996 resultados para Environmental transformations


Relevância:

20.00% 20.00%

Publicador:

Resumo:

We provide estimates of the costs associated with inducing substantial conversion of land from production of traditional crops to switchgrass. Higher traditional crop prices due to increased demand for corn from the ethanol industry has increased the relative advantage that row crops have over switchgrass. Results indicate that farmers will convert to switchgrass production only with significant conversion subsidies. To examine potential environmental consequences of conversion, we investigate three stylized landscape usage scenarios, one with an entire conversion of a watershed to switchgrass production, a second with the entire watershed planted to continuous corn under a 50% removal rate of the biomass, and a third scenario that places switchgrass on the most erodible land in the watershed and places continuous corn on the least erodible. For each of these illustrative scenarios, the watershed-scale Soil and Water Assessment Tool (SWAT) hydrological model (Arnold et al., 1998; Arnold and Forher, 2005) is used to evaluate the effect of these landscape uses on sediment and nutrient loadings in the Maquoketa Watershed in eastern Iowa.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Recent evidence supports and reinforces the concept that environmental cues may reprogramme somatic cells and change their natural fate. In the present review, we concentrate on environmental reprogramming and fate potency of different epithelial cells. These include stratified epithelia, such as the epidermis, hair follicle, cornea and oesophagus, as well as the thymic epithelium, which stands alone among simple and stratified epithelia, and has been shown recently to contain stem cells. In addition, we briefly discuss the pancreas as an example of plasticity of intrinsic progenitors and even differentiated cells. Of relevance, examples of plasticity and fate change characterize pathologies such as oesophageal metaplasia, whose possible cell origin is still debated, but has important implications as a pre-neoplastic event. Although much work remains to be done in order to unravel the full potential and plasticity of epithelial cells, exploitation of this phenomenon has already entered the clinical arena, and might provide new avenues for future cell therapy of these tissues.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In principle, a country can not endure negative genuine savings for longperiods of time without experiencing declining consumption. Nevertheless,theoreticians envisage two alternatives to explain how an exporter ofnon-renewable natural resources could experience permanent negativegenuine savings and still ensure sustainability. The first one allegesthat the capital gains arising from the expected improvement in theterms of trade would suffice to compensate for the negative savings ofthe resource exporter. The second alternative points at technologicalchange as a way to avoid economic collapse. This paper uses the dataof Venezuela and Mexico to empirically test the first of these twohypotheses. The results presented here prove that the terms oftrade do not suffice to compensate the depletion of oil reservesin these two open economies.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Growing demand for corn due to the expansion of ethanol has increased concerns that environmentally sensitive lands retired from agricultural production into the Conservation Reserve Program (CRP) will be cropped again. Iowa produces more ethanol than any other state in the United States, and it also produces the most corn. Thus, an examination of the impacts of higher crop prices on CRP land in Iowa can give insight into what we might expect nationally in the years ahead if crop prices remain high. We construct CRP land supply curves for various corn prices and then estimate the environmental impacts of cropping CRP land through the Environmental Policy Integrated Climate (EPIC) model. EPIC provides edge-of-field estimates of soil erosion, nutrient loss, and carbon sequestration. We find that incremental impacts increase dramatically as higher corn prices bring into production more and more environmentally fragile land. Maintaining current levels of environmental quality will require substantially higher spending levels. Even allowing for the cost savings that would accrue as CRP land leaves the program, a change in targeting strategies will likely be required to ensure that the most sensitive land does not leave the program.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This fact sheet answers questions such as, is it safe to swim in the water and who is monitoring the beaches in Iowa

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Recently, kernel-based Machine Learning methods have gained great popularity in many data analysis and data mining fields: pattern recognition, biocomputing, speech and vision, engineering, remote sensing etc. The paper describes the use of kernel methods to approach the processing of large datasets from environmental monitoring networks. Several typical problems of the environmental sciences and their solutions provided by kernel-based methods are considered: classification of categorical data (soil type classification), mapping of environmental and pollution continuous information (pollution of soil by radionuclides), mapping with auxiliary information (climatic data from Aral Sea region). The promising developments, such as automatic emergency hot spot detection and monitoring network optimization are discussed as well.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

