Linear Coding Schemes for the Distributed Computation of Subspaces

Let X-1,..., X-m be a set of m statistically dependent sources over the common alphabet F-q, that are linearly independent when considered as functions over the sample space. We consider a distributed function computation setting in which the receiver is interested in the lossless computation of the elements of an s-dimensional subspace W spanned by the elements of the row vector X-1,..., X-m]Gamma in which the (m x s) matrix Gamma has rank s. A sequence of three increasingly refined approaches is presented, all based on linear encoders. The first approach uses a common matrix to encode all the sources and a Korner-Marton like receiver to directly compute W. The second improves upon the first by showing that it is often more efficient to compute a carefully chosen superspace U of W. The superspace is identified by showing that the joint distribution of the {X-i} induces a unique decomposition of the set of all linear combinations of the {X-i}, into a chain of subspaces identified by a normalized measure of entropy. This subspace chain also suggests a third approach, one that employs nested codes. For any joint distribution of the {X-i} and any W, the sum-rate of the nested code approach is no larger than that under the Slepian-Wolf (SW) approach. Under the SW approach, W is computed by first recovering each of the {X-i}. For a large class of joint distributions and subspaces W, the nested code approach is shown to improve upon SW. Additionally, a class of source distributions and subspaces are identified, for which the nested-code approach is sum-rate optimal.

Scale-dependent relationships between tree species richness and ecosystem function in forests

1. The relationship between species richness and ecosystem function, as measured by productivity or biomass, is of long-standing theoretical and practical interest in ecology. This is especially true for forests, which represent a majority of global biomass, productivity and biodiversity. 2. Here, we conduct an analysis of relationships between tree species richness, biomass and productivity in 25 forest plots of area 8-50ha from across the world. The data were collected using standardized protocols, obviating the need to correct for methodological differences that plague many studies on this topic. 3. We found that at very small spatial grains (0.04ha) species richness was generally positively related to productivity and biomass within plots, with a doubling of species richness corresponding to an average 48% increase in productivity and 53% increase in biomass. At larger spatial grains (0.25ha, 1ha), results were mixed, with negative relationships becoming more common. The results were qualitatively similar but much weaker when we controlled for stem density: at the 0.04ha spatial grain, a doubling of species richness corresponded to a 5% increase in productivity and 7% increase in biomass. Productivity and biomass were themselves almost always positively related at all spatial grains. 4. Synthesis. This is the first cross-site study of the effect of tree species richness on forest biomass and productivity that systematically varies spatial grain within a controlled methodology. The scale-dependent results are consistent with theoretical models in which sampling effects and niche complementarity dominate at small scales, while environmental gradients drive patterns at large scales. Our study shows that the relationship of tree species richness with biomass and productivity changes qualitatively when moving from scales typical of forest surveys (0.04ha) to slightly larger scales (0.25 and 1ha). This needs to be recognized in forest conservation policy and management.

Joint Self-Iterating Equalization and Detection for Two-Dimensional Intersymbol-Interference Channels

We develop several novel signal detection algorithms for two-dimensional intersymbol-interference channels. The contribution of the paper is two-fold: (1) We extend the one-dimensional maximum a-posteriori (MAP) detection algorithm to operate over multiple rows and columns in an iterative manner. We study the performance vs. complexity trade-offs for various algorithmic options ranging from single row/column non-iterative detection to a multi-row/column iterative scheme and analyze the performance of the algorithm. (2) We develop a self-iterating 2-D linear minimum mean-squared based equalizer by extending the 1-D linear equalizer framework, and present an analysis of the algorithm. The iterative multi-row/column detector and the self-iterating equalizer are further connected together within a turbo framework. We analyze the combined 2-D iterative equalization and detection engine through analysis and simulations. The performance of the overall equalizer and detector is near MAP estimate with tractable complexity, and beats the Marrow Wolf detector by about at least 0.8 dB over certain 2-D ISI channels. The coded performance indicates about 8 dB of significant SNR gain over the uncoded 2-D equalizer-detector system.

On 2-D Non-Adjacent-Error Channel Models

In this work, we consider two-dimensional (2-D) binary channels in which the 2-D error patterns are constrained so that errors cannot occur in adjacent horizontal or vertical positions. We consider probabilistic and combinatorial models for such channels. A probabilistic model is obtained from a 2-D random field defined by Roth, Siegel and Wolf (2001). Based on the conjectured ergodicity of this random field, we obtain an expression for the capacity of the 2-D non-adjacent-errors channel. We also derive an upper bound for the asymptotic coding rate in the combinatorial model.

