On the relation of structure, perception and activity in marine planktonic copepods

The goal of this paper is to illustrate how in juvenile and adult subtropical marine planktonic copepods various structures or morphological features function in concert to detect prey and predators. Without motion by either food (e.g. flagellate, ciliate) or feeder (e.g. feeding current) or both (e.g. Acartia spp. and ciliate) few feeding activities will occur. Through motion a food particle is either perceived mechanically or chemically to be followed by appendage activities. A combination of mechano- and chemosensors on their cephalic appendages (and probably on other extremities) serve juvenile and adult copepods to perceive signals. Perception is followed by alternation of motion and sensing by these appendages, or by no motion at all (e.g. behavior by Eucalanus pileatus when perceiving a weak hydrodynamic signal). Non-moving and extended sensors (setae) are best suited for mechanical/hydrodynamic perceptions in those copepods which lack a feeding current and hardly move. Numerous mechanosensors arranged in three dimensions on the first antennae (A1) are required to perceive the precise location of moving prey at a distance (e.g. Oithona feeding on ciliates but also sinking particles). Those copepods which create a weak or intermittent feeding current can supplement nutrition with carnivory, which requires perception by the A1 (e.g. Centropages velificatus adults). These two groups require, in addition to perception of prey motion/location, rapid motion by their appendages (A1, second maxillae M2, etc.) to capture the prey. Nauplii, which satiate at far lower food levels than adults, have one of several means of food acquisition: encounter through forward motion, perception through feeding current, or perception of a moving food particle. The nearly continuous motion of most calanoid nauplii makes them vulnerable to predation because all three pairs of appendages are usually moving. Opposite are nauplii of cyclopoid and a few calanoid species which move only occasionally. Copepodid stages and adults use non-moving and often extended setae on the tips of their A1 to perceive predators at a distance. This structure and their pronounced escape motion may reduce their vulnerability to predation as compared to nauplii.     

Travel demand model system for the information era

The emergence of new information technologies and recent advances in existing technologies have provided new dimensions for travel demand decisions. In this paper we propose a comprehensive travel demand modeling framework to identify and model the urban development decisions of firms and developers and the mobility, activity and travel decisions of individuals and households, and to develop a system of models that can be used by decision makers and planners to evaluate the effects of changes in the transportation system and development of information technologies (e.g. various tele-commuting, tele-services and Intelligent Transportation Systems).The implementation of an operational model system based on this framework is envisioned as an incremental process starting with the current best practice of disaggregate travel demand model systems. To this end, we present an activity-based model system as the first stage in the development of an operational model system.     

Space,money, life-stage,and the allocation of time

Demographic, socioeconomic, seasonal, and scheduling factors affect the allocation of time to various activities. This paper examines those variables through exploration of the 1990 Nationwide Personal Transportation Survey, which has been inverted to track activity duration. Two key issues are considered. First, how much can activity duration and frequency explain travel duration? The analysis shows activity duration has positive and significant effects on travel duration, supporting recent arguments in favor of activity based models. Second, which recent trend is the main culprit in the rise in travel: suburbanization, rising personal incomes, or female labor force participation? This paper examines the share of time within a 24-hour budget allocated to several primary activities: home, work, shop, and other. The data suggest that income and location have modest effects on time allocation compared with the loss of discretionary time due to working.

     

Activity settings and travel behaviour: A social contact perspective

Using time-use data from Canada, Norway, and Sweden, this study briefly outlines the essence of the activity setting approach and illustrates one aspect of its usefulness by exploring the impact of social contact on travel behaviour. The activity system approach views behaviour in context. Activity settings are generic components of the activity system and studying them using time-use diaries can provide major insights into travel behaviour. Focusing on social contact, this paper characterizes the social environment in terms of social circle (interaction partners) and social space (location). The analysis shows that there are clear differences in the levels of social interaction across various groups, including those who work at home. The 1992 Canadian data showed people working at the workplace spend relatively more time with others, about 50% of total time awake. Working at home reduced the time with others to a low of 15.7%. when people worked at home the family benefited, almost doubling the time spent with them compared to those working at the workplace. Persons working at home only spend the most time alone. There is a tendency for persons with low social interaction to travel more. It is argued that individual need, or want, social contact and if they cannot find it at the workplace they will seek it elsewhere thus generating travel. Whether this is the result of need or opportunity is of minor relevance, what it does suggest is that working in isolation at home will not necessarily diminish travel but rather may simply change its purpose. This revised version was published online in June 2006 with corrections to the Cover Date.     

