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Selenium (Se) enrichment has been demonstrated to vary by several orders of magnitude among species of planktonic algae. This is a substantial source of uncertainty when modelling Se biodynamics in aquatic systems. In addition, Se bioconcentration data are largely lacking for periphytic species of algae, and for multi-species periphyton biofilms, adding to the challenge of modelling Se transfer in periphyton-based food webs. To better predict Se dynamics in periphyton dominated, freshwater ecosystems, the goal of this study was to assess the relative influence of periphyton community composition on the uptake of waterborne Se oxyanions. Naturally grown freshwater periphyton communities, sampled from five different water bodies, were exposed to environmentally relevant concentrations of selenite [Se(IV)] or selenate [Se(VI)] (nominal concentrations of 5 and 25 μg Se L−1) under similar, controlled laboratory conditions for a period of 8 days. Unique periphyton assemblages were derived from the five different field sites, as confirmed by light microscopy and targeted DNA sequencing of the plastid 23S rRNA gene in algae. Selenium accumulation demonstrated a maximum of 23.6-fold difference for Se(IV) enrichment and 2.1-fold difference for Se(VI) enrichment across the periphyton/biofilm assemblages tested. The assemblage from one field site demonstrated both high accumulation of Se(IV) and iron, and was subjected to additional experimentation to elucidate the mechanism(s) of Se accumulation. Selenite accumulation (at nominal concentrations of 5 and 25 μg Se L−1 and mean pH of 7.5 across all treatment replicates) was assessed in both unaltered and heat-killed periphyton, and in periphyton from the same site grown without light to exclude phototrophic organisms. Following an exposure length of 8 days, all periphyton treatments showed similar levels of Se accumulation, indicating that much of the apparent uptake of Se(IV) was due to non-biological processes (i.e., surface adsorption). The results of this study will help reduce uncertainty in the prediction of Se dynamics and food-chain transfer in freshwater environments. Further exploration of the ecological consequences of extracellular adsorption of Se(IV) to periphyton, rather than intracellular absorption, is recommended to further refine predictions related to Se biodynamics in freshwater food webs.

Dubowitz syndrome (DubS) is considered a recognizable syndrome characterized by a distinctive facial appearance and deficits in growth and development. There have been over 200 individuals reported with Dubowitz or a “Dubowitz-like” condition, although no single gene has been implicated as responsible for its cause. We have performed exome (ES) or genome sequencing (GS) for 31 individuals clinically diagnosed with DubS. After genome-wide sequencing, rare variant filtering and computational and Mendelian genomic analyses, a presumptive molecular diagnosis was made in 13/27 (48%) families. The molecular diagnoses included biallelic variants in SKIV2L, SLC35C1, BRCA1, NSUN2; de novo variants in ARID1B, ARID1A, CREBBP, POGZ, TAF1, HDAC8, and copy-number variation at1p36.11(ARID1A), 8q22.2(VPS13B), Xp22, and Xq13(HDAC8). Variants of unknown significance in known disease genes, and also in genes of uncertain significance, were observed in 7/27 (26%) additional families. Only one gene, HDAC8, could explain the phenotype in more than one family (N = 2). All but two of the genomic diagnoses were for genes discovered, or for conditions recognized, since the introduction of next-generation sequencing. Overall, the DubS-like clinical phenotype is associated with extensive locus heterogeneity and the molecular diagnoses made are for emerging clinical conditions sharing characteristic features that overlap the DubS phenotype.

