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831.
Getting closure: The role of urban forest canopy density in moderating summer surface temperatures in a large city 总被引:1,自引:0,他引:1
With a growing number of people living in urban areas, city residents are more frequently exposed to stresses related to the built environment including elevated summer surface temperatures contributing to the urban heat island (UHI) effect. This study examines the role of urban tree density in moderating surface temperature variation in a densely populated city (Toronto, Canada). By applying parallel aspatial (OLS) and spatial regression (GWR) approaches with satellite derived data describing tree canopy density and surface temperature, one dimension of tree canopy quality (i.e., canopy density) is shown to contribute directly to a reduction in the surface urban heat island (SUHI) effect at a local scale. Though the model fit differed between the two regression approaches, both exhibited moderately strong explanatory power and demonstrated that observed surface temperature decreases in locations with increasing high-density and closed tree canopy. Study findings provide an empirical basis to recommend that municipal urban forest strategies embrace canopy quality metrics, such as increasing the density of existing urban forest stands, as a part of tree planting objectives seeking to effectively deliver temperature moderation as a valuable ecosystem service. 相似文献
832.
The objective of this study was to evaluate the relative effects of watershed land-use on streambed substrate composition in eight low-order tropical streams. Data were collected at 24 sampling sites for eight wadeable streams in the Pirapó River Basin, southern Brazil. According to the percentage of impervious surfaces in the watershed, we defined the streams as either urban or rural. We estimate the percentages of the different streambed substrates, hydrological variables, and the rainfall intensity. The results showed that silt, sand and coarse particulate organic matter (CPOM) contributed to significant differences in streambed substrate composition between urban and rural streams. Silt, sand and CPOM were found in a higher mean proportion in the rural streams. Probably the urban streams have a greater bed load, promoted by precipitation and discharge, than rural streams, especially fine sediment. Rural streams have soft hydrographs, with stream flow slowly increasing during a rainstorm and subsequently decreasing over a long period after the rain event is over. These characteristics can provide the lixiviation of fine sediments into the stream channels due to land-surface clearance for agricultural activities and their accumulation in the streambed due to the moderate discharge regime. 相似文献
833.
Urbanization and other land cover changes have been particularly detrimental to wetlands throughout the planet. One wetland specialist that may be sensitive to land cover changes surrounding wetlands is the round-tailed muskrat (Neofiber alleni; hereafter RTM). The RTM is a wetland obligate rodent that appears to have declined over the last half century and is a species of concern in Florida, where it is a near endemic. To determine if urbanization or other land cover influenced the distribution of RTMs we took a multi-scaled approach to examine the occurrence of RTMs and their associated vegetation in North-Central Florida. We detected RTMs on 19 of 72 sample plots and used a Classification And Regression Tree (CART) to determine that dogfennel (Eupatorium capillifolium) was negatively associated with RTMs and maidencane (Panicum hemitomon) was positively associated with their occurrence on sampling plots. Examining the influence of landscape composition for 2 km surrounding our plots we found that RTM occurrence was negatively related to urban land cover. Further, we found that dogfennel increased and maidencane decreased as urbanization increased in the surrounding landscape. Our research suggests that conservation of RTMs and their associated vegetation should focus on limiting urban sprawl at least within 2 km of wetlands. 相似文献
834.
Linda S. Sprague Martinez Amanda J. Reich Cecilia A. Flores Uchenna J. Ndulue Doug Brugge David M. Gute 《Journal of Community Practice》2017,25(1):68-89
The Nuestro Futuro Saludable partnership designed a critical service-learning intervention focused on health equity and action. The 10-week afterschool intervention was implemented in a Boston middle school. Youths who took part in the intervention were knowledgeable about the social determinants of health in their communities, as well as to the barriers to health. Our findings indicate that engaging young people in a meaningful way will be critical if health improvement efforts are to be realized. We found that a critical service-learning framework that incorporates elements of applied inquiry and critical pedagogy was effective as a health intervention and provided opportunities for action. 相似文献
835.
ABSTRACTResearchers often approach employers to investigate employees’ work and family experiences. Organizational willingness to grant access to employees can vary, especially when the research topic is seen as controversial or contentious for the employer. This paper explores this methodological challenge using a research example from Manitoba, Canada, which explored the use of parental leave by male employees and the impact of managerial attitudes and corporate culture on usage. Sixty large employers were recruited with only seven of those organizations agreeing to participate. In this paper, the reasons organizations gave for declining to participate and the implications of their decisions for the research are examined. Although the final sample included 905 managers and employees, participating organizations tended to be employee-focused and family-friendly employers. Organizations declined participation for a variety of reasons: avoiding raising the issue with unions, awareness that their policies unfairly benefited female leave takers, and simply not seeing the relevance of a topic relating to men’s work–family experiences. A dialogue often absent from the literature, it is important to understand how employers can limit researchers’ access to employees on controversial topics. The existence of such barriers suggests alternative avenues to recruit participants directly when topics are contentious for employers. 相似文献
836.
