We use newly constructed state-specific data to explore the implications of common modeling choices for measures of research returns. Our results indicate that state-to-state spillover effects are important, that the R&D lag is longer than many studies have allowed, and that misspecification can give rise to significant biases. Across states, the average of the own-state benefit-cost ratios is 21:1; or 32:1 when the spillover benefits to other states are included. These ratios correspond to real internal rates of return of 9 or 10 percent per annum, much smaller than those typically reported in the literature, partly because we have corrected for a methodological flaw in computing rates of return.

Recently, there has been much interest among horticultural producers concerning the marketing of organic and locally produced food. A consumer survey was administered that asked respondents to choose an applesauce product from a list of products differentiated by price, and by labels that described fat content, nutrition content, and whether the product was grown organically and/or locally. Our analysis indicates that consumers were willing to pay more for locally grown applesauce compared to applesauce that was labeled USDA Organic, Low Fat, or No Sugar Added. Furthermore, we find evidence that increased knowledge of agriculture decreases the willingness to pay for organic and locally grown applesauce.

During early embryogenesis in Drosophila melanogaster, extensive vesicle transport occurs to build cell boundaries for 6,000 nuclei. Here we show that this important process depends on a functional complex formed between the tumour suppressor and adaptor protein Discs-Large (Dlg) 1 and the integral membrane protein Strabismus (Stbm)/Van Gogh (Vang) 2,3 . In support of this idea, embryos with mutations in either dlg or stbm displayed severe defects in plasma membrane formation. Conversely, overexpression of Dlg and Stbm synergistically induced excessive plasma membrane formation. In addition, ectopic co-expression of Stbm (which associated with postGolgi vesicles) and the mammalian Dlg homologue SAP97/hDlg 4,5 promoted translocation of SAP97 from the cytoplasm to both post-Golgi vesicles and the plasma membrane. This effect was dependent on the interaction between Stbm and SAP97. These findings suggest that the Dlg-Stbm complex recruits membrane-associated proteins and lipids from internal membranes to sites of new plasma membrane formation.Formation of new plasma membranes is dependent on the delivery of post-Golgi vesicles to a pre-existing plasma membrane. An excellent model system to study this process is the cellularization that occurs during early Drosophila embryogenesis. During cellularization, the embryonic plasma membrane must rapidly grow inwards to segregate thousands of nuclei, generated by synchronized cycles of nuclear division without cytokinesis, into individual cells 6 . This process occurs through addition of post-Golgi vesicles to defined regions of lengthening plasma membranes and may be required for establishing proper cell polarity 7 . The Dlg tumour suppressor is essential both for establishing proper cell polarity and for assembling multiprotein complexes at specialized cell-cell junctions 8 . Accumulating evidence also indicates that Dlg associates with its targets at intracellular membrane sites before accumulation at the plasma membrane 9-12 . The integral membrane protein Stbm, however, is a regulator of planar tissue polarity in the fly 2,3 , and mouse Loop-tail (Lp) and zebrafish trilobite mutants that also have mutations in stbm homologues display defects in gastrulation and neurogenesis 13,14 .Here,we report that Dlg binds to Stbm and that this complex is required for formation of new plasma membranes during cellularization. Note: Supplementary Information is available on the Nature Cell Biology website. COMPETING FINANCIAL INTERESTSThe authors declare that they have no competing financial interests. We identified Stbm as a binding partner of Dlg using the first and second Dlg PDZ domains (Dlg-PDZ1-2; Fig. 1a) as bait in the yeast two-hybrid system. Stbm contains four putative transmembrane domains and a consensus PDZ-domain-binding motif (PBM) at its extreme carboxyl terminus (Fig. 1a) 2 . In glutathione S -transferase (GST) pull-down assays, the 17 C-terminal residues of Stbm (GST-Stbm PBM ) were sufficient to mediate binding to Dlg-PDZ1-2 (see Supplementary Information,...

Agricultural research has transformed agriculture and in doing so contributed to the transformation of economies. Economic issues arise because agricultural research is subject to various market fail ures, because the resulting innovations and technological changes have important economic consequences for net income and its distri bution, and because the consequences are difficult to discern and attribute. Economists have developed models and measures of the economic consequences of agricultural R&D and related policies in contributions that relate to a very broad literature ranging across production economics, development economics, industrial organiza tion, economic history, welfare economics, political economy, econo metrics, and so on. A key general finding is that the social rate of return to investments in agricultural R&D has been generally high. Specific findings differ depending on methods and modeling assump tions, particularly assumptions concerning the research lag distribu tion, the nature of the research-induced technological change, and the nature of the markets for the affected commodities.

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Profits from generic advertising by a producer group often come partly at the expense of producers of closely related commodities. The resulting tendency toward excessive advertising is exacerbated by check-off funding. To analyze this beggar-thy-neighbor behavior we compare a scenario where different producer groups cooperate and choose their advertising expenditures jointly to maximize the sum of profits across the groups, and a scenario where they optimize independently. In an illustrative example using 1998 data for U.S. beef and pork, the noncooperatively chosen expenditure on beef and pork advertising is more than three times the cooperative optimum. Copyright 2001, Oxford University Press.

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