The ecology movement: a viewpoint

In the wake of a nation‐wide movement to save the environment in 1969, the President of the United States declared that “the 1970's must be the years when America pays its debt to our living environment. It is literally now or never.” This paper is an analysis of environmental politics as a political force today. The discussion traces the emergence of the environmental issue, examines trends in American politics, and concludes that a reassessment of the problem by the ecology movement is necessary.     

Watershed-Scale Impacts of Nitrogen from On-Site Wastewater Systems: Parameter Sensitivity and Model Calibration

A numerical watershed model was used to evaluate the potential influence of various point and nonpoint sources including on-site wastewater systems (OWS) on stream nitrate concentration in Turkey Creek Watershed, Colorado. A watershed analysis risk management framework model was used for this study, and was calibrated to observed stream nitrate concentrations using an automatic calibration tool. Parameter sensitivity analysis was done to select critical parameters for calibration and to reduce uncertainty in the simulated results. Sensitivity analysis of nitrate transport and transformation parameters showed that stream nitrate concentration is highly sensitive to cation exchange capacity, nitrification rate, base saturation of ammonium, initial concentration of ammonium in the soil, and some of the crop growth related parameters. The calibrated model was used to evaluate scenarios related to OWS including the impacts of population growth and new development and impacts of conversion of OWS to conventional sewers. The results showed that there would be a significant increase in stream nitrate concentration with increasing population. Conversion of OWS to sewers increased stream nitrate concentration but decreased nitrate concentration in the bottom soil layer indicating that OWS are beneficial with respect to stream nitrate concentration but may increase nitrate concentrations in groundwater.     

Multibreed genomic prediction using multitrait genomic residual maximum likelihood and multitask Bayesian variable selection

Genomic prediction is applicable to individuals of different breeds. Empirical results to date, however, show limited benefits in using information on multiple breeds in the context of genomic prediction. We investigated a multitask Bayesian model, presented previously by others, implemented in a Bayesian stochastic search variable selection (BSSVS) model. This model allowed for evidence of quantitative trait loci (QTL) to be accumulated across breeds or for both QTL that segregate across breeds and breed-specific QTL. In both cases, single nucleotide polymorphism effects were estimated with information from a single breed. Other models considered were a single-trait and multitrait genomic residual maximum likelihood (GREML) model, with breeds considered as different traits, and a single-trait BSSVS model. All single-trait models were applied to each of the 2 breeds separately and to the pooled data of both breeds. The data used included a training data set of 6,278 Holstein and 722 Jersey bulls, as well as 374 Jersey validation bulls. All animals had genotypes for 474,773 single nucleotide polymorphisms after editing and phenotypes for milk, fat, and protein yields. Using the same training data, BSSVS consistently outperformed GREML. The multitask BSSVS, however, did not outperform single-trait BSSVS, which used pooled Holstein and Jersey data for training. Thus, the rigorous assumption that the traits are the same in both breeds yielded a slightly better prediction than a model that had to estimate the correlation between the breeds from the data. Adding the Holstein data significantly increased the accuracy of the single-trait GREML and BSSVS in predicting the Jerseys for milk and protein, in line with estimated correlations between the breeds of 0.66 and 0.47 for milk and protein yields, whereas only the BSSVS model significantly improved the accuracy for fat yield with an estimated correlation between breeds of only 0.05. The relatively high genetic correlations for milk and protein yields, and the superiority of the pooling strategy, is likely the result of the observed admixture between both breeds in our data. The Bayesian model was able to detect several QTL in Holsteins, which likely enabled it to outperform GREML. The inability of the multitask Bayesian models to outperform a simple pooling strategy may be explained by the fact that the pooling strategy assumes equal effects in both breeds; furthermore, this assumption may be valid for moderate- to large-sized QTL, which are important for multibreed genomic prediction.     

Optimizing electrical poling for tetragonal,lead-free BZT–BCT piezoceramic alloys

The piezoelectric properties of tetragonal BZT–BCT materials have been shown to be improved by using the field cooling poling method. It is shown that the piezoelectric coefficient of tetragonal BZT–BCT materials increases with higher poling temperature, and the optimum poling temperature lies near the Curie temperatures for a broad range of compositions. It is also observed from in situ X-ray diffraction measurements with an applied electric field that the magnitude of domain alignment is enhanced with electrical poling at higher electric fields, whereas the remnant ferroelastic domain texture is not affected. Furthermore, these results show a direct correlation between the development of internal bias field, which is induced by the accumulation of defect charge carriers, and the enhanced piezoelectric coefficient. These observations suggest an important role played by the alignment of defect charge carriers in achieving optimum piezoelectric coefficient in lead-free piezoelectric ceramics.     

