Propagation of Data Error and Parametric Sensitivity in Computable General Equilibrium Models

While computable general equilibrium (CGE) models are a well-established tool in economic analyses, it is often difficult to disentangle the effects of policies of interest from that of the assumptions made regarding the underlying calibration data and model parameters. To characterize the behavior of a CGE model of carbon output with respect to two of these assumptions, we perform a large-scale Monte Carlo experiment to examine its sensitivity to base year calibration data and elasticity of substitution parameters in the absence of a policy change. By examining a variety of output variables at different levels of economic and geographic aggregation, we assess how these forms of uncertainty impact the conclusions that can be drawn from the model simulations. We find greater sensitivity to uncertainty in the elasticity of substitution parameters than to uncertainty in the base-year data as the projection period increases. While many model simulations were conducted to generate large output samples, we find that few are required to capture the mean model response of the variables tested. However, characterizing standard errors and empirical probability distribution functions is not possible without a large number of simulations.     

A Library-Based Approach to Task Parallelism in a Data-Parallel Language

Pure data-parallel languages such as High Performance Fortran version 1 (HPF) do not allow efficient expression of mixed task/data-parallel computations or the coupling of separately compiled data-parallel modules. In this paper, we show how these common parallel program structures can be represented, with only minor extensions to the HPF model, by using a coordination library based on the Message Passing Interface (MPI). This library allows data-parallel tasks to exchange distributed data structures using calls to simple communication functions. We present microbenchmark results that characterize the performance of this library and that quantify the impact of optimizations that allow reuse of communication schedules in common situations. In addition, results from two-dimensional FFT, convolution, and multiblock programs demonstrate that the HPF/MPI library can provide performance superior to that of pure HPF. We conclude that this synergistic combination of two parallel programming standards represents a useful approach to task parallelism in a data-parallel framework, increasing the range of problems addressable in HPF without requiring complex compiler technology.     

Citywide: Supporting Interactive Digital Experiences Across Physical Space

The Citywide project is exploring ways in which technology can provide people with rich and engaging digital experiences as they move through physical space, including historical experiences, performances and games. This paper describes some initial results and experiences with this project based upon two prototype demonstrators. In the first, we describe an application in which a search party explores an archaeological site, uncovering enacted scenes within the virtual world that are of a historical relevance to their particular physical location. In the second, we describe a museum experience where participants explore an outdoors location, hunting for buried virtual artifacts that they then bring back to a museum for a more detailed study. Our demonstrators employ a varied set of devices, including mobile wireless interfaces for locating hotspots of virtual activity when outdoors, to give different experiences of the virtual world depending upon location, task, available equipment and accuracy of tracking. We conclude by discussing some of the potential advantages of using an underlying shared virtual world to support interactive experiences across extended physical settings.     

Long-term aging of copper added to soils

Aging refers to the processes by which the mobility and bioavailability/toxicity of metals added to soil decline with time. Although long-term aging is a key process that needs to be considered in the risk assessment of metals in field soils, the long-term aging of Cu added to soils has not been studied in detail. In this study, the effects of aging on Cu isotopic exchangeability, total Cu in soil pore water, pore water free Cu2+ activity, and "available" Cu measured by the technique of diffusive gradient in thin film (DGT-Cu) were investigated in 19 European soils at two total Cu concentrations shown to inhibit plant (tomato) growth by 10 and 90%. After addition of Cu, the soils were leached, incubated outdoors, and sampled regularly over a 2-year period. The results showed that when water soluble Cu was added to soils, concentrations of Cu determined by each of the techniques tended to decrease rapidly initially, followed by further decreases at slow rates. Soil pH was a vital factor affecting the aging rate of Cu added to soils. The relatively low solubility products and low isotopic exchangeabilities of Cu in calcareous soils immediately after addition of soluble Cu2+ suggested Cu2+ probably precipitated in these soils as Cu2(OH)2CO3 (malachite) and Cu(OH)2. Isotopic dilution was found to be a robust technique for measuring rates of long-term aging reactions. A semi-mechanistic model was developed to describe the rate and extent of Cu aging across soils as affected by soil pH and other physicochemical parameters. Although not measured directly, it is inferred from soil physicochemical controls on Cu aging that processes of precipitation/nucleation of Cu in soils and hydrolysis of Cu2+ followed by a diffusion process controlled the decrease in Cu availability with time. The model was validated by testing it against field soils with different contamination histories and was found to successfully predict the isotopic exchangeability of Cu added to soils based on two parameters: soil pH and time.     

Short communication: Absorption of protein and immunoglobulin g in calves fed a colostrum replacer

A well-managed colostrum program on farms is the most important step in reducing disease in neonatal calves. In the last few years, colostrum replacers have increased in popularity and are designed to be an alternative to colostrum on farms that have poor colostrum quality, limited colostrum reserves, or to break the cycle of transmission for certain infectious diseases. However, it is important to make sure these products are effective and are capable of providing adequate serum immunoglobulin concentrations. The objective of this study was to evaluate the efficacy of a commercially available colostrum replacer product in dairy calves. Holstein calves from a single dairy were randomly assigned to 1 of 3 groups at birth. Group 1 (n = 21) calves were given 4 quarts of colostrum via esophageal feeder within 3 h of birth and served as the control group for this study. Group 2 (n = 21) received 2 packages of a colostrum replacer product, and group 3 (n = 21) received 3 packages of the colostrum replacer product within 3 h of birth. Blood samples from all calves were collected 24 h after colostrum administration and analyzed for serum total protein and IgG concentrations. Calves fed fresh colostrum had significantly higher serum total protein levels and IgG concentrations compared with calves fed the colostrum replacer product. Calves fed the colostrum replacer also had a significantly higher percentage of calves with failure of passive transfer (serum IgG <1,000 mg/dL). The colostrum replacer product evaluated in this study failed to routinely provide adequate IgG concentrations when fed according to label directions.     

Activity Sensors for Use in Psychiatric Evaluation

The need for objective methods of patient evaluation has long been recognized in clinical psychiatry. While the relationship between mood states and motor activity has been observed for many years, this relationship was never accurately defined due to the imprecise nature of the available observational techniques. This report describes two activity sensors and their related systems which objectively measure motor activity levels and patterns without affecting the patient's movements.     

SALT GLAZES FOR STRUCTURAL BUILDING UNITS*

The conditions necessary for the formation of a clear, transparent salt glaze on structural building units are described. Laboratory trials, which were made under these conditions or slight modifications of them, were studied by means of enlarged photographs of the surfaces and thin sections of the glazes. These pictures illustrate the process of formation of the glaze and show that glazes more than 0.001 in. thick are susceptible to crazing. Salt glazes usually are formed from 0.003 to 0.004 in. thick in order to obtain a smooth brilliant glaze, but such glazes craze badly. Much better glazes may be obtained with only a sufficient number of saltings to give a glaze thickness of approximately 0.001 in., followed by a maturing or smoothing treatment in which the salting temperature is held for some time, or borax is used during the latter part of the salting and (or) the early part of the cooling period.