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Objective To evaluate breast density notification legislation (BDNL) on breast imaging practice patterns, risk assessment, and supplemental screening. Methods A 20-question anonymous web-based survey was administered to practicing Society of Breast Imaging radiologists in the U.S. between February and April 2021 regarding breast cancer risk assessment, supplemental screening, and density measurements. Results were compared between facilities with and without BDNL using the two-sided Fisher’s exact test. Results One hundred and ninety-seven radiologists from 41 U.S. states, with (187/197, 95%) or without (10/197, 5%) BDNL, responded. Fifty-seven percent (113/197) performed breast cancer risk assessment, and 93% (183/197) offered supplemental screening for women with dense breasts. Between facilities with or without BDNL, there was no significant difference in whether risk assessment was (P = 0.19) or was not performed (P = 0.20). There was no significant difference in supplemental screening types (P > 0.05) between BDNL and non-BDNL facilities. Thirty-five percent (69/197) of facilities offered no supplemental screening studies, and 25% (49/197) had no future plans to offer supplemental screening. A statistically significant greater proportion of non-BDNL facilities offered no supplemental screening (P < 0.03) and had no plans to offer supplemental screening compared to BDNL facilities (P < 0.02). Conclusion Facilities in BDNL states often offer supplemental screening compared to facilities in non-BDNL states. Compared to BDNL facilities, a statistically significant proportion of non-BDNL facilities had no supplemental screening nor plans for implementation. Our data suggest that upcoming federal BDNL will impact how supplemental screening is addressed in currently non-BDNL states.

Breast density is an accepted independent risk factor for the future development of breast cancer, and greater breast density has the potential to mask malignancies on mammography, thus lowering the sensitivity of screening mammography. The risk associated with dense breast tissue has been shown to be modifiable with changes in breast density. Numerous studies have sought to identify factors that influence breast density, including age, genetic, racial/ethnic, prepubertal, adolescent, lifestyle, environmental, hormonal, and reproductive history factors. Qualitative, semiquantitative, and quantitative methods of breast density assessment have been developed, but to date there is no consensus assessment method or reference standard for breast density. Breast density has been incorporated into breast cancer risk models, and there is growing consciousness of the clinical implications of dense breast tissue in both the medical community and public arena. Efforts to improve breast cancer screening sensitivity for women with dense breasts have led to increased attention to supplemental screening methods in recent years, prompting the American College of Radiology to publish Appropriateness Criteria for supplemental screening based on breast density.

Purpose of Review To present recent literature regarding the assessment and clinical implications of background parenchymal enhancement on breast MRI. Recent Findings The qualitative assessment of BPE remains variable within the literature, as well as in clinical practice. Several different quantitative approaches have been investigated in recent years, most commonly region of interest-based and segmentation-based assessments. However, quantitative assessment has not become standard in clinical practice to date. Numerous studies have demonstrated a clear association between higher BPE and future breast cancer risk. While higher BPE does not appear to significantly impact cancer detection, it may result in a higher abnormal interpretation rate. BPE is also likely a marker of pathologic complete response after neoadjuvant chemotherapy, with decreases in BPE during and after neoadjuvant chemotherapy correlated with pCR. In contrast, pre-treatment BPE does not appear to be predictive of pCR. The association between BPE and prognosis is less clear, with heterogeneous results in the literature. Summary Assessment of BPE continues to evolve, with heterogeneity in approaches to both qualitative and quantitative assessment. The level of BPE has important clinical implications, with associations with future breast cancer risk and treatment response. BPE may also be an imaging marker of prognosis, but future research is needed on this topic.

