bluuebunny/crossref_metadata_2025 huggingface dataset:
How Much Can Informational Outreach Programs Increase Food Stamp Program Participation?
Authors: Levedahl J. William
Published: July 2006

Data from the Panel Survey of Income Dynamics (PSID) indicate that one‐fourth of the households eligible for the Food Stamp Program (FSP) do not know they are eligible. Using an FSP participation equation that incorporates a household's perceived FSP eligibility, it was estimated that informational outreach programs directed at these households have the potential of increasing the overall FSP participation rate by a maximum of 18% and benefit payments by 12.6%. These results can be useful in establishing realistic goals for FSP informational outreach programs.
Legal Status and Earnings of Agricultural Workers
Authors: Isé Sabrina , Perloff Jeffrey M.
Published: July 2006

Agricultural workers who work in the United States earn 15% more on average than do undocumented workers. These earnings differentials vary substantially with demographic characteristics. For example, much of the weekly earnings loss from not having legal status can be offset by language ability. Most of the earnings differential is due to wage differentials rather than hours differentials.
A Hedonic Analysis of Herbicides: Do User Safety and Water Quality Matter?
Authors: Beach E. Douglas , Carlson Gerald A.
Published: July 2006

Farmers may value water quality and user safety characteristics of herbicides as they select among products to obtain weed control. Expenditures per application in the U.S. corn and soybean herbicide markets are explained by several safety characteristics in addition to market and weed control characteristics. The explicit inclusion of safety characteristics in the farm decision model indicates that not all safety aspects of pesticide use are external to farmers. Leaching potential and user toxicity are statistically significant, but their elasticities are small relative to broadleaf and grass weed control efficacy.
Growth and Structural Change in U.S. Food and Fiber Industries: An Input‐Output Perspective
Authors: Lee Chinkook , Schluter Gerald
Published: July 2006

We analyze growth and structural change of the food and fiber industries in the U.S. economy, 1972–82. Growth and structural changes are examined in terms of how changes in a sector's output can be apportioned between changes in (1) domestic final demand, (2) export demand, (3) interindustry demand, and (4) domestic supply ratios. Results indicate that growth of U.S. agricultural sectors is nearly equally dependent upon exports and domestic demand, while growth of processed food and nonfood agricultural processing sectors is heavily dependent on domestic demand.
Substitution Effects in CVM Values
Authors: Cummings Ronald G. , Ganderton Philip T. , McGuckin Thomas
Published: July 2006

There is increasing recognition that statistical estimates of the average willingness to pay for environmental programs may be biased by the failure of respondents, or of the statistical methodology, to consider the effect of substitute programs and goods. We design and implement a CVM survey that estimates the impact of substitution effects on the willingness to pay for an environmental program. We find a statistically significant impact and suggest that the set of potential substitutes is very large.
Multiperiod Production with Forward and Option Markets
Authors: Lence Sergio H. , Hayes Dermot J. , Sakong Yong
Published: July 2006

Production and hedging in both forward and options markets are analyzed for forward‐looking firms that maximize expected utility. In the presence of unbiased forward and options prices, it is shown that such firms will use options as hedging instruments. This result contrasts with the conclusions from studies that assume myopic behavior, and occurs because forward‐looking agents care about the effect of future output prices on profits from future production cycles. Simulations support the theoretical results and show how the introduction of an options market influences the optimal forward position.
Evaluating Generic Milk Promotion Effectiveness with an Imperfect Competition Model
Authors: Suzuki Nobuhiro , Kaiser Harry M. , Lenz John E. , Forker Olan D. , Kobayashi Kohei
Published: July 2006

A framework is proposed for incorporating the degree of market competition in evaluating milk promotion effectiveness. The imperfect competition model allows simultaneity in price and quantity with an endogenous fluid milk premium. The model's usefulness is demonstrated with Japanese generic milk promotion data. Results show a conventional exogenous‐price or exogenous‐premium model will underestimate returns to milk promotion.
Asset Pricing Theory and the Predictable Variation in Agricultural Asset Returns
Authors: Bjornson Bruce
Published: July 2006

This study focuses on the time‐series predictability of agricultural returns and evaluates the ability of conditional asset pricing models to capture such predictability. The models all have time‐varying conditional risk premia and constant betas, as opposed to the unconditional specifications in prior studies. Results indicate significant time‐varying predictability in agricultural asset returns. An Arbitrage Pricing model with prespecified economic factors, including a market portfolio, shows some ability to explain the predictability. The greater flexibility and information in conditional asset pricing models make them more suitable than unconditional models for many problems in agricultural finance.
A Cross‐Section Demand Analysis of Spanish Provincial Food Consumption
Authors: Chung Ching‐Fan
Published: July 2006

I follow the differential approach in building three demand models of Spanish cross‐province food consumption patterns. The models include quadratic income terms for estimating the widely varying income responses one expects from cross‐section data. The proposed models are also flexible in permitting alternative levels of aggregation across goods. A nonnested testing procedure is used to identify the best model. Both the flexibility of the quadratic income term and the flexibility of alternative aggregation levels are important in the analysis of Spanish food consumption patterns.
Technology Transfer, Licensing Contracts, and Incentives for Further Innovation
Authors: Larson Bruce A. , Anderson Margot
Published: July 2006

