气候变化和人类活动对沙尘暴发生日数的影响——以内蒙古四子王旗为例

沙尘暴已经成为21世纪重大的环境问题之一;位于内蒙古自治区中部阴山北麓的四子王旗,荒漠化极为严重,多年来一直是发生沙尘暴平均日数的高值区中心,也是沙尘源区和沙尘东移进入京津的重要路径之一,沙尘暴频发的原因是人类活动和脆弱的自然环境耦合的结果;以该区为例讨论气候变化和人类活动耦合作用下沙尘暴的年发生日数特点。     

Aquatic resources and recreation behavior

While substantial effort has been undertaken to understand the consequences of industrial and agricultural uses for the environment, concern has also been expressed about its other uses, including recreation. Little is known about the relationship between recreational behavior and an environmental resource base. The present paper focuses upon participation in a specific outdoor recreation activity or activity‐cluster and dominant resource base where participation occurs. Resource bases identified were river, lake, ocean, swamp/marsh, forest/mountain, range/ farm and city/town. Emphasis is placed upon aquatic environs and participation in water‐based recreation. Water activities constituted from 14–30 percent of all outdoor activities taking place at those resource bases identified. Aquatic environments provided the resource base for 38 percent of all recreation participation events, water‐ and non‐water based, occurring during one reporting period. While participation in water‐based activities requires a water resource, the array of participation patterns reported suggests that resource bases defined as recreation places provide a wide range of opportunities for non‐resource‐dependent recreation activities. One conclusion is that resource bases cannot be distinguished by the recreation activities occurring on them. Resource bases in fact facilitate a wide range of recreation activities, some holding little direct connection with the resource base, nor are the conditions of the resource sufficient to predict behavioral outcomes.     

The leading indicator property of the term spread and the monetary policy factors in Japan

Many studies have observed the leading indicator property of the term spread (LIPTS), which indicates that the term spread—the difference between long- and short-term interest rates—has information on future economic conditions. We examine whether this property is related to monetary policy or not by using Japanese monthly data with consideration for structural changes. Results of structural change tests show that the term spread has predictive ability for the future economic activity from 1982:4 to 1997:8. Decomposing the term spread into three parts; one is explained by past monetary policy shocks, another is explained by expected future call rates and the other is the remaining part, we find that all three parts are significantly related to the future economic growth rate. Hence, we find that the monetary policy plays an important role for the LIPTS.     

休闲活动与主观幸福感

为了探讨休闲活动与主观幸福感之间的关系。文章采用休闲问卷、正性负性情绪量表和生活满意度量表对460名员工进行了调查。结果表明：（1）性别、是否有孩子等人口学变量影响休闲活动；（2）休闲活动对主观幸福感中的正性情绪和生活满意度有显著的正向预测作用，对负性情绪没有预测作用。     

在健美操课堂教学中培养学生自主学习能力的策略

健美操教学是以艺术创造作为手段,集舞蹈、体操以及音乐于一体,采用健美器械协助或徒手的方式开展教学的一种方式。目前健美操教学在各大高校中已基本普及,然而,课堂中培养学生的自主学习精神、创造探究意识却成了教学中的重点与难点。笔者结合健美操教学实践,探讨了课堂中培养学生自主学习能力的具体策略。     

Physical Activity of Remote Indigenous Australian Women: A Postcolonial Analysis of Lifestyle

In the context of rising chronic diseases amongst Indigenous peoples, there are calls for the adoption of more healthy “lifestyles.” In this context, this paper explores thoughts about physical activity from 21 Indigenous families through the voices of women and girls living in remote rural communities in the Torres Strait and Northern Peninsula Area, Australia. Speaking back to physical activity as a lifestyle “choice,” three consistent themes emerged: shame, gendered positioning, and welfarism. In conclusion, the perspectives of Torres Strait islanders and Northern Peninsula Area communities suggest that there are deeply embedded ways of thinking about the body, familial obligations, and the provision of and access to being active that are not consistent with Western health policies predicated upon individuals shouldering responsibility for “taking exercise.”     

The relationships between stress,health, and physically active leisure as a function of life‐cycle

This article examines relationships between stress, health, and participation in physically active leisure using data collected as part of the 1985 and 1990 U.S. National Health Interview Surveys (NHIS). In particular, the article analyzes: (a) the effects of life‐cycle progression (controlled for gender) on subjectively perceived stress and self‐reported health; (b) the role of physically active leisure in enhancing health or buffering adverse health outcomes of stress; and (c) the effects of selected social‐economic factors, such as education and income, on the relationships between life‐cycle, stress, health, and physically active leisure. According to our analyses: (1) stress is unevenly distributed across the life span; (2) stress‐reducing effects of physically active leisure are present among retired older people more so than in the middle‐aged life‐cycle groups; and (3) direct health‐enhancing effects of participation in physically active leisure are more evident than the buffering effects of leisure on stress‐health relationships. A critical discussion of methodological and substantive issues facing researchers interested in the relationships between leisure, stress, and health is provided.     

贪心算法求解最少资源问题的探讨

面对资源的日益紧缺,如何有效合理的利用资源一直是专家学者研究和探讨的热点问题。最少资源问题是对初步资源规划问题的探讨,可以为多个资源组合规划问题的基础研究提供有效的参考作用。传统的回溯法穷举虽然能找到最少资源问题的最优解但其时间复杂度会高于o(n!),往往耗时太多,不能满足问题的及时性。提出了一种以最早开始时间为贪心策略的求解最少资源问题的贪心算法,不仅能够找到最优解,而且其时间复杂度仅为o(n2),极大提高了算法的效率。     

Outdoor recreation participation and views on resource development and preservation

Abstract

Views on the preservation of resources versus their development for recreation are compared among participants in three types of outdoor recreation: “appreciative”; activities (cross‐country skiing, hiking, and canoeing); “consumptive”; activities (fishing and hunting); and “mechanized”; activities (motorboating, snowmo‐biling, and trail biking). The results from a 1984 questionnaire survey conducted in Edmonton and Calgary, Canada, indicate a stronger preservationist orientation among participants in appreciative activities, whereas (with the exception of hunters) participants in consumptive and mechanized activities hold stronger pro‐development views. These differences cannot be attributed to simultaneous variations in socioeco‐nomic characteristics or environmental attitudes among the recreational groups. The findings suggest that differences in outdoor recreational activity preferences represent an important source of variation in views about appropriate levels of preservation versus development of Alberta's natural and wildernesss resources.     

Time Changes for Lévy Processes

The goal of this paper is to consider pure jump Lévy processes of finite variation with an infinite arrival rate of jumps as models for the logarithm of asset prices. These processes may be written as time-changed Brownian motion. We exhibit the explicit time change for each of a wide class of Lévy processes and show that the time change is a weighted price move measure of time. Additionally, we present a number of Lévy processes that are analytically tractable, in their characteristic functions and Lévy densities, and hence are relevant for option pricing.