II migration. We further show that the type II migration of a Jupiter mass planet actually depends on its accretion rate. Only when the accretion is high do we retrieve the classical picture where no gas crosses the gap and the planet follows the disc spreading. These results impact our understanding of planet migration and planet population synthesis models. The e-poster presenting these results in French can be found here: L'e-poster présentant ces résultats en français est disponible à cette adresse: http://sf2a.eu/semaine-sf2a/2016/posterpdfs/156_179_49.pdf.

Compressed-sensing application - Pre-stack kirchhoff migration

KAUST Repository

Aldawood, Ali; Hoteit, Ibrahim; Alkhalifah, Tariq Ali

2013-01-01

Least-squares migration is a linearized form of waveform inversion that aims to enhance the spatial resolution of the subsurface reflectivity distribution and reduce the migration artifacts due to limited recording aperture, coarse sampling of sources and receivers, and low subsurface illumination. Least-squares migration, however, due to the nature of its minimization process, tends to produce smoothed and dispersed versions of the reflectivity of the subsurface. Assuming that the subsurface reflectivity distribution is sparse, we propose the addition of a non-quadratic L1-norm penalty term on the model space in the objective function. This aims to preserve the sparse nature of the subsurface reflectivity series and enhance resolution. We further use a compressed-sensing algorithm to solve the linear system, which utilizes the sparsity assumption to produce highly resolved migrated images. Thus, the Kirchhoff migration implementation is formulated as a Basis Pursuit denoise (BPDN) problem to obtain the sparse reflectivity model. Applications on synthetic data show that reflectivity models obtained using this compressed-sensing algorithm are highly accurate with optimal resolution.

Citizenship and migration in Arab Gulf monarchies

DEFF Research Database (Denmark)

Sater, J.

2014-01-01

In many industrialized countries, the issue of migration has traditionally raised the question of whether migrant groups fully enjoy citizenship rights. Political debates about models of migration emphasize either the values of cultural diversity or the value of integration into 'host' societies,...... the lack of both integration and citizenship is a defining principle. Using these two perspectives, this article examines the relationship between citizenship rights and migration in the Gulf region, drawing on data from the UAE along with Bahrain, Kuwait, and Qatar.......In many industrialized countries, the issue of migration has traditionally raised the question of whether migrant groups fully enjoy citizenship rights. Political debates about models of migration emphasize either the values of cultural diversity or the value of integration into 'host' societies......, whereas fear and security concerns are often embedded in more populist debates. In the Arab Gulf region, as in many other regions, such as East Asia, this debate has taken distinctively different shapes, partially because the concept of citizenship remains a contested notion not just with regard...

Service Migration Protocol for NFC Links

DEFF Research Database (Denmark)

Nickelsen, Anders; Schwefel, Hans-Peter; Martin, Miquel

2010-01-01

of use while preserving state. This paper focuses on the scenario of migration between two devices in which the actual migration procedure is executed over near-field communication (NFC) ad-hoc links. The NFC link is interesting as it gives the user the perception of trust and enables service continuity...

Intraperitoneal stone migration during percutaneos nephrolithotomy

Directory of Open Access Journals (Sweden)

Akif Diri

2014-12-01

Full Text Available Percutaneos nephrolithotomy (PNL is the standard care for renal stones larger than 2 cm. The procedure has some major and minor complications. Renal pelvis laceration and stone migration to the retroperitoneum is one of the rare condition. We report the first case of intraperitoneal stone migration during PNL.

Macrophage migration inhibitory factor as an incriminating agent in vitiligo.

Science.gov (United States)

Farag, Azza Gaber Antar; Hammam, Mostafa Ahmed; Habib, Mona SalahEldeen; Elnaidany, Nada Farag; Kamh, Mona Eaid

2018-03-01

Vitiligo is an autoimmune skin disorder in which the loss of melanocytes is mainly attributed to defective autoimmune mechanisms and, lately, there has been more emphasis on autoinflammatory mediators. Among these is the macrophage migration inhibitory factor, which is involved in many autoimmune skin diseases. However, little is known about the contribution of this factor to vitiligo vulgaris. To determine the hypothesized role of migration inhibitory factor in vitiligo via estimation of serum migration inhibitory factor levels and migration inhibitory factor mRNA concentrations in patients with vitiligo compared with healthy controls. We also aimed to assess whether there is a relationship between the values of serum migration inhibitory factor and/or migration inhibitory factor mRNA with disease duration, clinical type and severity in vitiligo patients. Evaluation of migration inhibitory factor serum level and migration inhibitory factor mRNA expression by ELISA and real-time PCR, respectively, were performed for 50 patients with different degrees of vitiligo severity and compared to 15 age- and gender-matched healthy volunteers as controls. There was a highly significant increase in serum migration inhibitory factor and migration inhibitory factor mRNA levels in vitiligo cases when compared to controls (pvitiligo patients, and each of them with duration and severity of vitiligo. In addition, patients with generalized vitiligo have significantly elevated serum migration inhibitory factor and mRNA levels than control subjects. Small number of investigated subjects. Migration inhibitory factor may have an active role in the development of vitiligo, and it may also be a useful index of disease severity. Consequently, migration inhibitory factor may be a new treatment target for vitiligo patients.

Gender Differences in Stressors Related to Migration and Acculturation in Patients with Psychiatric Disorders and Turkish Migration Background.

Science.gov (United States)

Müller, Matthias Johannes; Koch, Eckhardt

2017-06-01

Migration, acculturation, and psychiatric disorders may cause stress and adaptation processes differently in men and women, but empirical research is scarce. In a retrospective study n = 62 Turkish migrants and n = 62 native German inpatients with depressive or anxiety disorders, matched for age, gender, and diagnoses, were compared using a 10-item instrument for the assessment of migration- and acculturation related stressors (MIGSTR10). Gender differences in the prevalence of stressors and in the total sum of stressors were calculated and compared between migrants and indigenous patients. Results showed a higher global stress level in migrants and in women than in men with migration background. Regarding single stressors, the perceived loss of status was significantly more prevalent and more pronounced in men than in women (P stress should be taken into account in migration and acculturation research.

Taiwan’s Security Calculus of Cross-­Strait Migration

Directory of Open Access Journals (Sweden)

Ching Chang

2015-08-01

Full Text Available Migration across the Taiwan Strait is relatively insignificant by its scale but it is indeed indisputably politically sensitive. Given the long-term political separation and military rivalry across the Taiwan Strait in the past six decades while both sides of the Taiwan Strait nevertheless intensively engaged each other economically, commercially and culturally, a social trend of cross-Strait migration inevitably results. There are various interpretations on such a demographic development which has raised security concerns, which are in turn creating a biased judiciary arrangement on the migration activities. What are the factors behind the security calculus of cross-Strait migration? How can the security calculus justify its arguments and subsequently maintain unequal treatments with respect to cross-Strait immigrants? Are the rationales for maintaining a tight grip on cross-Strait migration in line with the political ideal proclaimed by the political factions in Taiwan still sensible? What is the potential for the trend of cross-Strait migration affecting the security calculus in the future? On the other hand, for the migration from Taiwan to Mainland China, how influential can it be on the security decision-making process of the Beijing leadership? Is there any impact possibly caused by cross-Strait migration – and is it essentially overstated? Or alternatively, is the overstated influence potentially caused by cross-Strait migration an intentionally staged political myth? What are the substantial impacts actually ever achieved by cross-Strait migration on the security dimension? What is the self-fulfilled conviction of cross-Strait migration? For all the inquiries noted above, the author of this paper would like to scrutinize the truth and separate it from numerous myths ever advocated by the different factions in Taiwan politics. A sound and neutral judgment to tell the exact influences likely enacted by cross-Strait migration would

