Activity and migration of Cory's shearwater

I describe some of the features that characterize the activity and migration of Cory’s shearwater during approximately one year. I also explore the influence of Moon, photoperiod, geographic position and life-history stage on the resulting patterns and the periodicity of the latter. I have principally used time series and regression analysis. Its use here is one of the first applications to the analysis of logger data in seabirds. An intriguing finding of this work is the lunar periodicity that pervades the annual cycle of this species.

Migration Flows and Quality of Life in a Metropolitan Area: the Case of Barcelona-Spain

The phenomenon of human migration is certainly not new and it has been studied from a variety of perspectives. Yet, the attention on human migration and its determinant has not been fading over time as confirmed by recent contributions (see for instance Cushing and Poot 2004 and Rebhun and Raveh 2006). In this paper we combine the recent theoretical contributions by Douglas (1997) and Wall (2001) with the methodological advancements of Guimarães et al. (2000, 2003) to model inter-municipal migration flows in the Barcelona area. In order to do that, we employ two different types of count models, i.e. the Poisson and negative binomial and compare the estimations obtained. Our results show that, even after controlling for the traditional migration factors, QoL (measured with a Composite Index which includes numerous aspects and also using a list of individual variables) is an important determinant of short distance migration movements in the Barcelona area.

Time scarcity and the market for news

We develop a theory of news coverage in environments of information abundance. News consumersare time-constrained and browse through news items that are available across competingoutlets, choosing which ones to read or skip. Media firms are aware of consumers' preferences andconstraints, and decide on rankings of news items that maximize their profits. We find that, evenwhen readers and outlets are rational and unbiased and when markets are competitive, readersmay read more than they would like to, and the stories they read may be significantly differentfrom the ones they prefer. Next, we derive implications on diverse aspects of new and traditionalmedia. These include a rationale for tabloid news, a theory of optimal advertisement placementin newscasts, and a justification for readers' migration to online media platforms in order to circumventinefficient rankings found in traditional media. We then analyze methods for restoringreader-efficient standards and discuss the political economy implications of the theory.

The Catalan migration to New York. A view from La Llumanera de Nova York (1874-1881)

The first issue of La Llumanera de Nova York came out in November 1874 and was not published until 1881. The challenge was certainly complicated: editing a newspaper in Catalan in New York, with the aim of influencing a group of potential readers who were distributed in the United States and, at the same time, become a medium that would bring the ideas of a new era, both from a political and cultural point of view

Migration of antimony from polyethylene terephthalate used in mineral water bottles.

The influence of storage time and temperature on Sb migration from PET bottles into mineral water was studied in short-term tests lasting up to 15 days and long-term studies lasting up to 220 days. Samples purchased were stored in three different coloured bottles: clear (CL), light blue (LB) and dark blue (DB). Sb migration was assayed by HG-AFS for total determination and HPLC-ICP-MS for speciation analysis. Migration studies showed that waters stored at 4 and 20 oC were not subject to Sb migration. At 40 oC there was a significant increase in Sb concentration, although the maximum limit established by the European Union (5.0 ug/L) was not exceeded, whereas at 60 oC samples were subject to considerable Sb migration after 30 days of storage. In this case, the maximum limit established by the European Union was exceeded and both Sb (V) and Sb (III) were detected.

Labor Mobility of the Chinese Graduates from British and Spanish Universities: What Happens to the "Talent Migration"?

The scholarship on migration in Europe heavily focuses on the integration of economically vulnerable migrants. In the age of commercialization of education, however, the European Union attracts a rising number of highly skilled non-EU migrants that take up studies across the continent. Despite economic downturn, the EU universities experience a rapid growth in the number of Chinese students, many of whom settle in Europe upon graduation. Surprisingly, although the number of Chinese students in the EU increases, scholars largely ignore the labor paths that these highly skilled migrants take upon graduating from European universities. This study aims to fill this gap by exploring the variation in the Chinese graduates’ labor incorporation patterns and in their spatial mobility. In this project, I also examine macro-level hypotheses predicting that the EU and host states’ labor market institutions, changes in the EU policies on the highly skilled and the outburst of economic crisis matter for the Chinese highly skilled social and spatial mobility. Seizing on surveys, interviews and on the bodies of literature on stratification and social mobility, economic incorporation, social capital and human capital, I look at the Chinese students that graduated from universities in Great Britain and Spain. These states differ in the university tuition fees, migration policies towards the highly skilled workers and in the period of the Chinese students’ influx, thus providing an economically and socially diverse sample. My research will contribute to the literature on the relations between migrants’ social mobility, class and status background and spatial mobility, at the same time adding a transnational level perspective to the study of highly skilled Asian migration.

The Role of the Delay Time in the Modeling of Biological Range Expansions

The time interval between successive migrations of biological species causes a delay time in the reaction-diffusion equations describing their space-time dynamics. This lowers the predicted speed of the waves of advance, as compared to classical models. It has been shown that this delay-time effect improves the modeling of human range expansions. Here, we demonstrate that it can also be important for other species. We present two new examples where the predictions of the time-delayed and the classical (Fisher) approaches are compared to experimental data. No free or adjustable parameters are used. We show that the importance of the delay effect depends on the dimensionless product of the initial growth rate and the delay time. We argue that the delay effect should be taken into account in the modeling of range expansions for biological species

Polynomial-time complexity for instances of the endomorphism problem in free groups

We say the endomorphism problem is solvable for an element W in a free group F if it can be decided effectively whether, given U in F, there is an endomorphism Φ of F sending W to U. This work analyzes an approach due to C. Edmunds and improved by C. Sims. Here we prove that the approach provides an efficient algorithm for solving the endomorphism problem when W is a two- generator word. We show that when W is a two-generator word this algorithm solves the problem in time polynomial in the length of U. This result gives a polynomial-time algorithm for solving, in free groups, two-variable equations in which all the variables occur on one side of the equality and all the constants on the other side.

Semidiscretization and long-time asymptotics of nonlinear diffusion equations

We review several results concerning the long time asymptotics of nonlinear diffusion models based on entropy and mass transport methods. Semidiscretization of these nonlinear diffusion models are proposed and their numerical properties analysed. We demonstrate the long time asymptotic results by numerical simulation and we discuss several open problems based on these numerical results. We show that for general nonlinear diffusion equations the long-time asymptotics can be characterized in terms of fixed points of certain maps which are contractions for the euclidean Wasserstein distance. In fact, we propose a new scaling for which we can prove that this family of fixed points converges to the Barenblatt solution for perturbations of homogeneous nonlinearities for values close to zero.

Intermediate asymptotics beyond homogeneity and self-similarity: long time behavior for [formula]

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