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An assessment of soil nematode food webs and nutrient pools in community gardens and vacant lots in two post-industrial American cities 总被引:1,自引:1,他引:0
Sharanbir S. Grewal Zhiqiang Cheng Sonia Masih Melinda Wolboldt Naureen Huda Alexandra Knight Parwinder S. Grewal 《Urban Ecosystems》2011,14(2):181-194
In the midst of the current economic crisis, there is renewed interest in transforming vacant lots into food-producing gardens.
This study analyzed whether vacant lots are suitable for food production, by comparing the soil nematode food webs and nutrient
pools of vacant lots and community gardens in two post-industrial U.S. cities, Akron and Cleveland, Ohio. Twelve vacant lots
and 12 community gardens were examined in the two cities. All six Akron community gardens were established just prior to the
initiation of this study, whereas the six in Cleveland were 15–30 years old. Soil pH, texture, moisture, organic matter, mineral
nitrogen content, microbial biomass, and nematode communities were measured in both cities. Soil decomposition rate was also
measured in Cleveland. Results show that the soils of vacant lots surpassed those of the newly-established Akron gardens and
were equal to the soils of the well-established Cleveland gardens in the amount of ammonium-nitrogen, total nematode population,
genus diversity, and maturity and structure indices. The soils of the vacant lots were lower than the community gardens in
the amounts of soil moisture, organic matter, and nitrate-nitrogen, which we associate with the addition of water, compost,
fertilizer, and tilling in the gardens. No significant difference was found between community gardens and vacant lots in microbial
biomass, decomposition rate, or nematode enrichment index, which seems to indicate that vacant lots are equal to community
gardens in nutrient availability and nutrient cycling. We conclude that barring any contamination, the soil in vacant lots
maybe suitable for the establishment of food gardens, which can provide many desirable ecosystem services and enhance human
well-being. We also find that the disturbance associated with tillage and conversion of a vacant lot into a community garden
has short-term ramifications for both nematode food webs and mineral-nitrogen content. 相似文献
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This study is the first attempt at placing the analysis of fertility in a temporal dynamic framework in the case of a developing
Asian economy such as Thailand by binding the relationship between fertility and its determinants within a cointegrated system.
The analysis is based on the application of the following recently developed dynamic time series techniques: cointegration,
vector error-correction modelling, variance decompositions and the impulse response functions. The results tend to indicate
that in the complex dynamic interactions, the importance of the conventional `structural' hypothesis as a significant factor
in bringing fertility down in the longer term cannot be denied. However, in the short to longer term, our findings, although
not fully supportive of any particular hypothesis, appear to be broadly consistent more with the hypothesis emphasising the
critical role played by the `ideational' or diffusion forces along with the demographic variables in ensuring `initial' fertility
decline than with the conventional `structural' hypothesis emphasising a significant socio-economic structural change as a
pre-condition for `initial' fertility decline.
Received: 7 April 1995/Accepted: 15 May 1998 相似文献
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Using a general systems rationale, this paper develops a theoretical structure for approaching the problem of management accounting. The management control problem is explicated in terms of maintaining a relationship between the enterprise's structure and its environment. An enterprise's structure is composed of three elements (and their inter-relations): a decision and control subsystem; a financial funds subsystem and an operating (physical transforms) subsystem. Portrayed in these terms, the problem of management accounting is shown to require a methodology which is able to take cognizance of economic, sociological, psychological and other aspects of the enterprise system. The model described here provides a general intellectual frame of reference for ordering the problem. 相似文献
4.
Summary The paper explores issues raised by research on patterns ofwelfare and mutual care among older Pakistani people and theirfamilies, with particular reference to their use, or lack ofuse of social care services. Qualitative interviews were conductedwith (self-defined) minority ethnic older people, professionalsin statutory services and in minority-led community-based groups.The organization of services is discussed, with special referenceto issues of power and control, the role of the voluntary (non-profit)and statutory sectors, the debate regarding the possible needfor specialist versus generic services, and the role of minority-ledinitiatives. Secondly, issues of service staffing are examined,and the dangers of marginalizing minority services and staffreviewed, especially with reference to divisions of labour inservice provision and staff's own perspectives. Thirdly, themethodological implications of the work are explores, includingissues of linguistic and cultural communication and workingwith relatively powerless social groups, whose views are sought.Examining the views of professional social care workers is alsoproblematized, with reference to their gate-keeping role. Itis argued that user perspectives are essential to the developmentof appropriate services for minority ethnic groups. In conclusion,the need to raise these issues in other work is discussed. 相似文献
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CW Kratzik WJ Reiter AM Riedl G Lunglmayr N Brandstätter E Rücklinger 《The aging male》2013,16(3):188-196
Aging in the male is accompanied by steroid hormonal decline, and men may develop symptoms associated with hypogonadism. Increased awareness of ‘andropause’ in recent years has led to greater demand for hormonal assessments, resulting in a rising burden for health economics. We conducted a cross-sectional study to define men at risk for hypogonadism, in whom further hormonal investigation should be performed.We examined 664 blue-collar workers aged 40–60 years at their workplace and determined hormonal status and body mass index (BMI). Men with an abnormal urogenital status and those on medication that might affect endocrine status were excluded from the study. All participants completed the validated Aging Male Symptom (AMS) questionnaire and obtained scores for psychological symptoms, somatovegetative symptoms, and sexual symptoms.Multiple logistic regression analyses revealed a significantly increased risk (represented by the odds ratio) of psychological symptoms for men with low levels of testosterone and/or bioavailable testosterone (BAT). Increased BMI as well as low testosterone levels and/or low BAT levels raised the risk of somatovegetative symptoms. Each decrease of BAT by 1?ng/ml caused an approximately 1.8-fold increase of the risk (odds ratio?=?1.832, p?=?0.005). Additional independent risk factors were increased age and low luteinizing hormone (LH) level. Men aged 55 years with BMI >?28?kg/m2 and with somatovegetative symptoms and moderate or severe psychological symptoms had a 7.2-fold increase in the risk of a BAT level <?1.5?ng/ml compared to men without these risk factors (p <?0.001). Sensitivity and specificity were 75% and 71%, respectively.The AMS score combined with age and BMI provides an easy and convenient method to identify men with probable androgen deficiency who require hormonal assessment. 相似文献
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