Peter Van Aelst Patrick van Erkel Evelien D’heer Raymond A. Harder 《Information, Communication & Society》2017,20(5):715-732
Attention in the mass media is seen as crucial for electoral success. However, most ordinary candidates hardly get any attention in the news. With social media outlets becoming ever more popular, the question is whether the overall asymmetry in attention for candidates still holds today. Do candidates who dominate the traditional media during the campaign also dominate the social media? Or can candidates make up for a lack of mass media coverage by attracting attention on these new media platforms? This paper aims to answer these questions by pairing Twitter activity and Twitter popularity with newspaper attention for a large number of individual candidates in the 2014 Belgian election campaign. We expand the normalization versus equalization debate by not only looking at how much a new medium is used, but also at its success in terms of popularity and audience reach. Our findings show that the two platforms are indeed related, mainly because a small political elite dominates both old and new media. Twitter popularity and Twitter activity (albeit to a lesser extent) are higher among powerful politicians. We elaborate on why these findings are so much in line with the normalization hypothesis. 相似文献
837.
Orestis Giotakos George Tsouvelas Evi Spourdalaki Mari Janikian Artemis Tsitsika 《International Gambling Studies》2017,17(1):20-29
Research has found gambling to be related to a variety of other addictive behaviours. The study objective was to evaluate the association of Internet gambling with Internet addiction, online sexual engagement, suicidality and substance use, in a sample of Greek adults. The study sample consisted of 789 military personnel. During their annual medical examination the study participants anonymously completed a series of self-reported questionnaires in relation to socio-demographic data, Internet gambling practices, online sexual engagement, Internet addiction, suicidality and psychoactive substance use. We found that Internet addiction significantly predicted engagement with online gambling, followed by substance use in general, and, in particular, the use of cocaine or heroin. Finally, two other predictive indicators were self-reported suicide attempts and engagement with online sex. Online gambling is associated with various behaviours related to impulsivity such as Internet addiction, online sexual engagement, suicidality and substance use. Future research will increase our knowledge on the contribution of new technologies and the Internet in Internet gambling dimensions, as well as on the associations with other high-risk behaviours such as substance use, pornography and suicidality. 相似文献
838.
Michelle Bosquet Enlow Katrina L. Devick Kelly J. Brunst Lianna R. Lipton Brent A. Coull Rosalind J. Wright 《Infancy》2017,22(4):492-513
Little research has examined the impact of maternal lifetime trauma exposure on infant temperament. We examined associations between maternal trauma history and infant negative affectivity and modification by prenatal cortisol exposure in a sociodemographically diverse sample of mother–infant dyads. During pregnancy, mothers completed measures of lifetime trauma exposure and current stressors. Third‐trimester cortisol output was assessed from maternal hair. When infants were 6 months old, mothers completed the Infant Behavior Questionnaire‐Revised. In analyses that controlled for infant sex and maternal age, education, race/ethnicity, and stress during pregnancy, greater maternal trauma exposure was associated with increased infant distress to limitations and sadness. Higher and lower prenatal cortisol exposure modified the magnitude and direction of association between maternal trauma history and infant rate of recovery from arousal. The association between maternal trauma history and infant distress to limitations was somewhat stronger among infants exposed to higher levels of prenatal cortisol. The analyses suggested that maternal lifetime trauma exposure is associated with several domains of infant negative affectivity independently of maternal stress exposures during pregnancy and that some of these associations may be modified by prenatal cortisol exposure. The findings have implications for understanding the intergenerational impact of trauma exposure on child developmental outcomes. 相似文献
839.
Lindsey J. Thomas Jennifer A. Jackl Jenny L. Crowley 《Journal of Family Communication》2017,17(3):238-253
Framed by Relational Dialectics Theory, this study explores the ways adult, former foster children discursively construct meanings of “family.” Contrapuntal analysis of 24 interviews revealed two discourses as competing to constitute family: the Discourse of Family as Irreplaceable and Inescapable (Permanence) and the Discourse of Family as Performative Kinning (Performance). Permanence was constituted by themes of biology and historical connection, reifying normative understandings. Performance, comprised of role enactment, need for tolerance, and unconditional love, challenged the Permanence discourse. Throughout the narratives, Performance competed with Permanence for dominance, illustrating the cultural pervasiveness and power of Permanence yet, in some moments, privileging the marginalized Performance discourse. This discursive competition constructed meanings of family in narratives of life before, during, and after foster care. Overall, participant’s talk constructed complex webs of family relationships, allowing access to an important social institution—family—regardless of the presence/absence of culturally valued markers of family (e.g., biology, legality). 相似文献
840.