ORIGINAL_ARTICLE Empirical Comparison of Direct Techniques for Measuring Attitudes Toward Risk The purpose of this study was to compare various direct techniques of measuring attitudes toward risk. The Equally Likely Certainty Equivalent with a Purely Hypothetical Risky prospect (ELCE-PH), The Equally Likely Certainty Equivalent with a Hypothetical but Realistic Risky prospect (ELCE-R) and Probability of Winning Demanded (PWD) models were used to elicit the risk attitude of a sample of farmers. These methods were then compared and evaluated. The criteria employed were (1) sample respondent capability in answering questions, (2) means and corresponding risk attitudes classification and (3) distribution of risk attitudes. According to the first criterion, the results showed PWD technique is the best one. While there are no differences among the three direct techniques on the basis of the second criterion. Also, the findings indicate that respondent education and age, family education, level of hypothetical income and a greater explanation by other people during interview have an influence on respondent capability in answering questions. These characteristics should therefore be considered when choosing the appropriate technique. http://jast.modares.ac.ir/article-1-5933-en.pdf 2010-05-16 163 170 Attitudes toward risk Certainty equivalent Probability of winning demanded J. Torkamani 1 Department of Agricultural Economics, College of Agriculture, Shiraz University, Shiraz, Islamic Republic of Iran. AUTHOR M. Abdolahi 2 Department of Agricultural Economics, College of Agriculture, Shiraz University, Shiraz, Islamic Republic of Iran. AUTHOR
ORIGINAL_ARTICLE In vitro Sucrose Uptake and Starch Synthesis by Isolated Wheat (Triticum aestivuim) Grains The aim of this study was to establish and optimise a simplified method of halved grain culture, in order to utilise it to evaluate the ability of isolated sinks (developing wheat grains) in sucrose uptake and conversion (defined by sink strength) under unlimited source conditions. Both sucrose uptake and starch synthesis increased linearly over the incubation periods used in this study. A biphasic pattern of sucrose uptake in response to external sucrose concentrations was evident. Starch synthesis also increased curvilinearly with respect to external sucrose concentration. 2,4-dinitrophenol (DNP)) inhibited both sucrose uptake and starch synthesis. An increase in pH from 6.5 to 8 reduced both sucrose uptake and, to a lesser extent, starch synthesis. From these observations, a metabolically active uptake of sucrose by endosperm cells concomitant with a diffusional influx of sucrose into the endosperm cells were both evident. The relative importance of both the active and diffusional movement of sucrose and the importance of transport across the plasma membrane is discussed in the text. http://jast.modares.ac.ir/article-1-259-en.pdf 2010-05-16 171 179 Wheat DNP In vitro sucrose uptake Starch synthesis A. Ahmadi 1 Department of Agronomy and Plant Breeding, College of Agriculture, University of Tehran, Karaj, Islamic Republic of Iran. AUTHOR D. A. Baker 2 Department of Biological Sciences, Wye College, University of London, Wye, Ashford, Kent TN 25 5AH, UK. AUTHOR
ORIGINAL_ARTICLE The Effects of Early Season Drought on Stomatal Conductance, Leaf-air Temperature Difference and Proline Accumulation in Sugar Beet Genotypes. Limited water for irrigation and the coincidence of early growth of sugar beet (Beta vulgaris L.) with the late growth of winter cereals in the Northeast (NE) of Iran, force farmers, to allocate their limited irrigation water to the cereal crops and thus their sugar beet crop is subjected to an early water stress. Finding cultivars which are able to withstand early water stress without a significant yield reduction is critical to the farmers’ economy. This study was conducted over a two-year period (1998 and 1999) to evaluate the response of nine sugar beet genotypes to drought stress and to determine the crop traits associated with drought resistance. The results showed that stomatal conductance, leaf-air temperature difference and proline accumulation were associated with levels of water stress in sugar beet genotypes. Among these indices, leaf-air temperature difference was a more precise parameter to measure. A negative correlation between Δ T (leaf -air temperature) and stomatal conductance was found. The correlation coefficients for 1998 and 1999 were -0.87 and -0.58, respectively. There was a positive correlation between Δ T and proline accumulation in sugar beet genotypes. The correlation coefficients for the 1998 and 1999 experiments were 0.61 and 0.49, respectively. The shoot: root ratio (S:R) measured at the end of the stress period showed that genotypes with a lower S:R often had a greater stomatal conductance. In general, genotypes with a lower S:R at the end of the stress period usually had a greater root dry weight. The correlation coefficients of S:R with root dry weight at the end of the stress period were -0.96 and -0.65 for 1998 and 1999, respectively. http://jast.modares.ac.ir/article-1-5731-en.pdf 2010-05-16 181 192 Drought Stress Proline Temperature Leaf conductance Shoot: root ratio Sugar beet R. Mohammadian 1 Khorasan Agricultural Research Center, Mashhad, Islamic Republic of Iran, P.O. Box: 91735-488. AUTHOR F. R. Khoyi 2 Faculty of Agriculture, Tabriz University, Tabriz, Islamic Republic of Iran. AUTHOR H. Rahimian 3 College of Agriculture, University of Tehran, Karaj, Islamic Republic of Iran. AUTHOR M. Moghadam 4 Faculty of Agriculture, Tabriz University, Tabriz, Islamic Republic of Iran. AUTHOR K. Ghassemi-Golezani 5 Faculty of Agriculture, Tabriz University, Tabriz, Islamic Republic of Iran. AUTHOR S. Y. Sadeghian 6 Sugar Beet Seed Institute, Karaj, Islamic Republic of Iran. AUTHOR
