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  • Closed Access
    Authors: 
    Roger Claassen; Ralph E. Heimlich; Robert M. House; Keith Wiebe;
    Publisher: Wiley

    Wetland protection is an issue of ongoing debate. Although it is widely agreed that wetland loss to agriculture has been declining in recent decades, the role of policy remains contentious. We analyze the effect of changes in wetland delineation rules that were proposed but rejected by Congress during the 1996 farm bill debate. Our research combines detailed, site-specific information on wetlands with a broader model of the agricultural economy. Using site-specific data, we analyze the potential agricultural profitability of a representative sample of actual wetlands. We estimate wetland acreage that would have been exempted from swampbuster and Section 404 of the Clean Water Act under the proposed delineation changes, the acreage of exempted wetland that could be profitably converted to crop production, and the associated commodity price, crop acreage, and farm income effects. We find that up to 82.7 million wetland acres would be exempted under the proposed delineation changes, of which as many as 12 million acres could be profitably converted to crop production. This conversion would have a dampening effect on commodity price and farm income. We conclude that (a accurately estimating the effect of resource policy depends critically on detailed information on resource quality and (b) commodity price and farm income effects imply that all agriculture producers—not only those who could expand cropland acreage through wetland drainage—have a stake in wetland policy.

  • Publication . Part of book or chapter of book . 2003
    Authors: 
    Loek Nieuwenhuis; Aimée Hoeve; C. Verhaar;
    Publisher: Routledge

    Knowledge infrastructures are changing at a swift pace: driving forces in the global economy and the increasingly rapid development of (information) technology are making it necessary for national governments to reconsider the organisation of national systems of innovation and knowledge production (Edquist 1997). The development of Mode 2 production systems of knowledge, as described by Gibbons (see Chapter 13), is in line with this trend.

  • Open Access
    Authors: 
    Alexis L. Hoffman; Armen R. Kemanian; Chris E. Forest;
    Publisher: Wiley

    Food security and agriculture productivity assessments in sub-Saharan Africa (SSA) require a better understanding of how climate and other drivers influence regional crop yields. In this paper, our objective was to identify the climate signal in the realized yields of maize, sorghum, and groundnut in SSA. We explored the relation between crop yields and scale-compatible climate data for the 1962-2014 period using Random Forest, a diagnostic machine learning technique. We found that improved agricultural technology and country fixed effects are three times more important than climate variables for explaining changes in crop yields in SSA. We also found that increasing temperatures reduced yields for all three crops in the temperature range observed in SSA, while precipitation increased yields up to a level roughly matching crop evapotranspiration. Crop yields exhibited both linear and nonlinear responses to temperature and precipitation, respectively. For maize, technology steadily increased yields by about 1% (13 kg/ha) per year while increasing temperatures decreased yields by 0.8% (10 kg/ha) per °C. This study demonstrates that although we should expect increases in future crop yields due to improving technology, the potential yields could be progressively reduced due to warmer and drier climates.

  • Open Access
    Authors: 
    Lauro Akio Okuyama; Carlos Roberto Riede; Man Mohan Kohli;
    Publisher: Academic Journals

    The test weight or hectoliter weight is an important parameter used to classify the quality of the grain. Globally, it is evaluated by using 250, 500 or 1000 ml devices. Despite its importance, there is no standard equipment to assess it in small samples from the research plots. This study aims to test a newly developed microchondrometer (15.30 ml) in the triticale and oats. A second microchondrometer (31.26 ml) was also designed to be tested in oats. The performance of the two microchondrometers, their comparison and relationship with 250 ml commercial chondrometer were analyzed using the t-test and Pearson's correlation coefficient. The results revealed no significant differences between two microchondrometers or their relationship with 250 ml chondrometer by t-test (p> 0.05). Based on two-year evaluations, the correlation between the 250 and 15.30 ml was highly significant (p <0.0001) for triticale (0.9873), and oats (0.9557 for 15.30 ml device and 0.9448 for 31.26 ml device). The correlation between 15.30 and 31.26 ml devices was also highly significant (p <0.0001) for oats (0.9399). These results suggest that in small samples, the 15.30 ml microchondrometer can be used successfully in triticale and oats to assess its test weight. Key words: Plant breeding, grain density, genotype screening.

