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1.

The growth and survival of urban trees and maintenance of urban forest canopy are important considerations in adaptation of urban regions to climate change, especially in relation to increasing frequency of extreme climatic events such as drought. However, urban forest growth and drought response may vary considerably within large urban landscapes across gradients in land use, urbanization, forest composition and structure, and environmental factors. We quantified urban forest growth and resilience and resistance to extreme drought in the greater Chicago metropolitan region based on patterns of annual basal area production from increment core analysis. We evaluated variation in growth and drought response in relation to a broad urban to rural gradient, land-use categories, local-scale environmental predictors, and forest community characteristics. Urban forest growth varied greatly among land-use classes and major genera. Plot-level variation in productivity was predicted most strongly (R2 = 0.53) by total plot-level basal area, canopy height, species composition, soil and ground-cover characteristics, and position within the urban-rural gradient. Urban forest growth was strongly related to regional meteorological drought. In periods of extreme drought conditions growth declined in the year of the drought (i.e., was not resistant to drought effects), but was highly resilient to drought in the subsequent 5 year period. Drought response did not vary consistently across land-use classes or among major genera, and site or community characteristics had little explanatory power in predicting drought response. Improved understanding of factors driving variation in urban forest growth and drought response could help inform adaptation-focused urban forest management strategies.

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2.
阎金明 《城市》2003,(5):21-23
一、国际大都市带的产生和发展 大都市带的概念最早由法国地理学家戈特曼(J.Gottman)提出,主要是指由在地域上集中分布的若干大城市和特大城市集聚而成的庞大的、多核心的、多层次的城市群,是大都市区的联合体.其实质是由一组不同等级城市所形成的相互串连、高度集中的经济中心地带.大都市带的产生是经济发展、科技进步、聚集效应等因素导致的产业、资源与人口在空间上的集聚与扩散运动的结果,交通运输和信息化的高度发达是大都市带得以产生和发展的重要推动力量.  相似文献   

3.
Anthropogenic alteration of the landscape has facilitated plant community change and non-native species invasion in urban areas. We used species occurrence data from over 2000 wetlands within the Chicago metropolitan region to classify urban wetlands into community types and examined non-native species composition across community types. Non-native species were widespread across the region, occurring in over 99% of wetlands. On average, 35% of the plant species in individual wetlands were non-native. A single non-native species, Phalaris arundinacea, was present in 74% of wetlands. Six wetland community types were identified (wet meadows, marshes, forested wetlands, farmed wetlands/mudflats, roadside marshes, and an undetermined wetland type), with each having aggressively spreading non-natives amongst the most common plant species. We conducted canonical correspondence analysis to evaluate the contribution of surrounding land cover, roads, and location of wetlands to plant community composition in these wetlands, and found that similar changes to the landscape have resulted in similar combinations of native and non-native species. Differences in species composition reflected spatial gradients in land use from urban to rural areas across the region, as well as proximity to major roads. Anthropogenic drivers have resulted in profound and pervasive changes to wetland communities across the region, creating novel habitats and ultimately novel community types.  相似文献   

4.
Trees provide important ecological services in cities, yet the vulnerability of the urban forest to massive tree losses from pest outbreaks could threaten those services, with unknown environmental consequences. The outbreak of emerald ash borer is an imminent threat to the ash population in North America. In the Minneapolis?CSaint Paul, Minnesota, metropolitan area, ash trees are present in 50?% of residential landscapes in Ramsey and Anoka Counties. We used a large survey of household activities, a tree inventory, a Household Flux Calculator accounting tool, and a set of annual evapotranspiration measurements, to quantify the current carbon, nitrogen, and phosphorus storage in ash trees, the cycling of these elements, and the total evapotranspiration from ash trees in residential areas in the metropolitan region. Ash represented 6?% of the trees in residential areas and the removal of the entire ash population would correspondingly reduce net primary production and carbon sequestration by only a few percent and would have negligible effects on losses of nitrogen and phosphorus from residential landscapes. Similarly, the effects of ash loss on the hydrologic cycle would be minimal and would depend largely on management choices for the ground currently underneath ash tree canopies. Overall, the percentage change in biogeochemical and hydrological fluxes corresponded closely with the percent of the total urban tree population that was represented by ash, suggesting that areas with higher densities of ash would experience correspondingly larger effects. A hypothetical tree replacement scenario with similar broadleaf species was determined to be likely to re-establish the original biogeochemical and hydrological conditions once the replacement trees reach maturity.  相似文献   