Objective To determine the impact of the COVID-19 pandemic on breast imaging education. Methods A 22-item survey addressing four themes during the early pandemic (time on service, structured education, clinical training, future plans) was emailed to Society of Breast Imaging members and members-in-training in July 2020. Responses were compared using McNemar’s and Mann-Whitney U tests; a general linear model was used for multivariate analysis. Results Of 136 responses (136/2824, 4.8%), 96 U.S. responses from radiologists with trainees, residents, and fellows were included. Clinical exposure declined during the early pandemic, with almost no medical students on service (66/67, 99%) and fewer clinical days for residents (78/89, 88%) and fellows (48/68, 71%). Conferences shifted to remote live format (57/78, 73%), with some canceled (15/78, 19%). Compared to pre-pandemic, resident diagnostic (75/78, 96% vs 26/78, 33%) (P < 0.001) and procedural (73/78, 94% vs 21/78, 27%) (P < 0.001) participation fell, as did fellow diagnostic (60/61, 98% vs 47/61, 77%) (P = 0.001) and procedural (60/61, 98% vs 43/61, 70%) (P < 0.001) participation. Most thought that the pandemic negatively influenced resident and fellow screening (64/77, 83% and 43/60, 72%, respectively), diagnostic (66/77, 86% and 37/60, 62%), and procedural (71/77, 92% and 37/61, 61%) education. However, a majority thought that decreased time on service (36/67, 54%) and patient contact (46/79, 58%) would not change residents’ pursuit of a breast imaging fellowship. Conclusion The pandemic has had a largely negative impact on breast imaging education, with reduction in exposure to all aspects of breast imaging. However, this may not affect career decisions.

Objective To determine the early impact of the COVID-19 pandemic on breast imaging centers in California and Texas and compare regional differences. Methods An 11-item survey was emailed to American College of Radiology accredited breast imaging facilities in California and Texas in August 2020. A question subset addressed March–April government restrictions on elective services (“during the shutdown” and “after reopening”). Comparisons were made between states with chi-square and Fisher’s tests, and timeframes with McNemar’s and paired t-tests. Results There were 54 respondents (54/240, 23%, 26 California, 28 Texas). Imaging volumes fell during the shutdown and remained below pre-pandemic levels after reopening, with reduction in screening greatest (ultrasound 12% of baseline, mammography 13%, MRI 23%), followed by diagnostic MRI (43%), procedures (44%), and diagnostics (45%). California reported higher volumes during the shutdown (procedures, MRI) and after reopening (diagnostics, procedures, MRI) versus Texas (P = 0.001–0.02). Most screened patients (52/54, 96% symptoms and 42/54, 78% temperatures), and 100% (53/53) modified check-in and check-out. Reading rooms or physician work were altered for social distancing (31/54, 57%). Physician mask (45/48, 94%), gown (15/48, 31%), eyewear (22/48, 46%), and face shield (22/48, 46%) use during procedures increased after reopening versus pre-pandemic (P Conclusion Breast imaging volumes during the early pandemic fell more severely in Texas than in California. Safety measures and financial impacts on physicians and staff were similar in both states.

Statement of problem Bonded porcelain veneers are widely used esthetic restorations. High success and survival rates have been reported, but failures do occur. Fractures are the commonest failure mode. Minimally invasive or thin veneers have gained popularity. Increased enamel and porcelain thickness improve the strength of veneers bonded to enamel, but less is known about dentin or mixed substrates. Purpose The purpose of this in vitro study was to measure the influences of tooth substrate type (all-enamel, all-dentin, or half-dentin-half-enamel) and veneer thickness on the loads needed to cause initial and catastrophic porcelain veneer failure. Material and methods Model discoid porcelain veneer specimens of varying thicknesses were bonded to the flattened facial surfaces of incisors with different enamel and dentin tooth substrates, artificially aged, and loaded to failure with a small sphere. Initial and catastrophic fracture events were identified and analyzed statistically and fractographically. Results Fracture events included initial Hertzian cracks, intermediate radial cracks, and catastrophic gross failure. All specimens retained some porcelain after catastrophic failure. Cement failure occurred at the cement–porcelain interface not at the cement–tooth interface. Porcelain veneers bonded to enamel were substantially stronger and more damage-tolerant than those bonded to dentin or mixed substrates. Increased porcelain thickness substantially raised the loads to catastrophic failure on enamel substrates but only moderately raised the loads to catastrophic failure on dentin or mixed substrates. The veneers bonded to half-dentin-half-enamel behaved remarkably like those bonded wholly to dentin. Conclusions Porcelain veneers bonded to enamel were substantially stronger and more damage-tolerant than those bonded to dentin or half-enamel-half dentin.

Congenital pseudoarthrosis of the clavicle is a rare entity that can be confused for a traumatic injury. We present 4 cases of congenital clavicular pseudoarthrosis and discuss its imaging findings that can help differentiate it from the more common clavicular facture. We also reviewed its epidemiology, embryology, and management based on available and most recent literature.

