地方农田生态系统价值动态评价——以2008~2014年河南省安阳市为例

Composition and structure of plant communities can be strongly influenced by plant interactions. Interactions among plants commonly comprise positive and negative effects operating simultaneously and bidirectionally. Thus, a thorough understanding of plant interactions requires experimental separation and quantitative assessment of the bidirectional positive and negative effects that add up to the net effects of plant interactions. Using the close spatial association of annual plants with a desert shrub (Ambrosia dumosa) in a sandy area of the Mojave Desert of California as a test system, we separated and quantified negative and positive effects of annuals on shrubs and of shrubs on annuals. We achieved the separation of negative and positive effects with an experimental design that included reciprocal removals of neighbors and simulations of physical effects of neighbors using artificial structures. All experimental manipulations were conducted on space originally occupied by Ambrosia shrubs to focus on immediate effects of neighbors on water availability rather than on long-term microenvironmental effects (e.g., nutrient accumulation). We quantified positive effects by calculating the difference between performance parameters of neighbors growing with artificial structures (thatch to mimic the physical effects of the presence of annuals and artificial canopies to mimic the physical effects of shrubs) and those of neighbors growing alone (removals). We estimated negative effects by calculating the difference between plant performance on control plots (shrubs and annuals growing together) and performances of plants growing with the artificial structures. Annuals had simultaneously strong negative and weak positive effects on shrub water status, growth, and reproductive output. Annuals also had an impact on the sex expression of shrubs by inducing shifts toward a higher male proportion in inflorescences of monoecious Ambrosia. In contrast, we found strong positive and weak or no negative effects of the shrubs on survival, biomass production, and seed production of the entire annual community and of selected annual species (the abundant native Chaenactis fremontii and the two dominant introduced annual species Bromus madritensis ssp. rubens and Schismus barbatus). Overall, in net effect, the interaction between shrubs and annuals can be described as facilitation or positive net effects of shrubs on annuals, and interference or negative net effects of annuals on shrubs. However, during the growing season, the ratios between positive and negative effects shifted. Annual plants benefited from the presence of shrubs to the greatest extent early in the growing season, and initial negative effects of annuals on shrubs declined as annuals senesced later in the season. Results of this study support the view that an experimental resolution of bidirectional positive and negative effects is necessary to achieve an accurate, mechanistic understanding of species interactions.

Purpose – The serial-multiple mediation of organizational cynicism and life satifaction in the impact of job autonomy on job performance. Design/methodology/approach – Research has been done towards employees of private hospital being active in Kirklareli province. Total 153 persons have participated in the research. SPSS 20.0 and Amos 20 package programs were used for data analysis. For testing hypotheses, it was tested with the IBM SPSS Process Macro application based on the bootstrap method. Findings – It is determined that job autonomy has a positive and meaningful effect on job performance and life satifaction. It is determined that job autonomy has a negative and meaningful effect on organizational cynicism. Model 1, in the research, It have been found as total effect value 0,270, direct effect value 0,233 and total indirect effect value 0,037. Besides, in the research, due to including zero value of bootstrap confidence intervals (-0,003-0,007), it is determined that job autonomy isn’t the serial-multiple mediation role of congnitive cynicism and life satisfaction in the impact of job performance. According to other result of research, Model 2, It have been found as total effect value 0,270, direct effect value 0,206 and total indirect effect value 0,064. In the research, due to including zero value of bootstrap confidence intervals (-0,004-0,012), it is determined that job autonomy isn’t the serial-multiple mediation role of c affective cynicism and life satisfaction in the impact of job performance. Discussion – In the research, it is determined to be relationships between job autonomy, job performance, organizational cynicism and life satisfaction variables. Previous studies in the literature is support this result. It is thought that job autonomy will have the serial-multiple mediation role of organizational cynicism and life satisfaction in the impact of job performance. However, in the results obtained, it has been tested that organizational cynicism and life satisfaction has no serial-multiple mediating effect.

