The process of agricultural technology generation in Brazil: a social audit.

The focus of agricultural technology studies in Brazil has been on technology diffusion or adoption. This approach stresses the neutrality of technology and its adoption depends on farmers' psychological and individual values. The agricultural technology generation process and the organisations in which technology is generated have not been considered as active factors. This thesis regards both as highly significant in farmers' adoption or rejection of technology. Approaches to development, modernisation and underdevelopment, along with agricultural globalisation, are the applied theoretical perspectives used to understand what happens in the underdeveloped countries in an integrated world system. This is an ex-post facto and cross-sectional study. The empirical data, based on a case study, was collected in Brazil, in and around the Brazilian Agricultural Research Organisation (EMBRAPA), a topdown state-owned organisation. Agricultural technology generation, its adoption, as well as the attitudes of users, clients, policy-makers, politicians and unions to the agricultural technology generation process were investigated. The fieldwork was conducted with eighty-seven agricultural researchers from four national agricultural research centres, one hundred and forty-four farmers, and eighty individuals and organisations' representatives. Qualitative and quantitative analyses indicated that the agricultural technology generation process is related more to scientific issues than to farmers' demands. The technology adopted by farmers was determined primarily by developments within the process of technology generation rather than through any persuasion. The thesis concludes that as a result of the process of technology generation in EMBRAP A, organised and capitalist farmers have been targeted rather than small or subsistence farmers. Therefore, the new farm as a whole research model is recommended, which explores the whole production system rather than specific agricultural products.Dissertation (Doctor in Philosophy)- School of Social Sciences, University of Sussex. Tese de doutorado

Black-hole horizons as probes of black-hole dynamics I: post-merger recoil in head-on collisions

The understanding of strong-field dynamics near black-hole horizons is a long-standing and challenging prob- lem in general relativity. Recent advances in numerical relativity and in the geometric characterization of black- hole horizons open new avenues into the problem. In this first paper in a series of two, we focus on the analysis of the recoil occurring in the merger of binary black holes, extending the analysis initiated in [1] with Robinson- Trautman spacetimes. More specifically, we probe spacetime dynamics through the correlation of quantities defined at the black-hole horizon and at null infinity. The geometry of these hypersurfaces responds to bulk gravitational fields acting as test screens in a scattering perspective of spacetime dynamics. Within a 3 + 1 approach we build an effective-curvature vector from the intrinsic geometry of dynamical-horizon sections and correlate its evolution with the flux of Bondi linear momentum at large distances. We employ this setup to study numerically the head-on collision of nonspinning black holes and demonstrate its validity to track the qualita- tive aspects of recoil dynamics at infinity. We also make contact with the suggestion that the antikick can be described in terms of a "slowness parameter" and how this can be computed from the local properties of the horizon. In a companion paper [2] we will further elaborate on the geometric aspects of this approach and on its relation with other approaches to characterize dynamical properties of black-hole horizons.Comment: final version published on PR

International Portfolio Diversification: Short-Term Financial Assets and Gold

Using a continuous-time finance-theoretic framework, this paper presents the optimal portfolio rule of an international investor who consumes N national composite goods and who holds N domestic-currency-denominated assets with known nominal interest rates in an environment where prices of goods, assets and exchange rates follow geometric Brownian motion. It is shown that the currency portfolio rule described in Macedo (1982a) is applicable to the case where there are N assets with a known price and one asset, gold, with a random rice in terms of the numeraire. Under these assumptions, it is found that the optimal portfolio of an investor consuming goods from all major industrialized countries (according to their weight in total trade) would be dominated in March 1981 by long positions in U.S. dollars (25%), yen (17%), D. marks (16%), French francs (15%) and pounds sterling (10%). An investor consuming only U.S. goods, by contrast, would hold 96% of his optimal portfolio in U.S. dollars. Because of the covariance of exchange rates and gold, the exclusion of the latter generates substantial reshuffling. The analysis of the evolution of portfolios over time shows that shares changed dramatically at the beginning of the period and did not begin to approach their March 1981 values until the end of 1975. In the case of the yen and the pound there were oscillations throughout the period. With respect to the dollar share in the optimal portfolio of the U.S. and international investor, it is found that, in the period between late 1974 and mid-1976, a period in which the dollar is considered to have been "strong", a large decline in its optimal share took place.