5.
A three month field study of informal student interaction within a lunch court was conducted in a city high school in Southern California. Attention was focused on the easily observed factors of student appearance, behavior and the use of space. Considerable group diversity differentiated the students. The principal cleavage was by race and ethnicity with whites, Blacks, and Chicanos segregating themselves. Within each group further subgroups were observed to cluster separately. Whites were the most differentiated with five subgroups, Blacks had two, and Chicanos had three. Whites and Chicanos differentiated themselves principally on the basis of cultural differences, while Blacks made distinctions amongst themselves on the basis of class. Each of the main groups, however, had their own anti-mainstream counter-culture. The implications of group diversity and the differential role of culture and class in subgroup interaction are also considered.The authors wish to acknowledge the extensive help received from several anonymous reviewers and the editors of this journal in earlier versions of this paper.  相似文献   

6.
We investigate gender homophily in the spatial proximity of children (6–12 years old) in a French primary school, using time-resolved data on face-to-face proximity recorded by means of wearable sensors. For strong ties, i.e., for pairs of children who interact more than a defined threshold, we find statistical evidence of gender preference that increases with grade. For weak ties, conversely, gender homophily is negatively correlated with grade for girls, and positively correlated with grade for boys. This different evolution with grade of weak and strong ties exposes a contrasted picture of gender homophily.  相似文献   

7.
The present article focuses on quantitative research carried out on a statistically representative sample of Italian primary schools with a high concentration of immigrant students. Research data show that schools with a higher number of immigrant students offer a greater number and a wider variety of intercultural initiatives. The presence of immigrant students serves as an effective stimulus in enhancing intercultural approaches. Furthermore, the opinions of head teachers about the proposal of ‘separate classes’ for immigrant students and the proposed ‘limit of 30% on the presence’ of immigrant students are negative. These judgements do not change in a statistically significant manner in relation to concentration of immigrant students: in particular, higher rates of immigrant students are not related to more positive opinions. Continuing education on intercultural issues is widely adopted, mainly on behalf of teachers and less often on behalf of head teachers and other school personnel. Finally, activities by ‘linguistic facilitators’ and ‘linguistic and cultural mediators’ are not significantly related to a decrease in perceived concern regarding problematic situations.  相似文献   

8.

Niche partitioning reduces interspecific competition, facilitating coexistence. In urban ecosystems, however, habitat loss reduces species’ ability to spatially partition activity. Temporal partitioning may thus increase in urban areas as species, unable to avoid each other spatially, partition time to avoid competition. In Midwestern US cities, eastern gray squirrels (Sciurus carolinensis) and fox squirrels (S. niger) co-occur and compete for resources. We identified urban gray and fox squirrel activity patterns and how they vary with season, land cover, and among sites where they do and do not co-occur using camera-trap data. Both species’ activity patterns varied with season and canopy and impervious surface cover. Gray squirrel activity patterns varied in the presence of fox squirrels only in the fall, providing limited support for our temporal partitioning hypothesis. Temporal niche partitioning may thus play a role in supporting these species co-existence when competition is seasonally-elevated (e.g., fall hording), but appears less important in other seasons.

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9.
Due to Brazil is a tropical country has activities in occupational exposure to cold restricted to few sectors especially the meatpacking industry. Taking into account that the country in 2010, was again the largest exporter of poultry meat in the world and consequently employing a large number of workers for their slaughter and processing. The search for greater productivity can result in an increase in work rate, as indicated in this sector as monotonous, repetitive and uncomfortable. According the Programa de Frigorífico it was found that within six years, about 20% of the six thousand workers in a slaughterhouse in southern Brazil, received welfare benefits due to musculoskeletal diseases. Adding to this, the lack of parameters for the Brazilian standardization concerning occupational activities carried out in cold. Although several epidemiological studies point to the cold as a risk factor for occurrence or aggravation of musculoskeletal disorders, research in this field is still limited and often contradictory conclusions. This article aims to review developments concerning the poultry industry and the fridge in Brazil, as well as raising the question about the increased productivity of the slaughterhouse, since it has already shown a high prevalence of musculoskeletal disorders related to work.  相似文献   

10.
This study concerns itself with a classroom project in English class where the film Bend it Like Beckham was shown to two multicultural classes in a high school in Oslo, Norway, with a view towards exploring students’ understandings and attitudes towards gender. Using an ethnographic methodology informed by feminist approaches, findings indicate that students, on the one hand, valorised modern values such as educational attainment, self-fulfillment and the equal sharing of domestic chores, while, on the other hand, they were equally eager to preserve traditional practices such as wearing the hijab and marrying within their own ethnicity and religion.  相似文献   