The purpose of this study was to determine the incidence of occult obstructing malignancy in the setting of asymptomatic biliary ductal dilatation incidentally detected and without identifiable cause on contrast-enhanced CT. A retrospective search identified patients with biliary ductal dilatation on contrast-enhanced CT from March 30, 2007 to November 1, 2017. Patients with biliary symptomatology or clinical concern for an obstructing process, an explanation for biliary ductal dilatation on index CT, intrahepatic without extrahepatic biliary ductal dilatation, concurrent pancreatic ductal dilatation, and inadequate follow-up were excluded. A reference standard of at least 1 year of imaging follow-up or 2 years of clinical follow-up was used to exclude occult obstructing malignancy. 156 patients were included; 120 patients met imaging follow-up criteria and 36 patients met clinical follow-up criteria. No cases of occult malignancy were identified as the source of biliary ductal dilatation (95% CI 0.0–1.9%). LFTs were available for 131 patients, of which 36 were elevated (27%). One case demonstrated a 1.2-cm ampullary adenoma on endoscopic retrograde cholangiopancreatography (occult on follow-up MRI, normal LFTs at the time of the index CT). Asymptomatic biliary ductal dilatation incidentally detected and without identifiable cause on contrast-enhanced CT is likely benign in patients with normal LFTs, and further workup may not be warranted.

Transport costs and product quality have received increased attention in the international trade literature. Product quality is a particularly important factor in international trade of high-valued commodities. We observe that significant transport costs for a relatively high quality product represent a natural trade barrier. In this case, transport costs may introduce product differentiation, protecting home-country production of the higher quality product and constraining the foreign exporter to shipping a lower quality substitute. With differential transport costs between a higher and a lower quality product, firms in both countries may gain by implicitly coordinating in an increasingly segmented market and choosing a high-price strategy for both products. Home-country producers clearly gain. Through product differentiation in an oligopolistic market, the foreign producers may also gain when the home producers exploit the transport cost advantage. The international orange juice market, with significant trade volumes in both lower quality frozen-concentrated juice and higher quality not-from-concentrate juice, provides compelling evidence supporting this model.

The purpose of this study was to determine the rate of malignancy in incidentally detected bilateral adrenal masses in patients with no known history of cancer.A retrospective search of CT reports of patients with incidentally detected bilateral adrenal nodules was performed from January 1, 2002, to January 1, 2014. Patients were excluded if they had a known cancer or suspected functioning adrenal tumor; 161 patients were included. Nodules were characterized as benign or malignant on the basis of imaging features at the index CT examination, imaging features at subsequent adrenal protocol CT or MRI, imaging stability for a minimum of 1 year, or clinical follow-up of a minimum of 2 years.Mean nodule size was 1.8 cm (range, 0.7-4.9 cm). There were no cases of primary or secondary adrenal malignancy (95% CI, 0.00-0.023). The nodules diagnosed on index CT scans were 73 adrenal adenomas and two myelolipomas. Seventy-four nodules were subsequently characterized as adrenal adenomas on the basis of imaging findings. Of the 113 indeterminate nodules that had imaging follow-up, 111 were stable at the latest follow-up examination. One nodule grew 26% over 8.1 years, and the other grew 59% over 12.4 years. Clinical follow-up of patients with 60 indeterminate nodules revealed no evidence of adrenal malignancy.No case of malignancy was found in 322 incidentally detected bilateral adrenal nodules at CT of patients without known cancer. Imaging follow-up of such lesions may be unnecessary.

Author(s): Xu, Y; Goodhue, RE; Chalfant, JA; Miller, T; Fennimore, SA | Abstract: One challenge of conducting research regarding agricultural production systems is that field trials are time consuming and expensive, limiting their scale and scope. Thus, policymakers and producers benefit from researchers extracting as much information as possible from each trial. We used the Monte Carlo techniques and the sensitivity analyses to enhance our analysis of the competitiveness of steam as an alternative to fumigation for preplant soil disinfestation in California strawberry production. Chloropicrin + 1,3-dichloropropene 59.6:39 (CP + 1,3-D) resulted in higher mean net returns than did steam. However, the Monte Carlo analysis showed that in one field trial there was a high probability that steam would be more profitable, whereas in the other it was quite unlikely. We also assessed the change in economic performance of steam when it was applied combined with soil amendments of mustard seed meal (MSM). Switching from steam to steam +MSMwould have reduced mean net returns. The Monte Carlo results showed that steam +MSMperformed at least as well as steam alone around half the time. We evaluated factors that were likely to affect the net returns, defined as total returns minus treatment, weeding, and harvest labor costs, of using steam in the near future. Reductions in application time increased net returns. A decrease in the price of propane increased net returns.