ORIGINAL_ARTICLE Feeding Whole Wheat With or Without a Dietary Enzyme or Grit to Laying Hens A 3*2*2 factorial experiment was conducted to study the effect of feeding whole wheat (0, 10, and 20%), a microbial enzyme source (Arabino-xylanase based enzyme for wheat at 0% and 0.1%) and 0% or 1% insoluble grit (number 3 layer size) on the performance of White Leghorn hens at 19 to 54 weeks of age. Each dietary treatment was replicated four times with ten hens, housed two to a cage, each. No main treatment effects or interactions were observed for egg production, feed efficiency, egg weight, body weight gain, or mortality. Feeding 20% whole wheat produced the lowest incidence of cracked, broken, or soft shelled eggs. Adding the enzyme significantly (P<0.05) reduced daily feed intake from 124.6 to 122.2 g. Enzyme addition also resulted in minor, but significant (P<0.05), increases in egg specific gravity from 1.0800 to 1.0806. Inclusion of 20% whole wheat does not adversely affect the productivity of White Leghorn hens and therefore can be used to reduce the cost of feed processing. http://jast.modares.ac.ir/article-1-9225-en.pdf 2010-05-16 193 198 Enzyme Grit Processing White Leghorn Whole wheat H. Kermanshahi 1 Department of Animal Science, College of Agriculture, Ferdowsi University of Mashhad, P.O. Box AUTHOR H. L. Classen 2 Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, Saskatchewan, Canada, S7N 0W0. AUTHOR
ORIGINAL_ARTICLE In Vitro Oocyte Maturation in a Hybrid Sturgeon, Bester: Changes in the Germinal Vesicle Breakdown and 17, 20β- dihydroxy-4-pregnen-3-one Production In order to determine the most effective hormones on the in vitro oocyte maturation (germinal vesicle breakdown - GVBD) in a hybrid sturgeon bester, ovarian follicles were incubated at the migratory nucleus stage in the presence of several steroids, gonadotropin preparations and forskolin. Occurrence of GVBD and 17,20β-dihydroxy-4-pregnen-3 -one (DHP) production were followed during an experimental period of one year of germinal vesicle (GV) migration. From all the steroids tested, three progesterone derivatives-17α- hydroxyprogesterone (17αOHP), 17, 20β, 21-trihydroxy-4-pregnen-3-one (17, 20 β, 21- triol), and DHP-were the most potent steroid inducers of GVBD, followed closely by deoxycorticosterone (DOC). No GVBD responses were found in ovarian follicles in July when the GV was still central. The responsiveness increased gradually from then and reached its peak in November when the GV had migrated fully towards the oocyte periphery. Their potencys gradually declined later from December and the oocytes lost their ability to mature the next July when degeneration set in. DHP production by ovarian follicle during successive months of nucleus migration demonstrated a relatively similar pattern of GVBD frequencies. These results indicated again a relevant role for DHP on oocyte maturation in the bester and also suggested that GV localization along with in vitro oocyte maturation assay can be used as practical tools for selecting the appropriate individuals in exogenous induced spawning in bester. http://jast.modares.ac.ir/article-1-10167-en.pdf 2010-05-16 199 207 In vitro Bester DHP GVBD Maturation B. Mojazi Amiri 1 Department of Fisheries and Environmental Sciences, Faculty of Natural Resources, University of Tehran, Karaj, 31585-4314, Islamic Republic of Iran, AUTHOR M. Maebayashi 2 Department of Research and Development, The Hokkaido Electric Power Co., Inc., Sapporo 004, Japan. AUTHOR N. Omoto 3 Department of Research and Development, The Hokkaido Electric Power Co., Inc., Sapporo 004, Japan. AUTHOR S. Adachi 4 Department of Biology, Faculty of Fisheries, Hokkaido University, Hakodate 041, Japan. AUTHOR K. Yamauchi 5 Department of Biology, Faculty of Fisheries, Hokkaido University, Hakodate 041, Japan. AUTHOR