11.
For people experiencing chronic homelessness, supportive housing with intensive social, health, and behavioral health services reduces the likelihood of re-entering homelessness and the public costs of associated acute medical care, shelter use, and incarceration. Due to a limited supply of supportive housing, it must be allocated to those most in need. This paper examines findings from a unique, region-wide method for prioritizing individuals for supportive housing based on utilization of high-cost public services and vulnerability if left on the street. A sample of 196 individuals were prioritized for housing based on this method, while a comparison group of 102 were housed not using the method. Results showed that those housed under the prioritization method achieved greater reductions in utilization of high-cost public services, but were also less likely to have positive dispositions when exiting the housing programs, suggesting the need for a greater intensity of supports and/or multiple “doses” of supportive housing before stability can be expected. The method described in the paper can provide a starting point for developing regional, comprehensive systems of coordinated, prioritized entry into supportive housing, such as those now required by US Department of Housing and Urban Development.  相似文献   

12.
This paper aims to contribute to the existing studies on the young women’s transition to adulthood in the case of Turkish women’s exclusion from the labour market. The issue is discussed largely within the boundaries of traditional gender restrictions that keep women out of employment. Herein, we argue that the gender-based control of young women, perceived as the reason for their exclusion from the labour market, may be used by disadvantaged women as a way of avoiding difficult and unfavourable employment situations. Similarly, the gender roles imposed on men could also not be fulfilled due to the same restrictive labour market conditions. Furthermore, we suggest that the poverty simultaneously strengthens and erodes the very base of the traditional gender structure for both young women and young men, while forcing the young women out of employment and the young men to the unstable working conditions. This argument is based on a study conducted in Alt?nda?, Ankara with a sample of 279 females and 340 males aged between 15 and 24. A mixed methodology, comprising a survey questionnaire followed by 60 in-depth interviews and 4 focus group discussions, was employed for this study.  相似文献   

13.
This paper discusses problems of identification which interfere with a borderline adolescent girl's completion of her adolescent developmental tasks. Therapeutic work entails the provision of a protective environment to assist processes of identification, separation and completion of structural restoration.  相似文献   

14.
Green infrastructure in urbanized areas has a dual purpose that achieves both sociological and ecological goals. To benefit society and the urban ecosystem, green infrastructure should be effectively managed. We investigated carabid diversity and assemblage structure as indicators of biodiversity in green infrastructures in a rapidly developing urban area to identify the habitat’s values. In addition, we attempted to reveal the effect of environmental variables (e.g., vegetation structure, soil, and disturbance) that strongly contribute to carabid diversity and assemblage structure. Of the collected organisms, 6,154 individuals representing 20 carabid species were identified in the green infrastructure. Those species with flight ability and that were found in dry habitats were widely distributed and dominated green infrastructures. Carabid assemblages changed significantly in response to management practices. These changes were both positive and negative, with the negative changes increasing the instability of the carabid assemblages through the destruction of their habitat. Other factors, such as the presence of original habitat, habitat age, and habitat succession, also had a considerable effect on carabid diversity. We revealed that management practices prevented habitat succession, and these interactive effects determined carabid diversity and structure in green infrastructures.  相似文献   

15.
 In this paper we introduce harmonic analysis (Fourier series) as a tool for characterizing the existence of Nash equilibria in two-dimensional spatial majority rule voting games with large electorates. We apply our methods both to traditional proximity models and to directional models. In the latter voters exhibit preferences over directions rather than over alternatives, per se. A directional equilibrium can be characterized as a Condorcet direction, in analogy to the Condorcet (majority) winner in the usual voting models, i.e., a direction which is preferred by a majority to (or at least is not beaten by) any other direction. We provide a parallel treatment of the total median condition for equilibrium under proximity voting and equilibrium conditions for directional voting that shows that the former result is in terms of a strict equality (a knife-edge result very unlikely to hold) while the latter is in terms of an inequality which is relatively easy to satisfy. For the Matthews [3] directional model and a variant of the Rabinowitz and Macdonald [7] directional model, we present a sufficiency condition for the existence of a Condorcet directional vector in terms of the odd-numbered components of the Fourier series representing the density distribution of the voter points. We interpret our theoretical results by looking at real-world voter distributions and direction fields among voter points derived from U.S. and Norwegian survey data. Received: 7 July 1995 / Accepted: 14 May 1996  相似文献   

