中国人口转变道路的探索和选择

从1949年到1978年,中国在进行社会主义道路探索的同时也在进行着对中国人口转变道路的探索。建国初期,通过开展群众卫生运动,死亡率迅速下降,开启了中国人口转变的进程。20世纪50年代,初次面对人口快速增长问题,中国提出了"实现有计划的生育"的理论和构想,人口转变的中国道路开始孕育。经历了"大跃进"时期的思想动摇、工作停滞和此后的人口继续快速增长等种种波折之后,人们在人口与社会经济矛盾激增的过程中明确了中国人口转变道路的方向。最后,在"文革"期间,脆弱的国民经济和日益增长的人口压力迫使中国选择了一条主动控制人口过快增长、实行计划生育的人口转变道路。这条道路是由时代发展特征和中国的特殊国情共同决定的。     

人口与消费对二氧化碳排放的动态影响——基于变参数模型的实证分析

近年来,随着全球气候的不断变暖,二氧化碳减排问题已经引起了世界性的关注。中国作为世界上最大的碳排放国,必须逐步降低经济发展过程中的碳排放。基于此,利用1978～2009年的相关数据和变参数模型,分析了人口数量和居民消费对我国二氧化碳排放的动态影响。结果表明,人口、消费与二氧化碳排放之间存在长期稳定的关系,二者对碳排放均有比较显著的影响。从总体来看,人口对碳排放的影响弹性要高于消费对碳排放的弹性,但是近年来两者之间的差距越来越小,说明消费对二氧化碳排放的影响力日益增大;随着时间波动,人口与消费对碳排放的影响弹性会呈现规律性的变化,并且可以将其划分为三个明显的阶段。依据上述结论,文章提出了相关政策建议,以减少由人口和消费带来的二氧化碳排放。     

Order statistics of independent identically distributed variables when the sum is known

In this paper we consider the situation where we know the sum of n independent observations from the same probability distribution. We investigate how to empirically determine the marginal probability distributions of the different order statistics conditional upon knowing the sum. This research was motivated by explorations in process improvement where we know the total expected value or variance of a key measure of an n-step process and would like to estimate the proportion of the expected value or variance that is contributed by the most important step (i.e. the single step having the largest expected value or variance), the two most important steps, etc. Both graphical and tabular results are presented for exponential, gamma and normal distributions.     

Chemistry of growth medium and leachate from green roof systems in south-central Texas

Installation of intensive and extensive green roofs is becoming popular for reducing runoff from impervious surfaces in many cities around the world. Most studies on runoff quality from green roofs have been conducted in cooler northern climates. We examined the losses and gains of nutrients, cations and selected anions in planted and unplanted growth medium and compared these to initial growth medium (IGM) typically used for green roof modules in south-central Texas. Water extracts of growth medium and leachate from three replicates of unplanted growth medium and three planted species (Sedum kamtschaticum, Delosperma cooperi and Talinum calycinum) were examined. During the first 6 months after establishment we observed high losses of nitrate (25 to 44 mg kg⁻¹), dissolved organic carbon (DOC: 155 to 190 mg kg⁻¹) and nitrogen (DON: 9.0 to 11.2 mg kg⁻¹) and orthophosphate-P (1 to 2 mg kg⁻¹). Average leachate concentrations based on four rain events 6 months after establishment ranged from 0.3 to 6.6 mg L⁻¹ in planted modules and 6.3 mg L⁻¹ in unplanted modules for nitrate-N, 38 to 42 mg L⁻¹ in planted modules and 32 mg L⁻¹ in unplanted modules for DOC, 2.1 to 3.1 mg L⁻¹ in planted modules and 2.1 mg L⁻¹ in unplanted modules for DON and 0.27 to 0.37 mg L⁻¹ in planted modules and 0.40 mg L⁻¹ in unplanted modules for orthophosphate-P. We suggest that after the establishment of green roofs, leachate losses may contribute some runoff concentrations of nitrogen, carbon and phosphorous in urban areas.     

Differences in Sleep Quality and Health-Related Quality of Life in Young Adults With Allergies and Asthma and Their Healthy Peers

Abstract

Objective: The current study examined the relationship between sleep quality and health-related quality of life (HRQOL). Participants: Participants were 501 undergraduate students with allergies (167), asthma + allergies (167), or with no history of a chronic illness (167) completed study measures from August 2011 to April 2012. Methods: The undergraduate students completed questionnaires online as part of a larger study of psychosocial adjustment of young adults. Results: Young adults with allergies and asthma + allergies reported significantly worse sleep quality and HRQOL than healthy peers. Additionally, those with allergies and asthma + allergies had significantly more sleep disturbances and used sleeping medication significantly more often in the previous month than healthy peers. Conclusions: These results highlight concerns regarding quality of life and sleep problems in an often-overlooked population. Importantly, sleep difficulties can result in difficulties in daily living and impairment in academic functioning.     

Social Facilitation Expectancies for Smoking: Psychometric Properties of a New Measure

Abstract

Objective: Expectancies about social outcomes for smoking are relevant to college student smokers, who frequently report “social smoking.” A new measure, the Social Facilitation Expectancies (SFE) scale, was developed to assess these beliefs. Participants: The SFE was administered to undergraduate college student smokers (N = 1,096; study completed in May 2011). Methods: Items were scored on a 5-point scale with a summed total score. The sample was randomly split and principle axis factoring and confirmatory factor analysis applied to determine scale structure. The structure was tested across sex and smoking groups and validation analyses were conducted. Results: A 9-item, 1-factor scale was replicated within each group. Higher SFE scores were observed among those with greater smoking experience and higher scores were associated with greater endorsement of other smoking-related beliefs. Conclusions: These preliminary findings provide support for the sound psychometric properties of this measure for use with young adult college students.     

Rates of Asymptomatic Nonurethral Gonorrhea and Chlamydia in a Population of University Men Who Have Sex With Men

ABSTRACT

Objective: To evaluate a text message (SMS) program as a booster to an in-person alcohol intervention with mandated college students. Participants: Undergraduates (N = 224; 46% female) who violated an on-campus alcohol policy over a 2-semester period in 2014. Methods: The SMS program sent drinking-related queries each Thursday and Sunday and provided tailored feedback for 6 weeks. Response rates to SMS drinking-related queries and the associations between weekend drinking plans, drinking-limit goal commitment, and alcohol consumption were examined. Gender differences were explored. Results: Ninety percent of SMS queries were completed. Weekend binge drinking decreased over 6 weeks, and drinking-limit goal commitment was associated with less alcohol consumption. Compared with women, men had greater reductions in alcohol consumption when they committed to a drinking-limit goal. Conclusions: Preliminary evidence suggests that an SMS program could be useful as a booster for helping mandated students reduce weekend binge drinking.