bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heritability of Changes in Bone Size and Bone Mass With Age in Premenopausal White Sisters
Authors: Hui Siu L , Koller Daniel L , Foroud Tatiana M , Econs Michael J , Johnston C Conrad , Peacock Munro 
Published: July 2006

Abstract
Femoral neck area expands and BMD decreases in premenopausal women. We used longitudinal DXA measurements on 388 premenopausal white sisters to show significant heritability of the rates of change in femoral neck area, BMC, and BMD.
Introduction: Bone mass and structure are highly heritable. However, genetic effects on age-related changes in bone mass and structure in adults have been much less studied.
Materials and Methods: DXA measurements were made on 388 healthy white premenopausal sisters from 178 families. Rates of change in femoral neck area, BMC, and BMD, as well as body weight, were calculated from two measurements made an average of 5.7 years apart. Mixed models were used to test whether bone changes were related to age or weight change. Variance components models were used to estimate the heritability of the rates of change. A method was proposed to correct for the underestimation of heritabilities caused by measurement errors of the rates of change.
Results: Femoral neck area increased with age, whereas BMD decreased. All of the rates of change at the femoral neck were positively correlated with weight change, but the rates of femoral neck changes did not vary with age. Adjusted for weight change, change in femoral neck BMC became negative. Significant heritabilities (0.29–0.36) were detected for changes in femoral neck BMC, BMD, and area adjusted for weight changes. Correction for DXA measurement error in the rate estimates increased the heritability estimates (from 0.29–0.36 range to 0.37–0.64 range).
Conclusions: Rates of change are heritable for femoral neck area, BMC, and BMD in premenopausal white women.
Activation of Sirt1 Decreases Adipocyte Formation During Osteoblast Differentiation of Mesenchymal Stem Cells
Authors: Bäckesjö Carl-Magnus , Li Yan , Lindgren Urban , Haldosén Lars-Arne 
Published: July 2006

Abstract
In vitro, mesenchymal stem cells differentiate to osteoblasts when exposed to bone-inducing medium. However, adipocytes are also formed. We showed that activation of the nuclear protein deacetylase Sirt1 reduces adipocyte formation and promotes osteoblast differentiation.
Introduction: Mesenchymal stem cells (MSCs) can differentiate into osteoblasts, adipocytes, chondrocytes, and myoblasts. It has been suggested that a reciprocal relationship exists between the differentiation of MSCs into osteoblasts and adipocytes. Peroxisome proliferator-activated receptor γ2 (PPARγ2) is a key element for the differentiation into adipocytes. Activation of Sirt1 has recently been shown to decrease adipocyte development from preadipocytes through inhibition of PPARγ2.
Materials and Methods: We used the mouse mesenchymal cell line C3H10T1/2 and primary rat bone marrow cells cultured in osteoblast differentiation medium with or without reagents affecting Sirt1 activity. Adipocyte levels were analyzed by light microscopy and flow cytometry (FACS) after staining with Oil red O and Nile red, respectively. Osteoblast and adipocyte markers were studied with quantitative real-time PCR. Mineralization in cultures of primary rat bone marrow stromal cells was studied by von Kossa and alizarin red staining.
Results: We found that Sirt1 is expressed in the mesenchymal cell line C3H10T1/2. Treatment with the plant polyphenol resveratrol as well as isonicotinamide, both of which activate Sirt1, blocked adipocyte development and increased the expression of osteoblast markers. Nicotinamide, which inhibits Sirt1, increased adipocyte number and increased expression of adipocyte markers. Furthermore, activation of Sirt1 prevented the increase in adipocytes caused by the PPARγ-agonist troglitazone. Finally, activation of Sirt1 in rat primary bone marrow stromal cells increased expression of osteoblast markers and also mineralization.
Conclusions: In this study, we targeted Sirt1 to control adipocyte development during differentiation of MSCs into osteoblasts. The finding that resveratrol and isonicotinamide markedly inhibited adipocyte and promoted osteoblast differentiation may be relevant in the search for new treatment regimens of osteoporosis but also important for the evolving field of cell-based tissue engineering.
A Disaggregate Approach to Aggregate Supply
Authors: Herdt Robert W. 
Published: July 2006