Technology licensing is common in agricultural and natural resource sectors. An important characteristic of technology licenses is that they provide incentives for further innovation on the part of the buyer. This paper develops a risk‐sharing model to analyze how risk preferences and expectations about further innovation possibilities alter technology payments and the incentives for complementary local innovation. Higher buyer risk aversion, which is associated with lower fixed payments, reduces the technology buyer's level of innovation. Sellers are generally better off when innovation is anticipated, but buyers are generally better off when innovation is unanticipated, although less innovation may be realized.
A Nonparametric Approach to the von Liebig‐Paris Technology
Authors: Chambers Robert G. , Lichtenberg Erik
Published: July 2006

We develop the dual implications of the von Liebig‐Paris nutrient‐response technology and parametric and nonparametric tests for this technology. We discuss the nonparametric approach using two different representations corresponding to optimistic and pessimistic nonparametric approximations of the technology. Application of the nonparametric approach to two experimental data sets and to two data sets generated by Monte Carlo methods confirms the presence of yield plateaus, but provides mixed evidence regarding input nonsubstitution. The optimistic representation exhibits virtually no input substitution, while the pessimistic representation shows considerable substitutability.
Feedforward Backpropagation Neural Networks in Prediction of Farmer Risk Preferences
Authors: Kastens Terry L. , Featherstone Allen M.
Published: July 2006

An out‐of‐sample prediction of Kansas farmers' responses to five surveyed questions involving risk is used to compare ordered multinomial logistic regression models with feedforward backpropagation neural network models. Although the logistic models often predict more accurately than the neural network models in a mean‐squared error sense, the neural network models are shown to be more accommodating of loss functions associated with a desire to predict certain combinations of categorical responses more accurately than others.
Input Demand under Yield and Revenue Insurance
Authors: Babcock Bruce A. , Hennessy David A.
Published: July 2006

Previous studies disagree on the effects of insurance on fertilizer application rates. The effect of increased fertilizer on the probability of low yields primarily determines whether fertilizer and insurance are substitutes or complements. We estimate conditional distributions of corn yields to determine if the technical relationship between yields and fertilizer supports the hypothesis that insurance increases optimal application rates. Our results indicate no support for this hypothesis. At all nitrogen fertilizer rates and reasonable levels of risk aversion, nitrogen fertilizer and insurance are substitutes, suggesting that those who purchase insurance are likely to decrease nitrogen fertilizer applications.
Marketing Quotas and Random Yields: Marginal Effects of Inframarginal Subsidies on Peanut Supply
Authors: Borges Robert B. , Thurman Walter N.
Published: July 2006

The U.S. peanut program restricts domestic sales with poundage quota but allows surplus production to be exported or crushed. Empirical analysis of North Carolina peanut production reveals that the marginal (and lower) price received by production above quota, that is the world price, is far more important in determining acreage than is the inframarginal subsidy of the quota support price.
A Multilevel, Multiobjective Policy Model: The Case of Marine Aquaculture Development
Authors: Sylvia Gilbert , Anderson James L. , Cai Deqin
Published: July 2006

Marine aquaculture development is often constrained due to the difficulty in accommodating the industry within the evolving framework of coastal zone regulatory policy. One contributing problem is the dearth of socioeconomic, environmental, and institutional knowledge. To address this issue, a dynamic multiobjective, multilevel policy model is formulated for net‐pen aquaculture development using effluent taxes as a policy instrument. Dynamic policy frontiers are generated by solving the aquacultural sector's problem, embedding the producer's dynamic response within the policy maker's problem, and then parameterizing on policy goals. The frontiers represent economic policy information consistent with the needs of a policy bargaining process.
The Implications of Model Specification for Welfare Estimation in Nested Logit Models
Authors: Kling Catherine L. , Thomson Cynthia J.
Published: July 2006

Nested logit models are increasingly being used to value environmental amenities. The implications of nesting structure, choice of estimator (FIML or sequential), and restrictions on parameters across nested groups on welfare estimates are examined. These issues have received little previous attention. Model selection criteria that can be used to distinguish among the models are extended and applied. Additionally, a simulation procedure is implemented to construct standard errors for the welfare measures.
System Theoretic Time‐Series Forecasts of Weekly Live Cattle Prices
Authors: Foster Kenneth A. , Havenner Arthur M. , Walburger Allan M.
Published: July 2006

Multivariate time‐series forecasts of weekly live cattle prices in six different geographic markets are developed using a procedure based on the principles of linear systems theory. These forecasts were found to be informative and superior to those obtained from an alternative model. Following the approach developed for stock prices by Cerchi and Havenner, arbitrage portfolios were constructed from the model parameters. A simulation exercise based on 208 weekly observations withheld from model specification and estimation suggests that these arbitrage activities would have been profitable in practice.
The Impact of Policies and Land Characteristics on Potential Groundwater Pollution in Wisconsin
Authors: Wu JunJie , Segerson Kathleen
Published: July 2006