A major source of uncertainty in predicting selenium (Se) distribution in aquatic food webs lies in the enrichment factor (EF), the ratio of Se bioconcentration in primary producers and microorganisms relative to the concentration of Se in the surrounding water. It has been well demonstrated that EFs can vary dramatically among individual algal taxa, but data are lacking regarding the influence of periphyton community composition on EFs for a given geochemical form of Se. Therefore, the goals of this study were first to assess whether different periphyton communities could be established in aquaria with the same starting inoculum using different light and nutrient regimes, and second, to determine if the periphyton assemblage composition influences the uptake of waterborne Se (as selenite) and subsequent Se transfer to a model macroinvertebrate primary consumer. Periphyton biofilms were grown in aquaria containing filtered pond water (from Saskatoon, SK) spiked with approximately 20 μg Se/L (mean measured concentration 21.0 ± 1.2 μg Se/L), added as selenite. Five different light and nutrient regimes were applied to the aquaria (three replicates per treatment) to influence biofilm community development. After 6 weeks of biofilm maturation, 40 to 80 immature cultured snails (Stagnicola elodes) were added to each aquarium. The bacterial and algal members of the periphyton community were characterized by targeted metagenomic analyses before and after addition of snails to ensure the snails themselves did not significantly alter the biofilm community. Samples were collected for Se analysis of water, periphyton, and whole-body snail. The nutrient and light treatments resulted in substantially different compositions of the periphytic biofilms, with each being relatively consistent across replicates and throughout the study. Although the aqueous concentration of dissolved Se administered to treatments was constant, uptake by the different periphytic biofilms differed significantly. Both the low-light (61.8 ± 12.1 μg Se/g d.w.) and high-light (30.5 ± 4.7 μg Se/g d.w.) biofilms, which were found to have high proportions of cyanobacteria, contained statistically higher concentrations of Se relative to the other treatments. Furthermore, the concentration of Se in bulk periphyton was predictive of Se bioaccumulation in grazing snails but as an inverse relationship, opposite to expectations. The trophic transfer factor was inversely correlated with periphyton enrichment factor (r = -0.841). A number of different bacterial and algal taxa were correlated (either positively or negatively) with Se accumulation in periphyton biofilm and snails. Recent advancements in genetic methods make it possible to conduct detailed characterization of periphyton assemblages and begin to understand the influence that periphyton composition has on Se biodynamics in aquatic systems.

A city tax model based on the analytic hierarchy process is developed. This model allows city officials to explicitly take into account the existence of multiple decision criteria in selecting new tax options. Opinions from tax experts are used to relate tax plans to decision criteria. The paper explores the feasibility of applying commonly available decision tools to facilitate and improve decision making in local government.

This study was undertaken to update earlier work by the authors that analyzed selected preharvest pricing strategies utilizing options markets to establish a price floor for part of the crop in the spring, with additional pricing done by use of short hedges in early summer. The timing of implementing these strategies was moved back to late February if the previous year's U.S. crop was a weather-induced short crop. A weather-induced short crop as opposed to a government program induced short crop was defined as one in which U.S. production fell below the previous year's use and the U.S. average yield was at least 6% below a trend yield. Previous work by the authors indicated that selected pre-harvest strategies applied to actual farms in Iowa and Ohio over the 1985-1998 time period generated net returns well above those from a naive strategy of systematically selling at harvest, with t-tests indicating statistical significance at the 5% level. Similar results were observed when the time period was extended to 2001. The results from this study may explain the observed increase in the use of forward pricing by farmers, the emergence of new pre-harvest marketing tools focusing on late winter and spring pricing opportunities, and the emphasis on pre-harvest pricing by market advisory services (Irwin et al., 2003). Results reported here suggest that over the past 18 to 29 years, farmers have had the potential to reap substantial economic benefits from improving both their pre-harvest and post-harvest marketing skills.