Religion, migration og integration

DEFF Research Database (Denmark)

Borup, Jørn

2010-01-01

Sammenhængen mellem religion og integration har de sidste år været genstand for debat. Artiklen kommer ind på begreber og sammenhænge relateret til området (migration, diaspora, assimilation, etnicitet, kultur) og ser på religionens mulige rolle som negativ eller positiv ressource i integrationss......Sammenhængen mellem religion og integration har de sidste år været genstand for debat. Artiklen kommer ind på begreber og sammenhænge relateret til området (migration, diaspora, assimilation, etnicitet, kultur) og ser på religionens mulige rolle som negativ eller positiv ressource i...

Women’s football migration

DEFF Research Database (Denmark)

Agergaard, Sine

What is intriguing about women’s football as a cultural phenomenon is that unlike men’s football the finances and media interest for the game are sparse. Nevertheless we have found that migration of female football players is growing steadily and women’s football is becoming global in nature....... The question is then what drives this globalization process? According to our study of women’s football migration into Scandinavia, one of the centers of women’s football, transnational networks play a crucial role in mobilizing global migratory moves. Using the concept of friends-of-friends networks from Bale...

Comparative test on nuclide migration in aerated zone

International Nuclear Information System (INIS)

Li Shushen; Zhao Yingjie; Wu Qinghua; Wang Zhiming; Hao Janzhong; Ji Shaowei; Guo Liangtian; Guo Zhiming

2002-01-01

In order to study the influence of different tracer source layer material on nuclide migration behavior, the comparative test on stable elements Sr, Nd and Ce migration in aerated loess zone was carried out using loess and arenaceous quartz as the tracer source layer materials respectively. The test lasted 470 days. During the test, four times of sampling were done. The testing results indicate that under artificial sprinkling of 5 mm/h and 3 h/d, Nd and Ce not only in loess tracer source layer but also in arenaceous quartz tracer source layer did not obviously downwards migrated. Concentration peak of Sr for loess layer migrated down about 15 cm in 470 d (mass center moved down about 10 cm) but for arenaceous quartz layer the concentration peak of Sr did not obviously migrated down (mass center moved down about 2.7 cm). The test results show that very thin arenaceous quartz layer with thickness of 7 mm is also able to shield unsaturated water flow obviously. This is the main reason why the nuclides in arenaceous quartz layer migrate down slowly

Return Migration among Elderly, Chronically Ill Bosnian Refugees

DEFF Research Database (Denmark)

Handlos, Line Neerup; Olwig, Karen Fog; Bygbjerg, Ib Christian

2015-01-01

Elderly migrants constitute a considerable share of global return migration; nevertheless, literature on the health aspects of the return migration among these migrants is still scarce. This study explores the significance of return migration among elderly, chronically ill Bosnian refugees from D...... of illness, health did matter. Viewed as physical, social and mental well-being in line with WHO's definition of health, health was indeed one of the most important factors when the decision to return was made....... that physical health, in the sense of the absence of illness and easy access to necessary health-care services and medicines, was not highly prioritized when the decision was made whether or not to return. However, if health is regarded more broadly as involving more than mere physical health and the absence......Elderly migrants constitute a considerable share of global return migration; nevertheless, literature on the health aspects of the return migration among these migrants is still scarce. This study explores the significance of return migration among elderly, chronically ill Bosnian refugees from...

Mitigation of artifacts in rtm with migration kernel decomposition

KAUST Repository

Zhan, Ge; Schuster, Gerard T.

2012-01-01

The migration kernel for reverse-time migration (RTM) can be decomposed into four component kernels using Born scattering and migration theory. Each component kernel has a unique physical interpretation and can be interpreted differently

Least-squares migration of multisource data with a deblurring filter

KAUST Repository

Dai, Wei; Wang, Xin; Schuster, Gerard T.

2011-01-01

Least-squares migration (LSM) has been shown to be able to produce high-quality migration images, but its computational cost is considered to be too high for practical imaging. We have developed a multisource least-squares migration algorithm (MLSM) to increase the computational efficiency by using the blended sources processing technique. To expedite convergence, a multisource deblurring filter is used as a preconditioner to reduce the data residual. This MLSM algorithm is applicable with Kirchhoff migration, wave-equation migration, or reverse time migration, and the gain in computational efficiency depends on the choice of migration method. Numerical results with Kirchhoff LSM on the 2D SEG/EAGE salt model show that an accurate image is obtained by migrating a supergather of 320 phase-encoded shots. When the encoding functions are the same for every iteration, the input/output cost of MLSM is reduced by 320 times. Empirical results show that the crosstalk noise introduced by blended sources is more effectively reduced when the encoding functions are changed at every iteration. The analysis of signal-to-noise ratio (S/N) suggests that not too many iterations are needed to enhance the S/N to an acceptable level. Therefore, when implemented with wave-equation migration or reverse time migration methods, the MLSM algorithm can be more efficient than the conventional migration method. © 2011 Society of Exploration Geophysicists.

Least-squares migration of multisource data with a deblurring filter

KAUST Repository

Dai, Wei

2011-09-01

Least-squares migration (LSM) has been shown to be able to produce high-quality migration images, but its computational cost is considered to be too high for practical imaging. We have developed a multisource least-squares migration algorithm (MLSM) to increase the computational efficiency by using the blended sources processing technique. To expedite convergence, a multisource deblurring filter is used as a preconditioner to reduce the data residual. This MLSM algorithm is applicable with Kirchhoff migration, wave-equation migration, or reverse time migration, and the gain in computational efficiency depends on the choice of migration method. Numerical results with Kirchhoff LSM on the 2D SEG/EAGE salt model show that an accurate image is obtained by migrating a supergather of 320 phase-encoded shots. When the encoding functions are the same for every iteration, the input/output cost of MLSM is reduced by 320 times. Empirical results show that the crosstalk noise introduced by blended sources is more effectively reduced when the encoding functions are changed at every iteration. The analysis of signal-to-noise ratio (S/N) suggests that not too many iterations are needed to enhance the S/N to an acceptable level. Therefore, when implemented with wave-equation migration or reverse time migration methods, the MLSM algorithm can be more efficient than the conventional migration method. © 2011 Society of Exploration Geophysicists.

Flexibility of continental navigation and migration in European mallards

DEFF Research Database (Denmark)

van Toor, Mariëlle L.; Hedenström, Anders; Waldenström, Jonas

2013-01-01

The ontogeny of continent-wide navigation mechanisms of the individual organism, despite being crucial for the understanding of animal movement and migration, is still poorly understood. Several previous studies, mainly conducted on passerines, indicate that inexperienced, juvenile birds may...... abilities. Here we tested whether immature mallard ducks correct for latitudinal displacement during fall migration within Europe. During two consecutive fall migration periods, we caught immature females on a stopover site in southeast Sweden, and translocated a group of them ca. 1,000 km to southern...... Germany. We followed the movements of the ducks via satellite GPS-tracking and observed their migration decisions during the fall and consecutive spring migration. The control animals released in Ottenby behaved as expected from banding recoveries: they continued migration during the winter and in spring...

