Etanol, meio ambiente e tecnologia: reflexões sobre a experiência brasileira.

O trabalho apresenta uma breve reflexão sobre os principais aspectos ambientais e tecnológicos da experiência brasileira voltada à produção e ao uso de etanol a partir da cana-de-açúcar. Ao se analisar toda a cadeia produtiva do etanol, observa-se que o aproveitamento estratégico de todos os subprodutos da cana-de-açúcar é condição essencial para a sustentabilidade do processo produtivo. Por sua vez, a queima da cana-de-açúcar para colheita e a expansão da monocultura canavieira são fatores que requerem maior atenção. O trabalho demonstra que a produção de etanol de cana-deaçúcar contribui para a sustentabilidade ambiental e que seu uso como combustível renovável é favorável em relação aos combustíveis fósseis

Exploring the three-dimensional organization of genomes: interpreting chromatin interaction data

How DNA is organized in three dimensions inside the cell nucleus and how this affects the ways in which cells access, read and interpret genetic information are among the longest standing questions in cell biology. Using newly developed molecular, genomic and computational approaches based on the chromosome conformation capture technology (such as 3C, 4C, 5C and Hi-C), the spatial organization of genomes is being explored at unprecedented resolution. Interpreting the increasingly large chromatin interaction data sets is now posing novel challenges. Here we describe several types of statistical and computational approaches that have recently been developed to analyse chromatin interaction data.National Institutes of Health (U.S.)National Human Genome Research Institute (U.S.) (HG003143)National Human Genome Research Institute (U.S.) (HG003143-06S1)W. M. Keck FoundationSpain. Ministerio de Ciencia e Innovación (BFU2010-19310/BMC)Human Frontier Science Program (Strasbourg, France) (RGP0044/2011)European Union (BLUEPRINT project (EU FP7 grant agreement 282510))National Cancer Institute (U.S.) (Physical Sciences Oncology Center at MIT, U54CA143874

The 3D Genome as Moderator of Chromosomal Communication

Proper expression of genes requires communication with their regulatory elements that can be located elsewhere along the chromosome. The physics of chromatin fibers imposes a range of constraints on such communication. The molecular and biophysical mechanisms by which chromosomal communication is established, or prevented, have become a topic of intense study, and important roles for the spatial organization of chromosomes are being discovered. Here we present a view of the interphase 3D genome characterized by extensive physical compartmentalization and insulation on the one hand and facilitated long-range interactions on the other. We propose the existence of topological machines dedicated to set up and to exploit a 3D genome organization to both promote and censor communication along and between chromosomes.National Human Genome Research Institute (U.S.) (Grant R01 HG003143)National Human Genome Research Institute (U.S.) (Grant U54 HG007010)National Human Genome Research Institute (U.S.) (Grant U01 HG007910)National Cancer Institute (U.S.) (Grant U54 CA193419)National Institutes of Health (U.S.) (Grant U54 DK107980)National Institutes of Health (U.S.) (Grant U01 DA 040588)National Institute of General Medical Sciences (U.S.) (Grant R01 GM 112720)National Institute of Allergy and Infectious Diseases (U.S.) (Grant U01 R01 AI 117839

Wave localization in strongly nonlinear Hertzian chains with mass defect

We investigate the dynamical response of a mass defect in a one-dimensional non-loaded horizontal chain of identical spheres which interact via the nonlinear Hertz potential. Our experiments show that the interaction of a solitary wave with a light intruder excites localized mode. In agreement with dimensional analysis, we find that the frequency of localized oscillations exceeds the incident wave frequency spectrum and nonlinearly depends on the size of the intruder and on the incident wave strength. The absence of tensile stress between grains allows some gaps to open, which in turn induce a significant enhancement of the oscillations amplitude. We performed numerical simulations that precisely describe our observations without any adjusting parameters.Comment: 4 pages, 5 figures, submitted for publicatio

