Conclusion: New Projects and Old Reminders

Globalization and the transnational networks established by economic integration have produced a context in which the gathering of knowledge about Latina/o and Latin American communities is largely devoid of any processual perspective. This means that we must construct an alternative methodology to capture the international and transnational social fields and arenas of this multinational population. Nowhere does this type of dialogue appear more necessary than in studies of immigration from Latin America to the United States. In particular, we maintain that the integration of Latin American and Latina/o studies requires viewing these new waves of migrants as part of a synchronic flow of capital, goods, and resources back and forth between the United States and their countries of origin. We have shown in our discussion of remittances that multiple levels of economic dependency result

PEP4Django - A Policy Enforcement Point for Python Web Applications

Traditionally, access control mechanisms have been hard-coded into application components. Such approach is error-prone, mixing business logic with access control concerns, and affecting the flexibility of security policies, as is the case with IFRN SUAP Django-based system. The externalization of access control rules allows their decoupling from business logic, through the use of authorization servers where access control policies are stored and queried for computing access decisions. In this context, this paper presents an approach that allows a Django Web application to delegate access control decisions to an external authorization server. The approach has been integrated into an enterprise level system, which has been used for experimentation. The results obtained indicate a negligible overhead, while allowing the modification of access control policies without interrupting the system

Limits of permutation sequences

A permutation sequence is said to be convergent if the density of occurrences of every fixed permutation in the elements of the sequence converges. We prove that such a convergent sequence has a natural limit object, namely a Lebesgue measurable function $Z:[0,1]^2 \to [0,1]$ with the additional properties that, for every fixed $x \in [0,1]$, the restriction $Z(x,\cdot)$ is a cumulative distribution function and, for every $y \in [0,1]$, the restriction $Z(\cdot,y)$ satisfies a "mass" condition. This limit process is well-behaved: every function in the class of limit objects is a limit of some permutation sequence, and two of these functions are limits of the same sequence if and only if they are equal almost everywhere. An ingredient in the proofs is a new model of random permutations, which generalizes previous models and might be interesting for its own sake.Comment: accepted for publication in the Journal of Combinatorial Theory, Series B. arXiv admin note: text overlap with arXiv:1106.166

Hawking radiation for a Proca field in D-dimensions

We study the wave equation of a massive vector boson in the background of a D-dimensional Schwarzschild black hole. The mass term introduces a coupling between two physical degrees of freedom of the field, and we solve the resulting system of ODEs numerically, without decoupling. We show how to define decoupled transmission factors from an S-matrix and compute them for various modes, masses and space-time dimensions. The mass term lifts the degeneracy between transverse modes, in D=4, and excites the longitudinal modes, in particular the s-wave. Moreover, it increases the contribution of waves with larger angular momentum, which can be dominant at intermediate energies. The transmission factors are then used to obtain the Hawking fluxes in this channel. Our results alert for the importance of modelling the longitudinal modes correctly, instead of treating them as decoupled scalars as in current black hole event generators; thus they can be used to improve such generators for phenomenological studies of TeV gravity scenarios.Comment: 21 pages, 3 figure