负载纳米水合氧化铁活性炭去除水中铅的实验研究

通过共沉淀法制备一种负载纳米水合氧化铁活性炭,研究其对铅的吸附性能、负载前后活性炭的结构的影响,并进行TEM和XRD表征分析。利用动态小柱实验探究不同p H值、进水浓度和空床接触时间对铅吸附能力的影响,同时比较负载前后活性炭处理实际河道水中铅的吸附穿透曲线。结果表明:无定型的纳米水合氧化铁成功负载于活性炭上,负载后的活性炭显著提高了铅的吸附性能,其对铅的吸附容量随p H值、空床接触时间的增大而增加,进水浓度的变化基本不影响铅的吸附容量。以实际河道水为处理对象,得出负载前后的活性炭穿透点运行的床体积分别为1233和11004,显著提高了9倍,表明负载纳米水合氧化铁活性炭可以有效去除实际水体中的铅,具有良好的应用前景。     

A bioeconomic model for estimating the optimal level of deer and tag sales

This paper presents a dynamic model that determines the optimal number of deer hunting permit sales, subject to the objective of maximizing the discounted economic benefits stream from both the consumptive and nonconsumptive uses of deer. This bioeconomic model integrates economic benefits estimated using the dichotomous choice contingent valuation method with biological growth constraints on deer. Using a hunting zone in California as a case study, the model found that the optimal levels of buck hunting permits sold should change on a rotational basis over time and that the current practice of not selling doe hunting permits for that zone is non optimal.     

员工职业生涯的心理契约的动态管理

员工的职业生涯是一个动态的过程。在这一过程的不同阶段,员工的需求、态度、工作行为都存在着较大的差别,员工与企业之间的心理契约在内容上也会发生变化。而心理契约作为一种隐性契约,具有显著的特殊性,这种特殊性在客观上要求企业对其进行动态管理。本文从职业生涯管理的视角阐述了员工不同职业生涯阶段心理契约的特点以及如何对其进行动态管理。     

Interbank Relationships and the Credit Channel in Germany

A crucial condition for the existence of a credit channel through bank loansis that monetary policy should be able to change bank loan supply. This papercontributes to the discussion on this issue by presenting empirical evidence fromdynamic panel estimations based on a dataset that comprises individual balancesheet information on all German banks. It shows that the average bank reduces itslending more sharply in reaction to a restrictive monetary policy measure the lowerits ratio of short-term interbank deposits to total assets. A dependence on its size canonly be found if explicitly controlled for this dominating effect. Overall, the evidenceis compatible with the existence of a credit channel but the results indicate that it is weakened by the network structures that exist in the German banking system.     

Does too much government spending depress the economic development of transition economies? Evidences from dynamic panel threshold analysis

This paper investigates the relationship between government size and economic growth and determines the optimal level of government spending to maximize economic growth. The paper applies a dynamic panel data analysis based upon a threshold model to test the threshold effect of government spending in 26 transition economies over the period spanning 1993–2016. According to the analysis results, government expenditures have a threshold effect on economic growth, and there is a non-linear relationship depicted as an Armey curve in these transition economies. The findings indicate that a government size above the threshold government spending level adversely affects economic growth, while a government size below the threshold level has a positive effect. Furthermore, there is a statistically significant relationship between the two variables above and below that optimal level, even if we divide the sample into developed and developing countries. Our findings suggest that governments in transition economies should consider optimal government size at around the estimated threshold level to support sustainable economic growth.     

Partial International Coordination in the Great Fish War

This study extends the great fish war model of Levhari and Mirman [Levhari, D. and Mirman, L. (1980) Bell Journal of Economics 11: 322–344] by incorporating a multiple country context into the model and investigates the existence of a partial coordination Nash equilibrium. First, findings of this paper suggest that a partial coordination scheme is sustainable only in limited cases. Any coalition that has more than two member countries cannot be sustained. Second, the existence and the number of coordinating countries depend critically on the magnitude of the biological and preference parameters. Finally, if the coalition is assumed to be a dominant player, there always exist one or two welfare-improving sustainable coalitions and the size of the sustainable coalitions depends on the parameters of the problem.     

