Effects of parasites on foraging and defense behavior of a termitophagous ant,Pheidole titanis Wheeler (Hymenoptera: Formicidae)

Summary Pheidole titanis Wheeler, an ant that occurs in desert and deciduous thorn forest in the southwestern United States and western Mexico, is a predator on termites. In the dry season well-coordinated raids against termite foraging parties occur early in the morning or late in the afternoon, whereas in the wet season most raids occur at night. This seasonal shift in the timing of raids is due to the increased activity of a fly (Diptera: Phoridae) that is a specialist parasitoid on P. titanis workers and soldiers. When parasitic flies discover P. titanis nest entrances or raiding columns, workers stop foraging and defend themselves against oviposition attacks. Flies are only active during the day and never interfere with foraging at night. However, P. titanis does not increase the frequency of raids at night and, as a result, colonies collect less food in the wet season compared to the dry season. Presence of parasitic flies also interferes with normal defense behavior of P. titanis against conspecific and heterospecific enemy ants. Dissections of P. titanis workers and soldiers suggest that the parasitism rate by flies is less than 2% and observations indicate that parasitic flies are much rarer than their host workers and soldiers. Nonetheless, these parasites exert a strong ecological impact on their host.     

Determination and implementation of optimal air quality standards

This paper utilizes two least-cost emission control strategies and develops rules for structuring and implementing optimal air quality standards. A strategy typical of those currently enforced, based on the State Implementation Plans (SIP's ), is compared to two least-cost strategies: (i) ambient least cost (ALC ), which achieves required air quality at least cost; and (ii) emissions least cost (ELC ), which achieves required emissions reduction at least cost. A demonstration is given of the theoretically derived result that the ALC strategy should be utilized in cost-benefit analyses to determine air quality standards and to generate emissions taxes. Preliminary analysis of the St. Louis area indicated tentative justification for a particulate ambient standard at least as strict as the current Federal primary standard. The efficiency, equity, and administrative costs for implementation of strategies based on the least-cost concept are also examined.     

USE OF A DAM BREAK MODEL TO ASSESS FLOODING AT HADDAM NECK NUCLEAR POWER PLANT1

Because of their proximity to necessary supplies of cooling water, nuclear power plants are susceptible to riverine flooding. Greater flood hazards exist where plants are located downstream of large dams. The consequences of the Quabbin Reservoir dam failure on the Haddam Neck Nuclear Power Plant situated on the Connecticut River were investigated using a dam break flood routing model. Reasons for selecting a particular model are presented and the input assumptions for the modeling process are developed. Relevant information concerning the level of manpower involvement is presented. The findings of this analysis demonstrate that the plant is adequately protected from the consequences of the postulated flood event.     

Focus of Attention at Work and Leader-Follower Relationships

Three different studies examine moderating effects of focus of attention at work on leader-follower relationships, using the typology developed by Howell, Dorfman, and Kerr (1986). Survey data were collected from over 1300 subjects. Results indicate that: (1) high focus on the supervisor while at work enhances leader behaviour-subordinate satisfaction and behaviour relationships, (2) high focus on off-job factors while at work enhances leader behaviour-subordinate satisfaction relationships, and (3) high focus on off-job factors while at work weakens leader behaviour-subordinate behaviour relationships. Theoretical implications for the study of organizational behaviour are discussed, as well as practical issues for enhancing leader behaviour effectiveness in work organizations.     

Soil reinforcement with recycled carpet wastes.

A root or fibre-reinforced soil behaves as a composite material in which fibres of relatively high tensile strength are embedded in a matrix of relatively plastic soil. Shear stresses in the soil mobilize tensile resistance in the fibres, which in turn impart greater strength to the soil. A research project has been undertaken to study the influence of synthetic fibrous materials for improving the strength characteristics of a fine sandy soil. One of the main objectives of the project is to explore the conversion of fibrous carpet waste into a value-added product for soil reinforcement. Drained triaxial tests were conducted on specimens, which were prepared in a cylindrical mould and compacted at their optimum water contents. The main test variables included the aspect ratio and the weight percentage of the fibrous strips. The results clearly show that fibrous inclusions derived from carpet wastes improve the shear strength of silty sands. A model developed to simulate the effect of the fibrous inclusions accurately predicts the influence of strip content, aspect ratio and confining pressure on the shear strength of reinforced sand.     

沿哥伦比亚--厄瓜多尔边界毁林速度和格局变化的卫星检测分析

本研究使用Landsat卫星数据来论证哥伦比亚-厄瓜多尔部分边界23年间(1973～1996)土地覆被变化的速度和格局.人类定居给这两个国家带来了大量毁林.变化的卫星检测分析表明,边界哥伦比亚一侧年毁林速度相对高得多.另外,哥伦比亚一侧森林覆被在研究期间几乎损失了43%,而在厄瓜多尔一侧只损失了22%.研究发现,在边界的任何一侧,都不存在单一的毁林驱动因素;但得出结论哥伦比亚一侧的毁林速度高可能是由于定居压力高、非法古柯种植加剧.卫星图像证明,在厄瓜多尔一侧,毁林格局反映出与石油勘探和开发有关的道路网络.     

The influence of plantation forestry on the pH and aluminium concentration of upland welsh streams: a re-examination

Previous studies relating forest presence to stream acidity and aluminium concentration were based on small numbers of catchments, often precluding the elimination of confounding influences on stream chemistry, such as geology or soil type. Spatial patterns in aluminium and pH data from 113 Welsh catchments of contrasting land use were therefore analysed in three different ranges of acid sensitivity (< 10, 10-15, 15-25 mg CaCO(3) litre(-1) total hardness). In each range, pH declined and aluminium increased significantly with increasing percentage forest cover. There was no evidence that the relationships reflected a spurious effect of forest location. Where aluminium concentrations were elevated under forest in a sub-set of 13 streams, aluminium was present predominantly in the labile form, most toxic to fish. Regressions of pH and aluminium on percentage forest cover provide a useful method of assessing the amount of forest in Welsh catchments which might give rise to given chemical conditions (e.g. pH <6, Al > 80 microg litre(-1)), though some difficulties are likely in accurately specifying the conditions desirable for fish or other biota.     

What Food is “Good” for You? Toward a Pragmatic Consideration of Multiple Values Domains

What makes a food good, for you? With respect to food, the expression “good for you” usually refers to the effect of the food on the nutritional health of the eater, but it can also pertain more broadly. The expression is often used by a person who is concerned with another person’s well-being, as part of an exhortation. But when framed as a question and addressed to you, as an individual, the question can require a response, calling for accountability beyond the realm of nutrition or other material qualities of the food. Economic value may be considered as a ratio: goodness/price. In this paper, we examine the numerator, exploring a broad range of values domains related to food, attempting to obtain a more comprehensive understanding of the meaning of goodness of food. We present a typology of values domains with respect to food, divided into three main categories: (1) material considerations, (2) psychological, psychosocial, and spiritual health, and (3) the well-being of society. This understanding that results from comprehensive consideration of these values domains has important implications for an individual for use in considering the question “what food is good for you?” in order to guide his or her future actions, helping to distinguish between what Dewey termed immediate good and reasonable good. A pragmatic approach to a fuller consideration of food-related values domains by individuals also has broad social, political, and economic implications. If, according to the FAO, food security involves both needs and preferences, consideration of what preferences are appropriate is fundamental to achieving food security. The questions about what is considered to be good food are central to questions about the sorts of food and agricultural systems human societies will seek to sustain. The approach to resolving this important aspect of sustainability might help inform a more general question as to appropriate limitations on preferences, a question fundamental to achieving sustainability in general.