New results on the genetic cryptanalysis of TEA and reduced-round versions of XTEA

Congress on Evolutionary Computation. Portland, USA, 19-23 June 2004Recently, a simple way of creating very efficient distinguishers for cryptographic primitives such as block ciphers or hash functions, was presented by the authors. Here, this cryptanalysis attack is shown to be successful when applied over reduced round versions of the block cipher XTEA. Additionally, a variant of this genetic attack is introduced and its results over TEA shown to be the most powerful published to date

Disjointly homogeneous Banach lattices and applications

This is a survey on disjointly homogeneous Banach lattices and their applicactions. Several structural properties of this class are analyzed. In addition we show how these spaces provide a natural framework for studying the compactness of powers of operators allowing for a unified treatment of well-known results.Comment: 20 pages, to appear in Proceedings Positivity VII Conference (2013

Finding efficient nonlinear functions by means of genetic programming

7th International Conference, KES 2003. Proceedings, Part I. Oxford, UK, September 3-5, 2003The design of highly nonlinear functions is relevant for a number of different applications, ranging from database hashing to message authentication. But, apart from useful, it is quite a challenging task. In this work, we propose the use of genetic programming for finding functions that optimize a particular nonlinear criteria, the avalanche effect, using only very efficient operations, so that the resulting functions are extremely efficient both in hardware and in software.Supported by the Spanish Ministerio de Ciencia y Tecnologia research project TIC2002-04498-C05-4Publicad

Current Reflections Regarding Women’s Participation in Mexico-United States Migration: Moving Towards a Quantitative Feminization of Migration?

The purpose of this paper is to offer a statistical approach to the debate on the feminization of the MexicoUnited States migration process. For this, the flows or the “stock” of the Mexican migration of the last decade from different statistical sources available both in Mexico and in the United States are presented. The review suggests that women have historically been part of male migration, but unfortunately they have been poorly attended by scholars and when they did they were considered only as companions, relegating them to a secondary role in the migration process. However, as of the 1980s, the migration of women becomes an undeniable fact. Since then, more and more work began to be carried out from various disciplinary and theoretical perspectives that claimed the participation of Mexican women in international migration processes. This is evidenced by the analysis of the results of the recent decade, now more and more women are migrating autonomously in search of better employment opportunities and better living conditions for their families

On the design of state-of-the-art pseudorandom number generators by means of genetic programming

Congress on Evolutionary Computation. Portland, EEUU, 19-23 June 2004The design of pseudorandom number generators by means of evolutionary computation is a classical problem. Today, it has been mostly and better accomplished by means of cellular automata and not many proposals, inside or outside this paradigm could claim to be both robust (passing all the statistical tests, including the most demanding ones) and fast, as is the case of the proposal we present here. Furthermore, for obtaining these generators, we use a radical approach, where our fitness function is not at all based in any measure of randomness, as is frequently the case in the literature, but of nonlinearity. Efficiency is assured by using only very efficient operators (both in hardware and software) and by limiting the number of terminals in the genetic programming implementation

Tensor products of topological abelian groups and Pontryagin duality

Let $G$ be the group of all \ZZ-valued homomorphisms of the Baer-Specker group \ZZ^\NN. The group $G$ is algebraically isomorphic to \ZZ^{(\NN)}, the infinite direct sum of the group of integers, and equipped with the topology of pointwise convergence on \ZZ^\NN, becomes a non reflexive prodiscrete group. It was an open question to find its dual group $\widehat{G}$. Here, we answer this question by proving that $\widehat{G}$ is topologically isomorphic to \ZZ^\NN\otimes_\mathcal{Q}\TT, the (locally quasi-convex) tensor product of \ZZ^\NN and \TT. Furthermore, we investigate the reflexivity properties of the groups of C_p(X,\ZZ), the group of all \ZZ-valued continuous functions on $X$ equipped with the pointwise convergence topology, and $A_p(X)$, the free abelian group on a $0$-dimensional space $X$ equipped with the topology t_p(C(X,\ZZ)) of pointwise convergence topology on C(X,\ZZ). In particular, we prove that \widehat{A_p(X)}\simeq C_p(X,\ZZ)\otimes_\mathcal{Q}\TT and we establish the existence of $0$-dimensional spaces $X$ such that C_p(X,\ZZ) is Pontryagin reflexive

Transcranial magnetic stimulation and EEG in studies of brain function

Transcranial magnetic stimulation (TMS) combined with electroencephalography (EEG) is a multimodal technique, with a temporal resolution of submilliseconds, for studying cortical excitability and connectivity. When TMS is combined with neuronavigation, resulting in so-called navigated TMS (nTMS), the technique becomes very powerful. However, despite the potential of TMS–EEG, its use for studying lateral areas has been restricted because the TMS pulse induces strong muscle artifacts, making the EEG data useless for further analyses. In this Thesis, methods for analyzing TMS-evoked EEG data from lateral areas are introduced. First, TMS–EEG is used to study Broca's area and dorsal premotor cortex. Due to the fact that those areas are close to cranial muscles, their stimulation evokes large muscle artifacts in EEG recordings. The behavior of the artifacts is described in detail. Two approaches to deal with large artifacts are presented. In the first approach, independent component analysis (ICA) is used. Here, FastICA algorithm is modified to make the search of the components more robust and easier, allowing one to get more stable results. The second approach presents methods for suppressing the artifacts rather than removing them. These methods were combined with source localization showing that the artifact suppression is efficient. The methods were tested with both real and simulated data, suggesting they are useful for artifact correction. For a better understanding of the effects of repetitive nTMS during naming tasks and the cortical organization of speech in general, here another study is introduced to understand the sensitivity of object and action naming tasks to repetitive nTMS. The distributions of cortical sites, where repetitive nTMS produced naming errors during both tasks, are compared. Thus, it is shown how this study can impact on both cognitive neuroscience and clinical practice. In the last part, the beamformer method is improved to study source localization, which makes it a robust method to study time-correlated sources. In this Thesis, I discuss how all these methods together can contribute to study brain connectivity of language and lateral areas with TMS–EEG, opening new possibilities for basic research and clinical applications