O presente trabalho visa estudar a importância de transformar os eventos culturais da ilha de São Vicente em produtos turísticos. Está mais do que provado que o turismo pode ser considerado o motor de desenvolvimento de qualquer economia, mas também que poderá levar a sérios problemas ambientais, sociais, culturais e até mesmo económicos com efeito a longo prazo, caso não for bem planeado. Dentro do turismo, o sector de eventos tem apresentado uma grande evolução, trazendo muitos benefícios e promoção para os destinos turísticos. Para além da importância que os eventos têm para os destinos turísticos, esta pesquisa também estudará o que é preciso ser feito a nível social, e em relação às infra-estruturas e serviços locais para serem transformados em produtos turísticos. Para efectuar essa transformação que poderá trazer muito mais benefícios tanto para a ilha como para a população local, será preciso que os eventos culturais da ilha sejam planeados e organizados, envolvendo todas as enti dades locais e a comunidade, de forma que possam criar soluções para desenvolver um turismo sustentável para São Vicente, e diminuir os impactos negativos no ambiente, na sociedade e na cultura. The goal of this Project is to study the importance of transforming the cultural events of São Vicente Island into touristic products. It is proved that tourism can be considered the development engine of any economy, but it can also lead to serious environmental, social, cultural end even economical problems with long term effects in case of bad planning. Within tourism, the events sector has seen a great evolution, bringing many benefits such as promotion to touristic destinations. Further to the importance that the events have to the touristic destinations, this research will also study what needs to be done concerning society and in relation to infrastructures and local services to be transformed into touristic products. To make these transformations come to life, something which can bring much more benefits to the island as well as to the local population, the cultural events of the island need to be planned and organized involving all the local entities, and the community, in the creation of solutions to develop a sustainable tourism for São Vicente and diminish the negative impacts on the environment, society and culture.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Power transformations of positive data tables, prior to applying the correspondence analysis algorithm, are shown to open up a family of methods with direct connections to the analysis of log-ratios. Two variations of this idea are illustrated. The first approach is simply to power the original data and perform a correspondence analysis this method is shown to converge to unweighted log-ratio analysis as the power parameter tends to zero. The second approach is to apply the power transformation to thecontingency ratios, that is the values in the table relative to expected values based on the marginals this method converges to weighted log-ratio analysis, or the spectral map. Two applications are described: first, a matrix of population genetic data which is inherently two-dimensional, and second, a larger cross-tabulation with higher dimensionality, from a linguistic analysis of several books.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Nonlinear regression problems can often be reduced to linearity by transforming the response variable (e.g., using the Box-Cox family of transformations). The classic estimates of the parameter defining the transformation as well as of the regression coefficients are based on the maximum likelihood criterion, assuming homoscedastic normal errors for the transformed response. These estimates are nonrobust in the presence of outliers and can be inconsistent when the errors are nonnormal or heteroscedastic. This article proposes new robust estimates that are consistent and asymptotically normal for any unimodal and homoscedastic error distribution. For this purpose, a robust version of conditional expectation is introduced for which the prediction mean squared error is replaced with an M scale. This concept is then used to develop a nonparametric criterion to estimate the transformation parameter as well as the regression coefficients. A finite sample estimate of this criterion based on a robust version of smearing is also proposed. Monte Carlo experiments show that the new estimates compare favorably with respect to the available competitors.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

1. Aim - Concerns over how global change will influence species distributions, in conjunction with increased emphasis on understanding niche dynamics in evolutionary and community contexts, highlight the growing need for robust methods to quantify niche differences between or within taxa. We propose a statistical framework to describe and compare environmental niches from occurrence and spatial environmental data.¦2. Location - Europe, North America, South America¦3. Methods - The framework applies kernel smoothers to densities of species occurrence in gridded environmental space to calculate metrics of niche overlap and test hypotheses regarding niche conservatism. We use this framework and simulated species with predefined distributions and amounts of niche overlap to evaluate several ordination and species distribution modeling techniques for quantifying niche overlap. We illustrate the approach with data on two well-studied invasive species.¦4. Results - We show that niche overlap can be accurately detected with the framework when variables driving the distributions are known. The method is robust to known and previously undocumented biases related to the dependence of species occurrences on the frequency of environmental conditions that occur across geographic space. The use of a kernel smoother makes the process of moving from geographical space to multivariate environmental space independent of both sampling effort and arbitrary choice of resolution in environmental space. However, the use of ordination and species distribution model techniques for selecting, combining and weighting variables on which niche overlap is calculated provide contrasting results.¦5. Main conclusions - The framework meets the increasing need for robust methods to quantify niche differences. It is appropriate to study niche differences between species, subspecies or intraspecific lineages that differ in their geographical distributions. Alternatively, it can be used to measure the degree to which the environmental niche of a species or intraspecific lineage has changed over time.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Audit report on the ADLM Counties Environmental Public Health Agency for the year ended June 30, 2007