986 resultados para Strong migration
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Aim - The aim of the study was to determine the potential for KV1 potassium channel blockers as inhibitors of human neoinitimal hyperplasia. Methods and results - Blood vessels were obtained from patients or mice and studied in culture. Reverse transcriptasepolymerase chain reaction and immunocytochemistry were used to detect gene expression. Whole-cell patch-clamp, intracellular calcium measurement, cell migration assays, and organ culture were used to assess channel function. KV1.3 was unique among the KV1 channels in showing preserved and up-regulated expression when the vascular smooth muscle cells switched to the proliferating phenotype. There was strong expression in neointimal formations. Voltage-dependent potassium current in proliferating cells was sensitive to three different blockers of KV1.3 channels. Calcium entry was also inhibited. All three blockers reduced vascular smooth muscle cell migration and the effects were non-additive. One of the blockers (margatoxin) was highly potent, suppressing cell migration with an IC of 85 pM. Two of the blockers were tested in organ-cultured human vein samples and both inhibited neointimal hyperplasia. Conclusion - KV1.3 potassium channels are functional in proliferating mouse and human vascular smooth muscle cells and have positive effects on cell migration. Blockers of the channels may be useful as inhibitors of neointimal hyperplasia and other unwanted vascular remodelling events. © 2010 The Author.
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We combine data from the Latin American Migration Project and the Mexican Migration Project to estimate models predicting the likelihood of taking of first and later trips to the United States from five nations: Mexico, the Dominican Republic, Costa Rica, Nicaragua, and Peru. The models test specific hypotheses about the effects of social capital on international migration and how these effects vary with respect to contextual factors. Our findings confirm the ubiquity of migrant networks and the universality of social capital effects throughout Latin America. They also reveal how the sizes of these effects are not uniform across settings. Social capital operates more powerfully on first as opposed to later trips and interacts with the cost of migration. In addition, effects are somewhat different when considering individual social capital (measuring strong ties) and community social capital (measuring weak ties). On first trips, the effect of strong ties in promoting migration increases with distance whereas the effect of weak ties decreases with distance. On later trips, the direction of effects for both individual and community social capital is negative for long distances but positive for short distances.
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This study examines changes in the Cuban family in the United States produced by time, migration, and the rise of new generations. The thesis will use a data set extracted from the 5% Public Use Microdata Series (PUMS) of the U.S. Decennial Census of Population for the years 1970, 1980 and 1990. Contingency table analysis and comparison of means were used to examine various family-related variables. The analysis points to changes in the traditional Cuban family towards less traditional family arrangements. The multigenerational feature of the Cuban household has diminished as the elderly have become independent and are more likely to be living on their own. Although female labor participation remains high, the occupational patterns of the first generation of Cuban women have diversified and a new trend has emerged for the second generation. The second generation of Cuban women demonstrates a strong inclination for white-collar occupations. Fertility rates remain low.
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This article analyses the motivations for return migration among the Ecuadorians and Bolivians who, after living in Spain, returned to their countries of origin during the economic crisis that started in 2008. From the analysis of 22 interviews in-depth which took place in Ecuador and 38 in Bolivia to women, men and young people from migrant families, this decision-making process is shown to be embedded into a gendered dynamics of relationships. Particular detail is given to affective and economic elements that had an influence on the decision to return, as well as to the strategies deployed to project their readjustment back in origin. Males and females occupy differential positions within the family, work and social circle, their expectations being built in a gendered manner. Despite the fact migration has brought women greater economic power within the family group, their reintegration upon return redefines their role as main managers in the household and the dynamics that allow their social reproduction. Men, for their part, aspire to refresh their role as providers in spite of their frail labour position upon return. Social mobility for females is passed on through generations by a strong investment on education for their daughters and sons, while for males this mobility revolves around setting up family businesses and around their demonstrative abilities.
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Thesis (Ph.D.)--University of Washington, 2016-08
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In this dissertation, I examine how migration narratives make an ambiguous contribution to the democratization of French national borders. National borders are essentially spaces of crises from which it is possible to study the constant evolution of national identity. Migration narratives, regardless of their ideological dimension, offer representations of the border and of the foreigner that result from a tension between the difficulty to think identity outside of the national frame and the questioning of such a strong tie between identity and the nation. At the border, identities are fundamentally unstable. The first part is focused on the north-eastern and the southern borders of France at the end of the 19th century. The French nationalist literature at the time, advocating for the return of Alsace-Lorraine to the Republic, is characterized by a tension between nationalism and regionalism. The ideology of latinity constitutes a second major feature of the discourse on French identity. Developed by Louis Bertrand, it claims that France can only be regenerated in Algeria. However, a gap between his fictional works and his essays reveals latinity as hybrid and heterogeneous. Borders are also polysemic, namely, they do have the same meaning for everyone. The second part of the dissertation focuses on the southern border of France from the 30s to the 90s. The study of films and novels demonstrate that former borders are still active, especially colonial borders. Finally, the third part of the dissertation addresses the representation of migrants who were trapped in the north of France, at the border of the Schengen area, from the 90s to 2009. Migration narratives bring attention to the totalitarian tendencies of the state, but they also struggle with the contradictions of the humanitarian discourse and the analogies made with previous immigration waves.
