Energy substitution in cotton production in the USA

The paper investigates the nature and extent of the substitution of energy for other inputs in the production of cotton in the USA. The specific inputs considered, in addition to energy, are labour, nitrogen fertilizer, phosphate fertilizer, pesticides and water. The results show that input use is responsive to variations in own prices and that some limited substitution does occur between energy, labour and nitrogen fertilizer.     

Aneurysmal bone cyst involving the distal phalanx of a child

BACKGROUND: The synthesis of nitric oxide (NO) in the colonic mucosa of patients affected by ulcerative colitis (UC) has been previously investigated using indirect measurements of enzyme activity and non-specific measurements of luminal NO gas. The aim of this study was to determine unequivocally if luminal NO gas in active UC is present in greater concentrations than in healthy control subjects. METHODS: Luminal gas was collected from eight patients with active UC and eight healthy volunteers. NO gas concentration was measured using diode laser spectroscopy. RESULTS: NO gas was detected in four of eight patients with active UC (range 0.13-1.1 nmol) and none of the healthy control subjects. CONCLUSION: NO gas is present in greater concentrations in patients with active UC than in control subjects. This supports the view that mucosal NO synthesis is increased in ulcerative colitis.     

Assessing the impact of the windfall profits tax on the US economy

The paper focuses on the effect that the elimination of the windfall profits tax (WPT) on crude oil would have on the various producing sectors, consuming sectors and household categories in the USA, where the interrelationships between these entities are explicitly considered. Special attention is given to the agricultural sectors of the economy. Thus, in the context of a general equilibrium model, the effect of the elimination of the WPT on the producing sectors in general and the three agricultural sectors plus forestry in particular, on the consuming sectors, on households and on the Government is calculated. Over the period 1984–1990, such a policy initiative would result in higher output by the non-crude-oil producing sectors (by about $1.783 billion), higher consumption of goods and services (by about $1.651 billion), and an increase in welfare (by about $1.625 billion). The Government will realize a decrease in revenue of about $1.362 billion while the domestic crude oil industry will experience an increase in output of approximately $1.217 billion. For the agricultural sectors, output overall will fall. Specifically, for the programme crops sector, output will decline by $39 million, for the livestock sector, output will fall by $14 million, for all other agricultural commodities, output will decline by $36 million and for forestry, output will be reduced by $29 million. Attendant on these reductions in output will be lower prices for the respective commodities.     

The impact of price variation on the production of crude oil and natural gas

This paper is directed at examining the impact of changing prices on the level of production of crude oil and natural gas in the United States. By using a cross correlation test for unidirectional causality, it is clearly demonstrated that for both crude oil and natural gas, domestic production is affected by changing prices. The implications are clear. The decontrol of the price of crude oil and the deregulation of natural gas prices will lead to additional production in the near term.     

Utilization of various sterols by lecithin-cholesterol acyltransferase as acyl acceptors

Highly purified lecithin-cholesterol acyltransferase of human plasma was used to study the utilization of various sterols as the acyl acceptor. The esterification of sterols was facilitated by the presence of a 3β-hydroxyl group and thetrans configuration of the A/B rings, as was evident from the lack of acceptor activity of all 3α-hydroxy sterols tested and coprostanol. Cholesterol analogs in which the side chain is modified, such as campesterol, β-sitosterol, desmosterol and stigmasterol, were less effective than cholesterol as acyl acceptors. However, androstan-3β-o1, which completely lacks the side chain, was found to be more active than cholesterol. The transfer of the acyl group to all effective sterols required the presence of the cofactor peptide apolipoprotein A-I.     

Energy and investment: An empirical examination

The view that the investment function is characterized by a stable relationship is subjected to an objective statistical test. The test utilizes a statistic which equals the ratio of the sum of squared residuals of one-period prediction from the k + 1 period to the rth period to the sum of squared residuals of one period prediction from the k + 1 to the Tth period, where k is the number of estimated coefficients in the model and T is the sample size. The results for the period 1947–1979 suggest that the investment function at the macroeconomic level and for 8 of the 11 two-digit SIC industries considered became unstable in 1973. For the other two-digit SIC industries investigated, the results indicate no appreciable (statistically significant) change in the relative importance of the underlying investment determinants.     

Methods for Quantifying and Characterizing Errors in Pixel-Based 3D Rendering

We present methods for measuring errors in the rendering of three-dimensional points, line segments, and polygons in pixel-based computer graphics systems. We present error metrics for each of these three cases. These methods are applied to rendering with OpenGL on two common hardware platforms under several rendering conditions. Results are presented and differences in measured errors are analyzed and characterized. We discuss possible extensions of this error analysis approach to other aspects of the process of generating visual representations of synthetic scenes.     

Tuning energetic levels in nanocrystal quantum dots through surface manipulations

We demonstrate tuning of the electronic level positions with respect to the vacuum level in colloidal InAs nanocrystals using surface ligand exchange. Electrochemical as well as scanning tunneling spectroscopy measurements reveal that the tuning is largely dependent on the nanocrystal size and the surface linking group, while the polarity of the ligand molecules has a lesser effect. The implications of affecting the electronic system of nanocrystal through its capping are illustrated through prototype devices.     

On the absence of detectable carrier multiplication in a transient absorption study of InAs/CdSe/ZnSe core/Shell1/Shell2 quantum dots

Tunable femtosecond pump-near IR probe measurements on InAs/CdSe/ZnSe core/shell1/shell2 nanocrystal quantum dots were conducted to quantify spontaneous carrier multiplication previously reported in this system. Experimental conditions were chosen to eliminate the need for determining absolute wavelength dependent cross sections of the nanocrystals and allow direct comparison of band edge absorption bleach kinetics for different excitation energies up to 3.7 times the band gap. Results for two sample sizes show no signs of carrier multiplication within that range. This result is discussed in light of reports describing occurrence of this novel phenomenon in quantum dots based on this as well as numerous other semiconductor materials.