831 research outputs found
Computer predictions of photochemical oxidant levels for initial precursor concentrations characteristic of southeastern Virginia
A computer study was performed with a photochemical box model, using a contemporary chemical mechanism and procedure, and a range of initial input pollutant concentrations thought to encompass those characteristic of the Southeastern Virginia region before a photochemical oxidant episode. The model predictions are consistent with the expectation of high summer afternoon ozone levels when initial nonmethane hydrocarbon (NMHC) levels are in the range 0.30-0.40 ppmC and NOx levels are in the range 0.02-0.05 ppm. Calculations made with a Lagrangian model, for one of the previously calculated cases, which had produced intermediate afternoon ozone levels, suggest that urban source additions of NMHC and NOx exacerbate the photochemical oxidant condition
Polynomial coefficients of thermochemical data for the C-H-O-N system
Thermodynamic data are required input for the finite kinetics and equilibrium computer programs needed for modeling the combustion of hydrocarbons in the fields of energy and pollution research. Least squares determined coefficients of the curve-fitted thermodynamic data for 193 species in the C-H-O-N system are presented in card image form and are of suitable format for use by common computer programs
Modeling Moisture Gradient Effects On Bending Properties
Moisture gradients are known to affect the bending properties of small clear beams, but no successful attempts have been made to quantify the influence of varying gradients. A three-dimensional, nonlinear finite element program was written for this purpose. Changes in compression and tension stress-strain relationships with varying equilibrated moisture contents were modeled from experimental results. These models were used with a paraboloid representation of moisture distribution to assign properties to individual elements in the finite element model. Comparisons with tests of equilibrated and non-equilibrated yellow poplar beams showed that the finite element model predicted expected trends, but moduli of rupture were consistently overpredicted
Expression of Prelamin A Confers Sensitivity of DNA Biosynthesis to Lovastatin on F9 Teratocarcinoma Cells
Nontimber Forest Products in the United States
A quiet revolution is taking place in America\u27s forests. Once seen primarily as stands of timber, our woodlands are now prized as a rich source of a wide range of commodities, from wild mushrooms and maple sugar to hundreds of medicinal plants whose uses have only begun to be fully realized. Now as timber harvesting becomes more mechanized and requires less labor, the image of the lumberjack is being replaced by that of the forager. This book provides the first comprehensive examination of nontimber forest products (NTFPs) in the United States, illustrating their diverse importance, describing the people who harvest them, and outlining the steps that are being taken to ensure access to them. As the first extensive national overview of NTFP policy and management specific to the United States, it brings together research from numerous disciplines and analytical perspectives-such as economics, mycology, history, ecology, law, entomology, forestry, geography, and anthropology—in order to provide a cohesive picture of the current and potential role of NTFPs. The contributors review the state of scientific knowledge of NTFPs by offering a survey of commercial and noncommercial products, an overview of uses and users, and discussions of sustainable management issues associated with ecology, cultural traditions, forest policy, and commerce. They examine some of the major social, economic, and biological benefits of NTFPs, while also addressing the potential negative consequences of NTFP harvesting on forest ecosystems and on NTFP species populations. Within this wealth of information are rich accounts of NTFP use drawn from all parts of the American landscape—from the Pacific Northwest to the Caribbean. From honey production to a review of nontimber forest economies still active in the United States—such as the Ojibway harvest of plants recounted here—the book takes in the whole breadth of recent NTFP issues, including ecological concerns associated with the expansion of NTFP markets and NTFP tenure issues on federally managed lands. No other volume offers such a comprehensive overview of NTFPs in North America. By examining all aspects of these products, it contributes to the development of more sophisticated policy and management frameworks for not only ensuring their ongoing use but also protecting the future of our forests. Description Eric T. Jones is an instructor and research professor in the Department of Forest Ecosystems and Society at Oregon State University. Rebecca J. McLain is director of research at the National Policy Consensus Center at Portland State University. Susan Charnley is a research social scientist at the Pacific Northwest Research Station of the USDA Forest Service. James Weigand is an ecologist at the US Department of the Interior, Bureau of Land Management. With a New Preface by Eric T. Jones, Rebecca J. McLain, Susan Charnley, and James Weigand. This Kansas Open Books title is funded by a grant from the National Endowment for the Humanities and the Andrew W. Mellon Foundation Humanities Open Book Program.https://digitalcommons.pittstate.edu/kansas_open_books/1035/thumbnail.jp
Analysis of Racked Wood Pallets
A rational analysis procedure for designing wood stringer pallets for use in warehouse storage racks was developed for manufacturers and pallet users and is part of a computerized automatic design and analysis program called the Pallet Design System (PDS). The procedure uses simplified analog models of pallets and matrix structural analysis methods to compute the stress and deflection of critical structural elements. Semi-rigid nail joints are modeled as spring elements. Pallets with 2, 3, 4, or 5 stringers and up to 15 deckboards can be analyzed with a variety of load types including distributed and concentrated loads. The strength and stiffness of experimental pallets were compared to predicted values and showed good agreement
Urban Forest Justice and the Rights to Wild Foods, Medicines, and Materials in the City
Urban forests are multifunctional socio-ecological landscapes, yet some of their social benefits remain poorly understood. This paper draws on ethnographic evidence from Seattle, Washington to demonstrate that urban forests contain nontimber forest products that contribute a variety of wild foods, medicines, and materials for the wellbeing of urban residents. We show that gathering wild plants and fungi in urban forests is a persistent subsistence and livelihood practice that provides sociocultural and material benefits to city residents, and creates opportunities for connecting with nature and enhancing social ties. We suggest that an orientation toward human-nature interactions in cities that conceptualizes the gathering of forest products as a legitimate social benefit may support and expand urban forest justice. Urban forest justice recognizes the rights of local people to have control over their own culturally appropriate wild food and health systems, including access to natural resources and to the decision-making processes affecting them
The Processing Pathway of Prelamin A
The conversion of mammalian prelamin A to mature lamin A proceeds through the removal of 18 amino acids from the carboxyl terminus. The initial step in this processing is the isoprenylation of a CAAX box cysteine. This proteolytic event is distinctive for prelamin A among the known prenylated mammalian proteins. Since the carboxyl terminus of prelamin A is removed during maturation, it is not obvious that this protein would undergo the two reactions subsequent to prenylation observed in other CAAX box proteins-the endoproteolytic removal of the carboxyl-terminal 3 amino acids and the subsequent methylation of the now carboxyl-terminal cysteine. To characterize the maturation of prelamin A further, we have developed a CHO-K1 cell line that possesses a dexamethasone-inducible human prelamin A against a genetic background of high mevalonate uptake. Utilizing this cell line in association with antibodies specific to the transgenic prelamin A, we have been able to demonstrate directly in vivo that prelamin A undergoes farnesylation and carboxymethylation prior to conversion to lamin A, as is the case for other prenylated proteins. We have demonstrated previously that in the absence of isoprenylation, conversion of prelamin A to lamin A is blocked, but that unprocessed prelamin A is transported to the nucleus where it can still undergo maturation. Consistent with the implications of these prior studies, we now demonstrate the presence of both subunits of farnesyl-protein transferase in the nucleus
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