  • Open Access Portuguese
    Authors: 
    Vássia Carvalho Soares; Maria Lucia Bianchi; Paulo Fernando Trugilho; Ariclene Júnior Pereira; Juliana Höfler;
    Publisher: Sociedade de Investigações Florestais

    Foram estudadas madeiras de híbridos de Eucalyptus grandis x Eucalyptus urophylla, em três idades diferentes, com o objetivo de avaliar o comportamento da madeira e do carvão vegetal produzido diante do aumento controlado de temperatura, bem como verificar a influência das características da madeira sobre o carvão vegetal. Foram realizadas análises químicas (extrativos totais, lignina, holocelulose, celulose, cinza e análise elementar) e térmicas (análise termogravimétrica - TG, análise térmica diferencial - DTA e calorimetria 1,67 ºC min-1 e temperatura final de 450 ºC. No carvão vegetal produzido, foram realizadas análise imediata, elementar e térmica. A densidade básica da madeira correlacionou-se positivamente com a relação carbono/ hidrogênio (C/H) e negativamente com os teores de cinza, nitrogênio, oxigênio, enxofre e relação siringil/ guaiacil (S/G). Os teores de cinza, nitrogênio, enxofre e S/G da madeira correlacionaram-se positivamente entre si e negativamente com a variável C/H da madeira. O teor de carbono fixo (TCF), o poder calorífico do carvão vegetal, o teor de carbono elementar e a relação C/H correlacionaram-se positivamente entre si e negativamente com o teor de materiais voláteis (TMV). O teor de lignina correlacionou-se positivamente com o rendimento gravimétrico em carvão (RGC) e negativamente com o TCF. Three different ages of . Eucalyptus grandis x . Eucalyptos urophylla wood hybrids were studied, with purpose of evaluating wood and charcoal behavior by temperature rising, and investigating the influence of wood characteristics on charcoal. Wood was analyzed chemically (total extractives, lignin, holocellulose, cellulose, ash and elementary composition) and thermally (thermogravimetry analysis - TG, differential thermal analysis - DTA and differential scanning calorimetry - DSC). Also, basic density and higher heating value were evaluated. Charcoal was produced in muffle furnace with constant heating rate of 1,67 ºC min-1 up to 450 ºC. In the produced charcoal, immediate analysis were conducted, elementary and thermal. The basic density of wood had positive correlation with C/H relation, and negative correlation with ash, nitrogen, oxygen, sulfur contents and S/G relation. The wood contents of ash, nitrogen, sulfur and S/G had positive correlation among each other, and negative correlation with C/H relation. In charcoal, the fixed carbon content, calorific value, elementary carbon content and C/H relation had positive correlation among each other, and negative correlation with volatiles content. The lignin had positive correlation with gravimetric yield in charcoal (RGC) and negative correlation with fixed carbon.

  • Closed Access
    Authors: 
    Guan Ming-jie; Zhang Qi-sheng;
    Publisher: Springer Science and Business Media LLC

    Dynamic properties of bamboo, Phyllostachys pubescens, with moisture content (MC) ranging from −130 to 130°C, were studied by dynamic mechanical analysis (DMA). The results showed that the hygrothermal effect on dynamic mechanical properties was negative. The storage modulus decreases with increasing temperature and MC, and glass transition temperature decreases with increasing MC. The glass transition temperature and tan delta of bamboo were 30.5°C, 0.02 and 10.61°C, 0.04, when MC was 10% and 34%, respectively.

  • Open Access
    Authors: 
    S. Brooks; Steven J. Hastings;
    Publisher: American Geophysical Union (AGU)

    On April 8, 1999, at approximately local solar noon, airborne measurements of longwave and shortwave radiation were conducted in the Barrow, Alaska, region. Over the pack ice (100 km north of Point Barrow), albedo averaged 0.83, net radiation flux (average 32.4 W m−2) was into the surface, and surface temperatures were positively correlated to observed cloudiness and measured sky temperatures. Over the coastal “fast” ice and tundra, albedo averaged 0.90, net radiation flux (average 2.7 W m−2) was out of the surface, and surface temperatures were not significantly correlated to observed cloudiness or measured sky temperatures. Albedo was not a significant function of observed variation in cloudiness or sky temperature but may have been affected by measurable snowfall the previous day at Barrow. Compared to growing season albedos, springtime albedos had lower coefficients of variation.

