Ethanol Production, Food and Forests

This paper investigates the direct and indirect impacts of ethanol production on land use, deforestation and food production. A partial equilibrium model of a national economy with two sectors and two regions, one of which includes a residual forest, is developed. It analyses how an exogenous increase in the ethanol price affects input allocation (land and labor) between sectors (energy crop and food). Three potential effects are identified. First, the standard and well-documented effect of direct land competition between rival uses increases deforestation and decreases food production. Second, an indirect displacement of food production across regions, provoked by a shift in the price of food, increases deforestation and reduces the total output of the food sector. Finally, labor mobility between sectors and regions tends to decrease food production but also deforestation. The overall impact of ethanol production on forest conversion is ambiguous, providing a number of interesting pointers to further, empirical research. --Ethanol,Deforestation,Indirect impacts,Land use,Migration

Análise econômica para a pecuária de corte em pastagens melhoradas no Acre.

A pecuária de corte é a atividade com maior expressão econômica do setor agropecuário do Estado do Acre, representando aproximadamente 40% do valor bruto da produção. Contudo, sistemas de produção caracterizados como tradicionais, que apresentam baixos índices zootécnicos, predominam na maior parte das pequenas, médias e grandes propriedades. Consequentemente, o setor apresenta baixa produtividade e rentabilidade e tem causado impactos ambientais negativos decorrentes de desmatamentos, que implicam em perda de biodiversidade e degradação dos solos. Observa-se que a retração da atividade é ocasionada por diversos fatores, com destaque para medidas voltadas à redução nas taxas de desmatamento, o que limita a expansão das áreas de pastagens, e para a baixa produtividade das pastagens de Brachiaria brizantha cv. Marandu (capim-brizantão), as quais apresentam grandes áreas em processo de degradação devido à elevada incidência da síndrome da morte do capim-braquiarão nos últimos 10 anos. Assim, denota-se a necessidade de uma reestruturação do sistema produtivo da pecuária de corte no estado, com base em novos padrões de produção eficientes, que respeitem a natureza e atendam às exigências crescentes da sociedade em geral com a conservação dos recursos naturais. Nesse contexto, há quase três décadas, a Embrapa Acre desenvolve tecnologias com o objetivo de responder ao desafi o de viabilizar sistemas de produção sustentáveis destinados à pecuária de corte, que sejam economicamente rentáveis e de reduzido impacto ambiental.bitstream/CPAF-AC-2010/23476/1/circtec-n51.pd

Instruções técnicas para o cultivo da gravioleira.

A graviola (Annona muricata L.) e uma fruteira tropical, ... Exigências edafoclimáticas ...Instalação do pomar.bitstream/CNPAT-2010/5378/1/It-002.pd

Momentum relaxation from the fluid/gravity correspondence

We provide a hydrodynamical description of a holographic theory with broken translation invariance. We use the fluid/gravity correspondence to systematically obtain both the constitutive relations for the currents and the Ward identity for momentum relaxation in a derivative expansion. Beyond leading order in the strength of momentum relaxation, our results differ from a model previously proposed by Hartnoll et al. As an application of these techniques we consider charge and heat transport in the boundary theory. We derive the low frequency thermoelectric transport coefficients of the holographic theory from the linearised hydrodynamics.Comment: 19 pages + appendix, v2: references added, typos corrected, v3: version published in JHE

Non-Equilibrium Field Dynamics of an Honest Holographic Superconductor

Most holographic models of superconducting systems neglect the effects of dynamical boundary gauge fields during the process of spontaneous symmetry-breaking. Usually a global symmetry gets broken. This yields a superfluid, which then is gauged "weakly" afterwards. In this work we build (and probe the dynamics of) a holographic model in which a local boundary symmetry is spontaneously broken instead. We compute two-point functions of dynamical non-Abelian gauge fields in the normal and in the broken phase, and find non-trivial gapless modes. Our AdS3 gravity dual realizes a p-wave superconductor in (1+1) dimensions. The ground state of this model also breaks (1+1)-dimensional parity spontaneously, while the Hamiltonian is parity-invariant. We discuss possible implications of our results for a wider class of holographic liquids.Comment: 32 pages, 12 figures; v3: string theory derivation of setup added (section 3.1), improved presentation, version accepted by JHEP; v2: paragraph added to discussion, figure added, references added, typos correcte

Boundary Conditions and Unitarity: the Maxwell-Chern-Simons System in AdS_3/CFT_2