Relations between information and communication technologies and international migration

Directory of Open Access Journals (Sweden)

Lukić Vesna

2017-01-01

Full Text Available The paper focuses on the topic of the impact of Information and Communication Technologies (ICT on the international migration phenomenon According to the discussed literature, there is an impression that ICTs change the essence of migration and monitoring of migration flows. It also suggests that migration and migrants’ needs shape the development of ICT services intended to them, but they also shape the content of social media. The impact of new technologies on international migration (before migration, during migration and upon arrival in the country of destination has been discussed through an overview of empirical research findings in Serbia and other countries. In this context, the ICT users relevant to the migration process (individuals and interest groups have been more closely determined and discussed, the aspects of the relations between ICTs and migration have been highlighted, as well as their implications for individuals and society. The considered aspects of relations of ICTs and international migration at different stages of the migration process and their severe implications for individuals and society, in our opinion, point to the need for cooperation of users of information and communication technologies relevant to the migration process in different domains ‒ the spheres of influence of ICTs. We believe that is how the potential of ICTs will be exploited in an adequate way, for benefit of both ‒ migrants and other relevant interested parties. While widely accepted by individuals, information and communication technologies have just begun to be recognized as important for migration policy in Serbia and generally, in terms of their opportunities and challenges. In Serbia, only recently (as of the 2011 Census there has been data available on the use of ICTs by certain migrant groups (long-term settled refugees from former Yugoslav republics. Also, the qualitative surveys on the use of ICTs during the migration by transit

MIGRATION AND REGIONAL DEVELOPMENT IN ROMANIA

Directory of Open Access Journals (Sweden)

CAMELIA ANGHEL

2017-12-01

Full Text Available Economic implications of demographic decline and the changing age structure will be more visible in Romania after 2020, when the working population will decrease gradually and "mature" groups will come in the elderly population. Diminishing populations will cause a change in the economic dependency ratio and total economic burden of the working population will increase. The changes known in activity rates in the future are hard to predict, especially in the current context of labor migration in Europe. In this context, a realistic vision of economic and social development in the coming decades is a necessity for Romania. Where the countries of origin of migrants fail to implement clear and efficient social and economic general reforms, migration and remittances get involved whose fundamental purpose is although they do not contribute to the sustainable development at the national level. Population migration has now become a global issue important to the development and welfare societies. Remittances are the main concern in studies of migration and development, migration transnational model several years as part of concerns about the economic future of many countries. Focus as well can be seen throughout this paper falls on cash remittances and consumer goods, on issues related to sustainable development, social development, human development. Many experts consider impossible the debate on economic development without taking into account human and social development, even sustainable development.

A pilgrim's progress: Seeking meaning in primordial germ cell migration.

Science.gov (United States)

Cantú, Andrea V; Laird, Diana J

2017-10-01

Comparative studies of primordial germ cell (PGC) development across organisms in many phyla reveal surprising diversity in the route of migration, timing and underlying molecular mechanisms, suggesting that the process of migration itself is conserved. However, beyond the perfunctory transport of cellular precursors to their later arising home of the gonads, does PGC migration serve a function? Here we propose that the process of migration plays an additional role in quality control, by eliminating PGCs incapable of completing migration as well as through mechanisms that favor PGCs capable of responding appropriately to migration cues. Focusing on PGCs in mice, we explore evidence for a selective capacity of migration, considering the tandem regulation of proliferation and migration, cell-intrinsic and extrinsic control, the potential for tumors derived from failed PGC migrants, the potential mechanisms by which migratory PGCs vary in their cellular behaviors, and corresponding effects on development. We discuss the implications of a selective role of PGC migration for in vitro gametogenesis. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Geography, Islands and Migration in an Era of Global Mobility

Directory of Open Access Journals (Sweden)

Russell King

2009-05-01

Full Text Available This paper examines the changing role of islands in the age of globalization and in an era of enhanced and diversified mobility. There are many types of islands, many metaphors of insularity, and many types of migration, so the interactions are far from simple. The ‘mobilities turn’ in migration studies recognizes the diversification in motivations and time-space regimes of human migration. After brief reviews of island studies and of migration studies, and the power of geography to capture and distil the interdisciplinarity and relationality of these two study domains, the paper explores various facets of the generally intense engagement that islands have with migration. Two particular scenarios are identified for islands and migration in the global era: the heuristic role of islands as ‘spatial laboratories’ for the study of diverse migration processes in microcosm; and the way in which, especially in the Mediterranean and near-Atlantic regions, islands have become critical locations in the geopolitics of irregular migration routes. The case of Malta is taken to illustrate some of these new insular migration dynamics.

Migration in Vulnerable Deltas: A Research Strategy

Science.gov (United States)

Hutton, C.; Nicholls, R. J.; Allan, A.

2015-12-01

C. Hutton1, & R. J. Nicholls1, , 1 University of Southampton, University Road, Southampton, Hampshire, United Kingdom, SO17 1BJ. cwh@geodata. soton.ac.ukAbstractGlobally, deltas contain 500 million people and with rising sea levels often linked to large number of forced migrants are expected in the coming century. However, migration is already a major process in deltas, such as the growth of major cities such as Dhaka and Kolkata. Climate and environmental change interacts with a range of catchment and delta level drivers, which encompass a nexus of sea-level rise, storms, freshwater and sediment supply from the catchment, land degradation, subsidence, agricultural loss and socio-economic stresses. DECCMA (Deltas, Vulnerability and Climate Change: Migration and Adaptation/CARRIA) is investigating migration in the Ganges-Brahmaputra-Meghna (GBM), Mahanadi and Volta Deltas, including the influence of climate change. The research will explore migration from a range of perspectives including governance and stakeholder analysis, demographic analysis, household surveys of sending and receiving areas, macro-economic analysis, and hazards and hotspot analysis both historically and into the future. Migration under climate change will depend on other adaptation in the deltas and this will be examined. Collectively, integrated analysis will be developed to examine migration, other adaptation and development pathways with a particular focus on the implications for the poorest. This will require the development of input scenarios, including expert-derived exogenous scenarios (e.g., climate change) and endogenous scenarios of the delta developed in a participatory manner. This applied research will facilitate decision support methods for the development of deltas under climate change, with a focus on migration and other adaptation strategies.

Neuronal Migration Disorders

Science.gov (United States)

... Understanding Sleep The Life and Death of a Neuron Genes At Work In The Brain Order Publications ... birth defects caused by the abnormal migration of neurons in the developing brain and nervous system. In ...