AbstractAnalyses of aggregate supply response in low‐income countries are practically nonexistent because of the index number problems and the difficulty of accounting for the effect of weather inherent in aggregate approaches. The disaggregate model presented here includes variables measuring weather, external capital inputs and technology, as well as crop and input prices, in individual crop supply functions. A technique for combining the direct and cross elasticities into a single aggregate elasticity is given, and the results obtained using the technique are outlined.
Specifying the Allocation of Income among Taxes, Consumption, and Savings in Linear Programming Models
Authors: Vandeputte J. M. , Baker C. B. 
Published: July 2006

AbstractThe proper specification of tax liabilities and consumption behavior is a significant problem in designing models for studying firm growth. A specification is suggested to represent allocation of income between consumption and savings in multiperiod linear programming models, while accounting for the effects of income tax. It is proposed as a method that conserves row space while providing flexibility in representing actual tax liabilities and actual consumption behavior in terms relevant for the study of growth alternatives and constraints.
Monthly Supply‐Demand Relationships for Fed Cattle and Hogs
Authors: Hayenga Marvin L. , Hacklander Duane 
Published: July 2006

AbstractMonthly livestock supply, demand, and price variations reflect phenomena often not isolated in annual or quarterly time series analysis. A five‐equation model of cattle and hog monthly supply and demand behavior at the live market level was estimated via two‐stage least squares. Regular monthly demand fluctuations, income and population changes, and the slaughter supply per packer work day were found to affect cattle and hog prices. Marketing behavior by farmers was affected by feedlot inventories and the recent price change which apparently influenced their short‐run price expectations and subsequent marketing response.
Fish Cycles: A Harmonic Analysis
Authors: Waugh Frederick V. , Miller Morton M. 
Published: July 2006

AbstractThe landings and prices of many species of fish exhibit rather regular cyclical movements. The paper uses traditional methods of harmonic analysis to measure the lengths and amplitudes of landings and price cycles for cod, haddock, and blackback flounder landed at specific New England ports. Also discussed, briefly, is the periodicity of the total U. S. catch of all food fish. Findings demonstrate the occurrence of pronounced seasonal (12‐month) cycles, as well as cycles of several years' duration. The authors stress the value of cyclical analysis as a forecasting device and as an aid to understanding the nature of demand for fishery products.
A Model of Competitive Behavior in Food Industries
Authors: Handy C. R. , Padberg D. I. 
Published: July 2006

AbstractWhile conventional industrial organization theory has been used to explain behavior of the food distribution oligopoly, a more careful analysis shows its behavior tendencies to be basically different from the manufacturing oligopoly. The larger distribution firm tends toward price competition while the smaller tends toward nonprice competition. The interaction between manufacturing and distribution oligopolies in the food industry provides a unique balance between progressiveness and economy which is not available in industries where the distribution oligopoly has not developed. This different consequence of large firms brings up some basic questions about antitrust objectives and philosophy.
Computing Equilibrium Solutions for Imperfectly Competitive Markets
Authors: Plessner Yakir 
Published: July 2006

AbstractIn most theoretical as well as empirical studies the conditions of free competition are assumed, and thus conclusions are subject to competitive behavior. In the real world, however, noncompetitive structures are quite common and deserve not less but, from several viewpoints, more attention than competitive ones. Assuming a linear demand system and constant returns to scale and using quadratic programming, it is shown how partial market equilibria for various leading firm and monopolistic structures can be computed. The operational usefulness of such computations is demonstrated via an application to an agricultural industry.
Price Elasticities from Panel Data: Meat, Poultry, and Fish
Authors: Purcell Joseph C. , Raunikar Robert 
Published: July 2006