The objective of our study was to characterize enhancement of muscle and bone that occurs on standardized four-phase contrast-enhanced CT.Two musculoskeletal radiologists reviewed standardized four-phase abdominal CT scans obtained with IV contrast material. The psoas area was measured, and the mean attenuation (in Hounsfield units) was recorded for the aorta, psoas muscles, posterior paraspinal muscles, and L4 vertebral body. CT attenuation measures were compared between anatomic regions and imaging phases with the paired t test; associations between measures were examined with the Pearson correlation coefficient (R).The study included 201 patients (97 men, 104 women; mean age, 57.7 ± 12.5 [SD] years). Subject age was inversely correlated with unenhanced attenuation in the psoas muscles, posterior paraspinal muscles, and L4 (p0.001). The psoas muscles, posterior paraspinal muscles, and L4 enhanced significantly (p0.001) at all three contrast-enhanced phases. The greatest muscle enhancement was observed on delayed phase scans, whereas the greatest enhancement in L4 was seen on portal phase imaging. The unenhanced attenuation of the psoas muscles was significantly and negatively correlated with enhancement of the psoas muscles at the portal and delayed phases (p0.05 and p0.01, respectively), but these correlations were not seen for the posterior paraspinal muscles. Age was positively correlated with posterior paraspinal muscle enhancement at the portal and delayed phases in men (p0.05 and p0.01, respectively) but not in women.Contrast enhancement of commonly measured muscle and bone regions is routinely observed and should be considered when using CT attenuation values as biomarkers of sarcopenia and osteoporosis. Furthermore, CT enhancement may be significantly influenced by age, sex, and unenhanced tissue attenuation.

Increasingly, agricultural markets are vertically coordinated. Often a thinning spot market coexists with coordinated transactions, raising the question of how private coordination affects the market as a whole. One of the greatest challenges when analyzing such market-level effects is obtaining information on private transactions. We utilize publicly available data to evaluate how informal contracts in the fresh strawberry market affect spot market prices using a generalized autoregressive conditional heteroskedastic in mean (GARCH-M) model. We find that these informal contracts increased spot prices, as argued by some industry members, while the effect on spot price volatility varied by production region. Copyright 2010, Oxford University Press.

California strawberry production accounts for 18% of total methyl bromide use in U.S. agriculture. Under the Montreal Protocol, methyl bromide was slated to be banned in the United States in 2005. A critical use exemption was obtained for U.S. agriculture for 2005 and 2006, but the phaseout of methyl bromide continues. We examine the ban's effects on the California strawberry industry, and on individual production regions in the state. Under the most likely scenario, industry revenue will decline by 6–17% due to the ban. The effects will differ by region, due to seasonal differences in demand and production, and the possibility of increased foreign competition. Copyright 2005, Oxford University Press.

In spite of the proliferation of flexible functional forms for consumer demand systems, the double-log demand model continues to be popular, especially in applied work calling for single-equation models. It is usually estimated in uncompensated form. It can also be estimated in compensated form, by deflating the income variable alone using Stone's price index. The compensated form has the same right-hand side as a single-equation version of the popular linear approximation to the Almost Ideal demand model, facilitating the construction of a test for choosing between the two alternatives. This paper demonstrates these results, develops the specification test, and illustrates its application using US meat consumption data. Simulations suggest that the test is well-behaved with good power in typical applications.

Some marketing orders allow an agricultural industry to regulate the flow of product to market. We examine a more common, but less controversial, aspect of marketing orders, the setting and enforcement of grades, and show that purposefully introducing error into the grading process reduces farmers' incentives to produce high-quality product, thus partially sustaining the adverse selection problem that would exist in the absence of grades. Because demand for high-quality product is generally inelastic relative to demand for low-quality product, grading error can increase industry profit. In principle, an industry can achieve through grading error the same allocation of product between high- and low-quality outlets as attainable through direct volume regulation. Copyright 2002, Oxford University Press.

