1,169 research outputs found

    A review of carbon monoxide sources, sinks, and concentrations in the earth's atmosphere

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    Carbon monoxide is a toxic pollutant which is continually introduced into the earth's atmosphere in significant quantities. There are apparently some mechanisms operating which destroy most of the CO in the atmosphere, i.e., a carbon monoxide sink. These mechanisms have not as yet been established in a quantitative sense. This report discusses the various possible removal mechanisms which warrant serious consideration. Particular emphasis is given to chemical reactions (especially that with OH), soil bacteria and other biological action, and transport effects. The sources of carbon monoxide, both natural and anthropogenic, are reviewed and it is noted that there is quite possibly a significant undefined natural source. Atmospheric CO concentrations are discussed and their implications on carbon monoxide lifetime, sinks and sources are considered

    Carbon monoxide pollution experiment

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    The experiment is designed to obtain data for the investigation of mechanisms by which CO is removed from the earth's atmosphere. The approach uses an orbiting platform to remotely map global CO concentrations and determine vertical CO profiles using a correlation interferometer measurement technique. The instrument is capable of measuring CO over the range of expected atmospheric burdens and of measuring trace atmospheric constituents

    Analysis of the feasibility of an experiment to measure carbon monoxide in the atmosphere

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    The feasibility of measuring atmospheric carbon monoxide from a remote platform using the correlation interferometry technique was considered. It has been determined that CO data can be obtained with an accuracy of 10 percent using this technique on the first overtone band of CO at 2.3 mu. That band has been found to be much more suitable than the stronger fundamental band at 4.6 mu. Calculations for both wavelengths are presented which illustrate the effects of atmospheric temperature profiles, inversion layers, ground temperature and emissivity, CO profile, reflectivity, and atmospheric pressure. The applicable radiative transfer theory on which these calculations are based is described together with the principles of the technique

    Development of a breadboard model correlation interferometer for the carbon monoxide pollution experiment

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    The breadboard model of the correlation interferometer for the Carbon Monoxide Pollution Experiment has been designed, fabricated, and tested. Laboratory, long-path, and atmospheric tests which were performed show the technique to be a feasible method for obtaining a global carbon monoxide map and a vertical carbon monoxide profile and similar information is readily obtainable for methane as well. In addition, the technique is readily applicable to other trace gases by minor instrumental changes. As shown by the results and the conclusions, it has been determined that CO and CH4 data can be obtained with an accuracy of 10% using this technique on the spectral region around 2.3 microns

    Modeling inflammation and oxidative stress in gastrointestinal disease development using novel organotypic culture systems.

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    Gastroesophageal reflux disease (GERD), Barrett's esophagus (BE), graft-versus-host disease (GVHD), and inflammatory bowel diseases such as ulcerative colitis and Crohn's disease are common human gastrointestinal diseases that share inflammation as a key driver for their development. A general outcome resulting from these chronic inflammatory conditions is increased oxidative stress. Oxidative stress is caused by the generation of reactive oxygen and nitrogen species that are part of the normal inflammatory response, but are also capable of damaging cellular DNA, protein, and organelles. Damage to DNA can include DNA strand breaks, point mutations due to DNA adducts, as well as alterations in methylation patterns leading to activation of oncogenes or inactivation of tumor suppressors. There are a number of significant long-term consequences associated with chronic oxidative stress, most notably cancer. Infiltrating immune cells and stromal components of tissue including fibroblasts contribute to dynamic changes occurring in tissue related to disease development. Immune cells can potentiate oxidative stress, and fibroblasts have the capacity to contribute to advanced growth and proliferation of the epithelium and any resultant cancers. Disease models for GERD, BE, GVHD, and ulcerative colitis based on three-dimensional human cell and tissue culture systems that recapitulate in vivo growth and differentiation in inflammatory-associated microphysiological environments would enhance our understanding of disease progression and improve our ability to test for disease-prevention strategies. The development of physiologically relevant, human cell-based culture systems is therefore a major focus of our research. These novel models will be of enormous value, allowing us to test hypotheses and advance our understanding of these disorders, and will have a translational impact allowing us to more rapidly develop therapeutic and chemopreventive agents. In summary, this work to develop advanced human cell-based models of inflammatory conditions will greatly improve our ability to study, prevent, and treat GERD, BE, GVHD, and inflammatory bowel disease. The work will also foster the development of novel therapeutic and preventive strategies that will improve patient care for these important clinical conditions

    Teaching Simulation Literacy in Adult Healthcare Education: A Qualitative Action Research Study

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    Teaching and learning with simulation is an increasingly important strategy of adult education in healthcare. This paper discusses the process and results of an action research study on developing a simulation instructor program where experiential learning was not only the topic, but the tool by which the learners received instruction

    Letter From Arta M. Bortner to the Pennsylvania Dutch Folklore Center, March 30, 1951

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    A handwritten letter from Arta M. Bortner addressed to the Pennsylvania Dutch Folklore Center, dated March 30, 1951. Within, Bortner provides details on a childhood school game and rhyme that young children used to play involving a bear and stolen sheep.https://digitalcommons.ursinus.edu/shoemaker_documents/1167/thumbnail.jp

    Identifiability of linear compartmental tree models

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    A foundational question in the theory of linear compartmental models is how to assess whether a model is identifiable -- that is, whether parameter values can be inferred from noiseless data -- directly from the combinatorics of the model. We completely answer this question for those models (with one input and one output) in which the underlying graph is a bidirectional tree. Such models include two families of models appearing often in biological applications: catenary and mammillary models. Our proofs are enabled by two supporting results, which are interesting in their own right. First, we give the first general formula for the coefficients of input-output equations (certain equations that can be used to determine identifiability). Second, we prove that identifiability is preserved when a model is enlarged in specific ways involving adding a new compartment with a bidirected edge to an existing compartment.Comment: 32 page

    The Set Splittablity Problem

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    A collection of sets is called splittable if there is a set S such that for each set B in the collection, the intersection of S and B is half the size of B. Splittability is a generalization of graph colorability, which is an active area of research with numerous applications such as scheduling and matching. We show that the problem of deciding whether a collection is splittable is NP-complete. Nevertheless we characterize splittability for some special collections. Finally we study a further generalization called p-splittability, in which the splitter S is required to contain a given fraction of each set B
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