In this paper we present an empirical framework for quantifying the extensive margin effects of commodity programs and chemical‐use taxes on potential groundwater pollution in Wisconsin. The approach emphasizes the role of the joint distribution of crops and site characteristics in determining policy impacts on groundwater contamination. The results indicate that for a given reduction in total polluting acreage an increase in the Acreage Reduction Program rate for corn is well targeted and would reduce high‐polluting acreage more than a chemical‐use tax or a target price policy in the areas where it might be needed most.
A Model of Price Determination for Fresh Produce with Application to California Iceberg Lettuce
Authors: Sexton Richard J. , Zhang Mingxia
Published: July 2006

Most fresh produce commodities are highly perishable. Thus, supply at any time is fixed at prices above marginal harvest costs. In this paper we develop a model of short‐run farm price determination for produce commodities that incorporates this key structural feature and also allows for imperfect competition in price determination. The model is empirically manifest in a switching regression framework and applied to California iceberg lettuce. Results support the general model relative to a model restricted to competitive behavior and suggest that retailer/buyers capture most of the rents from lettuce production and sale.
Valuing Target Price Support Programs with Average Option Pricing
Authors: Kang Taehoon , Brorsen B. Wade
Published: July 2006

The U.S. government deficiency payment program supplements farm income by transferring income from taxpayers to farmers. When revenue lost due to the acreage restriction exceeds revenue gained from participating in the program, farmers lose money by participating. Therefore, measuring expected revenue from the government program is important so that farmers can decide whether to participate in the program. This study uses a GARCH average‐option pricing model and the Black average‐option pricing model to predict the implicit premium of the U.S. government deficiency payment program. The average‐option pricing model considers the average price of the underlying asset over a fixed period. A regression model based on the simulation results is provided so that the average‐option models can be easily used to project deficiency payments. The results can be used by extension economists to help producers decide whether to participate in the program.
A Virtually Ideal Production System: Specifying and Estimating the VIPS Model
Authors: Chambers Robert G. , Pope Rulon D.
Published: July 2006

We characterize the class of profit functions termed VIPS for “virtually ideal production system.” VIPS is consistent with all derived demands being linear in numeric functions of output prices. A flexible but parsimonious version of the VIPS profit function is specified and the implied supply‐response system is estimated using aggregate U.S. agricultural data.
Substitution between Goods and Leisure in a Developing Country
Authors: Alderman Harold , Sahn David E.
Published: July 2006

The paper explores the substitutability between goods, female leisure, and male leisure. We find that goods and leisure are not separable. We then adapt the Almost Ideal Demand System (AIDS) to include leisure in the system in the same manner as commodities. The model is not sensitive to variations in the assumption of total time available for each individual's work and leisure. Results from Sri Lanka indicate the marginal propensity to consume leisure is quite high, especially in rural areas. This finding has important implications for transfer programs designed to raise food consumption. A somewhat surprising complementarity between male and female leisure was also observed. A number of goods were found to be complements to both male and female leisure.
A Dynamic Minimum Variance Hedge
Authors: Lence Sergio H. , Kimle Kevin L. , Hayenga Marvin L.
Published: July 2006

The study presents an operational dynamic minimum variance hedge ratio (DMV) that allows for updates of both cash and futures positions. It is shown that DMV is more general than other operational models in the hedging literature. including the traditional static minimum‐variance hedge ratio (SMV). Estimation of DMV is illustrated with a corn storage problem. The example reveals relatively noticeable differences among the magnitudes of DMV and alternative operational hedge ratios. However, gains in hedging effectiveness from using DMV instead of the simpler SMV are negligible.
Asymmetry and Rigidity in Farm‐Retail Price Transmission
Authors: Azzam Azzeddine M.
Published: July 2006

This article demonstrates how retail‐price transmission asymmetry can arise from intertemporal optimizing behavior among spatially competitive retailers facing concave spatial demand and shows that vigorous competition among retailers may not necessarily result in the larger retail‐price declines farmers expect during periods of declining farm prices. It also shows that, when this particular class of retailers incurs repricing costs, retail prices can be rigid over a range of upward and downward movements in the farm price. This suggests that the rigidity of retail prices, during periods of declining farm prices, could be due to repricing costs. It also suggests that the appropriate econometric model of price‐transmission is the model of friction, where Tobit analysis is the proper method of estimation rather than nonreversible functions.
Do Farm Workers Earn Less? An Analysis of the Farm Labor Problem
Authors: Gisser Micha , Dávila Alberto
Published: July 2006