Grading is important to ensure the production of high-quality foods, but it is usually done with error, distorting market signals and diminishing incentives to produce high-quality products. Size is the main quality criterion for dried prunes and the crucial characteristic in determining prune value. We studied the economic effects of errors in commodity grading, focusing in particular on the implications of one-way (asymmetric) grading errors, namely when small, low-quality product is erroneously classified as high quality, but not vice versa. In an application to the California prune industry, we estimated the extent to which large prunes are undervalued and small prunes are overvalued. We conclude that grading error means that prunes graded as high-quality may not really be high-quality prunes. The presence of these incorrectly graded prunes depresses the prices that growers are paid for high-quality prunes and increases the net returns for small prunes. As a result, growers face reduced incentives to produce larger prunes.

Generic advertising is important and controversial. In 1990, commodity organizations in the United States spent over $300 million on advertising (Lenz, Forker, and Hurst). The controversy over generic advertising is reflected in recent court cases, such as the 1996 Wileman case heard before the U.S. Supreme Court. Controversy over generic advertising also exists within the agricultural economics profession. A wide range of results can be found in past studies, partly because of different data sets and commodities, but also because of particular modeling choices. In this paper, we discuss some issues in studies of the demand

This article evaluates an industry-funded nutrition education program, Exercise Your Options, provided to junior high school children in California by the Dairy Council of California (DCC). The program consists of education materials provided to teachers to assist in teaching about nutritional topics. We make use of food records from before and after the program, along with records from a control group, to estimate the effects on consumption patterns of learning about nutrition. DCC's activities are funded through a per-unit assessment on California milk, making the returns to producers an interesting topic in light of recent controversy over marketing orders. This article compares the benefits to the dairy industry to the cost of the program to the dairy industry. Under a number of reasonable assumptions, the benefits to dairy producers from increased milk consumption outweigh the costs of the program. [Econ-Lit citations: D120, I120, Q130, Q180] © 1999 John Wiley & Sons, Inc.

The nonparametric approach to production or demand analysis involves testing data for compatibility with restrictions from theory. This avoids reliance on particular functional forms. When the data are not consistent with utility or profit maximization, adjustments in the data using linear programming can restore consistency. Such adjustments have been interpreted as taste changes or measures of technical change and technical change bias. This paper describes nonparametric approaches and shows that the programming methods that have been used yield results that are not invariant to the scaling of prices and quantities. A solution is proposed that solves the invariance problem. Copyright 1997, Oxford University Press.

Stable URL:http://links.jstor.org/sici?sici=0002-9092%28199605%2978%3A2%3C268%3ADRTAIT%3E2.0.CO%3B2-OAmerican Journal of Agricultural Economics is currently published by American Agricultural Economics Association.Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available athttp://www.jstor.org/about/terms.html. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtainedprior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content inthe JSTOR archive only for your personal, non-commercial use.Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained athttp://www.jstor.org/journals/aaea.html.Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printedpage of such transmission.The JSTOR Archive is a trusted digital repository providing for long-term preservation and access to leading academicjournals and scholarly literature from around the world. The Archive is supported by libraries, scholarly societies, publishers,and foundations. It is an initiative of JSTOR, a not-for-profit organization with a mission to help the scholarly community takeadvantage of advances in technology. For more information regarding JSTOR, please contact support@jstor.org.http://www.jstor.orgFri Feb 22 18:04:31 2008

The effects of advertising are examined in a dynamic almost ideal demand system, applied to weekly demands for six fresh-vegetable groups in Norway. A number of restrictions regarding dynamics, advertising, homogeneity, symmetry and seasonality are tested. The static almost ideal demand system is rejected. The estimated own-price elasticities are negative, of reasonable magnitudes, statistically significant, and relatively more elastic in the long run than the short run. The results show no significant positive effects of advertising on vegetable consumption. Copyright 1995 by Oxford University Press.

The effects of multivariate risk are examined in a model of portfolio choice. The conditions under which portfolio choices are separable from consumption decisions are derived. Unless the appropriate restrictions hold on investors' preferences or on the probability distribution of risks, the optimal portfolio is affected by other risks. This requires generalizing the usual measures of risk aversion. With one risky asset, matrix measures of risk aversion are used to generalize the results of Arrow (1965) and Pratt (1964) concerning the effects of risk aversion and wealth on the optimal portfolio. With two risky assets, the choices made by two investors coincide if and only if their generalized risk-aversion measures are identical. Ross's notion of stronger risk aversion is then used to characterize the effect of risk aversion on the level of investment in the riskier asset.

