827 resultados para ways of seeing
Resumo:
The Leopold Center was created by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. The Leopold Center believes contribute to a healthy ways of thinking about markets for Iowa farmers, a better understanding of local ecosystems, public policies and economic practices, and partnerships with consumers.
Resumo:
The Leopold Center was created by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. The Leopold Center believes contribute to a healthy ways of thinking about markets for Iowa farmers, a better understanding of local ecosystems, public policies and economic practices, and partnerships with consumers.
Resumo:
The Leopold Center was created by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. The Leopold Center believes contribute to a healthy ways of thinking about markets for Iowa farmers, a better understanding of local ecosystems, public policies and economic practices, and partnerships with consumers.
Resumo:
The Leopold Center was created by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. The Leopold Center believes contribute to a healthy ways of thinking about markets for Iowa farmers, a better understanding of local ecosystems, public policies and economic practices, and partnerships with consumers.
Resumo:
The Leopold Center was created by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. The Leopold Center believes contribute to a healthy ways of thinking about markets for Iowa farmers, a better understanding of local ecosystems, public policies and economic practices, and partnerships with consumers.
Resumo:
The Leopold Center was created by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. The Leopold Center believes contribute to a healthy ways of thinking about markets for Iowa farmers, a better understanding of local ecosystems, public policies and economic practices, and partnerships with consumers.
Resumo:
The Leopold Center was created by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. The Leopold Center believes contribute to a healthy ways of thinking about markets for Iowa farmers, a better understanding of local ecosystems, public policies and economic practices, and partnerships with consumers.
Resumo:
The Leopold Center was created by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. The Leopold Center believes contribute to a healthy ways of thinking about markets for Iowa farmers, a better understanding of local ecosystems, public policies and economic practices, and partnerships with consumers.
Resumo:
The Leopold Center was created by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. The Leopold Center believes contribute to a healthy ways of thinking about markets for Iowa farmers, a better understanding of local ecosystems, public policies and economic practices, and partnerships with consumers.
Resumo:
The Leopold Center was created by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. The Leopold Center believes contribute to a healthy ways of thinking about markets for Iowa farmers, a better understanding of local ecosystems, public policies and economic practices, and partnerships with consumers.
Resumo:
Understanding the oxidative reactivity of nanoparticles (NPs; <100 nm) could substantially contribute to explaining their toxicity. We attempted to refine the use of 2′7-dichlorodihydrofluorescein (DCFH) to characterize NP generation of reactive oxygen species (ROS). Several fluorescent probes have been applied to testing oxidative reactivity, but despite DCFH being one of the most popular for the detection of ROS, when it has been applied to NPs there have been an unexplainably wide variability in results. Without a uniform methodology, validating even robust results is impossible. This study, therefore, identified sources of conflicting results and investigated ways of reducing occurrence of artificial results. Existing techniques were tested and combined (using their most desirable features) to form a more reliable method for the measurement of NP reactivity in aqueous dispersions. We also investigated suitable sample ranges necessary to determine generation of ROS. Specifically, ultrafiltration and time-resolved scan absorbance spectra were used to study possible optical interference when using high sample concentrations. Robust results were achieved at a 5 µM DCFH working solution with 0.5 unit/mL horseradish peroxidase (HRP) dissolved in ethanol. Sonication in DCFH-HRP working solution provided more stable data with a relatively clean background. Optimal particle concentration depends on the type of NP and in general was in the µg/mL range. Major reasons for previously reported conflicting results due to interference were different experimental approaches and NP sample concentrations. The protocol presented here could form the basis of a standardized method for applying DCFH to detect generation of ROS by NPs.
Resumo:
The Leopold Center was created by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. The Leopold Center believes contribute to a healthy ways of thinking about markets for Iowa farmers, a better understanding of local ecosystems, public policies and economic practices, and partnerships with consumers.
Resumo:
The members of the Iowa Concrete Paving Association, the National Concrete Pavement Technology Center Research Committee, and the Iowa Highway Research Board commissioned a study to examine alternative ways of developing transverse joints in portland cement concrete pavements. The present study investigated six separate variations of vertical metal strips placed above and below the dowels in conventional baskets. In addition, the study investigated existing patented assemblies and a new assembly developed in Spain and used in Australia. The metal assemblies were placed in a new pavement and allowed to stay in place for 30 days before the Iowa Department of Transportation staff terminated the test by directing the contractor to saw and seal the joints. This report describes the design, construction, testing, and conclusions of the project.
Resumo:
Microsatellite loci mutate at an extremely high rate and are generally thought to evolve through a stepwise mutation model. Several differentiation statistics taking into account the particular mutation scheme of the microsatellite have been proposed. The most commonly used is R(ST) which is independent of the mutation rate under a generalized stepwise mutation model. F(ST) and R(ST) are commonly reported in the literature, but often differ widely. Here we compare their statistical performances using individual-based simulations of a finite island model. The simulations were run under different levels of gene flow, mutation rates, population number and sizes. In addition to the per locus statistical properties, we compare two ways of combining R(ST) over loci. Our simulations show that even under a strict stepwise mutation model, no statistic is best overall. All estimators suffer to different extents from large bias and variance. While R(ST) better reflects population differentiation in populations characterized by very low gene-exchange, F(ST) gives better estimates in cases of high levels of gene flow. The number of loci sampled (12, 24, or 96) has only a minor effect on the relative performance of the estimators under study. For all estimators there is a striking effect of the number of samples, with the differentiation estimates showing very odd distributions for two samples.
Resumo:
Heavy-ion reactions and other collective dynamical processes are frequently described by different theoretical approaches for the different stages of the process, like initial equilibration stage, intermediate locally equilibrated fluid dynamical stage, and final freeze-out stage. For the last stage, the best known is the Cooper-Frye description used to generate the phase space distribution of emitted, noninteracting particles from a fluid dynamical expansion or explosion, assuming a final ideal gas distribution, or (less frequently) an out-of-equilibrium distribution. In this work we do not want to replace the Cooper-Frye description, but rather clarify the ways of using it and how to choose the parameters of the distribution and, eventually, how to choose the form of the phase space distribution used in the Cooper-Frye formula. Moreover, the Cooper-Frye formula is used in connection with the freeze-out problem, while the discussion of transition between different stages of the collision is applicable to other transitions also. More recently, hadronization and molecular dynamics models have been matched to the end of a fluid dynamical stage to describe hadronization and freeze-out. The stages of the model description can be matched to each other on space-time hypersurfaces (just like through the frequently used freeze-out hypersurface). This work presents a generalized description of how to match the stages of the description of a reaction to each other, extending the methodology used at freeze-out, in simple covariant form which is easily applicable in its simplest version for most applications.