During the four decades extending from 1950 to 1960, the ratio of the farm to nonfarm wage fluctuated between 0.45 and 0.55. We employ the Oaxaca technique and the Public Use Microdata Sample of the 1990 Census to decompose the farm/nonfarm wage differential. We also use the American Chamber of Commerce Research Association (ACCRA) cost‐of‐living data to measure the impact of the farm/nonfarm cost‐of‐living index on the wage gap. First, we find that the observed wage gap is reduced by half when nominal wages are deflated by the (ACCRA) cost‐of‐living index. Second, by applying the Oaxaca method separately to a subsample of young employees and a subsample of old employees we find that while for the subsample of employees younger than thirty‐five years the real wage gap practically vanishes, the gap for the subsample of employees who are thirty‐five years of age and over is higher than that of the total sample. This finding lends strong support to the hypothesis that between 1950 and 1970 the process of farm out‐migration was positively selective.
The Structure of Multiplant Technologies
Authors: Chambers Robert G.
Published: July 2006

Multiplant technologies are studied, with particular attention on the notion of reaggregation introduced by Sil and Buccola. A weaker, less restrictive notion of reaggregation is formulated. The relation of varying notions of nonjointness (plant, input) to reaggregation is also studied, and specific functional structures are identified.
On Market Equilibrium Analysis
Authors: Chavas Jean‐Paul , Cox Thomas L.
Published: July 2006

In this paper we develop the implications of competitive market equilibrium for production and household behavior when some prices are endogenously determined. The properties of market equilibrium functions are explored, including the effects of pricing policy. A Slutsky‐type equation relating compensated and uncompensated market equilibrium functions is derived. Implications for multimarket welfare analysis are presented, focusing on the effects of pricing policy and technical change.
Theory and Measurement of Exotic Options in U.S. Agricultural Support Programs
Authors: Tirupattur Viswanath , Hauser Robert J. , Boyle Phelim P.
Published: July 2006

Theoretical models are derived for pricing derivative market instruments with payoff structures identical to those implied by the deficiency, Findley, and loan programs. Numerical approximation methods are used to obtain market premiums for the exotic contingent claims embedded in these types of programs. The application focuses on a comparison of the value of traditional support programs for corn to that of an exchange put offered under the Option Pilot Program. The comparison provides measures of expected cost to the government and of the value of the programs to the producer.
Functional Separability and Elasticities of Complementarity
Authors: Kim H. Youn
Published: July 2006

This paper presents an alternative characterization of separability based on elasticities of complementarity. Earlier studies have formulated separability restrictions in terms of the Allen elasticities of substitution. The Hicks and Antonelli elasticities of complementarity are presented to examine separability of production (utility) and distance functions. Whereas the Allen elasticities of substitution are valid under homothetic separability, the Hicks elasticities of complementarity are a universally relevant measure of separability for the production (utility) function. Separability of meat commodities is tested using the Antonelli elasticities with the consumer's preferences specified with the distance function.
Research and Productivity in Mexican Agriculture
Authors: Fernandez‐Cornejo Jorge , Shumway C. Richard
Published: July 2006

Partial and total factor productivity (TFP) measures of Mexican agriculture are calculated for 1960–90. The long‐run effects of research and international transfer of technology on TFP are examined over the 1940‐90 period using cointegration procedures. TFP increased at an average annual rate of 2.5%, exceeding the corresponding growth in the United States (2.1%). TFP grew particularly fast in the 1960s and 1970s. A 1% rise in research investment increased TFP by 0.13%, and a 1% increase in U.S. TFP translated into a 1.11% increase in Mexican TFP. The average annual rate of return to research investment is about 64%.
State‐ and County‐Level Determinants of Food Manufacturing Establishment Growth: 1987–93
Authors: Goetz Stephan J.
Published: July 2006

Empirical models are developed and estimated to identify economic determinants of food manufacturing establishment growth between 1987 and 1993. Separate growth equations are estimated for states and counties at the three‐digit SIC level. Significant agglomeration diseconomies are found to exist for nearly all subindustries at the county level, but not at the state level. The ability of rural counties to attract food processors to create local employment opportunities and market outlets for farmers varies considerably across subindustries.
Intrinsic Fish Characteristics and Intraseason Production Efficiency: A Management‐Level Bioeconomic Analysis of a Commercial Fishery
Authors: Larkin Sherry L. , Sylvia Gilbert
Published: July 2006

Biological changes in Pacific whiting (Merluccius productus) and corresponding production yields were used to model a vertically integrated fishery from harvest through processing. The seasonal bioeconomic programming model incorporated stock dynamics with the interactive economic effects of intrinsic fish quality, the harvest schedule, and quota allocation between heterogeneous user groups. The optimal management plan would maximize discounted net industry revenues (NPV) given a minimum spawning biomass. NPV was maximized when the intraseason timing of harvest coincided with the seasonal improvement in fish quality (e.g., following spawning and/or migration). NPV was only marginally affected, however, by the quota allocation between groups.
The Structure of Wages and Benefits in the U.S. Pork Industry
Authors: Hurley Terrance M. , Kliebenstein James , Orazem Peter F.
Published: July 2006

Pork production has evolved from relatively small, family‐run operations toward large‐scale operations with several employees. Important questions about the structure of compensation in this rapidly changing labor market are answered using probit and ordered probit models and data from a national survey of pork producers and their employees. The results suggest (i) the structure of wages in pork production is consistent with more developed labor markets; (ii) employees earn a wage premium for using advanced technology and working in larger operations; and (iii) employees are willing to accept lower wages in exchange for better benefits and working conditions.
Examining Quantity and Quality Effects of Restricting Nitrogen Applications to Feedgrains
Authors: Atwood Joseph A. , Helmers Glenn A.
Published: July 2006