The objectives of this research was to find the effect of the quality of system information, quality of information and perceived usefulness of accounting software to the satisfaction of the end user. This research was conducted at University of Bengkulu. Data collection with questionnaire that spread out to the respondents by census methodology. Then, the data analyzed using SPSS 16. The analysis that conducted in this research was validity test, reliability, normality, multicoliniearity and heteroscedasticity analysis, to get the data that is valid, reliable, normal,and free from multicolinieraity and heteroscedaticity. The result of analysis showed that for the first hypothetical (H1), the level of significancy the accounting software quality was <0,05 with the standardized beta value 0,370, imply that there is a significant and positive effect of the accounting software quality to the end user. For the second hypothetical (H2), there is total effect value 0,61 with significancy level at <0,05, conclude that there is a significant and positive effect of the accounting software quality to the end user by perceived usefulness. For the third hypothetical (H3), the significancy level of information quality was < 0,05 with the standardized beta value 0,314, imply that there is positive and significant effect of the quality of information to the satisfaction of the end user of accounting software. Finally, for the fourth hypothetical (H4), there is total effect value 0,204 with negative standardized value -0,11 and non significant, conclude that the quality of information have negative effect and not significant at level 0,987 to the satisfaction of the end user of accounting software by perceived usefulness

The dependence of oil production in the Gulf Cooperation Council (GCC) region may have environmental consequences. This research explores the nonlinear effects of oil rents and the economic growth of six GCC countries on their per capita CO2, CH4, N2O, and Greenhouse Gas (GHG) emissions, considering spatial linkages through 1980–2014. We apply fixed effects (FE) and corroborate the spatial dependency in all estimated pollution models. Spatial Durbin model (SDM) is utilized to estimate the direct and spillover effects. We find the inverted U-shaped relationship of economic growth with CO2, CH4, N2O and GHG emissions, and of oil rents with CH4 and GHG emissions. Monotonic positive effects of oil rents on CO2 emissions and U-shaped relationship between oil rents and N2O emissions are also found. Urbanization has positive effect on the CO2, CH4 and GHG emissions and has negative effect on N2O emissions. Financial market development (FMD) has negative effects on all types of investigated emissions. Foreign direct investment (FDI) has negative effects on CO2 and N2O emissions. Energy use has positive effects on CO2 and N2O emissions. Further, the neighboring spillover effects of economic growth, oil rents, urbanization, FDI, energy use and FMD are found statistically significant for some investigated emissions. Hence, oil rents, energy use, urbanization and economic growth are responsible for environmental degradation of home and neighboring countries in the GCC region, and we recommend implementing tighter laws to protect the environment.

K rivogorsky and Burton (2012) examine the association between dominant shareholders and firm performance for 1,533 firms from seven Continental European countries using ownership data from 2005 to 2007. The primary analysis in the paper tests the effects of four separate types of dominant owners (institutions, blockholders, banks, and individuals and families) on two measures of accounting performance (return on assets and return on shareholder funds) and a measure of firm value (market-to-book ratio). Supplemental tests examine cross-sectional differences in the effects of each type of dominant owner across individual countries. The main results indicate that banks and individual and family owners have a positive effect on firm performance, while institutions and blockholders have a negative effect on firm performance. The evidence from the within-country tests shows that the relation between particular shareholder types and firm performance varies across different jurisdictions, with dominant owners generally having a positive effect. Dominant shareholders have incentives and the ability to influence the firms in which they own a controlling interest. Dominant owners are motivated to utilize their control to monitor managerial actions because of their claims to the residual profits of the firm (Shleifer and Vishny 1997). Dominant shareholders also have the ability to monitor managerial actions because of their access to inside information and their ability to control internal forces designed to curb managerial actions that are not consistent with maximization of firm value. Thus, monitoring by dominant owners can serve to address the classic agency conflicts between shareholders and investors (Jensen and Meckling 1976), thereby having a positive effect on firm value. In an international context, however, country-level institutions, laws, and other regulatory features can interfere with dominant shareholders’ typical incentives and ability to monitor managerial behavior. Depending on a country’s institutional environment, dominant shareholders could be motivated by a different set of factors, perhaps leading them to take advantage of their ownership status to extract personal benefits from the firm. This type of situation would result in a negative relation between dominant ownership and firm value. Given the potential for either

Editor's evaluation: Competitive interactions between culturable bacteria are highly non-additive

Decision letter: Competitive interactions between culturable bacteria are highly non-additive

Uncovering the lifecycle GHG emissions and its reduction opportunities from the urban buildings: A case study of Macau

