Estimators for QST and coalescence times.

Comparisons of QST to FST can provide insights into the evolutionary processes that lead to differentiation, or lack thereof, among the phenotypes of different groups (e.g., populations, species), and these comparisons have been performed on a variety of taxa, including humans. Here, I show that for neutrally evolving (i.e., by genetic drift, mutation, and gene flow alone) quantitative characters, the two commonly used QST estimators have somewhat different interpretations in terms of coalescence times, particularly when the number of groups that have been sampled is small. A similar situation occurs for FST estimators. Consequently, when observations come from only a small number of groups, which is not an unusual situation, it is important to match estimators appropriately when comparing QST to FST

Oregon Mathematics Leadership Institute Project: Evaluation Results on Teacher Content Knowledge, Implementation Fidelity, and Student Achievement

The Oregon Mathematics Leadership Institute (OMLl) National Science Foundation Mathematics and Science Partnership project partners are Oregon State University, Portland State University, Teachers Development Group, and ten Oregon school districts. The primary activities of the project were a sequence of three intensive three-week residential institutes emphasizing mathematics content knowledge for teaching, collegial leadership, and the building of Professional Learning Communities. Teachers at all levels of grades K-12 participated together in the mathematics content courses. By the conclusion of the. third Summer Institute, teachers had shown significant improvements in mathematical content knowledge for teaching. Analysis of student achievement data in participating schools was initially inconclusive. However, once implementation fidelity traits were taken into account, a positive relationship between project participation and student achievement emerged. The degree to which schools implement the practices promoted by the OMLI project is a significant positive predictor of student perfomiance above and beyond what can be explained by the socioeconomic factor as indicated by the percentage of students who qualify for the free and reduced lunch program. This relationship is particularly acute at secondary levels, but additional factors appear to be at play at elementary grade levels

Viscosity dependence of the rates of diffusional processes

It is shown that the rates of diffusion-controlled processes may have a solvent vicosity independent part as well as a viscosity dependent part. Some relevant experiments involving intramolecular polypeptide movements are discussed, and implications for some experiments on diffusion in membranes are outlined

Protein folding, protein structure and the origin of life: Theoretical methods and solutions of dynamical problems

Theoretical methods and solutions of the dynamics of protein folding, protein aggregation, protein structure, and the origin of life are discussed. The elements of a dynamic model representing the initial stages of protein folding are presented. The calculation and experimental determination of the model parameters are discussed. The use of computer simulation for modeling protein folding is considered

Job Performance Comparisons - Mexican-American and Anglo Employees

A comparison of job performance of Mexican-American and non-Mexican-American employees in various city departments and in a large department store measured absentee rates, accident rates, efficiency ratings, promotional test scores, and sales records. The conclusions revealed that Mexican-Americans meet the same qualifications as non-Mexican-Americans in employment areas.Sociolog

RETAIL SALES: DO THEY MEAN REDUCED EXPENDITURES? GERMAN GROCERY EVIDENCE

Retail pricing strategies incorporate promotions, sales, and rigidities. A number of models have been proposed in particular to explain the occurrence of sales. Focussing on the market for fresh foods the model by Varian and the loss leader argument seem to be intuitively best fitting to the conditions in the fresh food market. From these models we derive several hypotheses that are tested for a unique data set of the German fresh food retail market. The data set consists of weekly prices for ten food items in 131 grocery shops over the period from 1995 to 2000. Following Varian sales should lead to reduced expenditures, while the loss leader argument assumes that consumers are lured into the shop by promotional sales which are covered by higher prices for other products. The results indicate that expenditures decrease with the number of sales in the short run but this effect is outweighed by a dynamic price adjustment thereafter.Food Consumption/Nutrition/Food Safety, Marketing,

FOOD RETAIL SALES (PRICING): THEORY AND EMPIRICAL EVIDENCE FOR GERMAN GROCERY STORES

Retail pricing indicates many phenomena, such as sales or rigidities. A number of models have been proposed in particular to explain the occurrence of sales. Focussing on the market for fresh foods the model by Varian and the loss leader argument seem to be intuitively best fitting to the conditions in the fresh food market. From these models we derive several hypotheses that are tested for a unique data set of the German fresh food retail market The data set consists of weekly prices for ten food items in 131 grocery shops over the period from 1995 to 2000. The results support to some extent the Varian model and also indicate some dynamic loss leader pricing. However, rejections of some hypothesis provide some hints for successive models adjustments. Promising extensions of the theory might be based on the consideration of menu and switching costs.Marketing,

Commodity Price Volatility under New Market Orientations

Recent national and international regulatory reforms (e.g. U.S. FAIR and other GATT compliance reforms) in agricultural markets has led some observers to wonder whether the private sector is able to produce a level of price volatility that is socially acceptable. In this paper, we examine the post reform track record of price volatility and its transmission across vertically linked and geographically linked markets. Livestock, grain, and dairy market data (monthly) are considered across the U.S. and E.C. The standard commodity-pricing model supports the hypothesis that competitive storage acts to reduce the volatility of cash prices. Further, speculative attacks and stock outs have been shown to induce increased volatility. This motivates a scope of consideration that includes prices as well as stock levels to assess their contribution to price volatility. The paper considers evidence based on three decades of monthly data and advanced time series techniques. First, univariate volatility estimates based on the autoregressive conditional heteroskedasticity (GARCH) model are evaluated and compared to historical temporal variation to highlight the importance of well grounded estimation of volatility. Next, the relationships between stocks and the conditional mean, as well as the conditional and unconditional variances of the price series, are assessed for dairy and grain products. Finally, reform associated changes in the structure of the transmission of volatility through vertical markets are considered for dairy products and across geographic markets is considered for grains.Price volatility; price risk; inventories; commodity prices;

Price and tax policy for semi-subsistence agriculture in Ethiopia

In the case of semi-subsistence agriculture where wage employment is not available, the role played by prices and taxes in determining production and consumption decisions is not clearly established by economic theories of household choice. This study demonstrates that where choices in production, consumption, and leisure can be made independently, farmers will decide what to grow on the basis of their preferences for marketed goods. The paper also points out that the choice will be affected by the level and type of taxation imposed. The paper shows the impact of four taxes -- agricultural revenue, land, production and marketed goods consumption -- on crop production and tax revenues. This paper also reports on a model of production in Ethiopia. The results of this study give strong evidence of the role of producer and consumer prices in semi-subsistence agriculture. In addition, the results show the importance of production capacity, household and climatic factors in agricultural development.Environmental Economics&Policies,Economic Theory&Research,Crops&Crop Management Systems,Agricultural Knowledge&Information Systems,Consumption