Simulation of bentonite colloid migration through granite

International Nuclear Information System (INIS)

Rosicka, Dana; Hokr, Milan

2012-01-01

Document available in extended abstract form only. Full text of publication follows: Colloidal bentonite particles generate at the interface of buffer and host rock in spent nuclear fuel repository due to an erosion process and migrate through granite by the water flow. Stability of these colloids and their migration possibilities have been studied on account of radionuclide transport possibility as colloid could carry adsorbed radionuclides in groundwater through granite. That is why a simulation of bentonite colloid migration in the surrounding of a repository might be requested. According to chemical condition as ionic strength and pH, the colloidal particles coagulate into clusters and that influence the migration of particles. The coagulation kinetics of natural bentonite colloids were experimentally studied in many articles, for example by light scattering techniques. We created a model of coagulation of bentonite colloids and simulation of a chosen experiment with use of the multicomponent reactive transport equation. The coagulation model describes clustering of particles due to attractive van der Waals forces as result of collision of particles due to heat fluctuation and different velocity of particles during sedimentation and velocity gradient of water flow. Next, the model includes influence of repulsive electrostatic forces among colloidal particles leading to stability of particles provided high surface charge of colloids. In the model, each group of clusters is transported as one solution component and the kinetics of coagulation are implemented as reactions between the components: a shift of particles among groups of particles with similar migration properties, according to size of the clusters of colloids. The simulation of migration of bentonite colloid through granite using the coagulation model was calibrated according to experiment results. On the basis of the simulation, one can estimate the basic processes that occur during bentonite colloid

Modelagem molecular aplicada ao desenvolvimento de moléculas com atividade antioxidante visando ao uso cosmético Molecular modeling applied to the development of molecules with antioxidant activity for cosmetic use

Directory of Open Access Journals (Sweden)

Luciana Scotti

2007-06-01

Full Text Available Várias hipóteses e constantes estudos são realizados com o intuito de elucidar o envelhecimento cutâneo. Para prevenir e contornar este processo torna-se necessário reforçar nossas defesas naturais antioxidantes endógenas. Diversas substâncias antioxidantes exógenas, como vitaminas, extratos vegetais, dentre outras, são utilizadas pela Cosmetologia nos produtos antienvelhecimento. O objetivo deste artigo é apresentar de que forma a Modelagem Molecular pode ser uma ferramenta útil na pesquisa por novas substâncias cosméticas antioxidantes para combater o envelhecimento cutâneo.Some hypotheses and constants studies are made with intention to elucidate the aging process. To prevent and to attenuate the cutaneous aging it becomes necessary to strengthen our endogenous antioxidant natural defenses. Diverse exogenous antioxidant substances, as vitamins, vegetal extracts and others, have been used by the Cosmetology in antiaging products. The objective of this paper is to show how the Molecular Modeling can be an useful tool in the research for new antioxidant cosmetic substances to face the cutaneous aging.

Migration decisions, agrarian structure, and gender: the case of Ecuador.

Science.gov (United States)

Bravo-ureta, B E; Quiroga, R E; Brea, J A

1996-07-01

This article briefly reviews the literature on migration in Latin America and examines migration decision making in Ecuador. Aggregate data are obtained from the 1974 census of agriculture and population for cantones. Individual level data are obtained from the 1982 census of population. Migration refers to all census persons who recorded differences in their present and previous place of residence during 1974-82. Migration is modeled as dependent upon gender, age, education, marital status, income at origin and at destination, and population pressure or agrarian reform. Logistic model findings indicate that migration decisions are influenced by individual characteristics of migrants and contextual variables. Migration varied by gender. The results confirm Todaro's hypothesis that the probability of migrating is related to income differences between place of destination and origin, but only for males. Findings suggest that females migrate for primary reasons other than economic ones. The probability of migration was greater with increased levels of education. The decision to migrate was affected by quality of life differences, such as literacy rates and levels of urbanization. The probability of migration was reduced by the effects of land reform. Population pressure had a significant effect in increasing migration. The effects of land reform differ from findings in Mexico by William E. Cole and Richard D. Sanders. Land reforms were initiated in 1964 in Ecuador, but by 1974 there was still considerable inequality in land distribution and increased population pressure. Traditional haciendas were modernized, and peasants increased their dependency on non-farm income.

Migration from New EU Member Countries

DEFF Research Database (Denmark)

Pytlikova, Mariola

2007-01-01

The main purpose of the paper is to give predictions of the migration potential from the 7 new EU member countries to the EEA/EU-13 countries. Being able to analyze 'real' migration behavior from these particular countries over the period 1990-2000 helps me to avoid problems related to (double) o...

Evolution of Mammalian Migrations for Refuge, Breeding, and Food

OpenAIRE

Gnanadesikan, Gitanjali E.; Pearse, William; Shaw, Allison K.

2017-01-01

Abstract Many organisms migrate between distinct habitats, exploiting variable resources while profoundly affecting ecosystem services, disease spread, and human welfare. However, the very characteristics that make migration captivating and significant also make it difficult to study, and we lack a comprehensive understanding of which species migrate and why. Here we show that, among mammals, migration is concentrated within Cetacea and Artiodactyla but also diffusely spread throughout the cl...

Quantitative multi-waves migration in elastic anisotropic media; Migration quantitative multi-ondes en milieu elastique anisotrope

Energy Technology Data Exchange (ETDEWEB)

Borgne, H.

2004-12-01

Seismic imaging is an important tool for ail exploration. From the filtered seismic traces and a subsurface velocity model, migration allows to localize the reflectors and to estimate physical properties of these interfaces. The subsurface is split up into a reference medium, corresponding to the low spatial frequencies (a smooth medium), and a perturbation medium, corresponding to the high spatial frequencies. The propagation of elastic waves in the medium of reference is modelled by the ray theory. The association of this theory with a principle of diffraction or reflection allows to take into account the high spatial frequencies: the Kirchhoff approach represents so the medium of perturbations with continuous surfaces, characterized by reflection coefficients. The target of the quantitative migration is to reconstruct this reflection coefficient, notably its behaviour according to the incidence angle. These information will open the way to seismic characterization of the reservoir domain, with. a stratigraphic inversion for instance. In order to improve the qualitative and quantitative migration results, one of the current challenges is to take into account the anisotropy of the subsurface. Taking into account rocks anisotropy in the imaging process of seismic data requires two improvements from the isotropic case. The first one roughly concerns the modelling aspect: an anisotropic propagator should be used to avoid a mis-positioning or bad focusing of the imaged reflectors. The second correction concerns the migration aspect: as anisotropy affects the reflectivity of subsurface, a specific anisotropic imaging formula should be applied in the migration kernel, in order to recover the correct A V A behavior of the subsurface reflectors, If the first correction is DOW made in most so-called anisotropic imaging algorithms, the second one is currently ignored. The first part of my work concerns theoretical aspects. 1 study first the preservation of amplitudes in the

A personality theory of U.S. migration geography.

Science.gov (United States)

Stetzer, F C

1985-01-01

"Neoclassical models of migration fail to account adequately for individual differences in propensity to migrate, rates of emigration from states and cities, and the generally high rates of population circulation common in the United States. This article proposes that migration propensity is related to an individual's personality. Using the facts that personality traits are generationally regenerative, both through inheritance and culture, and that the United States was settled in a series of migration waves from east to west, this theory predicts a spatial structuring of emigration rates which closely correspond to actual rates for states and major cities." excerpt

DEFINING HUMAN MIGRATION – A POLICY MAKERS PERSPECTIVE

Directory of Open Access Journals (Sweden)

Paul-Panfil IVAN

2015-06-01

Full Text Available Migration is a global phenomenon gradually increased in scope, impact and complexity. Practically all countries are simultaneously countries of destination, origin and transit for migrants. Traditionally migration flows are complemented by new changes generated by economic, demographic, political or social conditions, and these trends affect both the size and structure of the migrant population and also economies and societies. Of course this has sparked international interest from various NGOs and by the European Union and the United Nations. This paper aims to present the vision of international organizations concerned with migration and how they define migration and its typologies.