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This dissertation comprises three chapters. The first chapter motivates the use of a novel data set combining survey and administrative sources for the study of internal labor migration. By following a sample of individuals from the American Community Survey (ACS) across their employment outcomes over time according to the Longitudinal Employer-Household Dynamics (LEHD) database, I construct a measure of geographic labor mobility that allows me to exploit information about individuals prior to their move. This enables me to explore aspects of the migration decision, such as homeownership and employment status, in ways that have not previously been possible. In the second chapter, I use this data set to test the theory that falling home prices affect a worker’s propensity to take a job in a different metropolitan area from where he is currently located. Employing a within-CBSA and time estimation that compares homeowners to renters in their propensities to relocate for jobs, I find that homeowners who have experienced declines in the nominal value of their homes are approximately 12% less likely than average to take a new job in a location outside of the metropolitan area where they currently reside. This evidence is consistent with the hypothesis that housing lock-in has contributed to the decline in labor mobility of homeowners during the recent housing bust. The third chapter focuses on a sample of unemployed workers in the same data set, in order to compare the unemployment durations of those who find subsequent employment by relocating to a new metropolitan area, versus those who find employment in their original location. Using an instrumental variables strategy to address the endogeneity of the migration decision, I find that out-migrating for a new job significantly reduces the time to re-employment. These results stand in contrast to OLS estimates, which suggest that those who move have longer unemployment durations. This implies that those who migrate for jobs in the data may be particularly disadvantaged in their ability to find employment, and thus have strong short-term incentives to relocate.
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In this dissertation, I explore how workers’ human capital, local industry composition, and business cycles affect employment outcomes and residential migration for job losers and other workers. I first examine whether the poor employment outcomes of job losers are due to a lack of jobs that require their human capital within their local labor market. I answer this question by analyzing the extent to which the industry composition in the job loser’s local labor market affects employment outcomes when job loss occurs during expansions and during recessions. I find that if job losers reside in an area with a high employment concentration of their original industry of employment, they are 2.1-2.8 percent more likely to be re-employed at another job if job loss occurs during an expansion; I find an insignificant relationship in most specifications when job loss occurs during a recession, and in some specifications I even find a negative relationship between industry concentration and employment. I conclude that the industry composition within an area matters for job losers, since firms are more willing to hire workers from within their own industry, as these workers have more relevant accumulated human capital. However, firms are less likely to hire during a recession, making job losers’ human capital less important for job finding. Next, Erika McEntarfer, Henry Hyatt, and I examine whether the business cycle affects earnings changes for job losers, and the factors that explain these differences across time. We find that job losers who lost their job during the Great Recession have earnings changes that are 10 percent more negative relative to other job losers from other periods. This result is driven primarily by longer nonemployment lengths and worse subsequent job matches. Finally, Erika McEntarfer, Henry Hyatt, Alexandria Zhang, and I explore the extent to which residential migration is driven by job opportunities. We use four databases and find that changes in job moves explain some of the changes in residential migration, but the relationship is not as strong as previously documented. We find that migration patterns differ across databases, with some databases documenting steeper declines and more cyclicality.
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The security of strong designated verifier (SDV) signature schemes has thus far been analyzed only in a two-user setting. We observe that security in a two-user setting does not necessarily imply the same in a multi-user setting for SDV signatures. Moreover, we show that existing security notions do not adequately model the security of SDV signatures even in a two-user setting. We then propose revised notions of security in a multi-user setting and show that no existing scheme satisfies these notions. A new SDV signature scheme is then presented and proven secure under the revised notions in the standard model. For the purpose of constructing the SDV signature scheme, we propose a one-pass key establishment protocol in the standard model, which is of independent interest in itself.
