Simultaneous Analysis of Insurance Participation and Acreage Response from Subsidized Crop Insurance for Cotton

US crop insurance is subsidized to encourage producers to participate and reduce their risk exposure. However, what has been the impact of these subsidies on insurance demand and crop acres planted? Using a simultaneous system of two equations, we quantify both insurance participation and acreage response to subsidized crop insurance for cotton-producing counties across the US at the national and regional levels. We also quantify the impact of both the realized rate of return and the expected subsidy per pound, plus the combined effects of expected yield and price while accounting for the adoption of Bacillus thuringiensis (Bt) technology and other factors. Results show that both the rate of return and the expected subsidy per unit of production have a statistically significant and positive effect on the percentage of arable acres planted. Furthermore, the marginal effect of expected price on insurance participation is much more significant for low- than high-yield counties. Results indicate that not all regions respond the same to subsidized crop insurance and that subsidies should be based on dollars per expected unit of production rather than expected production to be less distorting. Overall, US cotton acreage response is estimated to be inelastic (0.58) to insurance participation.

Observations of Tripsacum dactyloides and T. floridanum (Poaceae): measuring climate and soil gradient effects on Tripsacum in Texas, U.S.A.

Reports of Tripsacum floridanum Porter ex Vasey in Texas have been countered with two arguments. First is that narrow-leafed Texas plants, when grown under favorable conditions, are more typical of wider-leafed T. dactyloides (L.) L. Second is that the offspring from crosses of T. dactyloides with T. floridanum are sterile or partially so. The support for these two claims is examined. The conclusion is narrow-leafed Texas plants typical of T. floridanum are in Texas, and crosses between the two produce fully fertile offspring. This raises the question of what factors are at play to segregate the wider-leafed from the narrower-leafed Texas populations. To investigate, two statistical models were constructed using separate data. First, a simultaneous system of seven equations was used to predict phenological and morphological plant characteristics given environmental factors. Second, a single logit equation predicted the probability of narrow-leafed diploid versus widerleafed diploid and tetraploid plants given environmental factors. Predictions allow for the measurement of plant characteristics from climate and soil gradients. Results suggest that narrow-leafed diploid plants occupy distinct habitats with the larger tetraploid plants coping by adapting mechanisms to overcome interspecies competition while the smaller diploid plants adapt with mechanisms to overcome stress. In conclusion, findings support consideration of T. floridanum as a variety of T. dactyloides and conservation implications are reviewed.

Effects of Iran's WTO Accession on the Cement Industry: A Dynamic Disequilibrium Adjustment Model (DDAM) of Simultaneous Equations

Many companies around the globe are re-examining their business operations to explore profitable growth in international markets.The attractiveness of the membership in WTO can be recognized not only in the growing number of its members but also as a result of increasing access to potential markets around the world. Iranian economy suffers from huge inefficiency in its trade relationships with other countries due to import compression policy and strict import controls. Iran's import profile is heavily skewed towards those tradable that are not strongly under the effects of WTO, indicating protectionism policy in the industry sector. Besides the need for easing protectionism, the emphasis placed on the growth of non-oil exports and reducing oil dependency as an objective in the five-year development plans provides a strong argument for joining WTO. Measuring technical efficiency in the cement industry in Iran suggests that companies with export-orientation policy have potentials to succeed in increasing their technical efficiency.The new discovering realm of WTO for Iran's trade policy has been evaluated in this paper. The pros and cons for joining induced us to investigate the effects of Iran's membership on the cement industry. By designing a dynamic disequilibrium adjustment model (DDAM), we use annual data for the period 1963-2002 to estimate a simultaneous system of econometric equations including cement supply, exports, imports, and consumption functions in order to quantify the effects of joining on the cement industry of Iran. One of the main challenges confronting the Iranian cement industry is to improve the competitiveness of the industry by reducing the subsidies, removing restrictions, and price controls. Indeed, the experience of other counties after joining WTO portrays a conflicting profile on the effects of accession on domestic economies. While some countries have developed important trading partners, others have suffered due to the loss of domestic industries. In this paper, we intend to examine the hypothesis of whether reducing the tariff rates will promote Iranian cement industry. The results reveal that joining WTO has negligible effects on consumption, production, and exports, though, will raise imports substantially.

Simultaneous system design and path planning: A sampling-based algorithm

This paper addresses the simultaneous design and path-planning problem, in which features associated to the bodies of a mobile system must be selected to find the best design that optimizes its motion between two given configurations. Solving individual path-planning problems for all possible designs and selecting the best result would be straightforward only for very simple cases. We propose a more efficient approach that combines discrete (design) and continuous (path) optimization in a single stage. It builds on an extension of a sampling-based algorithm, which simultaneously explores the configuration-space costmap of all possible designs, aiming to find the best path-design pair. The algorithm filters out unsuitable designs during the path search, which breaks down the combinatorial explosion. Illustrative results are presented for relatively simple (academic) robotic examples, showing that even in these simple cases, the computational cost can be reduced by two orders of magnitude with respect to the naïve approach. A preliminary application to challenging problems in computational biology related to protein design is also discussed.