This paper introduces a computational model of online collaborative learning system and investigates how the heterogeneity of opportunity cost among users initiates a vicious cycle of accumulation of unnecessary duplicate postings and eventually the system shuts down. Further examination explores how deterring newcomers improves collaborative learning system efficiency by reducing unnecessary d...

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We analyze the influence of tax progression on optimal investment policy and its value. We show that three possible optimal regimes arise, depending on the nature of the tax policy. If the exogenously given progression threshold lies between the optimal capital stocks in the case of higher and lower marginal profit taxes, then the optimal investment policy is independent of profit tax rates. Bu...

We analyze the impact of tax progression on optimal investment policy and its value by first demonstrating that optimal investment policy maximizes the value of the firm and the rate at which it is growing as a function of operating capital stock. Then we show that three possible optimal regimes arise depending on the nature of tax policy. If the exogenously given progression threshold lies bet...

We explore the implications of endogenous credit market imperfections for the relationship between property crime and the process of economic development. In the initial stages of development, property crime rises as the opportunities to gain from illegal activities expand. In later stages, however, crime falls as capital market imperfections are overcome and legal activities become more pro ta...

This chapter considers a recent trend in the application of stochastic games to economics characterized by the use of the latticetheoretic approach to capture the monotonic properties of Markovian equilibria. The topics covered are: (i) a general framework for discounted stochastic games with Lipschitz-continuous and monotone equilibrium strategies and values, (ii) a model of capital accumulati...

background this study demonstrates the removal efficiency of phenol from aqueous solutions by electrocoagulation process using aluminum electrodes and also investigates solution chemistry and polymeric natural organic matters on removal efficiency objectives: the main aim of this work was to focus on the removal of phenol by electrocoagulation process using aluminum electrodes. materials and me...

background facultative marine fungi could potentially be arsenic tolerant and may be able to remove this highly poisonous metal from the environment. objectives the objective of this work was to explore the degree of tolerance and removal efficiency of two facultative marine fungi. materials and methods facultative marine fungi aspergillus flavus and rhizopus spp. were exposed to 25 mg/l and 50...

in order to investigate the effect of different levels of biological fertilizers on potato performance (cv. marfona), an experiment was carried out as strip plot based on rcb design with 3 replications in 2011 at isfahan. treatments included nitrocara at 4 levels (0: control, 220, 330 and 440 ml.ha-1) as a first factor and nitroxin+ phosphate at 4 levels (0+0: control, 20+100, 30+150 and 50+200...

background: a pot experiment was conducted to determine the toxic effects of some heavy metals on the plant growth and seed yield of maize (zea mays l.). materials and metheds: heavy metals mn, pb, cd, cr and co individually and in combinations were added as chloride salts in solutions to the pots before sowing. the test plants for were harvested after 80 days of germination and evaluated for n...