Restricting the timing and level of nitrogen applications has been proposed as a response to nitrate contamination in Nebraska. Agronomic research indicates that reducing available nitrogen reduces both the yield (quantity) and protein content (quality) of feedgrains. A differential system is developed to estimate the social costs of regulation while simultaneously considering both quantity and quality effects of a tax and/or a rationing policy. The results indicate that ignoring the quality effects of a proposed policy can lead to erroneous estimates of changes in factor use, output responses, and the social costs of regulation.
A Dynamic Economic Analysis of Nitrate Leaching in Corn Production under Nonuniform Irrigation Conditions
Authors: Vickner Steven S. , Hoag Dana L. , Frasier W. Marshall , Ascough James C.
Published: July 2006

We develop a dynamic economic model that includes control variables for both nitrogen fertilizer and irrigation water to analyze interseasonal corn production and nitrate leaching in the presence of irrigation system nonuniformity. The economic model is used to estimate profit‐maximizing nutrient management plans under varying levels of system uniformity. The model is also used to appraise several policy options that have been proposed in the nitrate leaching literature as a means of regulating water quality. Investments in technology are considered, as well as limits on nitrate leaching, nitrogen fertilizer, and irrigation water.
Political Action Committee Contributions and U.S. Congressional Voting on Sugar Legislation
Authors: Brooks Jonathan C. , Cameron A. Colin , Carter Colin A.
Published: July 2006

This study examines the simultaneous relationship between Political Action Committee (PAC) contributions and congressional votes on U.S. sugar legislation. We extend the conventional analysis by specifying a three‐equation system in which each congressman's vote depends on contributions received from pro‐sugar and anti‐sugar coalitions, while the propensity of each of these coalitions to contribute depends simultaneously on the congressman's anticipated voting decision and the contributions of the opposing coalition. Logrolling is also accommodated by considering the effect that contributions from other coalitions have had on voting decisions. We find evidence of a three‐way linkage between votes and competing campaign contributions and conclude that the effectiveness of PAC contributions reflects the dominance of political pressure over ideological concerns.
Knowledge Capital and Cost Structure in the U.S. Food and Fiber Industries
Authors: Morrison Catherine J. , Siegel Donald
Published: July 2006

We explore the existence and extent of scale economies arising from three different external “knowledge capital” factors—investments in R…D, high‐tech, and human capital. These relationships are evaluated for the (two‐ and three‐digit level) food and fiber processing industries from the 1960s through the 1980s. The results generate strong evidence of scale economies but also suggest that the three knowledge capital factors have tended to reduce input use (and thus costs) for all privately demanded factors. The impacts on private capital are particularly large, although human capital appears to have a relatively large impact on labor use in the textiles industry.
Determination of Focal Pricing Regions for U.S. Fed Cattle
Authors: Walburger Allan M. , Foster Kenneth A.
Published: July 2006

Concerns over the imperfect market structure of the beef sector arise due to potential price discovery impacts. This study presents an effective way of providing information on price discovery that can be used to indicate regions within which prices follow similar dynamics. A state space model was fit to fourteen years of weekly data on nineteen price series from U.S. fed cattle markets. Tight regional market price interrelationships were discovered indicating that, in general, prices cannot move independently in the long run. The dynamics of the system of prices revealed the existence of between five and seven focal price discovery regions.
Testing for Behavioral Objective and Aggregation Opportunities in U.S. Agricultural Data
Authors: Williams Shon P. , Shumway C. Richard
Published: July 2006

To guide formulation of an aggregate model of U.S. agricultural production, this paper reports nonparametric test results for both behavioral objective and aggregation level. Nonparametric tests are implemented as heuristics to determine empirical support for simplified analytical structures. Evidence does not refute the joint hypothesis that producers behave collectively as though they are a price‐taking, profit‐maximizing firm with a convex technology subject to nonregressive technical change. The empirical results also support exhaustive aggregation of input categories, but much less aggregation of outputs. This paper reports the first known implementation of the nonparametric homothetic separability tests.
Optimal Sizes of Farms under Varying Tenure Forms, Including Renting, Ownership, State, and Collective Structures
Authors: Heady Earl O.
Published: July 2006

Variants in tenure forms cause a range of optimal farm sizes in countries of various stages of economic development. Aside from capital restraints, however, modifications can be made in cost functions associated with each tenure form. The optimal use of inputs and farm size then is theoretically the same for individually operated farms. In the case of private, state, and cooperative farms, however, the same resolution is not possible in the short run. If the objective of the cooperative farm is maximum profit per member, this tenure form always has an optimal size smaller than a private or state farm.
The Team Approach and Extension Economics
Authors: Duft Ken D.
Published: July 2006