  • Open Access
    Authors: 
    Ilkka Hannula; Esa Kurkela;
    Publisher: Elsevier BV
    Country: Finland

    A model for pressurised steam/O2-blown fluidised-bed gasification of biomass with catalytic reforming of hydrocarbons and tars was developed using Aspen Plus simulation software. Seven main blocks were used to model the fluidised-bed gasifier and two for the catalytic reformer. Modelling blocks were complemented with FORTRAN subroutines to simulate the observed non-equilibrium behaviour of the process. The model was fitted with experimental data derived from a 0.5 MW scale test rig operated with crushed wood pellets and forest residues and was shown to be capable of predicting product gas composition from gasification of clean wood. A parametric analysis indicated that a significant improvement in the syngas efficiency could be achieved by rising the filtration temperature and reformer conversions. Other improvement possibilities include fuel drying and lower reforming temperature.

  • Closed Access
    Authors: 
    Alf-Christian Schering; Ilvio Bruder; Susanne Jürgensmann; Holger Meyer; Christoph Schmitt;
    Publisher: Springer Berlin Heidelberg

    Especially in the field of cultural heritage preservation, one has to deal with information formerly collected on non-digital media such as paper, which is highly subject to deterioration and decay. The phrase "From Box to Bin" provokes, because it is connoted differently when not used in context of digitization. Most digitization projects follow a very straightforward workflow to convert documents into digital data. "From Box to Bin" literally depicts the workflow of our digitization project, based on a huge archive of ethnological documents, in which documents are filed in box es. On the one hand, our project is aimed at long time preservation of documents on film reels in metallic bins stored under the earth's surface in a closed mine. On the other hand, documents are converted into binary data, which will be provided for research within a digital archive system. In this article, we describe our very specific digitization workflow and the experiences, we have had with it so far.

  • Open Access English
    Authors: 
    Jô de Farias Lima; D. Montagner; S. S. Duarte; E. T. O. Yoshioka; Márcia Kelly Reis Dias; Marcos Tavares-Dias;
    Publisher: Embrapa Secretaria de Pesquisa e Desenvolvimento

    Abstract: The objective of this work was to evaluate a recirculating aquaculture system using biological aerated filters in tanks for tambaqui (Colossoma macropomum) fingerlings farming, with two initial stocking densities (1.4 and 2.5 kg m-3). The biofilters had similar materials (media) and the same granulometric standards, but inverted orders of the media (classic and inverted). The following were monitored for 90 days: water quality; zootechnical, parasitological, and hematological parameters; and hematimetric indices. Water temperature, oxygen levels, pH, electrical conductivity, and dissolved solids concentration were compatible with tambaqui farming and did not differ between the different biofilters and densities. The ammonia and nitrite value was associated with the stocking densities and not with biofilter. The zootechnical and hematological parameters and the hematimetric indices evaluated were not influenced either by the type of biofilter or by the stocking densities. Ichthyophthirius multifiliis, Anacanthorus spathulatus, Notozothecium janauachensis, and Mymarothecium boegeri were the parasites found. The aerated, classical, and inverted biological filters have similar efficiency in maintaining water quality parameters for tambaqui fingerling farming. Resumo: O objetivo deste trabalho foi avaliar um sistema de recirculação de água com uso de filtros biológicos aerados em tanques de criação de alevinos de tambaqui (Colossoma macropomum), com duas densidades de estocagem (1,4 e 2,5 kg m-3). Os biofiltros possuíam materiais semelhantes (meios) e os mesmos padrões granulométricos, mas com a ordem dos meios invertida (clássico e invertido). Foram monitorados durante 90 dias: a qualidade da água; os parâmetros zootécnicos, parasitológicos e hematológicos; e os índices hematimétricos. A temperatura da água, os níveis de oxigênio, o pH, a condutividade elétrica e a concentração de sólidos dissolvidos foram compatíveis com a produção de tambaqui e não diferiram entre os diferentes biofiltros e densidades. O valor de amônia e nitrito foi associado à densidade de estocagem e não ao biofiltro. Os parâmetros zootécnicos e hematológicos e os índices hematimétricos avaliados não foram influenciados nem pelo tipo de biofiltro nem pela densidade de estocagem. Ichthyophthirius multifiliis, Anacanthorus spathulatus, Notozothecium janauachensis e Mymarothecium boegeri foram os parasitas encontrados. Os filtros biológicos aerados, clássico e invertido têm similar eficiência na manutenção de parâmetros de qualidade de água para o cultivo de alevinos de tambaqui.