AbstractNational aggregate time series data are not amenable to tracing the consumer response to price changes as these changes occur in the market. This paper is designed to stimulate interest in the development of alternative sources of data and modification in estimating procedures to more nearly approach reality in estimating price‐quantity relationships. The analysis was based on data obtained from a group of consuming units on quantities of meats purchased and prices paid. The procedure was designed to trace the consumer response to price changes approximately as they occurred over time.
Reservation Prices on Credit Use: A Measure of Response to Uncertainty
Authors: Barry Peter J. , Baker C. B. 
Published: July 2006

AbstractLiquidity in the form of reserved credit is valuable to a business manager because it is available to counter uncertain expectations. This paper investigates the definition and method of estimating values or reservation prices associated with firm liquidity provided by unused credit. A multiperiod linear programming model is taken to reflect the behavior of decision makers in empirically observed situations. Credit reservation prices of decision makers were inferred by comparing growth information for real borrowers with growth information generated by the comparable model at alternative reservation prices. This method succeeded in associating a high credit reservation price with the conservative borrower and low credit reservation prices with a more liberal borrower.
Application of an Economic Model for Evaluating Government Program Costs for Rice
Authors: Grant Warren R. 
Published: July 2006

AbstractAlternative Government rice programs are important to rice producers, rice consumers, rice related industries, and Government (taxpayers). Supporting the rice producer's income above that determined by a “free market” requires an income transfer from another segment of society. The “best method” of support could depend upon the “best source” of income to transfer to the rice farm sector. The direct payment plan transfers income from the taxpayer, the two‐price plan draws additional support from the domestic rice consumer, and the current program (an adaptation of a two‐price plan) obtains the additional income for transfer from both.
A Decision Theoretic Approach to Crop Disease Prediction and Control
Authors: Carlson Gerald A. 
Published: July 2006

AbstractThe pesticide application practices of California peach growers in controlling peach brown‐rot are used to demonstrate how Bayesian decision theory procedures can be used to arrive at optimal crop disease control practices. Subjective probabilities of disease loss intensity are measured and used in the decision model. Information from an analyst (this researcher) is combined with farmers' subjective probabilities of disease loss by means of Bayes' theorem. Optimal pesticide use actions are computed for three different objective functions—maximum subjective expected returns, mean‐standard deviation of returns, and maximum expected returns with a minimum income side condition.
Forecasting Wheat Yields: An Application of Parametric Time Series Modeling
Authors: Schmitz Andrew , Watts Donald G. 
Published: July 2006

AbstractThe purpose of this paper is to use a recent development in statisical theory known as parametric modeling to forecast wheat yields in the United States, Canada, Australia, and Argentina. The essence of this approach is that the data are used for identifying and estimating random components in the form of moving average and autoregressive processes. It does not identify and measure structural relationships as is attempted when forecasting with econometric models. Exponential smoothing is also used to forecast yields in the United States and Canada. The Thiel coefficient is then computed to determine the forecasting accuracy of parametric modeling compared with exponential smoothing.
Farm Operators Under the Negative Income Tax
Authors: Meyer Charles W. , Saupe William E. 
Published: July 2006

AbstractIncome maintenance programs such as the negative income tax have been extensively discussed, but thus far little has been written about their impact on farm operators. This paper focuses on the effects of alternative definitions of income, including imputed returns to assets, on the accounting practices of farmers, and on the eligibility of farm families for payments. The influence of income maintenance on decision making of farm operators is analyzed, and attention is called to the need for further study of the consequences of major welfare reforms on the farm economy.
Price Signal Refraction in Pork Processing
Authors: Ikerd John E. , Cramer Charles L. 
Published: July 2006

