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Since Iran is one of the most important countries in producing as well as exporting pistachio and dates Therefore, in this study after calculating exchange rate volatility using the criterion of standard deviation of exchange rate moving average, the effects of this volatility on the export supply of mentioned crops was investigated. Autoregressive distributed lag model, one of the co-integration analysis methods, was used to reach the aim. Export supply function of pistachio to German, Unit Kingdom and Italy and export supply of dates to German, Unit Kingdom and Turkey were estimated. The results indicated that exchange rate volatility has different effects on export of the crops to understudy countries. Therefore in relation to trade policies, the effect of exchange rate volatility on trade should be considered with respect to destined country.

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Computable general equilibrium (CGE) models have become a standard tool of empirical economic analysis and were extensively used to assess the impact of trade liberalization by policy analysts. In this study, the effects of imports tariff reduction as a trade liberalization index are investigated on key economic variables using computable general equilibrium approach. The data used in this study are obtained from the social accounting matrix of year 2001 in which parameters of model are calibrated accordingly. Results of simulations show that if the imports tariff rate is cut by 50% and 100% across all sectors, total supply and investment will reduce while total exports, total imports, household income and consumption will increase.

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Conjunctive use of ground and surface water can increase reliability of the water supply by providing independent sources. In this study, corrected utility-efficient pro-gramming that allows for more than one seasonal irrigation depth for each crop was used to determine the amount of utility maximizing investment in the well capacity for conjunctive use. Results showed that optimum investment at the 15% discount rate for the small, medium and large representative farms with a low degree of risk aversion is 150341, 531592.7 and 1084648 thousand Rials, respectively, which decreases as aversion to risk increases.

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Backgrounds: Bacterial toxins are virulence factors that manipulate the functions of host cells and take over the control of main processes of living organisms. Importantly, they are non-curable, non-contagious, and non-infectious by chemotherapeutic agents and/or antibiotics. The multifactorial nature of the toxicity of bacterial toxins has made their investigation more complicated.
Methods: In this review, we investigated some biological activities, structure, and action mechanism of several bacterial toxins using data from studies published in major international databases.
Conclusion: Bacterial protein toxins are very diverse based on size, structure and mode of action. Based on the structure and the type of cell surface receptors, the mentioned toxins have activity on the cell surface (signal transmission, pore formation) or have intracellular activity. Many bacterial protein toxins have the ability to enter the cell by the endocytosis mechanism, and according to their intracellular targets, they can induce different intracellular effects, which in many cases lead to the death of the target cell. A large and interesting group of bacterial toxins are enterotoxins. The majority of toxigenic bacteria are environmental, and the digestive system is one of the most common ways of entering or encountering environmental bacteria or their toxic products through eating food. Many enteropathogenic bacteria produce enterotoxins in food, in the intestinal lumen or on the surface of the intestinal mucosa. Also, some entero-invasive bacteria penetrate the cells by inoculating some toxins into the intestinal cells. The challenge of studying bacterial toxins and enterotoxins lies in their complex nature and the need for comprehensive characterization, but the future holds promise with advancements in technology and interdisciplinary approaches to further our understanding and develop effective strategies for prevention and treatment.

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The aim of this study is to explore the feasibility of setting up a Commodities Futures Market in Iran. Specifications for the margin requirements, daily price movement limits, the length of expiration intervals, tick sizes and contract size of various potential future contracts are hereby examined. Saffron, pistachio and rice emerge as the three suitable Iranian agricultural commodities. A new computational method of Value at Risk (VaR) optimization model, using a nonparametric sampling approach, is employed to determine the daily margin requirements and daily price fluctuation limits. Expiration intervals are determined by the simulated daily future price with a minimum of volatility. The daily risk free interest rate and the minimum daily average trading value of a participant in the Tehran Stock Exchange (TSE) are used as benchmarks to determine the minimum tick size and contract size for each commodity. These contract specifications are the initially suggested quantities for setting up an agricultural futures market in Iran.