Iodo( trisyl) sulfane: Reactivity of a Stable Alkanesulfenyl Iodide towards Antithyroid Drugs

Iodination of tris(trimethylsilyl)methanethiol (trisylthiol, TsiSH) in tetrahydrofuran provides the new thermally stable alkanesulfenyl iodide iodo(trisyl)sulfane, TsiSI] as a violet solid. Iodo(trisyl)sulfane exhibits iodine-iodine contacts between pairs of TsiSI molecules in the solid state. Properties of TsiSI were studied by vibrational spectroscopy and with the help of density functional calculations. TsiSI reacts in the presence of triethylamine with the antithyroid drugs 6-n-propyl- and 6-methylthiouracil (PTU, MTU) and with N-methylmethimazole (MMI) to form unsymmetric disulfides that were investigated by means of X-ray crystallography. In the solid state, the PTU and MTU derivatives exist as hydrogen-bonded centrosymmetric dimers, whereas the MMI-derived disulfide is an unsymmetric monomer.

Local spatial structure of forest biomass and its consequences for remote sensing of carbon stocks

Advances in forest carbon mapping have the potential to greatly reduce uncertainties in the global carbon budget and to facilitate effective emissions mitigation strategies such as REDD+ (Reducing Emissions from Deforestation and Forest Degradation). Though broad-scale mapping is based primarily on remote sensing data, the accuracy of resulting forest carbon stock estimates depends critically on the quality of field measurements and calibration procedures. The mismatch in spatial scales between field inventory plots and larger pixels of current and planned remote sensing products for forest biomass mapping is of particular concern, as it has the potential to introduce errors, especially if forest biomass shows strong local spatial variation. Here, we used 30 large (8-50 ha) globally distributed permanent forest plots to quantify the spatial variability in aboveground biomass density (AGBD in Mgha(-1)) at spatial scales ranging from 5 to 250m (0.025-6.25 ha), and to evaluate the implications of this variability for calibrating remote sensing products using simulated remote sensing footprints. We found that local spatial variability in AGBD is large for standard plot sizes, averaging 46.3% for replicate 0.1 ha subplots within a single large plot, and 16.6% for 1 ha subplots. AGBD showed weak spatial autocorrelation at distances of 20-400 m, with autocorrelation higher in sites with higher topographic variability and statistically significant in half of the sites. We further show that when field calibration plots are smaller than the remote sensing pixels, the high local spatial variability in AGBD leads to a substantial ``dilution'' bias in calibration parameters, a bias that cannot be removed with standard statistical methods. Our results suggest that topography should be explicitly accounted for in future sampling strategies and that much care must be taken in designing calibration schemes if remote sensing of forest carbon is to achieve its promise.

CTFS-ForestGEO: a worldwide network monitoring forests in an era of global change

Global change is impacting forests worldwide, threatening biodiversity and ecosystem services including climate regulation. Understanding how forests respond is critical to forest conservation and climate protection. This review describes an international network of 59 long-term forest dynamics research sites (CTFS-ForestGEO) useful for characterizing forest responses to global change. Within very large plots (median size 25ha), all stems 1cm diameter are identified to species, mapped, and regularly recensused according to standardized protocols. CTFS-ForestGEO spans 25 degrees S-61 degrees N latitude, is generally representative of the range of bioclimatic, edaphic, and topographic conditions experienced by forests worldwide, and is the only forest monitoring network that applies a standardized protocol to each of the world's major forest biomes. Supplementary standardized measurements at subsets of the sites provide additional information on plants, animals, and ecosystem and environmental variables. CTFS-ForestGEO sites are experiencing multifaceted anthropogenic global change pressures including warming (average 0.61 degrees C), changes in precipitation (up to +/- 30% change), atmospheric deposition of nitrogen and sulfur compounds (up to 3.8g Nm(-2)yr(-1) and 3.1g Sm(-2)yr(-1)), and forest fragmentation in the surrounding landscape (up to 88% reduced tree cover within 5km). The broad suite of measurements made at CTFS-ForestGEO sites makes it possible to investigate the complex ways in which global change is impacting forest dynamics. Ongoing research across the CTFS-ForestGEO network is yielding insights into how and why the forests are changing, and continued monitoring will provide vital contributions to understanding worldwide forest diversity and dynamics in an era of global change.

Trace Driven Dynamic Deadlock Detection and Reproduction

Dynamic analysis techniques have been proposed to detect potential deadlocks. Analyzing and comprehending each potential deadlock to determine whether the deadlock is feasible in a real execution requires significant programmer effort. Moreover, empirical evidence shows that existing analyses are quite imprecise. This imprecision of the analyses further void the manual effort invested in reasoning about non-existent defects. In this paper, we address the problems of imprecision of existing analyses and the subsequent manual effort necessary to reason about deadlocks. We propose a novel approach for deadlock detection by designing a dynamic analysis that intelligently leverages execution traces. To reduce the manual effort, we replay the program by making the execution follow a schedule derived based on the observed trace. For a real deadlock, its feasibility is automatically verified if the replay causes the execution to deadlock. We have implemented our approach as part of WOLF and have analyzed many large (upto 160KLoC) Java programs. Our experimental results show that we are able to identify 74% of the reported defects as true (or false) positives automatically leaving very few defects for manual analysis. The overhead of our approach is negligible making it a compelling tool for practical adoption.

