31,876 research outputs found
Polarized minimal families of rational curves and higher Fano manifolds
In this paper we investigate Fano manifolds whose Chern characters
satisfy some positivity conditions. Our approach is via the study of
polarized minimal families of rational curves through a general
point . First we translate positivity properties of the Chern
characters of into properties of the pair . This allows us to
classify polarized minimal families of rational curves associated to Fano
manifolds satisfying and . As a first
application, we provide sufficient conditions for these manifolds to be covered
by subvarieties isomorphic to and . Moreover, this
classification enables us to find new examples of Fano manifolds satisfying
.Comment: 17 page
The Lagrangian description of aperiodic flows: a case study of the Kuroshio Current
This article reviews several recently developed Lagrangian tools and shows
how their combined use succeeds in obtaining a detailed description of purely
advective transport events in general aperiodic flows. In particular, because
of the climate impact of ocean transport processes, we illustrate a 2D
application on altimeter data sets over the area of the Kuroshio Current,
although the proposed techniques are general and applicable to arbitrary time
dependent aperiodic flows. The first challenge for describing transport in
aperiodical time dependent flows is obtaining a representation of the phase
portrait where the most relevant dynamical features may be identified. This
representation is accomplished by using global Lagrangian descriptors that when
applied for instance to the altimeter data sets retrieve over the ocean surface
a phase portrait where the geometry of interconnected dynamical systems is
visible. The phase portrait picture is essential because it evinces which
transport routes are acting on the whole flow. Once these routes are roughly
recognised it is possible to complete a detailed description by the direct
computation of the finite time stable and unstable manifolds of special
hyperbolic trajectories that act as organising centres of the flow.Comment: 40 pages, 24 figure
Banksâ capital, regulation and the financial crisis
This paper investigates whether regulatory capital requirements play an important role in determining banksâ equity capital. We estimate equity capital regressions using panel data of a sample of 560 banks for 2004-2010. Our results suggest that regulatory capital requirements are not first order determinants of banksâ capital structure. We document differences on the effect of most factors on banksâ share of equity according to the type of bank and to the region of the bank. Finally, we show that the determinants of this share are sensitive to the recent international financial crisis and to a set of regulatory country factors.info:eu-repo/semantics/publishedVersio
ELT teachers' stories of resilience (summary version)
© 2020 The Author(s).This article is a summary of the research project we were funded by the British Council to conduct between 2017 and 2019. It focuses on the construction and analysis of six early career ELT teachers' stories focusing on how they fostered resilience in their workplace.Peer reviewe
The hidden geometry of ocean flows
We introduce a new global Lagrangian descriptor that is applied to flows with
general time dependence (altimetric datasets). It succeeds in detecting
simultaneously, with great accuracy, invariant manifolds, hyperbolic and
non-hyperbolic flow regions.Comment: 4 pages, 4 figure
The impact of immigration on the wage structure : Spain 1995-2002
In this paper we estimate the impact of inward migration flows on the Spanish wage
structure over the period 1995-2002 by constructing counterfactual wage distributions
that provide the wages that would have been observed had individual and job
characteristics remain constant over time. Hence, we compute the impact of
immigration on the wage distribution from (i) the estimated wage gaps between similar
immigrants and native workers and (ii) the changes in the composition of employment
associated to the arrival of new immigrants.
Overall, we find that (i) the effects of immigration on wage changes are small and only
noticeable when job characteristics are included as determinants of wages, and (ii) the
correlation between the incidence of immigration in each decile of the wage distribution
and the change in native wages not explained by changes in their individual and job
characteristics is positive. These results suggest that other factors, besides immigration,
should be identified as the key determinants of the wage moderation observed since the
early nineties in Spain
The effect of immigration on the employment opportunities of native-born workers : some evidence for Spain
Spain is one of the European countries where immigration flows during the last decade have increased noticeably. The Spanish labor market institutions and the Spanish immigration policy exhibit some peculiarities which may be relevant when analyzing the impact of immigration. This paper provides a first approximation to the labor market effects of immigrants in Spain during the second half of the 1990s, the period in which immigration flows to Spain have accelerated. By using alternative datasets, we estimate both the impact of legal and total immigration flows on the employment rates of native workers, accounting for the possible occupationa l and geographical mobility of immigrants and native-born workers. Using different samples and estimation procedures, we have not found a significant negative effect of immigration on the employment rates of native workers. The corresponding estimated elasticity is low, around -0.1, when considering only legal immigrants, and is not significant when considering both legal and illegal immigrants
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