With the introduction of new Extension programs in such nontraditional areas as recreation, community resource development, environmental quality, etc., Extension economists will experience some loss of professional autonomy. Rarely will the resources required by these programs be found within the agricultural economics profession alone. This paper proposes that Extension economists adapt the team approach to their contemporary programs. More specifically, the Program Mission Organization is suggested as the interdisciplinary form of organization most applicable. The benefits and limitations of the team approach are then examined in light of a need for operational efficiency within and between all Extension economics programs.
A Simultaneous‐Equation Model of Spatial Equilibrium and Its Application to the Broiler Markets
Authors: Lee Tsoung‐Chao , Seaver Stanley K.
Published: July 2006

The simultaneous‐equation approach is used to formulate a positive spatial equilibrium model consisting of linear behavioral and definitional equations and bilinear equilibrium conditions. In contrast to the normative Takayama‐Judge quadratic spatial equilibrium model, the positive model leads to a smaller simplex tableau and permits evaluation of the effect of predetermined variables on spatial equilibrium. The model is applied to structural changes of broiler markets. Spatial equilibrium multipliers are presented to show the interregional competition of the existing broiler markets.
DECSERVIS: a tool for radioactive decay series visualisation
Authors: Azzam Saad , Suksi Juhani
Published: July 2006

We have developed an interactive visualisation tool, decay series visualisation (DECSERVIS), for exploring the three natural radioactive decay chains. Through DECSERVIS, one can investigate the full decay scheme of any natural decay chain radionuclide to obtain the number of nuclides, their masses, activities, and activity ratios, accounting for all the daughters, starting from initial conditions freely chosen by the user. The tool has been developed particularly for user friendly and flexible operation. Chain decay in closed systems can be explored as a function of time with various graphical presentations such as solid curve and column diagrams or animation. We present several exploration examples related to geological dating. DECSERVIS will be freely available on request.
Packing Modes in Some Mono‐ and Disubstituted Phenylpropiolic Acids: Repeated Occurrence of the Rare syn,anti Catemer
Authors: Das Dinabandhu , Desiraju Gautam R.
Published: July 2006

The catemer is an infinite one‐dimensional pattern formed by the carboxylic acid group in crystals, and is constituted with OH⋅⋅⋅O hydrogen bonds. The catemer is uncommon and may be contrasted with the ubiquitous carboxylic acid dimer, the favored mode of association of this functional group. Both catemers and dimers, however, have two OH⋅⋅⋅O hydrogen bonds for each carboxy group, so the reasons for the rarity of the catemer must lie elsewhere. In this paper, we describe a group of around 25 phenylpropiolic acids in which the catemer is the default packing mode. Exceptionally, the particular catemer that is found in this family is of the very rare syn,anti variety. We show that a necessary ingredient in catemer formation is a supportive CH⋅⋅⋅O hydrogen bond from a proximal CH group, which is located on the phenyl ring, ortho to the ethynyl group, and suitably activated by electron withdrawing substituents. When steric factors become noteworthy, alternative patterns are adopted, such as the syn,syn catemer and, in one case, a rare cisoid dimer. When electron‐donating groups, either through inductive effect such as methyl or through resonance such as halogens, are present on the phenyl ring, the dimer is formed in all but one case. Polymorphism seems not to be an issue in these carboxylic acids in that no compound would generally crystallize as both a dimer and a catemer. It may be concluded that a supporting interaction, in this case a CH⋅⋅⋅O hydrogen bond, is the essential condition for the formation of any carboxylic acid catemer. Catemers are so rare because it is difficult to set up this type of supporting interaction in most carboxylic acids.
Luminescent Molecular Copper(I) Alkynyl Open Cubes: Synthesis, Structural Characterization, Electronic Structure, Photophysics, and Photochemistry
Authors: Chan Chui‐Ling , Cheung Kai‐Leung , Lam Wai Han , Cheng Eddie Chung‐Chin , Zhu Nianyong , Choi Sam Wing‐Kin , Yam Vivian Wing‐Wah
Published: July 2006

A novel class of tetranuclear copper(I) alkynyl complexes with an “open‐cube” structure was synthesized. The crystal structure of [Cu4{P(p‐MeC6H4)3}4(μ3‐η1,η1,η2‐C≡C‐p‐MeOC6H4)3]PF6 was determined. These complexes were found to display dual emission behavior. Through systematic comparison studies on the electronic absorption and photoluminescence properties of a series of [Cu4(PR3)4(μ3‐η1,η1,η2‐C≡CR′)3]+ complexes, together with density functional theory (DFT) calculations at the PBE1PBE level on the model complex [Cu4(PH3)4(μ3‐η1,η1,η2‐C≡C‐p‐MeOC6H4)3]+, the nature of their emission origins was probed. Their photochemical properties were also investigated by oxidative quenching experiments and transient absorption spectroscopy.
3‐D QSAR Studies of Microtubule Stabilizing Antimitotic Agents Towards Six Cancer Cell Lines
Authors: Mohanraj Sumithra , Doble Mukesh
Published: July 2006