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Principal Topic A small firm is unlikely to possess internally the full range of knowledge and skills that it requires or could benefit from for the development of its business. The ability to acquire suitable external expertise - defined as knowledge or competence that is rare in the firm and acquired from the outside - when needed thus becomes a competitive factor in itself. Access to external expertise enables the firm to focus on its core competencies and removes the necessity to internalize every skill and competence. However, research on how small firms access external expertise is still scarce. The present study contributes to this under-developed discussion by analysing the role of trust and strong ties in the small firm's selection and evaluation of sources of external expertise (henceforth referred to as the 'business advisor' or 'advisor'). Granovetter (1973, 1361) defines the strength of a network tie as 'a (probably linear) combination of the amount of time, the emotional intensity, the intimacy (mutual confiding) and the reciprocal services which characterize the tie'. Strong ties in the context of the present investigation refer to sources of external expertise who are well known to the owner-manager, and who may be either informal (e.g., family, friends) or professional advisors (e.g., consultants, enterprise support officers, accountants or solicitors). Previous research has suggested that strong and weak ties have different fortes and the choice of business advisors could thus be critical to business performance) While previous research results suggest that small businesses favour previously well known business advisors, prior studies have also pointed out that an excessive reliance on a network of well known actors might hamper business development, as the range of expertise available through strong ties is limited. But are owner-managers of small businesses aware of this limitation and does it matter to them? Or does working with a well-known advisor compensate for it? Hence, our research model first examines the impact of the strength of tie on the business advisor's perceived performance. Next, we ask what encourages a small business owner-manager to seek advice from a strong tie. A recent exploratory study by Welter and Kautonen (2005) drew attention to the central role of trust in this context. However, while their study found support for the general proposition that trust plays an important role in the choice of advisors, how trust and its different dimensions actually affect this choice remained ambiguous. The present paper develops this discussion by considering the impact of the different dimensions of perceived trustworthiness, defined as benevolence, integrity and ability, on the strength of tie. Further, we suggest that the dimensions of perceived trustworthiness relevant in the choice of a strong tie vary between professional and informal advisors. Methodology/Key Propositions Our propositions are examined empirically based on survey data comprising 153 Finnish small businesses. The data are analysed utilizing the partial least squares (PLS) approach to structural equation modelling with SmartPLS 2.0. Being non-parametric, the PLS algorithm is particularly well-suited to analysing small datasets with non-normally distributed variables. Results and Implications The path model shows that the stronger the tie, the more positively the advisor's performance is perceived. Hypothesis 1, that strong ties will be associated with higher perceptions of performance is clearly supported. Benevolence is clearly the most significant predictor of the choice of a strong tie for external expertise. While ability also reaches a moderate level of statistical significance, integrity does not have a statistically significant impact on the choice of a strong tie. Hence, we found support for two out of three independent variables included in Hypothesis 2. Path coefficients differed between the professional and informal advisor subsamples. The results of the exploratory group comparison show that Hypothesis 3a regarding ability being associated with strong ties more pronouncedly when choosing a professional advisor was not supported. Hypothesis 3b arguing that benevolence is more strongly associated with strong ties in the context of choosing an informal advisor received some support because the path coefficient in the informal advisor subsample was much larger than in the professional advisor subsample. Hypothesis 3c postulating that integrity would be more strongly associated with strong ties in the choice of a professional advisor was supported. Integrity is the most important dimension of trustworthiness in this context. However, integrity is of no concern, or even negative, when using strong ties to choose an informal advisor. The findings of this study have practical relevance to the enterprise support community. First of all, given that the strength of tie has a significant positive impact on the advisor's perceived performance, this implies that small business owners appreciate working with advisors in long-term relationships. Therefore, advisors are well advised to invest into relationship building and maintenance in their work with small firms. Secondly, the results show that, especially in the context of professional advisors, the advisor's perceived integrity and benevolence weigh more than ability. This again emphasizes the need to invest time and effort into building a personal relationship with the owner-manager, rather than merely maintaining a professional image and credentials. Finally, this study demonstrates that the dimensions of perceived trustworthiness are orthogonal with different effects on the strength of tie and ultimately perceived performance. This means that entrepreneurs and advisors should consider the specific dimensions of ability, benevolence and integrity, rather than rely on general perceptions of trustworthiness in their advice relationships.
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The structures of two 1:1 proton-transfer red-black dye compounds formed by reaction of aniline yellow [4-(phenyldiazenyl)aniline] with 5-sulfosalicylic acid and benzenesulfonic acid, and a 1:2 nontransfer adduct compound with 3,5-dinitrobenzoic acid have been determined at either 130 or 200 K. The compounds are 2-(4-aminophenyl)-1-phenylhydrazin-1-ium 3-carboxy-4-hydroxybenzenesulfonate methanol solvate, C12H12N3+.C7H5O6S-.CH3OH (I), 2-(4-aminophenyl)-1-hydrazin-1-ium 4-(phenydiazinyl)anilinium bis(benzenesulfonate), 2C12H12N3+.2C6H5O3S-, (II) and 4-(phenyldiazenyl)aniline-3,5-dinitrobenzoic acid (1/2) C12H11N3.2C~7~H~4~N~2~O~6~, (III). In compound (I) the diaxenyl rather than the aniline group of aniline yellow is protonated and this group subsequently akes part in a primary hydrogen-bonding interaction with a sulfonate O-atom acceptor, producing overall a three-dimensional framework structure. A feature of the hydrogen bonding in (I) is a peripheral edge-on cation-anion association involving aromatic C--H...O hydrogen bonds, giving a conjoint R1/2(6)R1/2(7)R2/1(4)motif. In the dichroic crystals of (II), one of the two aniline yellow species in the asymmetric unit is diazenyl-group protonated while in the other the aniline group is protonated. Both of these groups form hydrogen bonds with sulfonate O-atom acceptors and thee, together with other associations give a one-dimensional chain structure. In compound (III), rather than proton-transfer, there is a preferential formation of a classic R2/2(8) cyclic head-to-head hydrogen-bonded carboxylic acid homodimer between the two 3,5-dinitrobenzoic acid molecules, which in association with the aniline yellow molecule that is disordered across a crystallographic inversion centre, result in an overall two-dimensional ribbon structure. This work has shown the correlation between structure and observed colour in crystalline aniline yellow compounds, illustrated graphically in the dichroic benzenesulfonate compound.