一种改进的多学习教与学优化算法

针对传统教与学算法在解决复杂多峰函数优化问题时,具有局部最优且搜索开发能力较差的缺点,提出了一种改进的多学习教与学优化算法,新算法为学员的每一维加入不同的教学因子,设计了基于学员均值比较的教师选择策略和向教师及学员学习的多学习策略。基于多个单峰和多峰函数的仿真结果表明,新算法跟传统的、改进的教与学算法相比,在稳定性、寻优精度和收敛速度方面更具优势。     

Environmental Awareness, Economic Orientation, and Farming Practices: A Comparison of Organic and Conventional Farmers

/ This study examines similarities and differences between organic and conventional farmers. We explore the factors that underlie farmers' conservation attitudes and behaviors, including demographic and farm characteristics, awareness of and concern for environmental problems associated with agriculture, economic orientation toward farming, and self-reported conservation practices. A series of intensive personal interviews was conducted with 25 farmers in Washtenaw County, Michigan, USA, using both qualitative and quantitative survey methods. The findings indicate that both groups of farmers share a concern for the economic risks associated with farming, although the organic farmers reported a significantly greater concern for long-term sustainability and a greater willingness to incur present risk to gain future benefits. Organic farmers expressed a greater awareness of and concern for environmental problems associated with agriculture. Organic farmers also scored significantly higher on a multifaceted measure of conservation practices, although both groups had a fairly high adoption rate. Implications of these findings are discussed, relative to economic risks of farming, implications for new farmers, effectiveness of conservation education and government programs, and impact of farm size and crop diversity.KEY WORDS: Environmental attitudes; Conservation behaviors; Organic farming; Agricultural sustainability     

Overview of the relationship between organizational and workplace factors and injury rates

This paper summarizes data from ten studies examining the relationship between organizational and workplace factors and injury rates. The studies were identified from a systematic literature search, as well as from other sources, and were included if they reported comparisons among at least 20 workplaces. Factors that were examined in at least two studies were identified. Their relationship with injury rates was determined. It was not possible to make quantitative comparisons between studies. We looked for ‘consistency’ or ‘contradiction’ in the relationships. Among the variables ‘consistency’ associated with lower injury rates were: empowerment of the workforce (in general matters); delegation of safety activities; and an active role (in health and safety) of top management. Among the ‘contradictory’ variables were the level and use of discipline for safety violations; and several others that were contradictory only in subgroups of the same study. We discuss the limitations of synthesizing results from the diverse studies.     

An assessment of historical change in two northern Minnesota lakes

Two northern Minnesota lakes that had been studied in detail 22 years earlier (1958) were restudied to determine the extent of alteration in ecological conditions. Approximately one year after the original investigation, a coal-fired power plant, which incremented sulfate loading by about 6 kg/ha-yr, began operation nine miles away. These lakes lie within a region judged susceptible to acidic precipitation, though each lake, based on its buffering capacity, would be judged only moderately sensitive. In spite of the influence of this plant and other anthropogenic inputs, the change in lake ecology was apparently minimal. Water clarity decreased in both lakes and some alteration in zooplankton community structure was observed. The long-term utility of lake surveys depends upon how carefully and completely conditions can be reconstructed from records and reports. Past surveys generally omit measures of variability for the data, allowing only qualitative comparisons to be drawn. In order to judge the graded responses of aquatic ecosystems, necessary to sound management, quantitative measures are needed.Deceased.     

Predicting biodiversity change: outside the climate envelope, beyond the species-area curve

Efforts to anticipate threats to biodiversity take the form of species richness predictions (SRPs) based on simple correlations with current climate and habitat area. We review the major approaches that have been used for SRP, species-area curves and climate envelopes, and suggest that alternative research efforts may provide more understanding and guidance for management. Extinction prediction suffers from a number of limitations related to data and the novelty of future environments. We suggest additional attention to (1) identification of variables related to biodiversity that are diagnostic and potentially more predictable than extinction, (2) constraints on species dispersal and reproduction that will determine population persistence and range shifts, including limited sources or potential immigrants for many regions, and (3) changes in biotic interactions and phenology. We suggest combinations of observational and experimental approaches within a framework available for ingesting heterogeneous data sources. Together, these recommendations amount to a shift in emphasis from prediction of extinction numbers to identification of vulnerabilities and leading indicators of change, as well as suggestions for surveillance tools needed to evaluate important variables and the experiments likely to provide most insight.     