Associations Between Sociodemographic Characteristics, Pre Migratory and Migratory Factors and Psychological Distress Just After Migration and After Resettlement: The Indian Migration Study.

Science.gov (United States)

Agrawal, Sutapa; Taylor, Fiona C; Moser, Kath; Narayanan, Gitanjali; Kinra, Sanjay; Prabhakaran, Dorairaj; Reddy, Kolli Srinath; Davey Smith, George; Ebrahim, Shah

2015-01-01

Migration is suspected to increase the risk for psychological distress for those who enter a new cultural environment. We investigated the association between sociodemographic characteristics, premigratory and migratory factors and psychological distress in rural-to-urban migrants just after migration and after resettlement. Data from the cross-sectional sib-pair designed Indian Migration Study (IMS, 2005-2007) were used. The analysis focused on 2112 participants aged ≥18 years from the total IMS sample ( n = 7067) who reported being migrant. Psychological distress was assessed based on the responses of the 7-questions in a five-point scale, where the respondents were asked to report about their feelings now and also asked to recall these feelings when they first migrated. The associations were analyzed using multiple logistic regression models. High prevalence of psychological distress was found just after migration (7.3%; 95% confidence interval [CI]: 6.2-8.4) than after settlement (4.7%; 95% CI: 3.8-5.6). Push factors as a reason behind migration and not being able to adjust in the new environment were the main correlates of psychological distress among both the male and female migrants, just after migration. Rural-urban migration is a major phenomenon in India and given the impact of premigratory and migratory related stressors on mental health, early intervention could prevent the development of psychological distress among the migrants.

The possibilities of compressed sensing based migration

KAUST Repository

Aldawood, Ali

2013-09-22

Linearized waveform inversion or Least-square migration helps reduce migration artifacts caused by limited acquisition aperture, coarse sampling of sources and receivers, and low subsurface illumination. However, leastsquare migration, based on L2-norm minimization of the misfit function, tends to produce a smeared (smoothed) depiction of the true subsurface reflectivity. Assuming that the subsurface reflectivity distribution is a sparse signal, we use a compressed-sensing (Basis Pursuit) algorithm to retrieve this sparse distribution from a small number of linear measurements. We applied a compressed-sensing algorithm to image a synthetic fault model using dense and sparse acquisition geometries. Tests on synthetic data demonstrate the ability of compressed-sensing to produce highly resolved migrated images. We, also, studied the robustness of the Basis Pursuit algorithm in the presence of Gaussian random noise.

Migration from atolls as climate change adaptation

DEFF Research Database (Denmark)

Birk, Thomas Ladegaard Kümmel; Rasmussen, Kjeld

2014-01-01

to migration that reduce the efficacy of positive outcomes to both migrants and their home communities, including high transport costs and problems in gaining access to housing, employment and government services in urban destination areas. If it is accepted that voluntary migration may play a positive role...... that migration currently improves access to financial and social capital, reduces pressure on natural resources and makes island communities less vulnerable to extreme weather events and other shocks — all factors that contribute positively to adaptive capacity. It also shows that there are major barriers...... in adaptation to climate change in exposed atoll communities, addressing some of the barriers to migration seems logical. This may be done by efforts to stimulate migrant income opportunities, by improving migrant living conditions and by improving the transport services to the islands....

The possibilities of compressed sensing based migration

KAUST Repository

Aldawood, Ali; Hoteit, Ibrahim; Alkhalifah, Tariq Ali

2013-01-01

Linearized waveform inversion or Least-square migration helps reduce migration artifacts caused by limited acquisition aperture, coarse sampling of sources and receivers, and low subsurface illumination. However, leastsquare migration, based on L2-norm minimization of the misfit function, tends to produce a smeared (smoothed) depiction of the true subsurface reflectivity. Assuming that the subsurface reflectivity distribution is a sparse signal, we use a compressed-sensing (Basis Pursuit) algorithm to retrieve this sparse distribution from a small number of linear measurements. We applied a compressed-sensing algorithm to image a synthetic fault model using dense and sparse acquisition geometries. Tests on synthetic data demonstrate the ability of compressed-sensing to produce highly resolved migrated images. We, also, studied the robustness of the Basis Pursuit algorithm in the presence of Gaussian random noise.

Migration of plasticisers from PVC and other polymers

DEFF Research Database (Denmark)

Lundsgaard, Rasmus

). In this work it is shown how diffusion coefficients can be obtained by regression of experimental migration data plotted as the square root of time. This was done from plasticiser migration data of GRINDSTEDr SOFT-N-SAFE, GRINDSTEDr ACETEM 95 CO (Acetem) and Epoxidised Soybean Oil (ESBO) migrating from......The main purpose of this thesis is to investigate, from a modeling point of view, the migration of GRINDSTEDr SOFT-N-SAFE (SNS) and other plasticisers from polyvinyl chloride (PVC) and polyolefin food package materials and into foodstuff (specifically the four food simulants set by EU legislation...... coefficients at 20◦C, except at higher temperatures. Using the finite element mesh method in Matlab and COMSOL environments the migration was modeled with a diffusion coefficient able to change with local plasticiser concentration. Three different models for this plasticiser concentration dependence...

Effects of seed migration on post-implant dosimetry of prostate brachytherapy

International Nuclear Information System (INIS)

Gao, M.; Wang, J. Z.; Nag, S.; Gupta, N.

2007-01-01

Brachytherapy using permanent seed implants has been an effective treatment for prostate cancer. However, seeds will migrate after implant, thus making the evaluation of post-implant dosimetry difficult. In this study, we developed a computer program to simulate seed migration and analyzed dosimetric changes due to seed migration at various migration amounts. The study was based on 14 patients treated with Pd-103 at the James Cancer Hospital. Modeling of seed migration, including direction, distance as well as day of migration, was based on clinical observations. Changes of commonly used dosimetric parameters as a function of migration amount (2, 4, 6 mm respectively), prostate size (from 20 to 90 cc), and prostate region (central vs peripheral) were studied. Change of biological outcome (tumor control probability) due to migration was also estimated. Migration reduced prostate D90 to 99±2% of original value in 2 mm migration, and the reduction increased to 94±6% in 6 mm migration. The reduction of prostate dose led to a 14% (40%) drop in the tumor control probability for 2 mm (6 mm) migration, assuming radiosensitive tumors. However, migration has less effect on a prostate implanted with a larger number of seeds. Prostate V100 was less sensitive to migration than D90 since its mean value was still 99% of original value even in 6 mm migration. Migration also showed a different effect in the peripheral region vs the central region of the prostate, where the peripheral mean dose tended to drop more significantly. Therefore, extra activity implanted in the peripheral region during pre-plan can be considered. The detrimental effects of migration were more severe in terms of increasing the dose to normal structures, as rectum V50 may be 70% higher and urethra V100 may be 50% higher in the case of 6 mm migration. Quantitative knowledge of these effects is helpful in treatment planning and post-implant evaluation

