甘南黄河重要水源补给生态功能区生态脆弱性及成因分析

甘南黄河重要水源补给生态功能区地处青藏高原的东北边缘,土地总面积为305.7万hm2,其中草地236.1万hm2,占77.2%,是干旱区生态环境变化的敏感地区。该区曾被誉为"黄河蓄水池"的玛曲湿地趋于干涸,生态环境变得十分脆弱。该文在对甘南黄河重要水源补给生态功能区的生态现状进行了剖析的基础上,依据有关生态脆弱性评价方法,结合天然草地分布的实际状况,建立了生态脆弱性评价体系,对该区的草地生态环境进行了综合评价。结果表明:甘南黄河重要水源补给生态功能区的生态环境均属于中度和强度脆弱范围,并就此分析了原因,以期对生态环境的治理提供参考。     

个人负债与政府负债的比较分析

不管是个人或是政府,负债都是具有一定风险的,如果确需负债,必须在资金使用的监控、披露制度的建设上予以加强,以减少债务风险;做好防范和化解财政风险的预案,以避免对国家宏观经济造成冲击。     

基于全寿命周期分析的电力设备费用模型

针对我国供电企业的实际情况,将电力设备费用分为一次投资费用和运行维护费用两部分,建立了电力设备全寿命周期费用定量模型。针对一次投资费用的特点,建立了基于时间分摊的一次投资费用模型;针对运行维护费用长期发生的特点,建立了基于灰色关联度确定分布类型的运行维护费用模型。同时,将两个费用模型综合考虑,建立了供电企业电力设备全寿命周期费用模型,据此可计算电力设备全寿命周期最小费用和最佳使用寿命。最后,以某变电站综合自动化项目为例,验证了该模型的有效性。     

The effects of government expenditure on imports in the Eurozone reconsidered: evidence from panel data

This study examines the impact of government expenditure on imports. The empirical analysis is based on annual data of the euro area countries for the period 1995–2015. We employ econometric methods that mitigate heterogeneity and cross-sectional dependence. We provide empirical indications that the components of expenditure have different impact on imports demand. The findings of this study indicate that the import context of government expenditure is lower than the import context of others expenditure components. Finally, we find that an increase in government expenditure leads to an increase in imports; this implies that, ceteris paribus that it can lead to a deterioration of the trade balance.     

Neutral agents and social tolerance: a dynamic perspective based on economic interaction model with local social cost functions

The influence of neutral agents on the evolutionary dynamics of social tolerance is discussed based on a recently proposed economic interaction model with local social cost functions. We show that the dynamical structure of social tolerance is completely changed even if a few neutral agents are introduced into the society. Especially, the full intolerance steady state, which is stable in previous works, becomes unstable and avoidable due to the economic incentive introduced by the neutral agents. The necessary condition of achieving full tolerance is also reduced compared to previous works without neutral agents.     

Investigating properties of commodity price responses to real and nominal shocks

This paper studies dynamic adjustments of 49 world commodity prices in response to innovations in the nominal exchange rate and the world real GDP. After we estimate the dynamic elasticity of the prices with respect to these shocks, we obtain the kernel density of our estimates to establish stylized facts on the adjustment process of the commodity price toward a new equilibrium path. Our empirical findings imply, on average, that the law of one price holds in the long-run, whereas the substantial degree of short-run price rigidity was observed in response to the nominal exchange rate shock. The real GDP shock tends to generate substantial price fluctuations in the short-run because adjustments of the supply can be limited, but have much weaker effects in the long-run as the supply eventually counterbalances the increase in the demand. Overall, we report persistent long-lasting effects of the nominal exchange rate shock on commodity prices relative to those of the real GDP shock.     

A secure hash function based on feedback iterative structure

Rapid growth of internet data has created enormous security challenges on authenticity, availability and integrity protection of these outsourced data. Hash function is one of the main solutions to face these challenges. This paper proposes a feedback iterative structure of hash function which utilises the variable feedback to resist attacks. Furthermore, to accelerate message diffusion, two novel modules are designed, one for iteration and the other for truncation. Experimental results show that the proposed hash function can effectively resist existing attacks. Moreover, comparing with other existing hash functions, it displays better on statistical performance, collision resistance and avalanche.     

Compound trend renewal process with discounted claims: a unified approach

We derive recursive formulas for the moments of compound trend renewal sums with discounted claims. An integral expression for the moment generating function of this risk process is then obtained, from which particular distribution functions are found. We extend the compound (deterministic) trend renewal process by assuming a stochastic trend, a stochastic force of net interest and a stochastic dependence between the inter-occurrence times and the severities of the claims. Finally, stochastic dominance ordering is also observed between the compound trend renewal process and an associated non-homogeneous Poisson process.     

WHAT AFFECTS EFFICIENCY IN LABOUR MARKET MATCHING AT DIFFERENT TERRITORIAL AGGREGATION LEVELS IN POLAND?

We analyse efficiency of a labour market matching process at different levels of territorial aggregation and in different time horizons. We apply a stochastic matching frontier to random, job queuing and stock‐flow models. We use data for Poland, a country with highly regionally diversified unemployment. We find that search and matching mechanisms significantly differ with territorial aggregation. Higher efficiency in small regions results from lower frictions. Larger regions enjoy better structural matching if only labour market participants have time to search. Different policy measures should be designed to improve labour market matching efficiency at different regional levels.     

INTERACTION TERMS IN POISSON AND LOG LINEAR REGRESSION MODELS

This paper develops a difference‐in‐semielasticities (DIS) interpretation for the coefficients of dichotomous variable interaction terms in nonlinear models with exponential conditional mean functions, including but not limited to Poisson, Negative Binomial, and log linear models. We show why these interaction term coefficients cannot be interpreted as a DIS or semielasticity in the same manner as continuous coefficients, which has been overlooked by some empirical researchers. Then we show how interaction terms can be easily transformed into a DIS and derive the asymptotic distribution of this estimator. We illustrate the discrepancy between the interaction term coefficient and the DIS using an empirical example evaluating the relationship between employment, private health insurance and physician office visits. Our results can be applied in treatment effect models when the outcome variable is logged and the dichotomous variables indicating treatment participation and the post‐treatment time period.