Measurement and Sources of Technical Inefficiency in the Tunisian Citrus Growing Sector

This paper investigates farm level technical inefficiency of production and its determinants in a sample of 150 citrus producing farms in Tunisia using a stochastic frontier production function approach applied to cross section data. Results indicate that technical efficiency of production in the sample of citrus producing farms investigated ranges from a minimum of 26.84% to a maximum of 97.98% with an average technical efficiency estimate of 86.23%. This suggests that citrus producers may increase their production by as much as 13.77% through more efficient use of production inputs. Further, the estimated coefficients in the technical inefficiency model indicate the positive effect on technical efficiency of the share of productive trees, the agricultural training, irrigation operations and the experience of farmer.Technical Efficiency, stochastic frontier production function, citrus farms, Tunisia, Productivity Analysis,

Measuring Irrigation Water Efficiency with a Stochastic Production Frontier: An Application for Citrus Producing Farms in Tunisia

The objective of this paper is to propose an alternative measure of irrigation water efficiency based on the concept of input- specific technical efficiency, which contracts with measures previously used in the literature. The proposed methodology is applied to a randomly selected sample of 144 citrus growing farms located in Nabeul (Tunisia). A stochastic production frontier approach, based on Battese and Coelli’s (1995) inefficiency effect model, is used to obtain farm-specific estimates of technical and irrigation water efficiency. In addition, a second-stage regression approach is used to identify the factors influencing irrigation water efficiency differentials across citrus growing farms. Results indicate that technical efficiency ranges from a minimum of 12.9% to a maximum of 90.7% with an average estimate of 67.7%. This suggests that citrus producers may increase their production by as much as 32.3% through more efficient use of production inputs. Further, mean irrigation water efficiency is found to be 53%, which is much lower than technical efficiency and also exhibits greater variability ranging from 1.6% to 98.87%. The estimated mean irrigation water efficiency implies that the observed quantity of marketable citrus could have been maintained by using the observed values of other inputs while using 47.0% less of irrigation water. Moreover, the estimated mean irrigation water technical cost efficiency is found to be 70.81% indicating a potential decrease of 29.19% in total cost by adjusting irrigation water to its efficient level. In addition, the vast majority of farms have achieved irrigation water technical cost efficiency greater than 90% (71% of farms). Finally, the analysis of the sources of efficiency differentials among farmers showed that farmer’s age, farm’s size, education level, agricultural training, the share of productive trees and the water disposable perception tend to affect positively the degree of both technical and irrigation water efficiency.Citrus, Efficiency, Tunisia, Water, Agricultural and Food Policy, Community/Rural/Urban Development, Demand and Price Analysis, Environmental Economics and Policy, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, International Relations/Trade, Marketing, Productivity Analysis, Research and Development/Tech Change/Emerging Technologies,

A Numerical Approach for Solving Optimal Control Problems Using the Boubaker Polynomials Expansion Scheme

In this paper, we present a computational method for solving optimal control problems and the controlled Duffing oscillator. This method is based on state parametrization. In fact, the state variable is approximated by Boubaker polynomials with unknown coefficients. The equation of motion, performance index and boundary conditions are converted into some algebraic equations. Thus, an optimal control problem converts to a optimization problem, which can then be solved easily. By this method, the numerical value of the performance index is obtained. Also, the control and state variables can be approximated as functions of time. Convergence of the algorithms is proved. Numerical results are given for several test examples to demonstrate the applicability and efficiency of the method