The antimitotic agent paclitaxel continues to play an important role in cancer chemotherapy. However, its inefficacy on certain resistant cells and toxic side effects had led to the search for new drugs with improved biological activity. Here the QSAR models for microtubule stabilizing anticancer agents were performed to correlate their physicochemical properties with biological activity. Single and multiple linear regression models for six cancer cell lines were obtained with R2≥0.65 and q$\rm{ {_{pre}^{2}}}$≥0.6. Molecular mechanics energy and log P of the molecules account for the activity of taxanes towards B16 melanoma and breast cancer cells, respectively. The lowest unoccupied molecular orbitals and the number of nitrogen atoms in the structure account for the biological activity of epothilone derivatives and rest of the drugs towards ovarian cells. The relation between the structural properties of microtubule stabilizing antimitotic compounds and their activities on different cell lines are investigated in this paper.
Nonlinear interactions between upper-hybrid and Alfvén modes in a magnetized plasma containing charged dust impurities
Authors: SHUKLA P. K. , STENFLO L.
Published: July 2006

We consider the nonlinear interactions between upper-hybrid (UH) and Alfvén modes in a magnetized electron–ion plasma containing a fraction of stationary charged dust grains. The interaction is governed by a pair of equations for the UH wave envelope including the relativistic electron mass increase and the density and compressional magnetic field fluctuations associated with the Alfvén modes that are, in turn, driven by the ponderomotive force of the UH waves. The coupled mode equations are then Fourier analyzed to obtain a new dispersion relation, which admits new classes of modulational instabilities. The existence of a cusp-shaped UH envelope soliton is also predicted. The result can have relevance to the electron acceleration by sharply localized UH waves in the dusty magnetosphere of Saturn.
RNA structural motifs: building blocks of a modular biomolecule
Authors: Hendrix Donna K. , Brenner Steven E. , Holbrook Stephen R.
Published: July 2006

1. Introduction 222

2. What is an RNA motif? 222

2.1 Sequence vs. structural motifs 222

2.2 RNA structural motifs 223

2.3 RNA structural elements vs. motifs 223

2.4 Specific recognition motifs 224

2.5 Tools for identifying and classifying elements and motifs 226

3. Types of RNA structural motifs 228

3.1 Helices 228

3.2 Hairpin loops 228

3.3 Internal loops 230

3.4 Junction loops/multiloops 230

3.5 Binding motifs 232

3.5.1 Metal binding 232

3.5.2 Natural and selected aptamers 234

3.6 Tertiary interactions 234

4. Future directions 236

5. Acknowledgments 239

6. References 239

RNAs are modular biomolecules, composed largely of conserved structural subunits, or motifs. These structural motifs comprise the secondary structure of RNA and are knit together via tertiary interactions into a compact, functional, three-dimensional structure and are to be distinguished from motifs defined by sequence or function. A relatively small number of structural motifs are found repeatedly in RNA hairpin and internal loops, and are observed to be composed of a limited number of common ‘structural elements’. In addition to secondary and tertiary structure motifs, there are functional motifs specific for certain biological roles and binding motifs that serve to complex metals or other ligands. Research is continuing into the identification and classification of RNA structural motifs and is being initiated to predict motifs from sequence, to trace their phylogenetic relationships and to use them as building blocks in RNA engineering.
Survival of meningococci outside of the host: implications for acquisition
Authors: SWAIN C. L. , MARTIN D. R.
Published: July 2006

Meningococci are regarded as being unlikely to survive outside of their human host although this has possibly been more assumed than demonstrated. Seven strains of meningococci were tested for their ability to survive on glass or plastic while retaining expression of their capsule and important outer membrane proteins. A known number of colony-forming units of each strain were dried onto glass and onto plastic and tested for viability over time. Survival on glass was significantly better than on plastic (P<0·0001). Isolates of the New Zealand epidemic strain, B:4:P1.7-2,4 survived better on glass than all other strains tested. Recovered isolates still expressed their capsules and outer membrane proteins. These findings raise the question of whether meningococci can be transferred from person to person via fomites contaminated with oropharyngeal secretions containing meningococci.
Types and typechecking for Communicating Quantum Processes
Authors: GAY SIMON J. , NAGARAJAN RAJAGOPAL
Published: July 2006

We define a language CQP (Communicating Quantum Processes) for modelling systems that combine quantum and classical communication and computation. CQP combines the communication primitives of the pi-calculus with primitives for measurement and transformation of the quantum state; in particular, quantum bits (qubits) can be transmitted from process to process along communication channels. CQP has a static type system, which classifies channels, distinguishes between quantum and classical data, and controls the use of quantum states. We formally define the syntax, operational semantics and type system of CQP, prove that the semantics preserves typing, and prove that typing guarantees that each qubit is owned by a unique process within a system. We also define a typechecking algorithm and prove that it is sound and complete with respect to the type system. We illustrate CQP by defining models of several quantum communication systems, and outline our plans for using CQP as the foundation for formal analysis and verification of combined quantum and classical systems.
A Situated Practice for (Re)Situating Selves: Trainee Counsellors and the Promise of Counselling
Authors: Bondi Liz
Published: July 2006

