DESIGNING THE OPTIMUM CONFIGURATIONS OF CIRCULAR AND SPHERICAL PRODUCT SPECIFICATIONS FOR MULTIPLE QUALITY CHARACTERISTICS

1. Introduction The problem of determining an optimal tolerance is equivalent to the problem of determining optimal specification limits, since the term tolerance refers to the distance between its lower and upper specification limits. Functional performance and economic considerations are the two primary factors affecting the design of tolerances. A tighttolerance usually implies high manufacturing cost due to additional manufacturing operations, slow processing rates, additional care on part…     

Effect of pregnancy and feeding pattern on tryptophan pyrrolase in the rat

Résumé Chez la rate, la dose de tryptophan pyrrolase fut augmentée du douxième au quinzième jour de gestation. L'activité de ces rates gravides ne changea pas quand leur nourriture fut modifiée.     

Effects of prescribed fall burning on a wetland plant community, with implications for management of plants and herbivores

An important contemporary challenge for adaptive resource management is assessing both the direct and indirect effects of management activities by designing appropriate monitoring programs and sound analysis methods. Here we evaluate the effects of prescribed fall burning on a wetland plant community that is managed primarily for spring-migrating geese. During late fall in 2 consecutive years, we burned vegetation in 4 replicate blocks (2.3 ha each) that traversed a natural moisture and associated vegetation gradient. We used ordination, gradient analysis, and contingency table analysis to evaluate how annual changes in relative abundance of plants were affected by burning as well as other important ecological factors. Burning increased species diversity of plants, especially in the 2 wetter vegetation zones, but had no effect on species richness or on the proportion of native plant species. Wetland plant species responded to prescribed burning independently, and their response often differed by vegetation zone and with annual variation in flooding. Burning enhanced the abundance of native foxtail barley ( Hordeum jubatum ) and reduced the abundance of introduced swamp timothy ( Crypsis shoenoides ). Saltgrass ( Distichlis spicata ), a native plant species, was usually less abundant following burning, although the level of response was different for each of the 3 vegetation zones. Two other introduced plant species, quackgrass ( Elytrigia repens ) and reed canarygrass ( Phalaris arundinaceae ), were less abundant after fall burning, especially when spring flooding was more extensive. Wild geese using the experimental blocks for feeding clearly preferred burned sites, suggesting that fall burning can enhance wetland use by geese during spring. Given that simple manipulations such as burning and flooding of a wetland system may often produce complex results, we suggest that on-going management schemes be regularly evaluated with field experiments such as those conducted in this study.     

Multifunctionality of extracellular and cell surface heparan sulfate proteoglycans

Heparan sulfate proteoglycans are a remarkably diverse family of glycosaminoglycan-bearing protein cores that include the syndecans, the glypicans, perlecan, agrin, and collagen XVIII. Members of this protein class play key roles during normal processes that occur during development, tissue morphogenesis, and wound healing. As key components of basement membranes in organs and tissues, they also participate in selective filtration of biological fluids, in establishing cellular barriers, and in modulation of angiogenesis. The ability to perform these functions is provided both by the features of the protein cores as well as by the unique properties of heparan sulfate, which is assembled as a polymer of N-acetylglucosamine and glucuronic acid and modified by specific enzymes to generate specialized biologically active structures. This article discusses the structures and functions of this amazing family of proteoglycans and provides a platform for further study of the individual members.     

Future fitness and helping in social queues

Helpers in primitively eusocial and cooperatively breeding animal societies forfeit their own reproduction to rear the offspring of a queen or breeding pair, but may eventually attain breeding status themselves. Kin selection provides a widely accepted theoretical framework for understanding these societies, but differences in genetic relatedness do not explain a universal societal feature: the huge variation between individuals in helping effort. An alternative explanation for this variation lies in a fundamental trade-off faced by helpers: by working harder, they increase the indirect component of their fitness, but simultaneously decrease their own future survival and fecundity. Here, we show that individuals work less hard when they stand to lose more future fitness through working. We experimentally manipulated two components of future fitness in social queues of hover wasps (Stenogastrinae): a helper's chance of inheriting an egg-laying position, and the workforce available to rear her offspring should she inherit. After each manipulation, helpers increased or decreased their effort as appropriate to the change in expected future fitness that they experienced. Although helping provides significant indirect fitness benefits for hover wasps, our study shows that variation in the costs associated with helping is the major determinant of helping effort.