Endogenous factors,external cues,and eccentric construction inPolistes annularis (Hymenoptera: Vespidae)

This study explores the relationship between various factors and the construction of the distinctive inclined, eccentric, and curved combs of Polistes annularis.Foundation and early construction show stereotypical inclination and bilateral symmetry. Eccentric comb shape is modestly related to inclination and highly repeatable by wasps building on combs of high inclination. Later construction by the foundresses or by their worker offspring is less stereotypical. Features associated with curvature of mature nests, such as nonhexagonal cells, are peculiar to construction by workers and occur nonrandomly, suggesting functional adaptation.     

浅谈我国高校教师激励机制建设

分析了我国高校教师的激励工作在社会外部环境、人员选用制度、业绩评估方法、报酬制度、激励方式等方面存在的问题,提出应从实施高校教师激励制度所要遵循的原则出发,选择正确的激励方法,构建合理的激励机制。     

The use, construction, and importance of canoes among the Maijuna of the Peruvian Amazon

Canoe construction was studied in a Maijuna community to better understand the role and significance of canoes in the life and subsistence strategies of an Amazonian group. In this community the types of canoes constructed and used by the Maijuna have changed considerably over the past 20 years. Twenty-seven species were identified as being specifically employed by the Maijuna to construct the type of dugout canoe currently being made in the community. The scarcity of preferred species used for canoe hulls directly affects the trees chosen for construction and may have been a contributing factor behind the complete switch from making the traditional type of dugout canoe.     

Webs of theridiid spiders: construction, structure and evolution

Understanding the web construction behaviour of theridiid (comb-footed) spiders is fundamental to formulating specific evolutionary hypotheses and predictions regarding the reduction of orb-webs. We describe for the first time in detail the web construction behaviour of Achaearanea tepidariorum , Latrodectus geometricus , Theridion sisyphium and T. varians as well as webs of a range of other theridiids. In our survey we distinguish four major web types. Among webs with gumfooted lines, we distinguish between webs with a central retreat ( Achaearanea -type) and those with a peripheral retreat ( Latrodectus -type). Among webs without gumfooted lines, we distinguish between those which contain viscid silk ( Theridion -type) and those with a sheet-like structure, which do not ( Coleosoma -type). Theridiid gumfoot-webs consist of frame lines that anchor them to surroundings and support threads which possess viscid silk. Building of gumfooted lines constitutes a unique stereotyped behaviour and is most probably homologous for Nesticidae and Theridiidae. Webs remained in place for extended periods and were expanded and repaired, but no regular pattern of replacement was observed. We suggest that the cost of producing and maintaining viscid silk might have led to web reduction, at least in theridiids.  © 2003 The Linnean Society of London. Biological Journal of the Linnean Society , 2003, 78 , 293−305.     

Fatal Occupational Injuries among Hispanic Construction Workers of Texas, 1997 to 1999

Hispanic construction workers, particularly those born outside of the United States, are a growing segment of the Texas workforce and are increasingly the victims of on-the-job fatalities. This study examines occupational fatality characteristics among Hispanic construction workers utilizing records collected by the Texas Workers' Compensation Commission for the Bureau of Labor Statistics, Census of Occupational Fatal Injuries program. Of the 370 fatalities recorded from 1997 to 1999, 179 cases (46.5%) involved Hispanic workers — 109 of who were born in a foreign country. The fatality rate for Hispanic construction workers was 23.5 per 100,000 workers compared to 21.2 for non-Hispanic workers. Many fatally injured Hispanic construction workers shared similar characteristics including: low skill level, young age and foreign birthplace. Hispanic workers employed as construction laborers, helpers, and roofers had the highest number of fatalities. Businesses with fewer than 10 workers employed forty-two % of all Hispanic decedents, and businesses with more than 100 employees comprised twenty % of fatalities. The leading causes of Hispanic fatalities were: transportation incidents, falls, and exposure to harmful substances.     

Energy requirement for foliage formation is not constant along canopy light gradients in temperate deciduous trees

Foliage construction cost (glucose requirement for formation of a unit foliar biomass, G , kg glu kg⁻¹), chemical composition and morphology were examined along a light gradient across the canopies in five deciduous species, which ranked according to increasing shade-tolerance as Populus tremula < Fraxinus excelsior < Tilia cordata = Corylus avellana < Fagus sylvatica . Light conditions in the canopy were estimated by a hemispheric photographic technique, allowing ranking of sample locations according to long-term light input incident to the sampled leaves (relative irradiance). G and foliage carbon concentration increased with increasing relative irradiance in F. excelsior , T. cordata and C. avellana , but wereindependent of irradiance in F. sylvatica and P. tremula . However, if G of non-structural-carbohydrate-free dry mass was considered, it also increased with increasing relative irradiance in P. tremula . A positive correlation between the concentration of carbon-rich lignin and irradiance, probably a result of the acclimation to greater water stress at higher light, was the major reason for the light-dependence of G . Lignin concentrations were highest in more shade-tolerant species, resulting in greatest carbon concentrations in these species. Since carbon concentration and G are directly linked, the leaves of shade-tolerant species were also more expensive to construct. As the result of these effects, G increased faster with increasing leaf dry mass per area which was mainly determined by relative irradiance, in shade-tolerators. Given that shade-tolerant species had lower leaf dry mass per area at common irradiance and that this saturated at lower relative irradiance than leaf dry mass per area in the intolerant species, it was concluded that enhanced energy requirements for foliage construction might constrain species morphological plasticity and the upper limit of leaf dry mass per area attainable at high light.     

Laboratory study of conspecific avoidance by host-colonizingDendroctonus frontalis Zimm. (Coleoptera: Scolytidae)

Bark/phloem disk sandwiches (100 cm²) were colonized with one to six mating pairs of the southern pine beetle, Dendroctonus frontalis Zimm., to observe gallery construction and evaluate if avoidance behavior occurs between beetles. Frequencies of turn aways, touches, and crosses (three characteristics used to describe conspecific interaction) all increased significantly with beetle density. A threshold of three mating pairs within the 100- cm² phloem area was the density at which avoidance behavior became evident. At a threshold of five mating pairs the number of gallery crossings was significantly greater than at lower densities. Single and paired female beetles introduced into artificial galleries crossed empty neighboring galleries significantly more often than when neighboring galleries were occupied with other D. frontalis. The data suggest that D. frontalis females can regulate gallery spacing within the host through their ability to detect nearby beetles and their galleries. Possible spacing mechanisms are discussed.