Impacts of China’s growth on the Brazilian trade

We evaluate whether the presence of China in world trade is ultimately beneficial or whether it is a threat to Brazil. Using a gravitational model and a panel data method, we find that the Chinese exports to countries other than Brazil are not hurting the Brazilian exports, although the exports of Brazilian manufactured goods have been displaced by commodities as a result of its commerce with China.Brazil; China; trade; gravitational model

Perfect Necklaces

We introduce a variant of de Bruijn words that we call perfect necklaces. Fix a finite alphabet. Recall that a word is a finite sequence of symbols in the alphabet and a circular word, or necklace, is the equivalence class of a word under rotations. For positive integers k and n, we call a necklace (k,n)-perfect if each word of length k occurs exactly n times at positions which are different modulo n for any convention on the starting point. We call a necklace perfect if it is (k,k)-perfect for some k. We prove that every arithmetic sequence with difference coprime with the alphabet size induces a perfect necklace. In particular, the concatenation of all words of the same length in lexicographic order yields a perfect necklace. For each k and n, we give a closed formula for the number of (k,n)-perfect necklaces. Finally, we prove that every infinite periodic sequence whose period coincides with some (k,n)-perfect necklace for any n, passes all statistical tests of size up to k, but not all larger tests. This last theorem motivated this work

Economía alimentaria : trabajos prácticos : guía 2012

111 p. Libro electrónicoLa producción de esta guía de trabajos prácticos surge de la necesidad de contar con material acorde a los contenidos y modalidad de la materia Economía Alimentaria I. En la misma se disponen los temas que se desarrollan en la materia. Cada capítulo se estructura con una introducción teórica y a continuación la guía de actividades con diferentes ejercicios que permitirá una mejor comprensión del ítem desarrollado como así también la ejemplificación de su aplicación en el trabajo profesional. En la confección de los prácticos se contó con la colaboración del Lic. Juan M. Quesada, y en la elaboración del capitulo referido a indicadores de precios alimentarios con la colaboración de la Lic. Luciana Carabelos. Agradecemos a ambos su contribución.1a ed

The Devil is in the Decoder: Classification, Regression and GANs

Many machine vision applications, such as semantic segmentation and depth prediction, require predictions for every pixel of the input image. Models for such problems usually consist of encoders which decrease spatial resolution while learning a high-dimensional representation, followed by decoders who recover the original input resolution and result in low-dimensional predictions. While encoders have been studied rigorously, relatively few studies address the decoder side. This paper presents an extensive comparison of a variety of decoders for a variety of pixel-wise tasks ranging from classification, regression to synthesis. Our contributions are: (1) Decoders matter: we observe significant variance in results between different types of decoders on various problems. (2) We introduce new residual-like connections for decoders. (3) We introduce a novel decoder: bilinear additive upsampling. (4) We explore prediction artifacts

Impacts of China’s growth on the Brazilian trade

We evaluate whether the presence of China in world trade is ultimately beneficial or whether it is a threat to Brazil. Using a gravitational model and a panel data method, we find that the Chinese exports to countries other than Brazil are not hurting the Brazilian exports, although the exports of Brazilian manufactured goods have been displaced by commodities as a result of its commerce with China

Gaussian random permutation and the boson point process

We construct an infinite volume spatial random permutation (χ,σ), where χ⊂ℝd is a point process and σ:χ→χ is a permutation (bijection), associated to the formal Hamiltonian H(χ,σ)=∑_x∈χ‖x−σ(x)‖2. The measures are parametrized by the density ρ of points and the temperature α. Feynman (1953) related spatial random permutations with boson systems and proposed that Bose-Einstein condensation occurs precisely when infinite cycles appear in the corresponding random permutation. Each finite cycle of σ induces a loop of points of χ. For ρ ≤ ρc we define (χ, σ) as a Poisson process of finite unrooted loops that we call Gaussian loop soup, analogous to the Brownian loop soup of Lawler and Werner (2004). We also construct Gaussian random interlacements, a Poisson process of double-infinite trajectories of random walks with Gaussian increments analogous to the Brownian random interlacements of Sznitman (2007). For d ≥ 3 and ρ > ρc we define (χ, σ) as the superposition of independent realizations of the Gaussian loop soup at density ρc and the Gaussian random interlacements at density ρ − ρc and call it a Gaussian random permutation at density ρ and temperature α. The resulting measure is Gibbs for the Hamiltonian H and the point marginal χ has the same distribution as the boson point process introduced by Macchi (1975) in the subcritical case and by Tamura-Ito (2007) in the supercritical case. Bose-Einstein condensation occurs when the Gaussian random permutation exhibits infinite trajectories.Fil: Armendáriz, María Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigaciones Matemáticas "Luis A. Santaló". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Matemáticas "Luis A. Santaló"; ArgentinaFil: Ferrari, Pablo Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigaciones Matemáticas "Luis A. Santaló". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Matemáticas "Luis A. Santaló"; ArgentinaFil: Yuhjtman, Sergio Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigaciones Matemáticas "Luis A. Santaló". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Matemáticas "Luis A. Santaló"; Argentin

Monocytes-based in vitro assay for a preliminary biocompatibility assessment of blood-contacting devices

The biological evaluation of biomaterials is currently defined by the ISO-10993 norm in which parts four and five are dedicated to emo-compatibility and cell toxicity, respectively. Our study will provide a novel in vitro experimental approach for the biocompatibility assessment of biomaterials or medical devices using human primary monocytes as cellular model. In these new settings, human monocytes are exposed to a medium containing the extractable compounds derived from materials or devices; subsequently, cell toxicity and pro-inflammatory effects are analysed through MTT assay, flow cytometry and enzyme-linked immunosorbent assay (ELISA) methodologies. These experimental procedures offer the advantage to use a human and primary cell context belonging to the immune system, in order to accurately predict the nature of blood/device interaction occurring during a clinical application. To validate the reliability of this method, we also reported a comparative study between two different membranes showing a different level of biocompatibility. On the bases of these data, it is possible to state that this new experimental model represents a good approach to investigate the effects induced by a biomaterial on cell death and inflammation using human, primary monocytes

High performance bilayer-graphene Terahertz detectors

We report bilayer-graphene field effect transistors operating as THz broadband photodetectors based on plasma-waves excitation. By employing wide-gate geometries or buried gate configurations, we achieve a responsivity $\sim 1.2V/W (1.3 mA/W)$ and a noise equivalent power $\sim 2\times 10^{-9} W/Hz^{-1/2}$ in the 0.29-0.38 THz range, in photovoltage and photocurrent mode. The potential of this technology for scalability to higher frequencies and the development of flexible devices makes our approach competitive for a future generation of THz detection systems.Comment: 8 pages, 5 figures. Submitted to Applied Physics Letter