AbstractA method of measuring pricing efficiency in objective, quantitative terms is presented. “Evaluation of pricing efficiency” has long been the terminology used in studies of pricing accuracy. The term “price signal refraction” as used here refers to the more specific, quantifiable, and testable concept dealt with in this article. The distortion of price signals passing through one or more levels of the market is analogous to the refraction of light rays. This study evaluated price refraction at one level of the pork market. Regression models were fitted to the individual carcass data from a sample of 300 carcasses. The data were subjected to objective statistical test. The findings indicated that price refraction attributable to weight was small and insignificant but refraction attributable to backfat was large and significant.
U.S. Import Demand for Green Coffee by Variety
Authors: Abaelu John Nduka , Manderscheid Lester V. 
Published: July 2006

AbstractTotal United States imports of green coffees were divided into three principal components: milds, brazils, and robustas. The aim was to clarify the demand relationships among the major coffee varieties traded internationally and the factors influencing coffee prices by variety. A nine‐equation model of the U. S. coffee market was constructed, consisting of import‐demand, export‐supply, and stock‐demand functions describing the structural mechanisms underlying the market for each of the three coffee varieties. Estimates of structural parameters were obtained by different estimation methods, but only three‐stage least‐squares results are reported in this article. Parameter estimates suggest that milds (the premium coffee variety) are normal economic goods, whereas brazils and robustas are inferior goods with respect to the U. S. economy. Income flexibility estimates at the mean were 0.39, −0.89, and −1.82, respectively, for milds, brazils, and robustas. Estimated price flexibilities at the mean were, for the three coffee varieties in the same order, −0.18, −0.21, and −0.36. These figures suggest that demand for individual coffee varieties is reasonably price‐elastic.
“Subsistence Agriculture”: Analytical Problems and Alternative Concepts
Authors: Miracle Marvin P. 
Published: July 2006

AbstractThis article argues that the concept of “subsistence agriculture”—widely encountered and long used in the literature—is not meaningful enough to be analytically useful as usually employed and should be abandoned. Particularly important for policy is the fact that use of the term “subsistence agriculture” leads to implicitly treating all small‐scale agriculture as a homogeneous residual made up of producers who vary little in their potential contribution to economic development. Data are presented which strongly suggest that small‐scale agriculture in less‐developed countries is not homogeneous so far as decision‐making situations are concerned. The second half of the article considers development of an alternative set of criteria for classifying small‐scale farmers that would reflect meaningful differences in decision‐making experience and decision‐making situations. A tentative set of such criteria for which data are now available, or could be developed with relative ease, are presented to illustrate the relevance of such a classification for development planning and policy.
Projecting the Size Distribution of Agricultural Firms—An Application of a Markov Process with Non‐Stationary Transition Probabilities
Authors: Hallberg M. C. 
Published: July 2006

AbstractThe first‐order Markov chain model is frequently used to project the future size distribution of firms in a particular industry. This model, however, is based on the rather restrictive assumption that the transition probabilities remain constant over time. This assumption was found to be inappropriate in the case of plants manufacturing frozen milk products in Pennsylvania during the period 1944–1963 and, if adopted, could lead to erroneous results as some actual predictions indicated. This article suggests a method, based on multiple regression techniques, of replacing the constant transition probabilities with probabilities which are a function of various factors including structural characteristics in the industry. The results of this procedure compared quite favorably with those of the assumption of constant probabilities.
Capitalized Values of Tobacco Allotments and the Rate of Return to Allotment Owners
Authors: Seagraves James A. 
Published: July 2006

AbstractTobacco allotments have been salable only along with the farms to which they are attached. Multiple regression allows one to isolate that part of total land value accounted for by allotments. Capitalized values of flue‐cured tobacco allotments were estimated for the period 1934–62. The ratio of annual earnings to these capitalized values, or the rate of return, fell from about .75 in the years 1944–46, when the program was first really effective, to a level of .16 for the period 1957–62. This decline reflects a dramatic increase in investor confidence in the future of the tobacco program and places tobacco allotments, which are widely thought to be highly profitable as monopoly rights go, in a class of relatively riskless investments. Government programs that reduce the risk of farm ownership are bound to increase the value of the assets and thereby reduce the rate of return. The rate of return allows us to predict the fall in capitalized value that will accompany future changes in expected income.
On Scientific Objectivity
Authors: Castle Emery N. 
Published: July 2006

