An economic evaluation of the osmoregulation gene technology to the Australian wheat industry

Episodes of rainfall irregularity and soil moisture deficit have focused attention on the widespread limitation of water supply on winter cereal crop production in Australia. This has motivated a number of efforts at breeding for improved drought tolerance. A recent example involves a cellular adaptation which mitigates water loss through solute accumulation (osmoregulation or osmotic adjustment). An assessment of the performance of osmoregulation yield response in the presence of climate change found that wheat cultivars with this gene are unlikely to be adversely affected by hotter and drier conditions across the wheat belt. The results of an economic evaluation of potential future innovations (wheat cultivars) from the osmoregulation gene technology are that for Australia the net present value could range from $388 million to$3.6 billion, depending on the adoption of wheat cultivars with the gene. Associated benefit-cost ratios ranged from 43:1 to 390:1, and internal rates of return were 16% to 27%. Even under pessimistic assumptions the returns are quite healthy. For NSW-only adoption, internal rates of return ranged from 10% to 22%. This osmoregulation technology has the potential for inclusion in wheat cultivars bred for other purposes, and for other crops. As such it has implications for agricultural plant breeders and farmers both in Australia and overseas, and there are substantial potential spillover benefits.economic evaluation, wheat breeding, osmoregulation, Crop Production/Industries, Research Methods/ Statistical Methods,

Clicks, Discontinuities, and Firm Demand Online

The market values of online platforms, such as Yahoo, stem from their ability to monetize the clicks they generate for firms advertising on their sites. We exploit a unique dataset on clicks from one of Yahoo's price comparison sites to estimate the determinants of clicks received by online retailers. We find that a firm enjoys a 60% jump in its clicks when it offers the lowest price at the site. This discontinuity is consistent with a variety of models that have been used to rationalize the price dispersion observed in online markets. We also show that one may use estimates of the determinants of a firm's clicks to obtain bounds on its underlying demand parameters, including own- and cross-price elasticities. Our results have potentially significant ramifications for online retailers, platforms, and policymakers: Failure to account for discontinuities distorts parameter estimates by 50 to 100 percent.

Estimating Firm-Level Demand at a Price Comparison Site: Accounting for Shoppers and the Number of Competitors

Clearinghouse models of online pricing---such as Varian (1980), Rosenthal (1980), Narasimhan (1988), and Baye-Morgan (2001)---view a price comparison site as an 'information clearinghouse' where shoppers and loyals obtain price and product information to make online purchases. These models predict that the responsiveness of a firm's demand to a change in its price depends on the number of sellers and whether the price change results in the firm charging the lowest price in the market. Using a unique firm-level dataset from Kelkoo.com (Yahoo!'s European price comparison site), we examine these predictions by providing estimates of the demand for PDAs. Our results indicate that the number of competing sellers and both the firm's location on the screen and relative ranking in the list of prices are important determinants of an online retailer's demand. We find that an online monopolist faces an elasticity of demand of about -2, while sellers competing against 10 other sellers face an elasticity of about -6. We also find empirical evidence of a discontinuous jump in a firm's demand as its price declines from the second-lowest to the lowest price. Our estimates suggest that about 13% of the consumers at Kelkoo are 'shoppers' who purchase from the seller offering the lowest price.Internet, Price Dispersion, Advertising

Did the Euro Foster Online Price Competition? Evidence from an International Price Comparison Site

We study the impact of the Euro on prices charged by online retailers within the EU. Our data spans the period before and after the Euro was introduced, covers a variety of products, and includes countries inside and outside of the Eurozone. After controlling for cost, demand, and market structure effects, we show that the pure Euro changeover effect is to raise average prices in the Eurozone by 3% and average minimum prices by 7%. Finally, we develop a model of online pricing in the context of currency unions, and show that these price patterns are broadly consistent with clearinghouse models.Price competition, internet

The death of massive stars - II. Observational constraints on the progenitors of type Ibc supernovae

The progenitors of many type II core-collapse supernovae have now been identified directly on pre-discovery imaging. Here we present an extensive search for the progenitors of type Ibc supernovae in all available pre-discovery imaging since 1998. There are 12 type Ibc supernovae with no detections of progenitors in either deep ground-based or Hubble Space Telescope archival imaging. The deepest absolute BVR magnitude limits are between -4 and -5. We compare these limits with the observed Wolf-Rayet population in the Large Magellanic Cloud and estimate a 16 per cent probability we have failed to detect such a progenitor by chance. Alternatively the progenitors evolve significantly before core-collapse or we have underestimated the extinction towards the progenitors. Reviewing the relative rates and ejecta mass estimates from lightcurve modelling of Ibc SNe, we find both incompatible with Wolf-Rayet stars with initial masses >25Msun being the only progenitors. We present binary evolution models that fit these observational constraints. Stars in binaries with initial masses <20Msun lose their hydrogen envelopes in binary interactions to become low mass helium stars. They retain a low mass hydrogen envelope until approximately 10,000 years before core-collapse; hence it is not surprising that galactic analogues have been difficult to identify.Comment: Accepted by MNRAS. 31 pages, 12 figures, 8 table

Some aspects of the phenomenon of superheating as exhibited by several fluids

After a brief definition of the phenomenon of superheating, two distinct aspects are studied in detail. The first, a statistical method is devised to predict most probable superheat at inception as a function of temperature ramp which the fluid experiences. The second deals with determining the location of inception in a flowing superheated liquid

Development of Ground-testable Phase Fresnel Lenses in Silicon

Diffractive/refractive optics, such as Phase Fresnel Lenses (PFL's), offer the potential to achieve excellent imaging performance in the x-ray and gamma-ray photon regimes. In principle, the angular resolution obtained with these devices can be diffraction limited. Furthermore, improvements in signal sensitivity can be achieved as virtually the entire flux incident on a lens can be concentrated onto a small detector area. In order to verify experimentally the imaging performance, we have fabricated PFL's in silicon using gray-scale lithography to produce the required Fresnel profile. These devices are to be evaluated in the recently constructed 600-meter x-ray interferometry testbed at NASA/GSFC. Profile measurements of the Fresnel structures in fabricated PFL's have been performed and have been used to obtain initial characterization of the expected PFL imaging efficiencies.Comment: Presented at GammaWave05: "Focusing Telescopes in Nuclear Astrophysics", Bonifacio, Corsica, September 2005, to be published in Experimental Astronomy, 8 pages, 3 figure