Dynamic behavior in a Cournot duopoly with social responsibility

In an oligopoly with isoelastic demand, the paper analyzes the quantity competition between NPM profit-maximizing firms and NRS socially responsible firms whose objective function is a linear combination of profit and consumer surplus. From the static analysis it follows that greater social responsibility has a competitive effect, since reduces the equilibrium price and increases the market share of socially responsible firms. In addition, it increases both the consumer surplus and total surplus. For the duopoly case, the dynamic study leads to the conclusion that, if at least one of the firms follows the gradient rule as an adjustment mechanism, an increase in the speed of adjustment is a source of instability. An increase in the value of the elasticity of demand as well as a reduction in the marginal cost has a stabilizing effect on the Cournot equilibrium. A higher level of social responsibility exerts a stabilizing role on the dynamics as long as demand is sufficiently elastic

Nonlinear Cournot and Bertrand-type dynamic triopoly with differentiated products and heterogeneous expectations

In a differentiated triopoly model with heterogeneous firms, the local stability of the Nash equilibrium under both quantity and price competition is analyzed. We find that the presence of a firm following a gradient rule based on marginal profits, and a player with adaptive expectations, determines the local stability of the Nash equilibrium, regardless the competition type, while the effects of the degree of product differentiation on the stability depend on the nature of products. Moreover, the Nash equilibrium is more stable under quantity competition than under price competition

Relationship between vitamin D3 deficiency and polycystic ovarian syndrome

Background: Vitamin D3 (VD3), a seco-steroid that is synthesized in skin and sequentially metabolized in liver and kidneys in humans, has been well-known for its function in maintaining calcium and phosphorus homeostasis and promoting bone mineralization. Polycystic ovary syndrome (PCOS) is a common cause of ovarian dysfunction in women with anovulation. Aim of this study is to show and evaluate VD3 level in women who are suffering from polycystic ovarian syndrome.Methods: This study was conducted on 200 women; group A: (study group) 100 infertile women who were suffering from PCOS and group B: (control group) 100 patients were selected with other cause of infertility than PCOS. US examination, hormonal profile (FSH, LH, AMH, TSH and prolactin level) and laboratory assay of serum VD3 level (postmenstrual) were done for every patient to evaluate relationship between VD3 deficiency and PCOS patients.Results: There was a significant relationship between group A compared to group B as regards irregular menstrual cycle, clinical hyperandrogenism, LH/FSH ratio and AMH. There was no significant difference between both groups as regards TSH, prolactin and VD3 level. VD was deficient in both groups as it was lower than normal level. There was a negative significant correlation between VD3 level and both hyperandrogenism and AMH.Conclusions: There was VD3 deficiency in PCO patients and infertile cases due to another factor, and negative significant correlation between VD3 level and clinical hyperandrogenism, LH/FSH ratio, menstrual cycle and AMH

Influence of host plants and some leaf contents on biological aspects of Tetranychus urticae Koch (Arachnida: Acari: Tetranychidae)

Abstract Background Phytophagous mites infest most host plants as vegetable, field crops, and ornamental plants. Tetranychus urticae spend most of its life cycle on plant, especially on leaves, and it causes serious damage. The development periods and reproduction of T. urticae are influenced by characteristics for host plant. Purpose of the study To know the effect of host plant on Tetranychus urticae in order to recognize the most suitable hosts for increasing population Tetranychus urticae to be used as food for the mites, as a bio-control agent against different pests. Results The results revealed that the hosts affected significantly on incubation period. Significant differences were found among different host plant leaves for longevity, life span periods and average oviposition period of T. urticae under controlled temperature (28.5 ±2 °C) and relative humidity (76 ±5 %). Average of the reproduction rate per female was higher when T. urticae was reared on leaves of mulberry, while the percentage of hatchability was highest when the females were fed on leaves of mulberry. The sex ratio was higher when it was fed on leaves of castor bean. Nitrogen content in host plant leaves varied, and differences were found between three host plants in concentrations concerning phosphorus, potassium, and total chlorophyll. The correlation between longevity period and nitrogen was highly significantly positive in the case of sweet potato, while the correlation between the duration spider mite life cycle and nitrogen content and the correlation between longevity periods with potassium were significantly positive in castor bean. Conclusions Total immature stages and life cycle were shortest when spider mite was fed on mulberry leaves. The greatest values of reproduction rate and hatchability were on mulberry leaves than on other crops and followed by castor bean. Sex ratio of T. urticae was highest on castor bean leaves. Developmental and reproduction rate of T. urticae are influenced by tissue nutrient content for host plant