Development of pathological anthropomorphic models using 3D modelling techniques for numerical dosimetry; Desenvolvimento de modelos antropomorficos patologicos usando tecnicas de modelagem 3D para dosimetria numerica

Energy Technology Data Exchange (ETDEWEB)

Costa, Kleber Souza Silva [Faculdade Integrada de Pernambuco (FACIPE), Recife, PE (Brazil); Barbosa, Antonio Konrado de Santana; Vieira, Jose Wilson [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco, Recife, PE (Brazil); Lima, Fernando Roberto de Andrade, E-mail: falima@cnen.gov.b [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

2011-10-26

Computational exposure models can be used to estimate human body absorbed dose in a series of situations such as X-Ray exams for diagnosis, accidents and medical treatments. These models are fundamentally composed of an anthropomorphic simulator (phantom), an algorithm that simulates a radioactive source and a Monte Carlo Code. The accuracy of data obtained in the simulation is strongly connected to the adequacy of such simulation to the real situation. The phantoms are one of the key factors for the researcher manipulation. They are generally developed in supine position and its anatomy is patronized by compiled data from international institutions such as ICRP or ICRU. Several pathologies modify the structure of organs and body tissues. In order to measure how significant these alterations are, an anthropomorphic model was developed for this study: patient mastectomies. This model was developed using voxel phantom FASH and then coupled with EGSnrc Monte Carlo code

Modelling and numerical simulation of the gasoline containing alcohol spilling in the groundwaters; Modelagem e simulacao numerica do derramamento de gasolina acrescida de alcool em aguas subterraneas

Energy Technology Data Exchange (ETDEWEB)

Cordazzo, Jonas; Maliska, Clovis R. [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica]. E-mails: jonas@sinmec.ufsc.br; maliska@sinmec.ufsc.br; Corseuil, Henry X. [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Engenharia Sanitaria e Ambiental]. E-mail: corseuil@ens.ufsc.br

2000-07-01

This work presents a model and the respective two-dimensional numerical solution for the problem of pollutant spilling on the soil saturated region,in finite volumes, with first order biodegradation model. The model is adapted to the brazilian gasoline considering the ethanol influence on the biodegradation of the BTEX constituents and on the ethanol co-solvence in the gasoline phenomenon.The gasoline sorption effect is taken into consideration, when considering linear sorption. The numerically solved transport equation take into consideration the dispersion, advection, sorption and the biodegradation of the MTEX compounds and the ethanol, as well. The groundwater velocity field is numerically solved by using the Darcy equations, allowing the regions with different permeabilities to be considered.

Gβ1 is required for neutrophil migration in zebrafish.

Science.gov (United States)

Ke, Wenfan; Ye, Ding; Mersch, Kacey; Xu, Hui; Chen, Songhai; Lin, Fang

2017-08-01

Signaling mediated by G protein-coupled receptors (GPCRs) is essential for the migration of cells toward chemoattractants. The recruitment of neutrophils to injured tissues in zebrafish larvae is a useful model for studying neutrophil migration and trafficking in vivo. Indeed, the study of this process led to the discovery that PI3Kγ is required for the polarity and motility of neutrophils, features that are necessary for the directed migration of these cells to wounds. However, the mechanism by which PI3Kγ is activated remains to be determined. Here we show that signaling by specifically the heterotrimeric G protein subunit Gβ1 is critical for neutrophil migration in response to wounding. In embryos treated with small-molecule inhibitors of Gβγ signaling, neutrophils failed to migrate to wound sites. Although both the Gβ1 and Gβ4 isoforms are expressed in migrating neutrophils, only deficiency for the former (morpholino-based knockdown) interfered with the directed migration of neutrophils towards wounds. The Gβ1 deficiency also impaired the ability of cells to change cell shape and reduced their general motility, defects that are similar to those in neutrophils deficient for PI3Kγ. Transplantation assays showed that the requirement for Gβ1 in neutrophil migration is cell autonomous. Finally, live imaging revealed that Gβ1 is required for polarized activation of PI3K, and for the actin dynamics that enable neutrophil migration. Collectively, our data indicate that Gβ1 signaling controls proper neutrophil migration by activating PI3K and modulating actin dynamics. Moreover, they illustrate a role for a specific Gβ isoform in chemotaxis in vivo. Copyright © 2017 Elsevier Inc. All rights reserved.

Thymocyte migration: an affair of multiple cellular interactions?

Directory of Open Access Journals (Sweden)

Savino W.

2003-01-01

Full Text Available Cell migration is a crucial event in the general process of thymocyte differentiation. The cellular interactions involved in the control of this migration are beginning to be defined. At least chemokines and extracellular matrix proteins appear to be part of the game. Cells of the thymic microenvironment produce these two groups of molecules, whereas developing thymocytes express the corresponding receptors. Moreover, although chemokines and extracellular matrix can drive thymocyte migration per se, a combined role for these molecules appears to contribute to the resulting migration patterns of thymocytes in their various stages of differentiation. The dynamics of chemokine and extracellular matrix production and degradation is not yet well understood. However, matrix metalloproteinases are likely to play a role in the breakdown of intrathymic extracellular matrix contents. Thus, the physiological migration of thymocytes should be envisioned as a resulting vector of multiple, simultaneous and/or sequential stimuli involving chemokines, adhesive and de-adhesive extracellular matrix proteins, as well as matrix metalloproteinases. Accordingly, it is conceivable that any pathological change in any of these loops may result in the alteration of normal thymocyte migration. This seems to be the case in murine infection by the protozoan parasite Trypanosoma cruzi, the causative agent of Chagas' disease. A better knowledge of the physiological mechanisms governing thymocyte migration will provide new clues for designing therapeutic strategies targeting developing T cells.

The possibilities of compressed-sensing-based Kirchhoff prestack migration

KAUST Repository

Aldawood, Ali; Hoteit, Ibrahim; Alkhalifah, Tariq Ali

2014-01-01

An approximate subsurface reflectivity distribution of the earth is usually obtained through the migration process. However, conventional migration algorithms, including those based on the least-squares approach, yield structure descriptions that are slightly smeared and of low resolution caused by the common migration artifacts due to limited aperture, coarse sampling, band-limited source, and low subsurface illumination. To alleviate this problem, we use the fact that minimizing the L1-norm of a signal promotes its sparsity. Thus, we formulated the Kirchhoff migration problem as a compressed-sensing (CS) basis pursuit denoise problem to solve for highly focused migrated images compared with those obtained by standard and least-squares migration algorithms. The results of various subsurface reflectivity models revealed that solutions computed using the CS based migration provide a more accurate subsurface reflectivity location and amplitude. We applied the CS algorithm to image synthetic data from a fault model using dense and sparse acquisition geometries. Our results suggest that the proposed approach may still provide highly resolved images with a relatively small number of measurements. We also evaluated the robustness of the basis pursuit denoise algorithm in the presence of Gaussian random observational noise and in the case of imaging the recorded data with inaccurate migration velocities.

