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Previous research revealed that stress wave nondestructive testing techniques could be used to evaluate the tensile and flexural properties of wood-based composite materials. Regression models were developed that related stress wave transmission characteristics (velocity and attenuation) to modulus of elasticity and strength. The developed regression models accounted for over 94% of these materials’ observed elastic properties and for over 90% of their observed strength. The original models were developed using wood-based particle composite specimens. The study presented in this paper...

The use of a variety of stress wave transmission techniques for the in-service condition assessment of deteriorated wood is well documented. This paper summarizes results from an extensive study designed to examine the relationship between ultrasound transmission times and the deterioration of exposed wood. Two hundred seventy (270) southern pine lumber specimens were evaluated nondestructively using a through transmission ultrasound technique after field exposure for periods of up to fifty seven (57) months. Ultrasound transmission times increased with exposure time. Several statistical...

Spatially nonuniform runoif reduces the water qua1iry perfortnance of constant- width filter strips. A geographic inlormation system (Gls)-based tool was developed and tested that ernploys terrain analysis to account lor spatially nonuniform runoffand produce more ellbctive filter strip designs.The computer program,AgBufTerBuilder, runs with ATcGIS versions 10.0 and 10.1 (Esri,Redlands,California) and uses digital elevation models to identify detailed spatial patterns of overland runoff to field margins.The tool then sizes filter dimensions according to those patterns using bufTer area...

EXCERPT FROM: Natural Disturbances and Historic Range Variation 2015. Throughout the history of upland hardwood forests of the Central Hardwood Region, natural disturbances have been integral to shaping forest structure and composition, and essential in maintaining diverse biotic communities. In this chapter, we introduce the geographic scope and dynamic history of climate, natural disturbances, and human influence on central hardwood forests. We briefly introduce biotic and abiotic agents of disturbance to provide a foundation for the book and further discussion of whether and how...

EXCERPT FROM: Natural Disturbances and Historic Range Variation 2015
Multiple natural disturbance types historically created conditions thatwere suitable for many, but not all, disturbance-dependent wildlife species in the Central Hardwood Region (CHR). In addition, some wildlife species, such as beavers, passenger pigeons, elk, and bison, historically functioned as keystone species by creating or maintaining unique disturbed habitats that otherwise would be rare. For millennia, humans (Native Americans, and later European settlers) also created and maintained early successional...

EXCERPT FROM: Natural Disturbances and Historic Range Variation 2015. The southern pine beetle (SPB) is a major disturbance in pine forests throughout the range of southern yellow pines, and is a significant influence on forests throughout several Central Hardwood Region (CHR) ecoregions. At endemic levels, SPB colonizes individual stressed or lightning-struck trees, acting as a natural thinning agent. During outbreaks, tree mortality from SPB may impact CHR forests by indirectly converting stands to other species types, or changing the stand age and structure. Southern pine beetle can...

The 19th International Nondestructive Testing and Evaluation of Wood Symposium was hosted by the University of Campinas, College of Agricultural Engineering (FEAGRI/UNICAMP), and the Brazilian Association of Nondestructive Testing and Evaluation (ABENDI) in Rio de Janeiro, Brazil, on September 22–25, 2015. This Symposium was a forum for those involved in nondestructive testing and evaluation (NDT/NDE) of wood and brought together many NDT/NDE users, suppliers, international researchers, representatives from various government agencies, and other groups to share research results, products,...

Host–parasite theory makes predictions about the influence of host abundance, competition for hosts, and parasite transmission on parasite population size, but many of these predictions are not well tested empirically. We experimentally examined these factors in ponds using two species of freshwater mussels with parasitic larvae that infect host fishes via different infection strategies. For both species, recruitment and larval survival were positively related to host abundance, but there was no apparent minimum host threshold and positive population growth occurred when an average of one...

Natural selection favors individuals that respond with effective and appropriate immune responses to macro or microparasites. Animals living in populations close to ecological carrying capacity experience increased intraspecific competition, and as a result are often in poor nutritional condition. Nutritional condition, in turn, affects the amount of endogenous resources that are available for investment in immune function. Our objective was to understand the relationship between immune function and density dependence mediated by trade-offs between immune function, nutritional condition,...

In this paper, we attempted to simulate stress wave propagation in virtual tree trunks and construct two dimensional (2D) wave-front maps in the longitudinal-radial section of the trunk. A tree trunk was modeled as an orthotropic cylinder in which wood properties along the fiber and in each of the two perpendicular directions were different. We used the COMSOL Multiphysics® software to conduct numerical simulations. Field stress wave timing measurements were then conducted on three freshly cut larch (Larix principis-rupprechtii Mayr) logs to validate the simulation results. The 2D wave...