10,901 research outputs found
Managing migration: the Brazilian case
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.international migration, immigration, emigration, migration management, migration policies, migration laws, Brazil
N_c and m_pi dependence of rho and sigma mesons from unitarized Chiral Perturbation Theory
We review our work on the rho and sigma resonances derived from the Inverse
Amplitude Method. In particular, we study the leading 1/N_c behavior of the
resonances masses and widths and their evolution with changing m_pi. The 1/N_c
expansion gives a clear definition of quark-antiquark states, which is neatly
satisfied by the rho but not by the sigma, showing that its dominant component
is not quark-antiquark. The m_pi dependence of the resonance properties is
relevant to connect with lattice studies. We show that our predictions compare
well with some lattice results and we find that the rho-pi-pi coupling constant
is m_pi independent, in contrast with the sigma-pi-pi coupling, that shows a
strong m_pi dependence.Comment: To appear in the Proceedings of the Chiral10 Workshop, June 21-24
2010. Valencia, Spai
Financial Integration, Financial Deepness and Global Imbalances
Large and persistent global financial imbalances need not be the harbinger of a world financial crash. Instead, we show that these imbalances can be the outcome of financial integration when countries differ in financial markets deepness. In particular, countries with more advanced financial markets accumulate foreign liabilities in a gradual, long-lasting process. Differences in financial deepness also affect the composition of foreign portfolios: countries with negative net foreign asset positions maintain positive net holdings of non-diversifiable equity and FDI. Abstracting from the potential impact of globalization on financial development, liberalization leads to sizable welfare gains for the more financially-developed countries and losses for the others. Three empirical observations motivate our analysis: (1)financial deepness varies widely even amongst industrial countries, with the United States ranking at the top; (2) the secular decline in the U.S. net foreign asset position started in the early 1980s, together with a gradual process of international capital markets liberalization; (3) net exports and current account balances are negatively correlated with indicators of financial development.
Chiral extrapolation of light resonances from one and two-loop unitarized Chiral Perturbation Theory versus lattice results
We study the pion mass dependence of the rho(770) and f_0(600) masses and
widths from one and two-loop unitarized Chiral Perturbation Theory. We show the
consistency of one-loop calculations with lattice results for the M_rho, f_pi
and the isospin 2 scattering length a_20.Then, we develop and apply the
modified Inverse Amplitude Method formalism for two-loop ChPT. In contrast to
the f_0(600), the rho(770) is rather sensitive to the two-loop ChPT parameters
--our main source of systematic uncertainty. We thus provide two-loop
unitarized fits constrained by lattice information on M_rho, f_pi, by the qqbar
leading 1/N_c behavior of the rho and by existing estimates of low energy
constants. These fits yield relatively stable predictions up to m_pi\simeq
300-350 MeV for the rho coupling and width as well as for all the f_0(600)
parameters. We confirm, to two-loops, the weak m_pi dependence of the rho
coupling and the KSRF relation, and the existence of two virtual f_0(600) poles
for sufficiently high m_pi. At two loops one of these poles becomes a bound
state when m_pi is somewhat larger than 300 MeV.Comment: 15 pages, to appear in Phys. Rev.
Multi-layer model for the web graph
This paper studies stochastic graph models of the WebGraph. We present a new model that describes the WebGraph as an ensemble of different regions generated by independent stochastic processes (in the spirit of a recent paper by Dill et al. [VLDB 2001]). Models such as the Copying Model [17] and Evolving Networks Model [3] are simulated and compared on several relevant measures such as degree and clique distribution
Gel Electrophoresis of DNA Knots in Weak and Strong Electric Fields
Gel electrophoresis allows to separate knotted DNA (nicked circular) of equal
length according to the knot type. At low electric fields, complex knots being
more compact, drift faster than simpler knots. Recent experiments have shown
that the drift velocity dependence on the knot type is inverted when changing
from low to high electric fields. We present a computer simulation on a lattice
of a closed, knotted, charged DNA chain drifting in an external electric field
in a topologically restricted medium. Using a simple Monte Carlo algorithm, the
dependence of the electrophoretic migration of the DNA molecules on the type of
knot and on the electric field intensity was investigated. The results are in
qualitative agreement with electrophoretic experiments done under conditions of
low and high electric fields: especially the inversion of the behavior from low
to high electric field could be reproduced. The knot topology imposes on the
problem the constrain of self-avoidance, which is the final cause of the
observed behavior in strong electric field.Comment: 17 pages, 5 figure
Eficiência de misturas de fungicidas no controle da antracnose do feijoeiro comum.
O objetivo deste trabalho foi o de estudar a eficiência de algumas misturas de fungicidas no controle da antracnose do feijoeiro comum.bitstream/CNPAF/21520/1/comt_55.pd
On Weyl Quantization from geometric Quantization
A. Weinstein has conjectured a nice looking formula for a deformed product of
functions on a hermitian symmetric space of non-compact type. We derive such a
formula for symmetric symplectic spaces using ideas from geometric quantization
and prequantization of symplectic groupoids. We compute the result explicitly
for the natural 2-dimensional symplectic manifolds: the euclidean plane, the
sphere and the hyperbolic plane. For the euclidean plane we obtain the well
known Moyal-Weyl product. The other cases show that Weinstein's original idea
should be interpreted with care. We conclude with comments on the status of our
result.Comment: 11 pages. (v2: corrected a couple of typos
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