Hyperlactatemia and Antiretroviral Therapy: The Swiss HIV Cohort Study

The prevalence, clinical presentation, and risk factors for hyperlactatemia among patients receiving antiretroviral therapy was determined during a 1-month period for patients in the Swiss HIV Cohort Study. Overall, 73 (8.3%) of 880 patients presented an increase in serum lactate of >1.1 times the upper normal limit (UNL). For 9 patients (1%), lactate elevation was moderate or severe (>2.2 times the UNL). Patients who presented with hyperlactatemia were more likely to be receiving stavudine with or without didanosine (odds ratio, 2.7; 95% confidence interval, 1.5-4.8), as compared with patients who received zidovudine-based regimens. The risk increased with increasing time receiving stavudine with or without didanosine. The association between hyperlactatemia and stavudine with or without didanosine was not biased by these medications being more recently available and, therefore, being given preferentially to patients who had prolonged use of nucleoside analog reverse-transcriptase inhibitors. Hyperlactatemia was associated with lipoatrophy, hyperlipidemia, and hyperglycemia. Age, sex, or stage of infection with human immunodeficiency virus were not predictive of hyperlactatemia. Determination of lactate levels may prove useful in the screening for mitochondrial toxicit

Alteration of ribosome function upon 5-fluorouracil treatment favors cancer cell drug-tolerance.

Mechanisms of drug-tolerance remain poorly understood and have been linked to genomic but also to non-genomic processes. 5-fluorouracil (5-FU), the most widely used chemotherapy in oncology is associated with resistance. While prescribed as an inhibitor of DNA replication, 5-FU alters all RNA pathways. Here, we show that 5-FU treatment leads to the production of fluorinated ribosomes exhibiting altered translational activities. 5-FU is incorporated into ribosomal RNAs of mature ribosomes in cancer cell lines, colorectal xenografts, and human tumors. Fluorinated ribosomes appear to be functional, yet, they display a selective translational activity towards mRNAs depending on the nature of their 5'-untranslated region. As a result, we find that sustained translation of IGF-1R mRNA, which encodes one of the most potent cell survival effectors, promotes the survival of 5-FU-treated colorectal cancer cells. Altogether, our results demonstrate that "man-made" fluorinated ribosomes favor the drug-tolerant cellular phenotype by promoting translation of survival genes

Management earnings forecasts and IPO performance: evidence of a regime change

Companies undertaking initial public offerings (IPOs) in Greece were obliged to include next-year profit forecast in their prospectuses, until the regulation changed in 2001 to voluntary forecasting. Drawing evidence from IPOs issued in the period 1993–2015, this is the first study to investigate the effect of disclosure regime on management earnings forecasts and IPO long-term performance. The findings show mainly positive forecast errors (forecasts are lower than actual earnings) and higher long-term returns during the mandatory period, suggesting that the mandatory disclosure requirement causes issuers to systematically bias profit forecasts downwards as they opt for the safety of accounting conservatism. The mandatory disclosure requirement artificially improves IPO share performance. Overall, our results show that mandatory disclosure of earnings forecasts can impede capital market efficiency once it goes beyond historical financial information to involve compulsory projections of future performance

Tolllike receptor 4 (TLR4) polymorphisms in Tunisian patients with Crohn's disease: genotype-phenotype correlation

<p>Abstract</p> <p>Background</p> <p>The immune responses to bacterial products through the pattern recognition receptor (PRR) play a pivotal role in pathogenesis of Crohn's disease. A recent study described an association between CD and some gene coding for bacterial receptor like NOD2/CARD15 gene and TLR4. In this study, we sought to determine whether TLR4 gene was associated with Crohn's disease (CD) among the Tunisian population and its correlation with clinical manifestation of the disease.</p> <p>Methods</p> <p>90 patients with CD and 80 healthy individuals are genotyped for the <it>Asp299Gly </it>and <it>Thr399Ile </it>polymorphisms by restriction fragment length polymorphism analysis.</p> <p>Results</p> <p>The allele and genotype frequency of the TLR4 polymorphisms did not differ between patients and controls. The genotype-phenotype correlation permitted to show that the <it>Thr399Ile </it>polymorphism was associated with early onset disease.</p> <p>Conclusion</p> <p>this study reported the absence of association between CD and TLR4 gene in the Tunisian population, but this gene could play a role in clinical expression of the disease.</p