Beyond demographic identities and motivation to learn: The effect of organizational identification on diversity training outcomes

There is a pressing need for better explanations of diversity training effectiveness so that organizations can administer training programs that facilitate positive intergroup interactions. In this paper, we consider the unique predictive effect of organizational identification on diversity training outcomes beyond the effects of the traditional predictors of demographic-based identities and motivation to learn across two samples of employees involved in diversity-related training at their employing organizations. Organizational identification predicted unique variance in voluntary participation in diversity training, diversity training-related knowledge application, motivation to transfer diversity training, and diversity training-related organizational citizenship behavior intentions. Research and practitioner implications are discussed based on our findings.     

Measuring participation by socially vulnerable groups in hazard mitigation planning,Bertie County,North Carolina

In accordance with the Disaster Mitigation Act, most US counties have a hazard mitigation plan (HMP) to reduce future disaster losses. HMPs are important as they can be used to proactively assess risk, direct future development, raise awareness and build consensus. Using a population-based sample, we interviewed residents of Bertie County, NC, about their awareness of and participation in the HMP process to determine if demographics, social vulnerability or hazard vulnerability were associated with increased awareness or participation. We also assessed whether these factors were associated with knowledge of policy changes and investments that were adopted in the HMP. Overall, the unemployed were the only group less likely to report awareness of or participation in HMP development. African-Americans, mobile home residents, the poor, short-term residents and those with less disaster experience were less likely to be aware of policies and investments prioritised in the HMP. Targeted efforts to increase awareness could potentially improve disaster outcomes among vulnerable populations.     

Studies on phytotoxic effect of aluminium on growth and some morphological parameters of Vigna radiata L. Wilczek

Aluminium toxicity is a major deterrent for plant growth in acid soils below pH 5.0. This study deals with effect of aluminium toxicity on growth of mungbean (Vigna radiata L. Wilczek) seedlings. Seed germination (in %) declined with increased content of Al2(SO4)3, while promotive effect was observed at very low dosage. Different concentrations of aluminum sulphate salt were applied to mungbean seeds. Measurement of aluminium content in mungbean leaves was done through atomic absorption spectrophotometer. Root length (root and hypocotyl length) and shoot length (shoot and epicotyl length) was measured at seven days old seedling stage. Different concentrations of Al2(SO4)3 were found to have significant effect both on shoot and root length. Leaf area, fresh and dry weight was significantly reduced. Increased stomatal frequency and trichome density with an increase in concentrations of Al2(S04)3 was observed through scanning electron microscope.     

Measurement of effective air diffusion coefficients for trichloroethene in undisturbed soil cores

In this study, we measure effective diffusion coefficients for trichloroethene in undisturbed soil samples taken from Picatinny Arsenal, New Jersey. The measured effective diffusion coefficients ranged from 0.0053 to 0.0609 cm2/s over a range of air-filled porosity of 0.23-0.49. The experimental data were compared to several previously published relations that predict diffusion coefficients as a function of air-filled porosity and porosity. A multiple linear regression analysis was developed to determine if a modification of the exponents in Millington's [Science 130 (1959) 100] relation would better fit the experimental data. The literature relations appeared to generally underpredict the effective diffusion coefficient for the soil cores studied in this work. Inclusion of a particle-size distribution parameter, d10, did not significantly improve the fit of the linear regression equation. The effective diffusion coefficient and porosity data were used to recalculate estimates of diffusive flux through the subsurface made in a previous study performed at the field site. It was determined that the method of calculation used in the previous study resulted in an underprediction of diffusive flux from the subsurface. We conclude that although Millington's [Science 130 (1959) 100] relation works well to predict effective diffusion coefficients in homogeneous soils with relatively uniform particle-size distributions, it may be inaccurate for many natural soils with heterogeneous structure and/or non-uniform particle-size distributions.