AbstractThe research process is never devoid of value judgments. Nevertheless, motivation of the researcher does not necessarily render work unobjective in a scientific sense. Threats to scientific objectivity include the difficulty of changing a publicly expressed viewpoint, a vested interest in a particular theory, the desire to avoid controversy, and the desire for financial gain. The researcher must be careful, however, to avoid equating his own views with the “public interest” and condemning those with opposing views as lacking scientific objectivity.
Reflections on the Organization of Regional Research Activities
Authors: Harris Marshall , Hildreth R. J. 
Published: July 2006

AbstractRegional research in economics under the Research and Marketing Act of 1946 is at a crossroad. If certain organizational problems are not resolved, commitments by administrators and reseachers to regional research will continue to decline. The habits of thought of administrators, inherent weaknesses in the committee setup, and experience with focusing research on state and local problems made it easy to plan and conduct “regional” research with little regard to regional problems and team effort. Regional research should extend a warm welcome under an inspiring environment to well‐qualified researchers. Suggestions for improvement of regional research include: (1) experimentation with programs of regional research in contrast to a series of narrowly defined, uncoordinated, short‐term projects; (2) the appointment in some cases of regional coordinators to effectuate the policies and plans of regional committees; (3) the establishment of regional research centers with small staffs for certain types of projects; and (4) more flexibility in size and composition of regional committees.
The Lockset Method of Sequential Programming Applied to Routing Delivery and Pickup Trucks
Authors: Schruben Leonard W. , Clifton Ruth E. 
Published: July 2006

AbstractThe lockset method of sequential programming was used in this study to route feed delivery trucks and indicated potential distance savings of as much as 20 percent in comparison to the actual routes used by the business concerns. It was also found that in some cases the number of trucks required to make the deliveries could have been reduced from the number actually used, without changing the day of delivery. Feed manufacturing firms from New England to California supplied information on actual deliveries. An ex post routing of the same trucks to deliver the same quantities to the same receivers was made and the distance and number of trucks needed were compared with the distance and number of trucks actually used. Typical distance reductions were from 8 percent to 12 percent. In no case did the actual routing show fewer miles than the routes discovered by use of the lockset method. The system is computerized to enable a dispatcher to design delivery routes and issue loading instructions for each truck as soon as orders for a given day are known.
Toward Effective Standardization of Hams
Authors: Kendrick J. G. , Hassler J. B. 
Published: July 2006

AbstractOrderly marketing requires standardized products. Current USDA inspection criteria prevent the packer from completely standardizing cured hams on the basis of protein and moisture content. It is argued that changes in the current cured meat inspection procedures might result in (1) a more standardized product for consumers and (2) more accurate price signals for farmers, which could increase the reward to those swine producers whose product is of high quality. If the inspection criteria were changed so that cured hams could be standardized on the basis of a moisture‐protein ratio of 3.79∶1, a simultaneous equation model indicates that the gross live‐weight price differential between swine producing high‐protein hams and those producing low‐protein hams could widen to $2.42 per hundredweight.
Price Elasticity of the Demand for Cigarettes in the United States
Authors: Lyon Herbert L. , Simon Julian L. 
Published: July 2006

AbstractThe retail price elasticity of demand for cigarettes is a particularly important parameter for social decisions at this time. Results from prior cigarette elasticity studies vary widely, ranging from −0.10 to −1.48. Temporal changes may explain some of this variation, but differences in research methods are more important. The quasi‐experimental approach used in this article yields an elasticity estimate (−0.511) free of many of the extraneous and irrelevant systematic influences that afflict time‐series and cross‐section methods. In addition, the length of run of the elasticity is known and explicit. The method provides built‐in protections against bias from trends in collinear variables and produces sensible estimates with reasonably small and measurable dispersion.