基于双论域粗糙集的大学生综合成绩影响因素研究

利用双论域粗糙集理论,从个人、家庭、学校、社会四个方面对大学生综合成绩的影响因素进行了研究。对问卷调查获取到的大学生综合成绩与影响因素的数据进行了相关性分析,得到了综合成绩和影响因素之间的二元关系;然后利用双论域粗糙集的规则提取算法,分别获得了由综合成绩导出影响因素以及由影响因素确定综合成绩的规则。     

The impact of swidden decline on livelihoods and ecosystem services in Southeast Asia: A review of the evidence from 1990 to 2015

Global economic change and policy interventions are driving transitions from long-fallow swidden (LFS) systems to alternative land uses in Southeast Asia’s uplands. This study presents a systematic review of how these transitions impact upon livelihoods and ecosystem services in the region. Over 17 000 studies published between 1950 and 2015 were narrowed, based on relevance and quality, to 93 studies for further analysis. Our analysis of land-use transitions from swidden to intensified cropping systems showed several outcomes: more households had increased overall income, but these benefits came at significant cost such as reductions of customary practice, socio-economic wellbeing, livelihood options, and staple yields. Examining the effects of transitions on soil properties revealed negative impacts on soil organic carbon, cation-exchange capacity, and aboveground carbon. Taken together, the proximate and underlying drivers of the transitions from LFS to alternative land uses, especially intensified perennial and annual cash cropping, led to significant declines in pre-existing livelihood security and the ecosystem services supporting this security. Our results suggest that policies imposing land-use transitions on upland farmers so as to improve livelihoods and environments have been misguided; in the context of varied land uses, swidden agriculture can support livelihoods and ecosystem services that will help buffer the impacts of climate change in Southeast Asia.     

Do recommended driving limits affect teen-reported traffic violations and crashes during the first 12 months of independent driving?

OBJECTIVES: Motor vehicle crashes are highly elevated among newly licensed teenage drivers. Limits on high-risk driving conditions by driver licensing policies and parents can protect novice teens from negative driving outcomes, while they experience and driving proficiency. The purpose of this research was to evaluate the effects of strict parent-imposed driving limits on driving outcomes during the first year of licensure. METHODS: A sample of 3,743 Connecticut teens was recruited and randomized to the Checkpoints Program or comparison condition. Assessments conducted at baseline, licensure, 3-, 6-, and 12-months postlicensure included parent-imposed driving limits, traffic violations, and crashes. Bivariate and multivariate analyses were conducted to assess the effects of strict parent limits on traffic violations and crashes during the first year of licensure. RESULTS: Thirty percent of teens reported at least one traffic violation and 40% reported at least one crash. More strict parent-imposed limits at licensure, 3-, 6-, and 12-months postlicensure, were associated with fewer violations and crashes in multivariate analyses. Notably, adherence to recommended night curfew was consistently associated with fewer violations and crashes. CONCLUSIONS: The findings indicate that strict parent-imposed limits may protect novice teen drivers from negative driving outcomes.     

Land Management Restrictions and Options for Change in Perpetual Conservation Easements

Conservation organizations rely on conservation easements for diverse purposes, including protection of species and natural communities, working forests, and open space. This research investigated how perpetual conservation easements incorporated property rights, responsibilities, and options for change over time in land management. We compared 34 conservation easements held by one federal, three state, and four nonprofit organizations in Wisconsin. They incorporated six mechanisms for ongoing land management decision-making: management plans (74 %), modifications to permitted landowner uses with discretionary consent (65 %), amendment clauses (53 %), easement holder rights to conduct land management (50 %), reference to laws or policies as compliance terms (47 %), and conditional use permits (12 %). Easements with purposes to protect species and natural communities had more ecological monitoring rights, organizational control over land management, and mechanisms for change than easements with general open space purposes. Forestry purposes were associated with mechanisms for change but not necessarily with ecological monitoring rights or organizational control over land management. The Natural Resources Conservation Service-Wetland Reserve Program had a particularly consistent approach with high control over land use and some discretion to modify uses through permits. Conservation staff perceived a need to respond to changing social and ecological conditions but were divided on whether climate change was likely to negatively impact their conservation easements. Many conservation easements involved significant constraints on easement holders’ options for altering land management to achieve conservation purposes over time. This study suggests the need for greater attention to easement drafting, monitoring, and ongoing decision processes to ensure the public benefits of land conservation in changing landscapes.     