Public policies as specification errors

Treating public policies as computable dynamic general equilibrium model specification errors offers computational and conceptional advantages for comparing models with data. The set of policies calculated to rationalize observed behaviors raises the substantive economic question whether, in any particular market, actual public policies sufficiently coincide with the model's behavior-rationalizing policies, or whether the model offers correct hypotheses about the determinants of demand and supply. As illustrations, public policies are calculated to rationalize, with respect to the stochastic neoclassical growth model, capital market behavior since WWII and labor market behavior in 1929–1950. One conclusion is that capital taxation drives a wedge between consumption growth and the expected pre-tax capital return, in the direction and amount predicted by the theory, and that capital taxation is the major intertemporal distortion in the postwar capital market. Second, a good theory of the Great Depression labor market must explain why measured MRS and MPL diverged so dramatically in 1929–1933 and why the wedge persisted.     

The optimal portfolio for the two-pillar mandatory pension system: the case of Poland

In the recent decade, there has been observed across the Central and Eastern European states the regulatory trend towards the increase of the non-financial (first) pension pillar size at the expense of the financial (second) pillar. It tends to question the consequences of this shift for the future retirement benefits. Applying the portfolio approach we address this issue by running a series of simulations to find out how to allocate pension contributions between both pillars in an optimal way. Our study contributes to the existing literature as follows. First, we do not perform the assessment of the predetermined regulatory solutions, but we look for an optimal one. Moreover, we allow our optimal rule to be time-varying, if necessary, which would be a true novelty in this research area. Second, we do not base our estimates on historical trends; rather, we apply the long-term economy’s projection to account for the society’s ageing impact, which is a crucially important factor for the solvency of the pension system. Adapting some of the simulation assumptions to fit the Polish case, our results confirm that current regulations underestimate the role of the capital pillar and the optimal allocation between both pillars should be time-varying.     

Consistency and optimality in a dynamic game of pollution control II: Monopoly

This paper continues a line of research begun in Batabyal (1995a). I model the interaction between a regulator and a monopolistic, polluting firm as a Stackelberg differential game in which the regulator leads. The firm creates pollution, which results in a stock externality. I analyze the intertemporal effects of alternate pollution control measures. The principal issue here concerns the dynamic inconsistency of the optimal solution. Inter alia, I compare the steady state levels of pollution under optimal and under dynamically consistent policies.     

Take a risk: Preferring prevention over control of biological invaders

Scientists have argued that invasive species can be managed most cost effectively with greater investments in prevention. Further, under ideas like the precautionary principle it is reasonable to expect that a cautious manager would use more prevention relative to control because it keeps more invaders out. Yet, this is not typically done. In many cases, private and public resources are invested primarily to control existing invaders rather than to prevent new invasions. Managers frequently wait until after invaders have arrived and then scramble to limit the damages. We believe these paradoxical decisions can be understood by recognizing the link between typical human preferences for risk bearing and the technology of risk reduction. We demonstrate quantitatively how managers perceived to be cautious or averse to risk tend to shy away from prevention relative to control. This counterintuitive result arises because control is a safer choice than prevention because its productivity is relatively less risky: it works to remove existing invaders from the system. In contrast, the productivity of prevention is more uncertain because prevention only reduces the chance of invasion, it does not eliminate it, and invasion may not occur even in the absence of prevention. Managers' averse to risk will inherently avoid as much uncertainty as possible, whether the source of uncertainty regards ecological outcomes or economic productivity. Implications for environmental decision making are clear. In invasive species management, if managers act as though they are risk averse, their caution can backfire when it leads to more control rather than prevention. The social consequences of this choice are a greater probability of future invasions and lower social welfare. Our results suggest that social welfare is highest when managers were willing to “take a risk” with prevention.