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This research presents the study on mechanical buckling of thick-walled cylindrical shell made of functionally graded materials with ring supported under uniform axial and lateral loads. The mechanical properties of shell are variable along the thickness direction. First the governing equations on the buckling of the FGM cylindrical shell supported with ring are established based on third-order shear deformation theory. Then the governing characteristic equations were employed, using energy method and by applying the Ritz technique. In the following with solving characteristic equations, the critical load buckling of the FGM thick-walled cylindrical shell supported with axial and lateral loads are calculated. The boundary conditions represented by end conditions of the FGM shell are the following: clamped-clamped and free-free. To verify the validity of the proposed analytical method the results of this research are compared with the results came from using the finite element software. Finally, the effects of the different parameters such as thickness variations, boundary conditions, loading conditions and geometrical parameters of shell and ring on the buckling behavior of FGM thick-walled cylindrical shell are investigated. The results showed that by increasing the FGM volume fraction power in the shell structure, the critical buckling load increases and the location of the ring support has the significant effect on the critical buckling load. The results presented can be used as an important benchmark for researchers to validate their numerical and analytical methods.

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Intervening government and performing environmental policies are among solutions for reducing production externalities and achieving sustainable development. Indeed, institutional quality is an effective factor in selecting optimal environment policies. This paper tries to identify optimal environmental policy among common public tools for intervening (pollution taxes and permits) in the presence of environmental and economic uncertainties with various institutional quality degrees. In this paper, institutional quality is included in a dynamic stochastic general equilibrium model and its effect on choosing environmental policy is considered. The results showed that pollution permit is preferred to taxation on pollution with various institutional quality degrees. In addition, with improvement in institutional quality, if only shock is an environmental shocks, then taxation on pollution will be an optimal policy.

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Adoption of multiple climate change adaptation strategies is the most important solution to mitigate the negative consequences of climate change. Therefore, in the present study, economic and social characteristics that affect the intensity of adaptation strategies in the Bakhtegan-Tashk Basin, Iran, were examined using an ordered probit model. A total of 300 farmers were selected using a multi-stage sampling method. The results showed that household income level, access to the credit, availability of irrigation water, number of crops, and farmer membership in agricultural extension classes had significant positive effects on the intensity of adaptation to climate change. Therefore, it is suggested that the government facilitates the use of different climate change adaptive strategies by increasing financial incentives. Also, changing the cropping pattern by planting less water demanding crops that are appropriate for the region is recommended.

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Conservation tillage systems have been promoted by governments in many regions of the world as an effective strategy to reduce soil and water losses caused by conventional ‎farming practices. Considering adoption of the conservation tillage system, in addition to the uncertainty in economic ‎aspects, the attitude of farmers is also important. To assess the risk efficiency of ‎‎five tillage ‎‎‎alternatives (Low-tillage, No-tillage, Conventional tillage, and two Rotational-tillage systems), we used Stochastic Efficiency with Respect to ‎a Function approach for the ‎typical ‎wheat-‎corn ‎‎production system in Marvdasht, Bakhtegan Basin, Iran, using ‎‎‎four-year (2010–2014) field data set. Risk-neutral farmers’ ‎preferred the conventional ‎tillage method over ‎conservation tillage methods, relying on the higher net return ‎‎of the wheat-corn rotation. However, at the higher risk-aversion degrees, the ranking of ‎conventional tillage tended ‎to decline rapidly and ‎the two rotational tillage systems were preferred over other alternatives. The ‎comparison of certainty equivalents of ‎conservation tillage ‎treatments indicated the ‎‎superiority ‎of low-‎tillage over no-tillage at ‎all levels of risk aversion. The results of ‎risk premium ‎estimation ‎in ‎this study revealed that ‎providing subsidy resources is not enough to promote the adoption of conservation tillage practices, and it is ‎necessary to support risk-averse farmers by enhancing their knowledge about the risk-efficient options.