background and objective: lactic acid is widely used in the food, chemical and pharmaceutical industries. the major problems associated with lactic acid production are substrate and end-product inhibition, and by-product formation. membrane technology represents one of the most effective processes for lactic acid production. the aim of this work is to increase cell density and lactic acid produ...

This study set out to analyses rice total factor productivity in Nigeria ecological zones and the growth trend from 1996 to 2010. Statistical information on domestic and imported quantities of rice was obtained for 15 years (1996 to 2010) from the AGROSTAT system of the statistical division of the Food and Agriculture Organization (FAO), Federal Ministry of Agriculture statistical bulletins, Ce...

We examine relative prices, relative productivity levels, and competitiveness in the sawmills and wood preservation industry in the United States and Canada between 1958 and 2003 by using purchasing power parities and bilateral trans log production function. Our results show that the competitiveness of the Canadian industry is facilitated by higher relative productivity levels and depreciation ...

This paper develops a positive theory of overlapping income taxation in a federation of states. Its main motivation comes from the observation that in the U.S. states income tax rates are significantly lower than the federal income tax rate. The analysis shows that in a federal system total productivity dispersion between the states determines the federal tax rate. In fact, there exists a posit...

manufacturing process frequently employs optimization of machining parameters in order to improve product quality as well as to enhance productivity. the material removal rate is a significant indicator of the productivity and cost efficiency of the process. taguchi method has been implemented for assessing favorable (optimal) machining condition during the machining of nylon by considering thr...

For the last half-century American agriculture has been one of the most regulated, yet most successful, sectors of the American economy. The federal government administers programs to restrict production, control prices, and provide special credit for farmers. Still, what is striking about this regulation is that its introduction in the 1930s coincided with the start of a revolution in agricult...

The average lifetime of sows as observed in production herds is primarily influenced by management decisions. Usually the farmer decides to cull a sow, either because he expects that a gilt's average productivity is higher than the marginal productivity of the sow, or because the current number of sows exceeds the production capacity, e.g. in the farrowing department. Several studies have shown...

Although nitrate limitation in most natural wetlands results in pseudo-first-order reductions, large site-to-site variations in apparent denitrification rates cannot be easily explained by water quality (e.g., pH, Temp, DOC) or plant productivity. Our microcosm results show increasing nitrate removal efficiencies at higher ratios of total applied plant carbon to nitrate reduced, suggesting that...

Both lactic acid productivity and cell growth were linearly correlated with yeast extract supplementation in batch fermentation. During conventional continuous operation, although fresh feed was introduced into the bioreactor with a significantly low dilution rate (0.04 h(-1)), the amount of yeast extract employed was not enough to maintain the growth of microorganism. However, when the fresh f...