During the past decade, the Linear Approximate (LA) Almost Ideal Demand System and the Rotterdam model have been adopted by agricultural economists as the demand systems of choice in most applications. The apparent explanation is that the two models are both (second-order) locally flexible and compatible with demand theory, they have identical data requirements and are equally parsimonious with respect to parameters, and both are linear in the parameters. While the two models are thus equally attractive in most respects, and indeed appear very similar in structure, they lead to different results in some applications. This article develops a test of each against the other. In an illustrative application to U.S. meat demand, the Almost Ideal model is rejected while the Rotterdam model is not.

Why aren't all agricultural economists Bayesians? We all speculate, using probabilistic statements, about such things as whether the President will propose a particular policy, whether the A's will win their division, or whether corn prices will rise by 10% or more following this summer's flooding. We all update our assessments when information is received, and likely obey all of the basic rules from probability theory, including Bayes' Theorem. If we are unwilling to speculate about one of these events, it is more likely from concerns about being wrong than from any aversion to using subjective definitions of probability. It is also not the case that we are averse to

Parametric tests for structural change are conditional on the joint hypothesis of functional form and other aspects of the model specification. This problem is often disregarded. Monte Carlo evidence using three data sets indicates that apparently innocuous specification errors can lead to substantial increases in the probability of finding structural change when it is not present in the data-generating mechanism. Significant Chow tests and autocorrelation are much more likely when the wrong functional form is used. Maximum Chow tests falsely reject stable preferences much more often than their nominal size suggests, even when the correct model is estimated.

Using a newly defined notion of aversion to income risk, the behavior of the marketed-surplus producer under price risk is characterized. Unlike the familiar case first examined by Sandmo, output depends on both ordinal preferences for goods and on risk attitudes. Conditions are found that yield an output level under risk that is smaller than under certainty. If these conditions do not hold, both risk and risk aversion may have a positive effect on output. Implications for econometric studies of risk attitudes are considered and illustrated with an example. Finally, we examine the effect of uncertainty on the peasant's long-run equilibrium.

An almost ideal demand system for meats is estimated using Canadian data. A Bayesian approach is used to impose inequality restrictions on substitution elasticities, via Monte Carlo integration and importance sampling, in order to conform with prior beliefs about curvature and monotonicity restrictions and substitution relationships. Results are more consistent with the concavity and monotonicity restrictions from demand theory than with the added restriction that all meats are substitutes.

The widely used mean-variance approach to decisions under uncertainty requires estimates of the parameters of the joint distribution of returns. When optimal behavior is determined using estimates, rather than the true values, the decision is a random variable. We consider the reliability of mean-variance analysis by examining the bias and variance-covariance matrix for the decision vector. The latter shows that decisions based on estimated parameters can have a large variance around the true optimum. The results show that optimal decisions can differ substantially from those based on mean-variance analysis.

In agriculture, relatively few efficacious control measures may be available for an invasive pest. In the case of a new insect pest, insecticide use decisions are affected by regulations associated with its registration, insect population dynamics, and seasonal market price cycles. We assess the costs and benefits of environmental regulations designed to regulate insecticide applications on an invasive species. We construct a bioeconomic model, based on detailed scientific data, of management decisions for a specific invasion: greenhouse whiteflies in California-grown strawberries. The empirical model integrates whitefly population dynamics, the effect of whitefly feeding on strawberry yields, and weekly strawberry price. We use the model to assess the optimality of alternative treatment programs on a simulated greenhouse whitefly population. Our results show that regulations may lead growers to “under-spray” when placed in an economic context, and provide some general lessons about the design of optimal invasive species control policies.

This study examines supermarket retailer behavior in the procurement of iceberg lettuce from California and Arizona, vine-ripe and mature-green tomatoes from California, and mature-green tomatoes from Florida. The analysis relies upon both a reduced-form specification of farm-retail price spreads and a structural model of procurement for a perishable commodity with inelastic supply. The evidence supports a conclusion that buyers have been able to exercise oligopsony power in procuring iceberg lettuce from grower-shippers in California and Arizona. The evidence regarding buyer market power is more mixed for fresh tomatoes. The apparent success of the Florida mature-green tomato industry in enforcing a price floor and capturing a significant share of the surplus in excess of the price floor demonstrates the potential benefits to producers from coordinated behavior.

