Ecology of urban lawns under three common management programs

Turfgrass lawns are a central part of urban and suburban landscapes throughout North America and are often managed using repeated applications of chemical fertilizers and pesticides. These inputs are expensive and may negatively affect ecological processes in lawns. Therefore, we evaluated the influence of three most common lawn care programs on ecological characteristics of turfgrass lawns. Twenty-eight home lawns, separated into 3 groups based on the lawn care program (professional, do-it-yourself [DIY], and no-input), were studied. Data on lawn quality, weed and insect infestation, disease incidence, soil nematode community, soil nitrogen pools, microbial biomass (MBN), and soil organic matter (SOM) were collected. Results indicated that professional lawn care resulted in the highest aesthetic lawn quality mainly due to better weed control, compared to DIY and no-input programs. However, professional and DIY programs negatively affected MBN and SOM pools and enhanced disease (rust) severity. No significant differences in soil nematode population and nematode community indices across the three programs were found, indicating no differences in net ecosystem productivity among the three programs. Overall, soil nematode food web in turfgrass lawns represented a disturbed food web compared to natural grasslands and forest ecosystems, irrespective of the lawn care program used.     

The human development spectrum: Sub-spectra and social indicators for use in development project planning,design, and implementation

A spectrum of human development has been observed which has application in international development project planning, design, and implementation. Based on experience with privately funded development projects in Latin America, Asia, and Africa, seven components or sub-spectra of the human development spectrum which are vital to effective development projects are identified: need, resources, technology, social conscience, integrity, attitude, and problem solving. Their implications for the development process are explained, and indicators for each sub-spectrum are described.     

Adoption,personality disorder and parental guilt: Implications of genetic research for social work

Few adoptive parents are aware that serious behavioral and personality problems can occur in adopted children. When such problems are manifested, parents are often guilt-ridden, believing that they are to blame. Recent research suggests that the risks associated with adoption may be genetically linked. Social workers who counsel adoptive parents need to be aware of potential problems, explain possible risks to them, and use these research findings to positive effect.     

Grounded theory research: Procedures,canons, and evaluative criteria

Using grounded theory as an example, this paper examines three methodological questions that are generally applicable to all qualitative methods. How should the usual scientific canons be reinterpreted for qualitative research? How should researchers report the procedures and canons used in their research? What evaluative criteria should be used in judging the research products? We propose that the criteria should be adapted to fit the procedures of the method. We demonstrate how this can be done for grounded theory and suggest criteria for evaluating studies following this approach. We argue that other qualitative researchers might be similarly specific about their procedures and evaluative criteria.     

TheChallenger launch decision: case and teaching note

The following is a brief reconstruction of the major events preceding the launch of the Space Shuttle Challengeron January 28th, 1986, based upon testimony offered at the hearings of the Presidential Commission (1986).     

Rényi statistics for testing hypotheses in mixed linear regression models

Rényi divergences are used to propose some statistics for testing general hypotheses in mixed linear regression models. The asymptotic distribution of these tests statistics, of the Kullback–Leibler and of the likelihood ratio statistics are provided, assuming that the sample size and the number of levels of the random factors tend to infinity. A simulation study is carried out to analyze and compare the behavior of the proposed tests when the sample size and number of levels are small.     

Indications for the use of low-osmolar contrast agents.

The recent introduction of low-osmolar contrast agents for use in radiology procedures presents a dilemma for health care managers concerned about cost and quality. The new agents are reported to be safer and are better tolerated by patients, but they are very costly. Earlier this year, a survey was sent to hospital-based members of the American College of Physician Executives to determine what policy existed for the use of these agents. As a result of the survey, we have a better picture of the indications for low-osmolar contrast agents being used in clinical practice throughout the United States.