Discretionary activity time allocation of individuals between in-home and out-of-home and between weekdays and weekends

This paper formulates a model for the allocation of total weekly discretionary time of individuals between in-home and out- of-home locations and between weekdays and the weekend. The model formulation takes the form of a continuous utility-maximizing resource allocation problem. The formulation is applied to an empirical analysis using data drawn from a 1985 time-use survey conducted in the Netherlands. This survey gathered time-use information from individuals over a period of one week and also collected detailed household-personal socio-demographic data. The empirical analysis uses household socio-demographics, individual socio-demographics, and work-related characteristics as the explanatory variables. Among the explanatory variables, age of the individual and work duration during the weekdays appear to be the most important determinants of discretionary time allocation.     

南疆铁路吐鱼段风沙活动规律研究

通过对南疆铁路吐鱼段戈壁大风区风沙流进行现场观测研究,得出该地区大风显现明显的季节性变化,每年的春季是大风高发季节,年平均大风日数高达136d。大风携沙量的垂直分布十分明显,集沙量与高度显现e的负指数变化,高度越高集沙量越小;2m以下区域是风沙灾害防护的重点区域,其大风携沙量占总携沙量的96%左右。沙粒颗分试验结果表明,戈壁风沙运动存在较明显的分层现象,沙粒粒径以0.1~0.25mm为主。     

Study of the ship design process model for collaborative design

The ship design process model is the basis for developing the ship collaborative design system under network environment. According to the characteristics of the ship design, a method for dividing the ship design process into three layers is pat forward, that is project layer, design task layer and design activity layer, then the formalized definitions of the ship design process model, the decomposing principles of the ship design process and the architecture of the ship collaborative design （SDPM） system are presented. This method simplifies the activity network, makes the optimization and adjustment of the design plan convenient and also makes the design process easier to control and change, at last the architecture of the ship collaborative design system is discussed.     

基于Android系统的手机文件管理器的设计与实现

基于Android SDK 2.1,设计了一款实用的手机文件管理器,能够较好地实现Android 文件系统的文件浏览、文件管理、文件搜索、参数设置等功能.文中介绍文件管理器在整个Android系统架构中的层次,通过自定义适配器实现文件系统信息在listview上的显示.根据文件管理器的功能并结合Android activity的生命周期,设计了应用的界面及不同activity之间的 转换,把MVC模式应用到文件管理操作的实现过程中,同时探讨了开发中用到的3种Android 数据存储方式.     

教学活动中情绪唤醒于表象的意义

在教学活动全过程中,表象既是方式也是目的。任何教学内容都要借表象（主观的或客观的）才能进行教授和学习,习得的形式无论是记忆还是上升为理性认识,或各种程度的外显内隐,都伴随表象生成。表象的形象化程度和在心理层面上的操作性高低直接影响和反应教学效果。而情绪唤醒的水平高低能直接影响表象的生成和储存质量,因此利用情绪唤醒手段,促进表象形成,有利于教学活动的实施。     

镜花水月女儿国——论《镜花缘》进步的女性观

《镜花缘》是一部反映女性生活的作品,作者在小说中大胆地突破封建礼教的规定,倾情地描写了各类女性的杰出才能及其大胆的行为,表现了其进步的女性观。从男女角色地位、社会活动范围等方面来探讨了书中才女是怎样摆脱了封建束缚,成为社会活动的积极参与者,并在广阔的社会领域实现了个人价值的,充分体现了作者难能可贵而又进步的妇女观。