A new approach to high-shear mixer granulation using positron emission particle tracking

Positron emission particle tracking (PEPT) can provide quantitative information on particle motion in a mixer. For the first time, the present study clarifies the flow patterns of particles and granules during the process in which granules are formed in high-shear mixer granulation in three dimensions using PEPT. A number of different regions with size-dependent flows account for the variations in frequency and velocity of collisions between differently sized granules in the kernel when segregation occurs in the granulator. These findings offer a better understanding of the product properties and process attributes of high-shear mixer granulation, which will be of direct benefit as pharmaceutical and other products become more complex.     

Characterizing Mood Management as Need Satisfaction: The Effects of Intrinsic Needs on Selective Exposure and Mood Repair

This study attempted to (a) extend traditional mood management theory research by investigating the influence of the intrinsic needs for competence and autonomy on selective exposure to video games and (b) test the influence of satisfying these needs on resultant mood repair. An experiment varied satisfaction of competence and autonomy needs using false feedback. Subjects then selected media that varied in level of user demand. Measures of need satisfaction were taken before and after media selection. Results demonstrated that (a) thwarted intrinsic needs significantly predict the choice of video games with different levels of user demand and (b) the satisfaction of these needs predicts enjoyment. Findings indicate that mood management can result from mood repair through need satisfaction.     

Modeling Fracture of Sn-Rich (Pb-Free) Solder Joints Under Mechanical Shock Conditions

With the increasing focus on developing environmentally benign electronic packages, lead-free solder alloys have received a great deal of attention. Mishandling of packages during manufacture, assembly, or by the user may cause solder joint failure. In this work, we conducted finite-element analysis to model solder joint fracture under dynamic loading conditions. The solder is modeled as a porous plastic material, and the intermetallic compound (IMC) material is characterized as an elastic material. The fracture of the solder is governed by void nucleation, and the IMC fracture is brittle in nature. The randomness of the void volume fraction in the solder and the defects in the IMC are considered and implemented in the finite-element package ABAQUS. The finite-element results show that the fracture mechanisms of the solder joints depend on the strain rate and IMC thickness. High strain rate and larger IMC thickness favor IMC-controlled fracture, which is brittle in nature. Low strain rate and smaller IMC thickness lead to solder-controlled fracture, which is governed by void growth and nucleation. Based on this finding, a mechanistic explanation for solder joint fracture is suggested.     

Mechanism reduction for multicomponent surrogates: A case study using toluene reference fuels

Strategies and recommendations for performing skeletal reductions of multicomponent surrogate fuels are presented, through the generation and validation of skeletal mechanisms for a three-component toluene reference fuel. Using the directed relation graph with error propagation and sensitivity analysis method followed by a further unimportant reaction elimination stage, skeletal mechanisms valid over comprehensive and high-temperature ranges of conditions were developed at varying levels of detail. These skeletal mechanisms were generated based on autoignition simulations, and validation using ignition delay predictions showed good agreement with the detailed mechanism in the target range of conditions. When validated using phenomena other than autoignition, such as perfectly stirred reactor and laminar flame propagation, tight error control or more restrictions on the reduction during the sensitivity analysis stage were needed to ensure good agreement. In addition, tight error limits were needed for close prediction of ignition delay when varying the mixture composition away from that used for the reduction. In homogeneous compression-ignition engine simulations, the skeletal mechanisms closely matched the point of ignition and accurately predicted species profiles for lean to stoichiometric conditions. Furthermore, the efficacy of generating a multicomponent skeletal mechanism was compared to combining skeletal mechanisms produced separately for neat fuel components; using the same error limits, the latter resulted in a larger skeletal mechanism size that also lacked important cross reactions between fuel components. Based on the present results, general guidelines for reducing detailed mechanisms for multicomponent fuels are discussed.     

Acidity Loading Behavior in Coal-Mined Watersheds

In this paper, we propose a method (the Stoertz Water Quality Evaluation Method) to estimate the reduction in acidity load at mean annual discharge (l) in acid mine drainage impaired streams. For a given stream, acidity loading (L), defined as the product of measured acidity concentration and discharge (Q) for a range of streamflow conditions, is proportional to l and the ratio (Q_n) of Q and the mean daily discharge (Q), according to the following equations: L = l (Q/Q)^F = l Q_n ^F and log L = log l + F log Q_n, where F is a ‘flushing factor’ characterizing the stream loading behavior, such that F = 0 in pure dilution, F > 0 for flushing behavior, and F < 0 for sparing behavior. The assumed power-law relation between acidity load and discharge is supported by test cases. Acidity load at mean annual discharge can be a useful measure of the quantity of acid removed by mine drainage treatment, particularly where data for pre- and post-treatment cases can be compared. The proposed measure allows resource managers to assess and report the effectiveness of source control, passive treatment, and active treatment in alleviating acidity loads. This method can also be used to assess inputs of contamination to streams compared to pristine or background conditions.