The California Department of Pesticide Regulation (DPR) restricts pesticide use to reduce negative impacts on human health and the environment. The DPR implemented methyl bromide use regulations in 2001. Our study demonstrates that the estimated 2001 costs of these regulations for the California strawberry industry were quite substantial (more than $26 million total), equivalent to roughly 25% of estimated industry returns over total cash costs in 2001. These impacts were unevenly distributed across growers. Growers with small fields in urban areas had higher per-acre costs than growers with large fields in agricultural areas.

The nonparametric approach to consumer-demand analysis—based on revealed-preference axioms—is reviewed. Particular attention is paid to questions of size and power of tests for consistency of data with the existence of a stable, well-behaved utility function that could have generated the data. An application to Australian meat demand is used to show how these notions can be quantified and how prior information about elasticities, following Sakong and Hayes, may be used to increase the power of the approach.

Objections to mean-variance analysis center on the requirement that the distributions be normal or the resulting inattention to higher-order moments when the solution is viewed as an approximation. A nonparametric approach to decision making under uncertainty is developed in this paper using expected utility maximization, the exponential utility function, and an empirical moment-generating function. A decision rule is obtained for land allocation under uncertainty which is not tied to a particular family of distributions and accounts for all moments of the distribution.

School-based teacher support teams are being established by many educational agencies in an effort to assist teachers in more effectively serving students with learning and behavior problems within the general classroom setting. This article addresses questions most frequently asked by educators who are interested in establishing or strengthening school-based teams. Data are summarized from five studies conducted on 96 teams in seven states with respect to intervention goals of teams, team impact on student performance and the special education referral process, reactions of classroom teachers to teams, factors related to team effectiveness or ineffectiveness, and recommendations for improving team effectiveness.

Health concerns are thought by many to have shifted consumption away from red meats, though econometric evidence is mixed. Testing for structural change is difficult, especially when on e time series is used for both estimating demand equations and testin g their stability. Specification errors may suggest a shift where non e has occurred. Using nonparametric demand analysis, the authors find that meat consumption patterns in the United States and Australia ca n be explained using only relative prices and expenditures. Only impo sing particular functional forms can reverse the conclusion, suggesti ng that specification errors in econometric demand studies can accoun t for findings of taste changes. Copyright 1988 by University of Chicago Press.

The Fourier flexible form possesses desirable asymptotic properties that are not shared by other flexible forms such as the translog, generalized Leontief, and generalized Box-Cox. One of them is that an elasticity of substitution can be estimated with negligible bias in sufficiently large samples regardless of what the true form actually is, save that it be smooth enough. This article reports the results of an experiment designed to determine whether or not this property obtains in samples of the sizes customarily encountered in practice. A three-input, homothetic version of the generalized Box-Cox cost function was used to generate technologies that were oriented in a two-dimensional design space according to a central composite rotatable design; the two factors of the design were the Box-Cox parameter and a measure of the dispersion of the substitution matrix. The Fourier cost function was used to estimate the substitution elasticities at each design point, and the bias at each point was estimated using the Monte Carlo method. A response surface over the entire design space was fitted to these estimates. An examination of the surface reveals that the bias is small over the entire design space. Roughly speaking, the estimates of elasticities of substitution are unbiased to three significant digits using the Fourier flexible form no matter what the true technology. Our conclusion is that the small bias property of the Fourier form does obtain in samples of reasonable size; this claim must be tampered by the usual caveats associated with inductive inference.

(1974). IDENTIFYING LEARNING DISABILITIES IN THE CLASSROOM. The Slow Learning Child: Vol. 21, No. 1, pp. 3-14.

This article describes a simulated reading activity which LD teachers can use to help classroom teachers experience the same anxieties, frustrations, and failure that learning disabled children experience every day under group norm instruction. This activity helps teachers develop insight into children's attitudes toward the learning task, their fellow students, the teacher, and the instructional methods and materials which are used. The activity also enables an awareness of differences In learning styles among participants.