The possibilities of compressed-sensing-based Kirchhoff prestack migration

KAUST Repository

Aldawood, Ali

2014-05-08

An approximate subsurface reflectivity distribution of the earth is usually obtained through the migration process. However, conventional migration algorithms, including those based on the least-squares approach, yield structure descriptions that are slightly smeared and of low resolution caused by the common migration artifacts due to limited aperture, coarse sampling, band-limited source, and low subsurface illumination. To alleviate this problem, we use the fact that minimizing the L1-norm of a signal promotes its sparsity. Thus, we formulated the Kirchhoff migration problem as a compressed-sensing (CS) basis pursuit denoise problem to solve for highly focused migrated images compared with those obtained by standard and least-squares migration algorithms. The results of various subsurface reflectivity models revealed that solutions computed using the CS based migration provide a more accurate subsurface reflectivity location and amplitude. We applied the CS algorithm to image synthetic data from a fault model using dense and sparse acquisition geometries. Our results suggest that the proposed approach may still provide highly resolved images with a relatively small number of measurements. We also evaluated the robustness of the basis pursuit denoise algorithm in the presence of Gaussian random observational noise and in the case of imaging the recorded data with inaccurate migration velocities.

Reverse time migration by Krylov subspace reduced order modeling

Science.gov (United States)

Basir, Hadi Mahdavi; Javaherian, Abdolrahim; Shomali, Zaher Hossein; Firouz-Abadi, Roohollah Dehghani; Gholamy, Shaban Ali

2018-04-01

Imaging is a key step in seismic data processing. To date, a myriad of advanced pre-stack depth migration approaches have been developed; however, reverse time migration (RTM) is still considered as the high-end imaging algorithm. The main limitations associated with the performance cost of reverse time migration are the intensive computation of the forward and backward simulations, time consumption, and memory allocation related to imaging condition. Based on the reduced order modeling, we proposed an algorithm, which can be adapted to all the aforementioned factors. Our proposed method benefit from Krylov subspaces method to compute certain mode shapes of the velocity model computed by as an orthogonal base of reduced order modeling. Reverse time migration by reduced order modeling is helpful concerning the highly parallel computation and strongly reduces the memory requirement of reverse time migration. The synthetic model results showed that suggested method can decrease the computational costs of reverse time migration by several orders of magnitudes, compared with reverse time migration by finite element method.

Migration Dilemmas of Islanders: Commuting Leading to Migration or Remaining at Home

Directory of Open Access Journals (Sweden)

Ivan Lajić

2001-09-01

Full Text Available The paper presents and discusses the results of an empirical survey carried out in April 2000 on the islands Prvić, Zlarin and Krapanj in the Šibenik coastal area. These islands are part of a group of islands marked by the highest rates of depopulation, in which even recently daily commuting was one of the most expressed forms of mechanical population development. Daily commuting is seen as an initial state leading to permanent migration, i.e. to out-migration. Potential migrants become familiar with the social, economic, cultural and other traits of their future destination area, which makes it easier for them to leave their places of origin. Thus, for the purposes of the research, the survey selected a population of daily commuters, mainly young people of working age who usually constitute the segment of the population most Iikely to migrate. The survey used both a questionnaire and interviews. Respondents belonged to two relevant groups of the island population: employees commuting each day to work and pupils commuting daily to school. Even though the sample included practically the entire island population with the given migrational and socio-demographic characteristics, the total number of respondents was still too small for the application of standard methods of statistical analysis. In order to gain better insight into the pre-migrational situation on the islands, a few adult islander commuters were added to the group of commuting employees. The goal of the research was to gain an understanding of commuting phenomena in the island micro-society, especially of the migration dilemmas of young islanders. The most frequent variables in the survey were: island/settlement, gender and school. Commuting between the island and mainland is the dominant form of spatial mobility among islanders and constitutes an essential part of their daily life. The most frequent reasons for commuting among islanders are school attendance, going to work, going

Directional Cell Migration in Response to Repeated Substratum Stretching

Science.gov (United States)

Okimura, Chika; Iwadate, Yoshiaki

2017-10-01

Crawling migration plays an essential role in a variety of biological phenomena, including development, wound healing, and immune system function. Migration properties such as anterior-posterior polarity, directionality, and velocity are regulated not only by the reception of a chemoattractant but also by sensing mechanical inputs from the external environment. In this review, we describe the mechanical response of migrating cells, particularly under repeated stretching of the elastic substratum, highlighting the fact that there appear to be two independent mechanosensing systems that generate the polarity needed for migration. Cells that have no stress fibers, such as Dictyostelium cells and neutrophil-like differentiated HL-60 cells, migrate perpendicular to the stretching direction via myosin II localization. Cells that do possess stress fibers, however, such as fish keratocytes, migrate parallel to the stretching via a stress-fiber-dependent process.

Simulation of vacancy migration energy in Cu under high strain

International Nuclear Information System (INIS)

Sato, K.; Yoshiie, T.; Satoh, Y.; Xu, Q.; Kiritani, M.

2003-01-01

The activation energy for the migration of vacancies in Cu under high strain was calculated by computer simulation using static methods. The migration energy of vacancies was 0.98 eV in the absence of deformation. It varied with the migration direction and stress direction because the distance between a vacancy and its neighboring atoms changes by deformation. For example, the migration energy for the shortest migration distance was reduced to 9.6 and 39.4% of its initial value by 10% compression and 20% elongation, respectively, while that for the longest migration distance was raised to 171.7 by 20% elongation. If many vacancies are created during high-speed deformation, the lowering of migration energy enables vacancies to escape to sinks such as surfaces, even during the shorter deformation period. The critical strain rate above which the strain rate dependence of vacancy accumulation ceases to exist increases with the lowering of vacancy migration energy

Sorption and migration of neptunium in porous sedimentary materials

International Nuclear Information System (INIS)

Tanaka, Tadao; Mukai, Masayuki; Nakayama, Shinichi

2005-01-01

Column migration experiments of neptunium were conducted for porous sedimentary materials: coastal sand, tuffaceous sand, ando soil, reddish soil, yellowish soil and loess, and migration behavior, sorption mechanisms and chemical formation of Np were investigated. The migration behavior of Np in each material was much different each other, due to chemical formation in solution and/or sorption mechanism of Np. Mathematical models of different concepts were applied to the experimental results to interpret the sorption mechanism and the migration behavior. It can be concluded that both of instantaneous equilibrium sorption and sorption-desorption kinetics have to be considered to model the Np migration in sedimentary materials. (author)

International Student Migration to Germany

OpenAIRE

Donata Bessey

2007-01-01

This paper presents first empirical evidence on international student migration to Germany. I use a novel approach that analyzes student mobility using an augmented gravity equation and find evidence of strong network effects and of the importance of distance - results familiar from the empirical migration literature. However, the importance of disposable income in the home country does not seem to be too big for students, while the fact of being a politically unfree country decreases migrati...

Roosts and migrations of swallows

OpenAIRE

Winkler, David W.

2006-01-01

Swallows of the north temperate zone display a wide variety of territorial behaviour during the breeding season, but as soon as breeding is over, they all appear to adopt a pattern of independent diurnal foraging interleaved with aggregation every night in dense roosts. Swallows generally migrate during the day, feeding on the wing. On many stretches of their annual journeys, their migrations can thus be seen as the simple spatial translation of nocturnal roost sites with foraging routes stra...

