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Crop growth and yield varies among locations due to differences in environmental parameters, such as temperature, relative humidity, solar radiation and vapor pressure deficit. Previous research has shown that increasing vapor pressure deficit has a negative effect on radiation use efficiency of many crops. In this study, the radiation use efficiency of cot-ton (Gossypium hirsutum L.) grown in two contrasting production environments, Arkansas and California, was evaluated for two years, in 2006 and 2007. Temperature, relative humidity, vapor pressure deficit and photosyntheti-cally active radiation were recorded at both locations. Although the crop in California accumulated more dry matter during the period of the study, the radiation use efficiency was found to be lower compared to Arkansas. Radiation use efficiency for the Arkansas and California locations was estimated at 2.060 and 1.518 g?MJ–1 of intercepted photosynthetically active radiation, respectively. The higher productivity observed in California can be attributed to larger amounts of incident and intercepted radiation in this location. Radiation use efficiency of cotton was estimated to decrease with increasing vapor pressure deficit by a slope of –0.47 g?MJ–1?kPa–1.

This paper, the first in a series provides the background of the project, reports on the early phases of construction with the descriptions of the pre and post flooded conditions related to vegetation and land cover types surrounding the reservoir. Currently there are plans to develop the so called “Lower Churchill Area” by establishing new power plants at Gull Island and at Muskrat Falls with associated reservoirs. These new plants would use the discharged water of the plant from Churchill Falls and the additional water collected from some of the Churchill River Basin. The information provided by these papers could have relevance to the environmental evaluation of these new developments. The Churchill Falls Hydro Project (called the “Upper Churchill Development”) in Labrador, Canada, was initiated in the late 1960s and the 5428-MW hydro generating plant constructed was then among the largest in the world. At that time, in general, not much attention was paid to the impact of such development on the flooding of vegetation especially forest stands. Both forested and un-forested terrestrial vegetation types were flooded (244 915 ha). Some islands were created and in addition portions of existing areas were flooded to form islands (74 075 ha) in the Main (Smallwood) Reservoir area. The flooded area of forest and un-forested land in the reservoir is 77% while the islands is 23 percent. The percentages of forested and un-forested areas lost to flooding are 64% and 36% respectively. The percent of commercial forests lost to flooding is approximately 1% and the non-commerci- al forests is 99% (with a total volume of approximately 10 million cubic meters of wood).

In studying the avalanches and noise in a model of hysteresis loops we have developed two relatively straightforward algorithms which have allowed us to study large systems efficiently. Our model is the random-field Ising model at zero temperature, with deterministic albeit random dynamics. The first algorithm, implemented using sorted lists, scales in computer time as O(N log N), and asymptotically uses N (sizeof(double)+ sizeof(int)) bits of memory. The second algorithm, which never generates the random fields, scales in time as O(N \log N) and asymptotically needs storage of only one bit per spin, about 96 times less memory than the first algorithm. We present results for system sizes of up to a billion spins, which can be run on a workstation with 128MB of RAM in a few hours. We also show that important physical questions were resolved only with the largest of these simulations.

Motivated by the idea of developing a ``hydrodynamic'' description of spatiotemporal chaos, we have investigated the defect--defect correlation functions in the defect turbulence regime of the two--dimensional, anisotropic complex Ginzburg--Landau equation. We compare our results with the predictions of generic scale invariance. Using the topological nature of the defects, we prove that defect--defect correlations cannot decay as slowly as predicted by generic scale invariance. We also present results on the fluctuations of the amplitude field $A$., Comment: 25 pages, LaTeX, 15 figures appended in a uuencoded compressed tar file

We present a model for evolution and extinction in large ecosystems. The model incorporates the effects of interactions between species and the influences of abiotic environmental factors. We study the properties of the model by approximate analytic solution and also by numerical simulation, and use it to make predictions about the distribution of extinctions and species lifetimes that we would expect to see in real ecosystems. It should be possible to test these predictions against the fossil record. The model indicates that a possible mechanism for mass extinction is the coincidence of a large coevolutionary avalanche in the ecosystem with a severe environmental disturbance., Comment: Postscript (compressed etc. using uufiles), 16 pages, with 15 embedded figures