An in-depth look at parent-imposed driving rules: their strengths and weaknesses

Introduction: With a growing interest in increasing parental involvement in teen driving, it is important to find out what parents are already doing. Method This study assessed the content, delivery, rigidity, and consequences of 143 driving rules reported by 24 parent-teen dyads. Results: Strengths included that driving rules covered the full range of concerns, especially night driving limits and passenger limits, and most parents and teens reported that violations would be followed by consequences, especially talk/warn or no driving. Weaknesses included that many rules were not very strict and only half showed parent-teen agreement on content. Conclusions: These findings suggest that teen driving rules are not clearly defined.     

Effects of rearview cameras and rear parking sensors on police-reported backing crashes

Objective: The objective of this study was to examine the effectiveness of rearview cameras, rear parking sensors, and both systems combined in preventing police-reported backing crashes.

Methods: Negative binomial regression was used to compare rates of police-reported backing crash involvements per insured vehicle year in 22 U.S. states during 2009–2014 between passenger vehicle models with backing technologies and the same vehicle models where the optional systems were not purchased, controlling for other factors affecting crash risk. Rearview cameras were examined from four automakers, rear parking sensors from 2 automakers, and both systems combined from a single automaker.

Results: Rearview cameras reduced backing crash involvement rates by 17%. Reductions were larger for drivers 70 and older (36%) than for drivers younger than 70 (16%); however, estimates for older and younger drivers did not differ significantly from one another. The Buick Lucerne's rear parking sensor system reduced backing crash involvement rates significantly by 34%, but the reduction for Mercedes-Benz vehicles fit with a sensor system was small and not statistically significant. When averaged between the 2 automakers, effects were significantly larger for drivers 70 and older (38% reduction) than for drivers younger than 70 (1% increase); effects were significant for older but not younger drivers. Backing crash involvement rates were 13% lower among Mercedes-Benz vehicles with a rearview camera and parking sensors than among vehicles without, but this finding was not significant.

Discussion: Rearview cameras are effective in preventing police-reported backing crashes. Effects of rear parking sensors are less straightforward; it is unclear whether the Buick Lucerne system's benefits are due to the older age of its drivers, characteristics of the vehicle or system, or a combination. Systems may be especially beneficial to older drivers who might have limitations that make backing challenging. Although effect estimates did not differ significantly between older and younger drivers for both system types, the magnitude of the differences was large and the pattern of results was consistent across 6 of the 7 systems examined. When rear visibility systems become required equipment on new passenger vehicles in 2018, rearview cameras can be expected to prevent 1 in 6 backing crashes reported to police that involve equipped vehicles.     

Assessing the effects of surface-bound humic acid on the phototoxicity of anatase and rutile TiO2 nanoparticles in vitro

In this study,the cytotoxicity of two different crystal phases of TiO₂ nanoparticles,with surface modification by humic acid（HA）,to Escherichia coli,was assessed.The physicochemical properties of TiO₂ nanoparticles were thoroughly characterized.Three different initial concentrations,namely 50,100,and 200 ppm,of HA were used for synthesis of HA coated TiO₂ nanoparticles（denoted as A/RHA50,A/RHA100,and A/RHA200,respectively）.Results indicate that rutile（LC50（concentration that causes 50%mortality compared the control group）=6.5）was more toxic than anatase（LC₅0=278.8）under simulated sunlight（SSL）irradiation,possibly due to an extremely narrow band gap.It is noted that HA coating increased the toxicity of anatase,but decreased that of rutile.Additionally,AHA50 and RHA50had the biggest differences compared to uncoated anatase and rutile with LC₅0of 201.9 and21.6,respectively.We then investigated the formation of reactive oxygen species（ROS）by TiO₂ nanoparticles in terms of hydroxyl radicals（OH）and superoxide anions（O₂^-）.Data suggested that O₂^- was the main ROS that accounted for the higher toxicity of rutile upon SSL irradiation.We also observed that HA coating decreased the generation of OH and O₂^- on rutile,but increased O₂^- formation on anatase.Results from TEM analysis also indicated that HA coated rutile tended to be attached to the surface of E.coli more than anatase.