The intersectional genetics landscape for humans

BACKGROUND: The human body is made up of hundreds-perhaps thousands-of cell types and states, most of which are currently inaccessible genetically. Intersectional genetic approaches can increase the number of genetically accessible cells, but the scope and safety of these approaches have not been systematically assessed. A typical intersectional method acts like an "AND" logic gate by converting the input of 2 or more active, yet unspecific, regulatory elements (REs) into a single cell type specific synthetic output. RESULTS: Here, we systematically assessed the intersectional genetics landscape of the human genome using a subset of cells from a large RE usage atlas (Functional ANnoTation Of the Mammalian genome 5 consortium, FANTOM5) obtained by cap analysis of gene expression sequencing (CAGE-seq). We developed the heuristics and algorithms to retrieve and quality-rank "AND" gate intersections. Of the 154 primary cell types surveyed, >90% can be distinguished from each other with as few as 3 to 4 active REs, with quantifiable safety and robustness. We call these minimal intersections of active REs with cell-type diagnostic potential "versatile entry codes" (VEnCodes). Each of the 158 cancer cell types surveyed could also be distinguished from the healthy primary cell types with small VEnCodes, most of which were robust to intra- and interindividual variation. Methods for the cross-validation of CAGE-seq-derived VEnCodes and for the extraction of VEnCodes from pooled single-cell sequencing data are also presented. CONCLUSIONS: Our work provides a systematic view of the intersectional genetics landscape in humans and demonstrates the potential of these approaches for future gene delivery technologies.publishersversionpublishe

Fixação de nitrogênio pela soja em sistemas de cultivo contínuo e rotacionado com pecuária nos Cerrados.

Quantificou-se a contribuição da fixação biológica de N2 (FBN) na cultura da soja em um Latossolo Vermelho-Escuro, utilizando-se a técnica da abundância natural do isótopo 15N. Foram estudados cinco tratamentos: 1) soja de primeiro ano em solo cultivado por quatro anos com Brachiaria decumbens, sob pastejo, e preparado mecanicamente (arado, grade pesada e niveladora); 2) mesmas condições anteriores, mas com plantio direto da soja; 3) soja em cultivo contínuo por cinco anos, como cultura de verão, sem plantio de milheto no outono/ inverno, e solo preparado de forma convencional (arado, grade pesada e niveladora); 4) soja com cultivo contínuo por cinco anos, com cultivo de outono/inverno de milheto (Pennisetum atropurpureum) e preparo de solo conservacionista (arado de disco, aiveca e subsolador); 5) mesmas condições anteriores, mas com plantio direto. Amostras de plantas foram coletadas no estádio vegetativo, enchimento de grãos, na maturação, e na colheita final de grãos. Em cada coleta analisaram-se as produções de matéria seca (MS) e teores de N e 15N. As produções de MS e N total acumulado foram semelhantes no estádio vegetativo, mas as plantas no plantio direto mostraram taxas de FBN acima de 50%, enquanto que as de plantio convencional estavam abaixo de 40%. No enchimento de grãos, as produções de MS, N total e as taxas de FBN(entre 60% e 68%) foram semelhantes em todos os sistemas de preparo do solo. Na maturação dos grãos, o preparo de solo convencional resultou numa maior produção de MS do que no plantio direto. Os grãos apresentaram a maior parte do N fixado (66% a 82%), ficando entre 51% e 68% para a parte aérea e entre 15% e 32% para as raízes. No balanço do N total obtido por FBN e o que foi alocado aos grãos, obtiveram-se valores indicativos de que a maior parte do N fixado seria retirada do sistema na colheita de grãos, o que foi confirmado na colheita final. A soja de plantio direto mostrou um balanço ligeiramente mais positivo do que a soja de plantio convencional. Como a soja é pouco dependente do N do solo, usando eficientemente o N de fixação, este seria poupado como resíduo para uso de culturas subseqüentes, o que explicaria o efeito benéfico imediato observado na prática em sistemas produtivos de rotação de cultura entre soja e cereais ou pastagem. No entanto, os resultados obtidos indicam que a soja, que tem um índice de colheita alto (proporção do N total nos grãos em relação ao N total da planta), não contribui significativamente para aumento dos teores de N total do solo capazes de beneficiar por longo tempo as culturas em sucessão.bitstream/CNPGC/10292/1/BP14.pd

Phytoplankton production modelling in three marine ecosystems—static versus dynamic approach

Phytoplankton productivity is usually determined from water samples incubated at a number of irradiance levels during several hours. The resultant productivity-irradiance (P–E) curves are then used to estimate local and/or global phytoplankton production. However, there is growing evidence that these curves, referred as static, underestimate phytoplankton photosynthesis to a great deal, by assuming a stable response to light over the incubation period. One of the drawbacks of static P–E curves is the overestimation of photoinhibition. In this work, three one-dimensional vertically resolved models were developed as simply as possible, to investigate differences between static and dynamic phytoplankton productivity in three marine ecosystems: a turbid estuary, a coastal area and an open ocean ecosystem. The results show that, when photoinhibition development time is considered (dynamic model), the primary production estimates are always higher than when calculated with the static model. The quantitative importance of these differences varies with the type of ecosystem and it appears to be more important in coastal areas and estuaries (from 21 to 72%) than in oceanic waters (10%). Thus, these results suggest that primary production estimates, obtained under the assumption of a static behaviour response to light, may underestimate the real values of global phytoplankton primary production. Calculations suggest that the quantitative importance of this underestimation may be larger than the global missing carbon sink