We consider the holography of the Abelian Maxwell-Chern-Simons (MCS) system in Lorentzian three-dimensional asymptotically-AdS spacetimes, and discuss a broad class of boundary conditions consistent with conservation of the symplectic structure. As is well-known, the MCS theory contains a massive sector dual to a vector operator in the boundary theory, and a topological sector consisting of flat connections dual to U(1) chiral currents; the boundary conditions we examine include double-trace deformations in these two sectors, as well as a class of boundary conditions that mix the vector operators with the chiral currents. We carefully study the symplectic product of bulk modes and show that almost all such boundary conditions induce instabilities and/or ghost excitations, consistent with violations of unitarity bounds in the dual theory.Comment: 50+1 pages, 6 figures, PDFLaTeX; v2: added references, corrected typo

Gauss-Bonnet Black Holes and Heavy Fermion Metals

We consider charged black holes in Einstein-Gauss-Bonnet Gravity with Lifshitz boundary conditions. We find that this class of models can reproduce the anomalous specific heat of condensed matter systems exhibiting non-Fermi-liquid behaviour at low temperatures. We find that the temperature dependence of the Sommerfeld ratio is sensitive to the choice of Gauss-Bonnet coupling parameter for a given value of the Lifshitz scaling parameter. We propose that this class of models is dual to a class of models of non-Fermi-liquid systems proposed by Castro-Neto et.al.Comment: 17 pages, 6 figures, pdfLatex; small corrections to figure 10 in this versio

RELICS: The Reionization Lensing Cluster Survey and the Brightest High-z Galaxies

Massive foreground galaxy clusters magnify and distort the light of objects behind them, permitting a view into both the extremely distant and intrinsically faint galaxy populations. We present here the z ~ 6-8 candidate high-redshift galaxies from the Reionization Lensing Cluster Survey (RELICS), a Hubble and Spitzer Space Telescope survey of 41 massive galaxy clusters spanning an area of ≈200 arcmin². These clusters were selected to be excellent lenses, and we find similar high-redshift sample sizes and magnitude distributions as the Cluster Lensing And Supernova survey with Hubble (CLASH). We discover 257, 57, and eight candidate galaxies at z ~ 6, 7, and 8 respectively, (322 in total). The observed (lensed) magnitudes of the z ~ 6 candidates are as bright as AB mag ~23, making them among the brightest known at these redshifts, comparable with discoveries from much wider, blank-field surveys. RELICS demonstrates the efficiency of using strong gravitational lenses to produce high-redshift samples in the epoch of reionization. These brightly observed galaxies are excellent targets for follow-up study with current and future observatories, including the James Webb Space Telescope

Aspectos da cadeia produtiva da castanha-do-brasil no estado do Acre, Brasil.

No estado do Acre, poucas cadeias produtivas apresentaram tantas mudanças quanto a da castanha-do-brasil nos últimos anos. Estas mudanças foram motivadas por uma sequência de políticas públicas direcionadas ao setor e pela estruturação de uma cooperativa central de produtores extrativistas. Esta nota de pesquisa analisa, com base em dados secundários e relatos de pessoas envolvidas nos diferentes elos da cadeia produtiva, aspectos econômicos referentes ao beneficiamento e à comercialização da castanha-do-brasil, com o objetivo de registrar e entender as principais mudanças estruturantes ocorridas nesta cadeia produtiva nos últimos dez anos

Evidence for a nuclear compartment of transcription and splicing located at chromosome domain boundaries

The nuclear topography of splicing snRNPs, mRNA transcripts and chromosome domains in various mammalian cell types are described. The visualization of splicing snRNPs, defined by the Sm antigen, and coiled bodies, revealed distinctly different distribution patterns in these cell types. Heat shock experiments confirmed that the distribution patterns also depend on physiological parameters. Using a combination of fluorescencein situ hybridization and immunodetection protocols, individual chromosome domains were visualized simultaneously with the Sm antigen or the transcript of an integrated human papilloma virus genome. Three-dimensional analysis of fluorescence-stained target regions was performed by confocal laser scanning microscopy. RNA transcripts and components of the splicing machinery were found to be generally excluded from the interior of the territories occupied by the individual chromosomes. Based on these findings we present a model for the functional compartmentalization of the cell nucleus. According to this model the space between chromosome domains, including the surface areas of these domains, defines a three-dimensional network-like compartment, termed the interchromosome domain (ICD) compartment, in which transcription and splicing of mRNA occurs