ORIGINAL_ARTICLE Growth Response of Eight Hardwood Species to Current and Past Climatic Variations Using Regression Models The impact of climatic variations on basal area growth of basswood (BA) (Tilia americana L.), American beech (BE) (Fagus grandifolia Enrh.), bitternut hickory (BH) (Caria cordiformis (Wang.) K. Koch), largetooth aspen (LA) (Populus grandidentata Michx.), red maple (RM) (Acer rubrum L.), red oak (RO) (Quercus rubra L.), sugar maple (SM) (Acer saccharum Marsh.), and white ash (WA) (Fraxinus americana L.) was studied in a southern province of Quebec, Canada (45o 25 ’ N, 73 o 57 ’ W). In total, forty-eight climatic variations of precipitation (P) (13 variables), temperature (T) (13 variables), heat index (H), (11 variables), and evapotranspiration (11 variables) from the current (C) and past three years (P1, P2, & P3) were tested in regression models to find the best model of the relationship between those independent variables and the last ten years (1985-1994) of basal area growth of the species. Simple individual linear and second degree, mixed, and combination of multiple regression models were used to develop the best regression model for each tree species, separately. The best models explained 79% , 80% , 99% , 91% , 71%, 99% , 49% , and 98% of the total variance of the growth in BA, BE, BH, LA, RM, RO, SM and WA, respectively. The growth in BH, LA, RM, RO, SM, and WA were more associated with the previous year’s climatic variations rather than the current year’s. Bitternut hickory, LA, RM, SM, and WA growth were more related to the first year rather than the second or third preceding year variables. The June heat index of the third previous year of variables explained only 7% of the growth of white ash. It was concluded that the impact of climatic variables on tree growth may vary and may depend on the species and other unknown variables. Also, the results suggested that the first and second previous climatic variables have an important role on the growth of some species. American beech, BH, RO, and WA seem to be a good species to use for the study in dendrochronological and dendroclimatological studies. http://jast.modares.ac.ir/article-1-10373-en.pdf 2010-05-16 209 225 Basal area growth Climatic variations Regression models H. Jalilvand 1 Department of Forestry, Faculty of Natural Resources, Mazandaran University, P.O.Box 737, Sari, Islamic Republic of Iran. AUTHOR s. gh. Jalali 2 Tarbiat Modarres University, Noor, Mazandaran, 46414, Islamic Republic of Iran. AUTHOR M. Akbarian 3 Tarbiat Modarres University, Noor, Mazandaran, 46414, Islamic Republic of Iran. AUTHOR M. Tabari 4 Tarbiat Modarres University, Noor, Mazandaran, 46414, Islamic Republic of Iran. AUTHOR S. M. Hosseini 5 Tarbiat Modarres University, Noor, Mazandaran, 46414, Islamic Republic of Iran. AUTHOR
ORIGINAL_ARTICLE Sensitivity of Soil Coupled Heat and Mass Transfer Governing Equations to Hydraulic and Thermal Conductivities A pressure-based coupled heat and mass transfer model was used to simulate temperature and soil suction in a drying process within a clay soil column. Closed form functions were used for all parameters needed in the governing equations. Model predictions were compared with experimental data using the mean relative percentage deviation method. Thermocouples and mini-gypsum blocks were used to monitor the data collected hourly at different depths of the soil column. The model showed very high sensitivity to the proposed hydraulic conductivity function, while lower sensitivity was found for the proposed thermal conductivity function. This result highlights the importance of a proper hydraulic conductivity estimate while a rough estimate for thermal conductivity would have no significant adverse effect on the predicted values. http://jast.modares.ac.ir/article-1-2335-en.pdf 2010-05-16 227 235 Matric suction Drying process Mini-gypsum blocks porous media A. Keyhani 1 Department of Power and Machinery, Faculty of Agriculture, University of Tehran, Karaj, Islamic Republic of Iran. AUTHOR D. Wulfsohn 2 Institute for Maskinteknik, Aalborg Universitet, Potoppianstraede 101, 922 Aalborg Oest, Denmark. AUTHOR
ORIGINAL_ARTICLE Process Optimization of Ricotta Cheese According to Iranian Preferences In this study, the optimum combination of major factors affecting the acceptability of whey-based Ricotta cheese i.e. fat at three levels (0, 5, 10%), salt at three levels (0, 1, 2%), and starter culture at two levels (0, 3%) was determined in a complete randomized design method with a factorial experiment. Ricotta cheese trials made by mixing whey and milk in a ratio of 5:1 were then organoleptically judged on the basis of the main attributes such as color, flavor, texture, and overall acceptability. The collected data were then statistically analyzed using a seven point hedonic method. The results show that the addition of fat had a significant effect on all sensory attributes (p< 0.05). The incorporation of salt in the formulation also had a significant effect on flavor, color, and overall acceptability (p< 0.05) as well as on texture (p< 0.01), whereas the addition of starter culture had a significant effect only on texture (p< 0.01) and overall acceptability (p< 0.05). It was concluded that a combination of 5% fat, 2% salt, and 3% starter culture gains a higher score and could be recommended as the preferred formulation for Iranian consumers. http://jast.modares.ac.ir/article-1-10450-en.pdf 2010-05-16 237 240 Whey formulation Process optimization Ricotta cheese M. B. Habibi Najafi 1 Department of Food Science & Technology Faculty of Agriculture, Ferdowsi University of Mashhad, P. O. Box 91775-1163, Mashhad, Islamic Republic of Iran. AUTHOR A. Moatamedzadegan 2 Department of Food Science & Technology Faculty of Agriculture, Ferdowsi University of Mashhad, P. O. Box 91775-1163, Mashhad, Islamic Republic of Iran. AUTHOR