In the 1995/96 crop year, record high corn futures prices and inverted spreads eroded the cash flows and financial capabilities of both farmer hedgers and elevators who implemented the rollover provisions in hedge-to-arrive (HTA) contracts. Participants in the 1995/96 corn market who used the exotic HTA multiple-year mechanism faced large unexpected margin calls and/or sharply lower "net" prices than expected, as the July-December old crop-new crop inverted corn spread widened to very large negative levels. We evaluate the soybean futures spreads in the 1948-1997 period, and the associated monetary risks inherent in the rollover provisions of the HTA contracts. In the 50 years in which current soybean May, July, and November contracts have been trading, the probability of old crop-new crop spreads being in the plus/minus 10 percent range of the old crop "normal" price was approximately 75 percent and the probability of having negative spreads exceeding 10 percent was only 20 to 25 percent. However, the high-price years (over 20 percent above normal old crop price) had a 100 percent probability of having a negative spread and a 50 to 60 percent probability of having a negative spread exceeding 10 percent. Merchandisers offering HTA contracts should be aware of these risks and communicate them to farmers considering their HTA contracts.

To test the effectiveness in managing net income risk and profit levels, pre-harvest corn and soybean options-based pricing strategies and crop yield and revenue insurance products were modeled for case study farms in three states. These combinations reduced income variability while increasing net incomes relative to harvest cash marketings. Adding crop insurance to pre-harvest pricing strategies reduced net incomes from those with pre-harvest pricing alone, but produced larger incomes than uninsured harvest sales. The Ohio model farm was modified to reflect (1) a debt-free operation, (2) a cash renter, and (3) a buyer-renter operation. No strategy was able to cover opportunity costs on investments for types (1) and (3). Both crop insurance and pre-harvest strategies are effective tools especially for highly leveraged farms.

Pre-harvest corn and soybean options-based pricing strategies, and crop yield and revenue insurance were applied to model farms in three states. These combinations reduced income variability while increasing net incomes relative to uninsured harvest cash sales. Adding crop insurances to pre-harvest pricing reduced net incomes from those with pre-harvest pricing alone, but produced larger incomes than uninsured harvest sales. The Ohio model farm was modified to reflect (1) a debt-free operation, (2) a cash renter, and (3) a buyer-renter operation. No strategy was able to cover opportunity costs on investments for types (1) and (3). For farm type (3), mean net cash-flow returns were negative for harvest cash sales, but positive when pre-harvest pricing was added with and without insurance.

A quality-of-life index (QLI), a proxy measure of utility, is constructed by factor-weighted and simple-summation weighted aggregation of socio-psychological measures of well-being. The socio-psychological measures were constructed from quality of life domains taken from selected years of the General Social Surveys [General Social Surveys, 1972-1993: Cumulative Code Book. Principal Investigator, James A. Davis; Director and Co-Principal Investigator, Tom W. Smith - Chicago: National Opinion Research Center, 1993. (National Data Program for the Social Sciences Series, no. 13).]. The Quality of Life Indices (QLI) indices are regressed on selected socio-demographic variables using quadratic, Cobb-Douglas, square root, and semilog functional forms. QLI is much influenced by income, education, and health. As measured here, QLI is not much influenced by year of measurement, sector, or by region of residence. Much variability in the QLI is unique to individuals, and our results are suited to predict group, rather than individual well-being. Practitioners computing the benefit-cost ratio for a public program, project, or policy can weight dollars by income groups with marginal utilities derived from this study. That methodology will matter: even the 'conservative' quadratic equation indicates that the marginal utility of income (MUI) for families with very low incomes is half as large as for families with median incomes. © 1997 Elsevier Science B.V.

Grain producers price grain prior to harvest to reduce financial risk and to enhance net returns. Since accomplishing the second objective is debatable, alternative corn and soybean pre-harvest options/hedge marketing strategies were designed to test the hypothesis that pre-harvest pricing could generate statistically higher average net returns than harvest sales, without increasing income variability. Weekly seasonal futures price patterns from 1975 to 1994 were used to time marketings. The strategies were applied to Iowa and Ohio model farms. For the 1985-96 period, the hypothesis was accepted.

A tax model for the city of Richmond is developed and tested, in close cooperation with local public leaders and with tax experts. To construct and test the model, Expert Choice, a commercially available decision support system based on the analytic hierarchy process is used. A Delphi approach is used to have tax experts compare the alternative tax plans with respect to specific decision criteria.