Exploring the nexus between agriculture and greenhouse gas emissions in BIMSTEC region: The role of renewable energy and human capital as moderators

One of the most important issues that limits the performance and reliability of SiC power MOSFETs is the threshold voltage instability under normal operation conditions. This phenomenon has been recently studied using dc sweep measurements. In this work, we studied the threshold voltage instability using fast I-V measurements. The results show that under positive bias, VTH shifts to more positive values, while it shifts to more negative values under negative bias. Fast I-V measurements reveal the full extent of the VTH instability, underestimated by the dc measurements. Furthermore, fast measurements allow the separation of negative and positive bias stress effects. A physical model involving fast transient charge trapping and de-trapping at and near the SiC/SiO2 interface is proposed.

Energy-related activities are a major contributor of greenhouse gas (GHG) emissions. A growing body of knowledge clearly depicts the links between human activities and climate change. Over the last century the burning of fossil fuels such as coal and oil and other human activities has released carbon dioxide (CO2) emissions and other heat-trapping GHG emissions into the atmosphere and thus increased the concentration of atmospheric CO2 emissions. The main human activities that emit CO2 emissions are (1) the combustion of fossil fuels to generate electricity, accounting for about 37% of total U.S. CO2 emissions and 31% of total U.S. GHG emissions in 2013, (2) the combustion of fossil fuels such as gasoline and diesel to transport people and goods, accounting for about 31% of total U.S. CO2 emissions and 26% of total U.S. GHG emissions in 2013, and (3) industrial processes such as the production and consumption of minerals and chemicals, accounting for about 15% of total U.S. CO2 emissions and 12% of total ...

Positive and negative direct current (dc) bias effects were investigated for the synthesis of hydrogenated amorphous carbon films in radio frequency plasma chemical vapor deposition at 0.025 Torr and 200 °C. The applied bias ranged from +250 to −500 V. Both the positive and negative dc bias effects are discussed on the basis of surface and cross-sectional morphology by scanning electron microscopy, deposition rate, threshold energy for photoelectron emission, contact angle, and adhesive strength of these films. For a negative bias, the surface of the film is very flat. The surface of the film deposited with no bias is somewhat pebbly while that of the film deposited with a positive bias is very rough and shows the presence of pores in the cross section. A negative bias substantially increases the deposition rate, refractive index, wettability, and adhesive strength. With no bias (ground potential), as compared to with a positive bias, there is a little increase in the wettability and adhesive force. The no bias case did not affect the properties arising from structural change, such as refractive index (density) and threshold energy for photoelectron emission (incorporated hydrogen). A positive bias did not affect these physical properties of the hydrogenated amorphous carbon films. These positive, negative, and no bias effects depend on the kinds of collision species and their collision energy against the substrate in the radio frequency plasma according to the additional bias conditions.

To explores the interface between vertical programmes (VPs) and general health services (GHS) in sub-Saharan Africa. Using semi-structured interviews, we analysed the perceptions of a selection of experienced mid-level managers of health systems and of VP originating in francophone Africa on the nature and quality of this interface. The respondents acknowledged that VPs lead to both positive and negative effects on the functioning of GHS. The overall result, however, cannot be viewed as a simple summation of the positive effects possibly compensating for the negative ones. Indeed, some of the negative effects have a profound impact on the management and operation of the health care delivery system and may undermine the long-term institutional capacity of the general health systems. The quality and the nature of the interface between VP and GHS strongly vary in time, between settings and programmes. We argue for more systematic monitoring of the interface between VP and GHS, so as to identify and address, in a timely manner, significant disruptive effects and deficiencies in a perspective of systemic capacity building of health systems.