Welfarism vs. extra-welfarism

'Extra-welfarism' has received some attention in health economics, yet there is little consensus on what distinguishes it from more conventional 'welfarist economics'. In this paper, we seek to identify the characteristics of each in order to make a systematic comparison of the ways in which they evaluate alternative social states. The focus, though this is not intended to be exclusive, is on health. Specifically, we highlight four areas in which the two schools differ: (i) the outcomes considered relevant in an evaluation; (ii) the sources of valuation of the relevant outcomes; (iii) the basis of weighting of relevant outcomes and (iv) interpersonal comparisons. We conclude that these differences are substantive. (C) 2007 Elsevier B.V. All rights reserved

Defining and detecting quantum speedup

The development of small-scale digital and analog quantum devices raises the question of how to fairly assess and compare the computational power of classical and quantum devices, and of how to detect quantum speedup. Here we show how to define and measure quantum speedup in various scenarios, and how to avoid pitfalls that might mask or fake quantum speedup. We illustrate our discussion with data from a randomized benchmark test on a D-Wave Two device with up to 503 qubits. Comparing the performance of the device on random spin glass instances with limited precision to simulated classical and quantum annealers, we find no evidence of quantum speedup when the entire data set is considered, and obtain inconclusive results when comparing subsets of instances on an instance-by-instance basis. Our results for one particular benchmark do not rule out the possibility of speedup for other classes of problems and illustrate that quantum speedup is elusive and can depend on the question posed

Emulsification in binary liquids containing colloidal particles: a structure-factor analysis

We present a quantitative confocal-microscopy study of the transient and final microstructure of particle-stabilised emulsions formed via demixing in a binary liquid. To this end, we have developed an image-analysis method that relies on structure factors obtained from discrete Fourier transforms of individual frames in confocal image sequences. Radially averaging the squared modulus of these Fourier transforms before peak fitting allows extraction of dominant length scales over the entire temperature range of the quench. Our procedure even yields information just after droplet nucleation, when the (fluorescence) contrast between the two separating phases is scarcely discernable in the images. We find that our emulsions are stabilised on experimental time scales by interfacial particles and that they are likely to have bimodal droplet-size distributions. We attribute the latter to coalescence together with creaming being the main coarsening mechanism during the late stages of emulsification and we support this claim with (direct) confocal-microscopy observations. In addition, our results imply that the observed droplets emerge from particle-promoted nucleation, possibly followed by a free-growth regime. Finally, we argue that creaming strongly affects droplet growth during the early stages of emulsification. Future investigations could clarify the link between quench conditions and resulting microstructure, paving the way for tailor-made particle-stabilised emulsions from binary liquids.Comment: http://iopscience.iop.org/0953-8984/22/45/455102

Intensification of smallholder livestock production through utilisation of crop residues for livestock feed in Tanzania

Poor feed utilisation and seasonal feed availability are considered contributory factors leading to less-than-optimal livestock productivity on smallholder farms in Babati, Tanzania. Cereal and legume crop residues, such as dry or green maize stover and bean haulms, are commonly fed to livestock but are also of low quality and they are poorly used by farmers. Improving the efficiency with which the crop residues can be used as animal feed appears the first step towards solving critical feed shortage. Studies on maize crop residue uses and trade-offs on smallholder crop-livestock farmers have proven on an economic perspective that it is logical to prioritise its use for feed over soil fertility management. A study was conducted to assess availability of types, quantity and quality of crop residues and other feed resources for livestock on farms. The study aimed to understand how cereal and legume crop residues are harvested, stored, processed and used in different farms. It also aimed to identity gaps in managing crop residues in intensified systems and factors that may affect adoption. Post-harvest forage processing technologies such as feed choppers offer potential to enhance use of crop residues for livestock feeding. This not only reduces feed wastage but also enhances feed intake and quality. It also has potential to improve quantity and quality of manure. Following the study a feed chopping technology to enhance utilisation was introduced to farmers. The findings showed that the average household tropical livestock unit (TLU) is 3.8 (se = 0.15). Crop residues are the major contributor to livestock diet in the dry season. The most dominant cereal crop residues are maize stover (57%) and rice straw (20%) while the most common legumes straws are pigeon pea (4%); bean (12%), groundnut (5%) and cowpea (2%) haulms. On average the maize stover yield on farms is 9.3 t ha-1 (se = 0.28). There is a lot of feed waste on farms due to chopping by using a machete. Yield of maize stover from a hectare of land can sustain one TLU of livestock for 247 days