Dairy Farm Management Adjustments to Biofuels-Induced Changes in Agricultural Markets

A mathematical programming model of a representative New York dairy farm is developed to identify optimal management adjustments to increased availability of corn distillers dried grains with solubles (DDGS). While at current prices DDGS feeding is limited to dry cows and young stock, as prices decrease, DDGS in lactating cow rations increase from 7.4% to 20% on a dry matter basis. While expected changes in net farm returns are modest, more important is the consideration of changes in nutrient management practices necessary to deal with increasing levels of nitrogen and phosphorus in the animal waste.Production, Management, Agribusiness, Agricultural Finance, Farm Management, Financial Economics, Resource /Energy Economics and Policy,

The design and evaluation of grazing incidence relay optics

X-ray astronomy, both solar and celestial, has many needs for high spatial resolution observations which have to be performed with electronic detectors. If the resolution is not to be detector limited, plate scales in excess of 25 microns arc/sec, corresponding to focal lengths greater than 5 m, are required. In situations where the physical size is restricted, the problem can be solved by the use of grazing incidence relay optics. A system was developed which employs externally polished hyperboloid-hyperboloid surfaces to be used in conjunction with a Wolter-Schwarzschild primary. The secondary is located in front of the primary focus and provides a magnification of 4, while the system has a plate scale of 28 microns arc/sec and a length of 1.9 m. The design, tolerance specification, fabrication and performance at visible and X-ray wavelengths of this optical system are described

Formation of a reliable intermediate band in Si heavily coimplanted with chalcogens (S, Se, Te) and group III elements (B, Al)

This first-principles study describes the properties of Si implanted with several chalcogen species (S, Se, Te) at doses considerably above the equilibrium solubility limit, especially when coimplanted with the group III atoms B and Al. The measurements of chalcogen-implanted Si show strong optical absorption in the infrared range. The calculations carried out show that substitution of Si by chalcogen atoms requires lower formation energy than the interstitial implantation. In the resulting electronic structure, at concentrations close to 0.5%, an impurity band determined by the properties of the chalcogens introduced is observed in the forbidden energy gap of Si. Although this band is a few tenths of an electron volt wide, it remains energetically isolated from both the valence and the conduction bands. Appropriate coimplantation with group III elements allows control over the occupation of the intermediate band while modifying its energies only slightly. A moderate energy gain (especially small for B) seems to be obtained when p-doping atoms occupy the sites next to those of the chalcogens. Therefore, the apparent electrostatic attraction between species that in isolation would act as acceptors and double donors is smaller than expected. The intermediate-band properties have been preserved for all of the coimplanted compounds analyzed here, regardless of the species involved or the distance between them, which constitutes an appreciable advantage for the design of new experimental materials

Role of the hydrological cycle in regulating the planetary climate system of a simple nonlinear dynamical model

International audienceWe present the construction of a dynamic area fraction model (DAFM), representing a new class of models for an earth-like planet. The model presented here has no spatial dimensions, but contains coupled parameterizations for all the major components of the hydrological cycle involving liquid, solid and vapor phases. We investigate the nature of feedback processes with this model in regulating Earth's climate as a highly nonlinear coupled system. The model includes solar radiation, evapotranspiration from dynamically competing trees and grasses, an ocean, an ice cap, precipitation, dynamic clouds, and a static carbon greenhouse effect. This model therefore shares some of the characteristics of an Earth System Model of Intermediate complexity. We perform two experiments with this model to determine the potential effects of positive and negative feedbacks due to a dynamic hydrological cycle, and due to the relative distribution of trees and grasses, in regulating global mean temperature. In the first experiment, we vary the intensity of insolation on the model's surface both with and without an active (fully coupled) water cycle. In the second, we test the strength of feedbacks with biota in a fully coupled model by varying the optimal growing temperature for our two plant species (trees and grasses). We find that the negative feedbacks associated with the water cycle are far more powerful than those associated with the biota, but that the biota still play a significant role in shaping the model climate. third experiment, we vary the heat and moisture transport coefficient in an attempt to represent changing atmospheric circulations