Geographies of care and welfare have neglected to consider a group of interrelated practices including counselling, psychotherapy, and psychoanalysis, which are found in many different settings within modern welfare systems. In a number of influential studies, these psychological therapies have been described as self-oriented, narcissistic, and intensely individualistic. However, these commentaries fail to consider the specificity of particular practices. Counselling, for example, is a situated practice, shaped by particular contexts and values. The views of people just beginning a counselling training programme can be read as describing the practice as a relational means to individualistic ends. However, analysis of their stories about themselves suggests more complex understandings of self as shaped and reshaped in relation to others and as illustrating the feminist concept of relational autonomy. Their accounts suggest that counselling offers the promise of a practice through which both practitioners' selves and clients' selves may be reshaped and resituated.
An Environmental Justice Analysis of British Air Quality
Authors: Mitchell Gordon , Dorling Danny
Published: July 2006

This paper presents the results of the first national study of air quality in Britain to consider the implications of its distribution across over ten thousand local communities in terms of potential environmental injustice. We consider the recent history of the environmental justice debate in Britain, Europe, and the USA and, in the light of this, estimate how one aspect of air pollution, nitrogen dioxide (NO2) levels, affects different population groups differentially across Britain. We also estimate the extent to which people living in each community in Britain contribute towards this pollution, with the aid of information on the characteristics of the vehicles they own. We find that, although community NO x emission and ambient NO2 concentration are strongly related, the communities that have access to fewest cars tend to suffer from the highest levels of air pollution, whereas those in which car ownership is greatest enjoy the cleanest air. Pollution is most concentrated in areas where young children and their parents are more likely to live and least concentrated in areas to which the elderly tend to migrate. Those communities that are most polluted and which also emit the least pollution tend to be amongst the poorest in Britain. There is therefore evidence of environmental injustice in the distribution and production of poor air quality in Britain. However, the spatial distribution of those who produce and receive most of that pollution have to be considered simultaneously to see this injustice clearly.
An opposite role for
tau
in circadian rhythms revealed by mathematical modeling
Authors: Gallego Monica , Eide Erik J. , Woolf Margaret F. , Virshup David M. , Forger Daniel B.
Published: July 2006

Biological clocks with a period of ≈24 h (circadian) exist in most organisms and time a variety of functions, including sleep–wake cycles, hormone release, bioluminescence, and core body temperature fluctuations. Much of our understanding of the clock mechanism comes from the identification of specific mutations that affect circadian behavior. A widely studied mutation in casein kinase I (CKI), the CKIε
tau
mutant, has been shown to cause a loss of kinase function
in vitro
, but it has been difficult to reconcile this loss of function with the current model of circadian clock function. Here we show that mathematical modeling predicts the opposite, that the kinase mutant CKIε
tau
increases kinase activity, and we verify this prediction experimentally. CKIε
tau
is a highly specific gain-of-function mutation that increases the
in vivo
phosphorylation and degradation of the circadian regulators PER1 and PER2. These findings experimentally validate a mathematical modeling approach to a complex biological function, clarify the role of CKI in the clock, and demonstrate that a specific mutation can be both a gain and a loss of function depending on the substrate.
COPII–Golgi protein interactions regulate COPII coat assembly and Golgi size
Authors: Guo Yusong , Linstedt Adam D.
Published: July 2006

Under experimental conditions, the Golgi apparatus can undergo de novo biogenesis from the endoplasmic reticulum (ER), involving a rapid phase of growth followed by a return to steady state, but the mechanisms that control growth are unknown. Quantification of coat protein complex (COP) II assembly revealed a dramatic up-regulation at exit sites driven by increased levels of Golgi proteins in the ER. Analysis in a permeabilized cell assay indicated that up-regulation of COPII assembly occurred in the absence GTP hydrolysis and any cytosolic factors other than the COPII prebudding complex Sar1p–Sec23p–Sec24p. Remarkably, acting via a direct interaction with Sar1p, increased expression of the Golgi enzyme N-acetylgalactosaminyl transferase-2 induced increased COPII assembly on the ER and an overall increase in the size of the Golgi apparatus. These results suggest that direct interactions between Golgi proteins exiting the ER and COPII components regulate ER exit, providing a variable exit rate mechanism that ensures homeostasis of the Golgi apparatus.
Hailing and boarding: the psychological impact of US coast guard boardings
Authors: Mueller G.O.W. , Adler Freda
Published: July 2006

Measures the impact of armed US Coast Guard boardings on those aboard boarded vessels. A sample of fifty subjects (half members of a graduate class on “Maritime Crime and its Prevention”, half others), completed questionnaires after experiencing a (pre‐arranged but undisclosed) interception and boarding by a US Coast Guard Cutter of the vessel on which they were traveling. Subjects reported satisfaction with the conduct of the boarding, but experienced different anxiety levels during the encounter, ranging from low levels (one third), medium levels (one third) to relatively high levels of anxiety. Boarding parties should be concerned with the latter group. Training and sensitivity to deal with that group needs to be emphasized.