16.
The present study attempts to assess the substantive and theoretical implications of using different analytical techniques to identify groups of highly interlocked corporations within large corporate networks. Specifically, it compares the interlock groups identified using direct factor analysis with those identified using hierarchical cluster analysis. A comparison of these two sets of empirical results suggests that these two analytical techniques yield surprisingly similar findings even though they employ disparate methodological rationales and computational algorithms. Nevertheless, some minor but significant differences in the results provided by these two techniques arise as a consequence of different assumptions implicit in these techniques concerning the possibility of overlap between interlock groups. Finally, the convergence of these two analyses confirms that interlock groups are concrete empirical aggregations within corporate networks which cannot be dismissed as the artifacts of particular analytical methodologies.  相似文献   

17.
It is the purpose of this article to discuss the development and application of a logic model in the context of a large scientific research program within the Commonwealth Scientific and Industrial Research Organisation (CSIRO). CSIRO is Australia's national science agency and is a publicly funded part of Australia's innovation system. It conducts mission-driven scientific research focussed on delivering results with relevance and impact for Australia, where impact is defined and measured in economic, environmental and social terms at the national level. The Australian Government has recently signalled an increasing emphasis on performance assessment and evaluation, which in the CSIRO context implies an increasing emphasis on ensuring and demonstrating the impact of its research programs. CSIRO continues to develop and improve its approaches to impact planning and evaluation, including conducting a trial of a program logic approach in the CSIRO Preventative Health National Research Flagship. During the trial, improvements were observed in clarity of the research goals and path to impact, as well as in alignment of science and support function activities with national challenge goals. Further benefits were observed in terms of communication of the goals and expected impact of CSIRO's research programs both within CSIRO and externally. The key lesson learned was that significant value was achieved through the process itself, as well as the outcome. Recommendations based on the CSIRO trial may be of interest to managers of scientific research considering developing similar logic models for their research projects. The CSIRO experience has shown that there are significant benefits to be gained, especially if the project participants have a major role in the process of developing the logic model.  相似文献   

18.
This study presents the challenge involved in the negotiation and construction of a standard process in a major petroleum company that has the purpose of guiding the implementation of ergonomic studies in the development of projects, systemising the implementation of ergonomics design. The standard was created by a multi-disciplinary working group consisting of specialists in ergonomics, who work in a number of different areas of the company. The objective was to guide "how to" undertake ergonomics in all projects, taking into consideration the development of the ergonomic appraisals of work. It also established that all the process, in each project phase, should be accompanied by a specialist in ergonomics. This process as an innovation in the conception of projects in this company, signals a change of culture, and, for this reason requires broad dissemination throughout the several company leadership levels, and training of professionals in projects of ergonomics design. An implementation plan was also prepared and approved by the corporate governance, complementing the proposed challenge. In this way, this major oil company will implement new procedures of ergonomics design to promote health, safety, and wellbeing of the workforce, besides improving the performance and reliability of its systems and processes.  相似文献   

19.
20.
The habitat suitability index and environmental flow requirements were assessed for ten species of macroinvertebrates in a 2 km length section of the urban Boti? creek (average flow 0.4 m3 s?1) in Prague. Boti? creek has been affected by two combined sewer overflows (CSO). Spring, summer and fall seasonal environmental flow requirements were identified using the Physical HABitat SIMulation System (PHABSIM) approach for the whole macroinvertebrate community: Spring – optimal flow 0.32–0.38 m3 s?1, minimal flow 0.20–0.21 m3 s?1 and maximal acceptable flow 0.91–0.93 m3 s?1; Summer - optimal flow 0.42–0.45 m3 s?1, minimal flow 0.19–0.21 m3 s?1 and maximal acceptable flow 0.95–1.00 m3 s?1; Fall - optimal flow 0.38–0.48 m3 s?1, minimal flow 0.22–0.23 m3 s?1 and maximal acceptable flow 0.95–0.98 m3 s?1. The seasonal variability of environmental flow for all three categories is approximately 10%. Environmental flow requirements of the studied species and their life stages vary with depth, velocity and bottom substratum. Due to inflow from the CSOs, the optimal and maximal acceptable flow are not maintained and the maximal flow is exceeded by more than twice its value. Although the Instream Flow Incremental Methodology (IFIM) was primarily designed for large impounded rivers, the study proved its applicability in small streams affected by urbanization and urban drainage.  相似文献   

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