Las puertas de la India : consideraciones sobre la indología moderna

Resumen: El presente trabajo pretende ser una introducción al pensamiento de la India. Comienza considerando el desarrollo de la Indología, en sus distintas etapas y corrientes metodológicas, e incluye una precisión sobre estos estudios en la Argentina. Luego de centrarse en la perspectiva hermenéutica, se detallan las épocas de la tradición clásica de la India y las características básicas de su espiritualidad. La autora se adentra a continuación en cuatro nociones que pueden comprenderse como portales de acceso al mundo Indio: mâyâ, karma, yoga y moksha. A la luz de estas nociones tan específicas, la conclusión plantea el diálogo entre disciplinas y culturas como vía para comprender la profunda interdependencia del mundo.

Tarifa social de telefonia

Consultoria Legislativa - Área XIV - Comunicação Social, Informática, Telecomunicações, Sistema Postal, Ciência e Tecnologia.

A maioridade penal no Brasil e em outros países

Consultoria Legislativa - Área II - Direito Civil e Processual Civil, Direito Penal e Processual Penal, de Família.

O controle do Executivo no Parlamento brasileiro : o caso da Câmara dos Deputados

Descreve a função de controle do Executivo pelo Legislativo e os procedimentos utilizados em seu exercício no Parlamento brasileiro; analisa a efetividade desse exercício e propõe alternativas.

Carta de El-Rei D. Manuel ao Rei Catholico narrando-lhe as viagens portuguezas à India desde 1500 até 1505

Esta obra saiu nas Memórias da comissão portuguesa para comemorar o centenário do descobrimento da América. Traz em apêncide a Relação análoga de Lunardo Cha Masser e dois documentos de Cantino e Pasqualigo. Contém, ainda, a primeira notícia impressa sobre o descobrimento do Brasil em carta ao Rei da Espanha.

The Rain Forests of Home: an Atlas of People and Place

pdf contains 31 pages

Decada primeira (-terceira) da Asia de João de Barros : dos feitos que os portuguezes fezerão no descobrimento & conquista dos mares & terras do Oriente : dirigida ao Senado da Camara desta cidade de Lisboa : com todas as licenças necessarias.

João de Barros, historiador, renascentista português, nasceu por volta de 1496, provavelmente em Viseu, e morreu em 20 de outubro de 1570, na quinta de S. Lourenço, próximo da Ribeira de Litém. Entrou para o serviço do Rei D. Manuel desde menino, onde teve seus primeiros mestres e escreveu sua primeira obra, um romance de cavalaria, a Chronica do Imperador Clarimundo. Em 1525, foi nomeado tesoureiro e, em 1533, feitor da Casa da Índia, posto que lhe permitiu ter acesso a numerosas e autênticas fontes, tornando-se um dos historiadores mais importantes da expansão portuguesa. Quando o governo de D. João III estabeleceu para o Brasil o regime das capitanias hereditárias, a João de Barros e a dois associados (Aires da Cunha e Fernão de Álvares de Andrade) foi concedido o trato de terra que ia do Rio Grande ao Maranhão. Em 1531, morreu Lourenço de Cáceres, que deveria escrever a história da Índia, e foi esta, então, confiada a João de Barros, seu sobrinho. Em 1552, saía a primeira das Décadas da Ásia. Além dos trabalhos históricos , escreveu o tratado Rópica pneuma (Mercado espiritual); o Diálogo da viciosa vergonha; o Diálogo sobre preceitos morais; uma gramática da língua portuguesa e uma cartilha para aprender a ler. Dedicou-se às línguas e às letras clássicas, à Geografia, à História e à Cosmografia. A obra está assim dividida: da primeira à quarta década, por João de Barros, em oito volumes; um volume contendo a obra de João de Barros, por Manuel Severim de Faria , e o índice das quatro décadas; da quarta à décima segunda década, de Diogo do Couto, em quinze volumes, aí incluído o índice das Décadas de Couto. Contém, ainda, nas obras, retratos de João de Barros, do Infante D. Henrique e de Afonso de Albuquerque e cinco cartas geográficas. Segundo Brunet, as Décadas XI e XII parecem estar abreviadas. Classifica, também, esta como uma bela edição e que substitui com vantagens as anteriores. A primeira edição Da Asia de João de Barros e de Diogo de Couto foi publicada em Lisboa, em 1522, por Germão Galhardo.