Publications by authors named "Helmke M"

The iPlant Collaborative (iPlant) is a United States National Science Foundation (NSF) funded project that aims to create an innovative, comprehensive, and foundational cyberinfrastructure in support of plant biology research (PSCIC, 2006). iPlant is developing cyberinfrastructure that uniquely enables scientists throughout the diverse fields that comprise plant biology to address Grand Challenges in new ways, to stimulate and facilitate cross-disciplinary research, to promote biology and computer science research interactions, and to train the next generation of scientists on the use of cyberinfrastructure in research and education. Meeting humanity's projected demands for agricultural and forest products and the expectation that natural ecosystems be managed sustainably will require synergies from the application of information technologies.

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Discrete-fracture and dual-porosity models are infrequently used to simulate solute transport through fractured unconsolidated deposits, despite their more common application in fractured rock where distinct flow regimes are hypothesized. In this study, we apply four fracture transport models--the mobile-immobile model (MIM), parallel-plate discrete-fracture model (PDFM), and stochastic and deterministic discrete-fracture models (DFMs)--to demonstrate their utility for simulating solute transport through fractured till. Model results were compared to breakthrough curves (BTCs) for the conservative tracers potassium bromide (KBr), pentafluorobenzoic acid (PFBA), and 1,4-piperazinediethanesulfonic acid (PIPES) in a large-diameter column of fractured till.

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Fractures in till may provide pathways for agricultural chemicals to contaminate aquifers and surface waters. This study was conducted to quantify the influence of fractures on solute fate and transport using three conservative and two nonconservative tracers. The conservative tracers were potassium bromide (KBr), pentafluorobenzoic acid (PFBA), and 1,4-piperazinediethanesulfonic acid disodium salt (PIPES); the nonconservative tracers were nitrate and atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine].

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Using the in-situ DNA hybridization we studied 62 liver biopsies from 34 patients for the presence of CMV-, EBV-, HBV-, and HSV-Genome. In the first biopsies positivity-rates were as follows: CMV 62%, EBV 71%, HBV 15%, HSV 15%. In 6 cases a conversion from a negative intranuclear CMV-status to a positive status was seen correlating with an increase in serological titers and with clinical signs of viral infection.

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We herein propose a classification of rejection in cardiac allografts based on the original Stanford work. Our modified classification, as a work hypothesis, defines the following grades: mild acute rejection (A-1), corresponding to Billingham's "mild rejection"; mild acute rejection with probable conversion to moderate rejection (A-2); moderate acute rejection (A-3), comparable to Billingham's "moderate rejection"; and severe acute rejection (A-4), morphologically identical with the respective grade in the Billingham classification. The resolution of rejection has been classified into two grades--early (A-5a) and late (A-5b) resolution--according to the development of granulation tissues.

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