The determinants of internal migration in Turkey

OpenAIRE

Gökhan, Ali; Gokhan, Ali; Filiztekin, Alpay

2008-01-01

Internal migration has had a great impact on Turkey’s population dynamics for decades. According to the 2000 population census, nearly 28% percent of the population was born in a different province that they now reside in. This ratio goes up to 62% for Istanbul, a major province that has drawn migrants for years. Although, it is claimed in numerous studies that rural-urban migration that centers on a few urban areas seems to be the predominant pattern of internal migration, we aim to investig...

Investigations of pollutant migration using lysimeters; Untersuchungen zur Schadstoff-Migration in Lysimetern

Energy Technology Data Exchange (ETDEWEB)

Klotz, D. (ed.)

2002-07-01

The third GSF Lysimeter Workshop focused on pollutant migration in underground strata, i.e. the dispersion of water constituents as referred to water transport on the basis of ideal tracer investigations. [German] Der am 29./30.04.2002 stattgefundene Workshop 'Untersuchungen zur Schadstoffmigration in Lysimetern' war der dritte GSF-Lysimeterworkshop nach denen in den Jahren 1998 und 2000 veranstalteten. Nachdem in den Jahren 1998 und 2000 der Wassertransport und die Bestimmung der Sickerwassergeschwindigkeit in Lysimetern im Mittelpunkt standen, war 2002 die Schadstoffmigration im Untergrund der Schwerpunkt der Vortraege und Poster. Unter Migration wird das Ausbreitungsverhalten von Wasserinhalts-(Fremd-, Schad-)Stoffen bezogen auf den Wassertransport, bestimmt mit idealen Tracern, verstanden. (orig.)

Migration and the Wage Curve:

DEFF Research Database (Denmark)

Brücker, Herbert; Jahn, Elke J.

in a general equilibrium framework. For the empirical analysis we employ the IABS, a two percent sample of the German labor force. We find that the elasticity of the wage curve is particularly high for young workers and workers with a university degree, while it is low for older workers and workers......  Based on a wage curve approach we examine the labor market effects of migration in Germany. The wage curve relies on the assumption that wages respond to a change in the unemployment rate, albeit imperfectly. This allows one to derive the wage and employment effects of migration simultaneously...... with a vocational degree. The wage and employment effects of migration are moderate: a 1 percent increase in the German labor force through immigration increases the aggregate unemployment rate by less than 0.1 percentage points and reduces average wages by less 0.1 percent. While native workers benefit from...

Migration: The Present State, Problems and Perspectives of Research Paradigms

Directory of Open Access Journals (Sweden)

Silva Mežnarić

2003-12-01

Full Text Available Two prevailing paradigms in contemporary international migration research – migration as unpredictable explosion and migration as mainly predictable long cycles movement – are put into question. Both paradigms are not valid in explaining latest development in international migration field. They are too robust for reality which is satiated with novel developments in the field of volume, directions, labour markets and structure of migration flows, both voluntary and involuntary. Individual independent migrant as decision maker is coming to the fore. Therefore the reassessment of theoretical and conceptual apparatus of migration is imminent. As to the methods, mathematically supported sociological models of contemporary migration could be needed. On the basis of “new intuition”, the principles of simplicity, parsimony, and universality could lead to a theoretical innovation.

Mediterranean Migrations: Regionalisms Versus Globalisation

Directory of Open Access Journals (Sweden)

Martin Baldwin-Eduards

2004-06-01

Full Text Available This paper challenges the claim of globalisation as a cause ofimmigration into Southern Europe and, on an empirical basis, identifies regionalisation as being the primary issue, along with networked migratory patterns. However, the changing patterns of immigration do present challenges to both state and society. It is argued here that recent policy responses in Portugal, Italy and Spain have been inconsistent and irrational – reflecting more the ‘securitisation’ of migration than European reality. Earlier policy innovations are identified, by country and date: most of these have now been abandoned. It is suggested that all of Southern Europe has converged onto a statist, restrictionist model of immigration control that was formerly held only by Greece. The principal characteristics of this model are outlined, along with a migration flowchart and indicative data for migrant flows and sub-flows in Italy and Spain. In the final section, I try to show that the needs of the economy cannot be predicted, immigration cannot becontrolled in the manner currently being enforced across Southern Europe, and attempts to do so will damage rather than improve economic productivity and growth. The concept of an accomodating immigration policy is advanced, whereby the state tries to manage the needs of both employers and potential migrants. Six guidelines for policy development are suggested – most of which have alreadybeen successfully carried out in the European Union. These are the following: migration in order to find a job; circular cross-border migration; EU level negotiation of readmission agreements; the need for a variety of migration-for-employment schemes; legal residence should not depend upon continuity of employment; and discreet legalisation will still be needed in Southern Europe.

Sedimentary record of erg migration

Science.gov (United States)

Porter, M. L.

1986-06-01

The sedimentary record of erg (eolian sand sea) migration consists of an idealized threefold division of sand-sea facies sequences. The basal division, here termed the fore-erg, is composed of a hierarchy of eolian sand bodies contained within sediments of the flanking depositional environment. These sand bodies consist of eolian strata deposited by small dune complexes, zibars, and sand sheets. The fore-erg represents the downwind, leading edge of the erg and records the onset of eolian sedimentation. Basin subsidence coupled with erg migration places the medial division, termed the central erg, over the fore-erg strata. The central erg, represented by a thick accumulation of large-scale, cross-stratified sandstone, is the product of large draa complexes. Eolian influence on regional sedimentation patterns is greatest in the central erg, and most of the sand transported and deposited in the erg is contained within this region. Reduction in sand supply and continued erg migration will cover the central-erg deposits with a veneer of back-erg deposits. This upper division of the erg facies sequence resembles closely the fore-erg region. Similar types of eolian strata are present and organized in sand bodies encased in sediments of the upwind flanking depositional environment(s). Back-erg deposits may be thin due to limited eolian influence on sedimentation or incomplete erg migration, or they may be completely absent because of great susceptibility to postdepositional erosion. Tectonic, climatic, and eustatic influences on sand-sea deposition will produce distinctive variations or modifications of the idealized erg facies sequence. The resulting variants in the sedimentary record of erg migration are illustrated with ancient examples from western North America, Europe, southern Africa, and South America.

Annual spatiotemporal migration schedules in three larger insectivorous birds

DEFF Research Database (Denmark)

Jacobsen, Lars Bo; Jensen, Niels Odder; Willemoes, Mikkel

2017-01-01

Background: Knowledge of spatiotemporal migration patterns is important for our understanding of migration ecology and ultimately conservation of migratory species. We studied the annual migration schedules of European nightjar, a large nocturnal insectivore and compared it with two other larger ...

Plane-wave Least-squares Reverse Time Migration

KAUST Repository

Dai, Wei; Schuster, Gerard T.

2012-01-01

convergence for least-squares migration even when the migration velocity is not completely accurate. To significantly reduce computation cost, linear phase shift encoding is applied to hundreds of shot gathers to produce dozens of planes waves. A