Regional Differences in Stream Water Nitrogen, Phosphorus, and Sediment Responses to Forest Harvesting in the Conterminous USA.

Forest harvesting and management techniques were hypothesized to result in significant differences in stream water N (NO-N), P (total P [TP]), and total suspended sediment (TSS) responses among regions of United States. The objectives were (i) to determine the mean response periods after harvesting for each water quality variable, (ii) to compare the regional response yields, and (iii) to determine relationships among water quality, rainfall, and flow. Watershed-scale studies where best management practices were implemented provided a basis for water quality analyses. A mixed model was used to estimate the time from harvest to time when the harvested site yielded similar export as the reference site (response period). Normalized water quality yields were calculated as response yields (kg ha yr) times estimated response periods. Significant differences among yields were identified using ANOVA and Tukey test (α = 0.05), and relationships between water quality and hydrologic variables were identified using multivariate analysis (α = 0.05). The ratio of estimated mean response period for TSS to NO-N and TP, each individually, was approximately two. The mean normalized NO-N response yield was greater for the northern than the southern and/or western regions. Normalized NO-N and TSS response yields were greater for plantations than for other harvest types. The TSS export significantly increased with discharge from plantations. The literature-based response periods used in this study were not fully monitored, and soil surface manipulations after harvesting pose a significant influence on sediment export in the United States.

Computer vision guided virtual craniofacial reconstruction.

The problem of virtual craniofacial reconstruction from a sequence of computed tomography (CT) images is addressed and is modeled as a rigid surface registration problem. Two different classes of surface matching algorithms, namely the data aligned rigidity constrained exhaustive search (DARCES) algorithm and the iterative closest point (ICP) algorithm are first used in isolation. Since the human bone can be reasonably approximated as a rigid body, 3D rigid surface registration techniques such as the DARCES and ICP algorithms are deemed to be well suited for the purpose of aligning the fractured bone fragments. A synergistic combination of these two algorithms, termed as the hybrid DARCES-ICP algorithm, is proposed. The hybrid algorithm is shown to result in a more accurate mandibular reconstruction when compared to the individual algorithms used in isolation. The proposed scheme for virtual reconstructive surgery would prove to be of tremendous benefit to the operating surgeons as it would allow them to pre-visualize the reconstructed mandible (i.e., the end-product of their work), before performing the actual surgical procedure. Experimental results on both phantom and real (human) patient datasets are presented.

Evaluation of Anammox and denitrification during anaerobic digestion of poultry manure.

Two approaches based on ne w process development and biological nitrogen transformation were investigated in a bench study for removing nitrogen as N2 gas from poultry waste while stabilizing the wastes. The process, known as "Anammox", was explored in batch anaerobic culture using serum bottles. The Anammox process involves the use of nitrite as an electron acceptor in the bacterially mediated oxidation of ammonia to yield N2. Studies are described wherein nitrite was added to poultry waste and the effects on ammonium levels were monitored. About 13-22% ammonium removal was observed with the inoculation of returned activated sludge, and the total ammonium reduction was not proportional to the reduction of nitrite, thereby suggesting that Anammox was less competitive under the conditions in our studies. The addition of nitrite and nitrate was not inhibitory to the process based on gas generation and COD reduction. The classical nitrogen removal process of nitrification followed with denitrification offers a more reliable basis for nitrogen removal from poultry wastes.

Control of Soilborne Pathogenic Fungi in Fields of Sweet Onion.

Populations of soil fungi from fields planted to sweet onion were assayed on selective media. In pathogenicity tests, Rhizoctonia solani AG-4, Pythium irregulare, and Phoma terrestris were the fungi most virulent on onion seedlings. Plots were fumigated with methyl bromide (MBR), chloropicrin (CP), MBR + CP (67% + 33%), metam sodium, 1,3,-dichloropropene (1,3-D), or 1,3-D + 17% CP in four field experiments in 2 years. Sweet onion was transplanted or direct seeded in October or November and harvested in April or May. MBR + CP and CP were effective in reducing populations of Phoma terrestris, Pythium spp., Fusarium spp., and R. solani AG-4 in soil. Metam-sodium and 1,3-D + 17% CP were less efficacious, and MBR and 1,3-D were ineffective. There were no differences in the percentage of bulbs with decay at harvest or after curing among treatments. Increased yield of marketable bulbs was associated with control of soilborne pathogenic fungi. In fields continuously cropped to onion, decreased yield was primarily associated with control of pink-root induced by Phoma terrestris, and P. terrestris was identified in soil from 74% of the fields assayed.