Researchers recently proposed a model describing the trade-offs between the positive and negative effects of nitrogen (N) fertilization on biomass and/or abundance of soil biota. The positive effects presumably result from the bottom-up influences of fertilizer-enhanced plant growth and from the improved soil habitat for soil biota. The negative effects presumably result from degradation of soil physico-chemical properties (e.g., salt effect, aluminum toxicity, calcium or magnesium deficiency, soil pH decline, and soil carbon resource availability reduction). The magnitude of these effects determines the net effect (or trade-off) of N fertilization on the biomass and/or abundance of soil biota. Our understanding of how positive and negative effects generate different net effects with changes in the N fertilization level is inadequate. In this paper, we propose two patterns of positive and negative effects (i.e., S-shaped and linear curves when the effects are plotted on fertilization level) and consider the many possibilities for the trade-offs. Specifically, there were 7 possible trade-offs between S-shaped positive effects and linear negative effects, 9 possibilities of the trade-off between linear positive effects and linear negative effects, 20 possibilities of the trade-off between S-shaped positive effects and S-shaped negative effects, and 9 possibilities of the trade-off between linear positive effects and S-shaped negative effects. In addition, the net effect might change or remain neutral (±), positive (+), or negative (−) with increasing nitrogen application. The hypothetical model could help explain the inconsistent results of the impacts of fertilization on soil biota reported in previous studies and could increase our understanding of the responses of soil biota to fertilization and other environmental disturbances.

Introduction: Light livestock is one of the main resources of the red meat supply. In our country, annual growth rate of light livestock production is decreased by 6.4 percent in 1383 -93. In the other words, the required input price of light livestock producing have fluctuations that have much effect on producer decisions quality. Therefore, more attention to light livestock nurturing and factors that are effective on the rate of its supply is understood more than before. So, the article goals include effective factors considering on light livestock supply rate. About the studied subject, many studies have been proformed locally and globally, that include Adam (5) in South Africa, Fisher and Wall in Canada and Australia, Jezghani and Moghaddasi(7), Azizi(3) in Iran. Material and Methods: Research seasonal data includes years 1381-91 and for three provinces of East Azerbaijan, Isfahan & Qom. Price fluctuation is investigated by GARCH models. These models are concentrated on homogenous variance contradiction (stable variance) and instead heterogeneous variance should be encountered as a problem, it is tried the heterogeneous variance is used in modeling. So, a prediction is estimated for every error period variance. The supply function has estimated in an article, is using the method of the state space model which permit seasonal, trend & unobservable cycle elements change during time randomly. The state space model is returned to standard regression model in the unobservable elements absence. The used method for the article for seasonal elements is time fixed seasonal variations. Data analysis: The research indicates that there is inputs prices and light livestock price. Barley price with past season lag, alfalfa price in one and two past season and the light livestock price with past season lag become significant and all GARCH coefficients in every three mentioned variant is less than one percent and significant. According to the effect of independent variants on light livestock supply in province of East Azerbaijan, it is determined that light livestock expected price has positive and significant effect, inputs expected price has negative and significant effect on light livestock supply, variance coefficient of light livestock price has negative and significant effect on light livestock supply, barely input price variance has negative and significant effect on light livestock supply. By considering the effect of independent variants on light livestock supply in Isfahan province , it is determined that expected price of light livestock has positive and a significant effect on light livestock supply, expected price of input on supply rate has negative and significant effect, variance coefficient of light livestock price has negative and significant effect on light livestock supply rates. Barely price variance has a negative and significant effect on light livestock supply. By considering the effect of independent variants on the rate of light cattle supply in Qom province, it is determined that light livestock expected price has positive and significant effect on light livestock supply rates, input expected price has negative and a significant effect on supply rate, variance coefficient of light livestock price has negative and significant effect on light livestock supply rate, barely an input price variance has negative and significant effect on light livestock supply. Summer, autumn and winter seasonal fluctuations, in a province of east Azerbaijan has a negative and significant effect on light livestock supply. Summer and autumn seasonal fluctuations in Isfahan and Qom had negative and significant effect on light livestock supply while winter seasonal fluctuation had a positive and significant effect on light livestock supply. The trend has a positive and significant effect on light livestock supply rate in three provinces. In the other words, trend fluctuation has a positive effect on supply rate. In three provinces, light livestock supply rate has positive and significant cyclic fluctuations with random coefficient in every year. Results: In the provinces of East Azerbaijan, Isfahan, Qom, light livestock expected price has a positive and significant effect on its supply rate. While light livestock price variance has a negative and significant effect on its supply rate. Inputs expect price of and its variance has a negative and significant effect on its supply rate. Cyclic and trend fluctuations have a positive and significant effect on the flight cattle supply rate. Light livestock supply is less elastic than the ratio of inputs price and light livestock price change. The effect of light livestock price risk is greater than the inputs price risk.