36 research outputs found

    Diagnostics of Carbon Nanotube Formation in a Laser Produced Plume: Spectroscopic in situ nanotube detection using spectral absorption and surface temperature measurements by black body emission

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    Carbon nanotubes hold great promise for material advancements in the areas of composites and electronics. The advancement of research in these areas is dependent upon the availability of carbon nanotubes to a broad spectrum of academic and industrial researchers. Although there has been much progress made in reducing the costs of carbon nanotubes and increasing the quality and purity of the products, an increase in demand for still less expensive and specific nanotubes types has also grown. This summer's work has involved two experiments that have been designed to further the understanding of the dynamics and chemical mechanisms of carbon nanotube formation. It is expected that a better understanding of the process of formation of nanotubes will aid current production designs and stimulate ideas for future production designs increasing the quantity, quality, and production control of carbon nanotubes. The first experiment involved the measurement of surface temperature of the target as a function of time with respect to the ablation lasers. A peak surface temperature of 5000 K was determined from spectral analysis of black body emission from the target surface. The surface temperature as a function of various changes in operating parameters was also obtained. This data is expected to aid the modeling of ablation and plume dynamics. The second experiment involved a time and spatial measurement of the spectrally resolved absorbance of the laser produced plume. This experiment explored the possibility of developing absorbance and fluorescence to detect carbon nanotubes during production. To attain control over the production of nanotubes with specific properties and reduce costs, a real time in situ diagnostics method would be very beneficial. Results from this summer's work indicate that detection of nanotubes during production may possibly be used for production feed back control

    A SYSTEMS APPROACH FOR EVALUATING ON-FARM SITE-SPECIFIC MANAGEMENT TRIALS: A CASE STUDY WITH VARIABLE RATE MANURE AND CROP QUALITY RESPONSE TO INPUTS

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    Site-specific application of manure has the potential to improve crop production and environmental quality. If manure is applied where it is needed, in the quantity required by the crop, over application, with attendant runoff and leaching problems can be reduced. To implement this approach growers need site-specific crop response information. Increasing availability of site-specific yield information offers a way to estimate such crop responses. The objective of this study is to develop a methodology for estimating site-specific response of corn and soybeans to manure given soil test information, and to use that methodology to analyze an on-farm manure management trial conducted near Sleepy Eye, Minnesota. Both quantity and quality of the crop is considered.Research Methods/ Statistical Methods,

    MANAGING PHOSPHOROUS SOIL DYNAMICS OVER SPACE AND TIME

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    Understanding the relationship between soil fertility dynamics and crop response is conceptually appealing. Even more appealing is comprehension of the spatial and temporal heterogeneity of these connections over a production surface and across seasons. Knowledge of these interactions is complicated because nutrient carryover dynamics and crop response to inputs are determined simultaneously on the one-hand, and sequentially on the other. A second problem enters when crops are rotated, for example, in the corn-soybean system commonly practiced in the Corn Belt. This paper examines the nutrient carryover-crop response nexus using data from a corn-soybean, variable-rate nitrogen (N) and phosphorous (P) experiment conducted over five years. Site-specific corn response to N and P and soybean response to P are simultaneously estimated with a P carryover equation. These estimates are used in a dynamic programming model to map site-specific optimal N and P fertilizer policies, soil P evolution, and profitability. The net present value of managing N and P site-specifically is compared to a strategy where these inputs are managed uniformly following extension guidelines. The results suggest that when P-carryover is managed, site-specific returns to the variable-rate strategies are higher than returns to a conventional, uniform strategy.Crop Production/Industries,

    In-Situ Diagnostics of Carbon Nanotube Production by Laser Ablation

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    This presentation involves emission and laser induced fluorescence (LIP) data obtained during carbon nanotube production by double pulse laser oven method. Recent LIP data of nickel indicate longer decay (of the order of few milliseconds) of nickel atomic vapor. This contrasts with less than a millisecond decays of C2 and C3 observed in the plume. The possible role of nickel in the kinetics of carbon nanotube formation will be discussed. Evolution of the laser ablated plume is recorded as plume images which are correlated with the transient emission and LIP dat

    Economic Impact of South Dakota’s Regional Water Systems

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    Regional water systems are a primary conduit of water supply for much of South Dakota’s rural and small community populations. As of 2006, greater than one-third of South Dakota’s population was served by water supplied from regional water systems, and when Lewis and Clark Rural Water delivers water to Sioux Falls, over one-half of South Dakota’s population will be served by regional water systems. Greater than 75% of incorporated communities with public water supplies are served by regional water systems, either as bulk communities or as individual customers. Many farms and agricultural industries use rural water for domestic use, livestock watering, and industrial processing. These users have connected to regional water systems to obtain a reliable, safe, and high quality water source. This report summarizes the results of a study of the economic impacts of regional water systems in South Dakota. The scope of this study was limited to soliciting financial information from South Dakota’s regional rural water systems using this information to quantify direct, indirect, and induced economic impacts of these systems as a result of their construction and annual operations

    Positive Youth Development at Camps for Youth with Chronic Illness: A Systematic Review of the Literature

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    This study aimed to systematically review all the literature on camps for youth with childhood onset chronic illness (COCI) utilizing the Positive Youth Development (PYD) framework to assess camp processes and psychosocial outcomes. This paper describes a unique dataset of 425 included studies published over the last 70 years and gives a broad overview of camp demographics, processes that align with PYD’s Big 3 (sustained adult-youth relationships, skill-building, and youth leadership) and measured outcomes that align with the PYD’s 5 Cs (Competence, Confidence, Character, Social Connectedness, and Compassion). Among the included studies, 36% included diabetes camps, 15% included camps accepting multiple illnesses, 12% included cancer camps, and 11% included asthma camps. The majority of participants were under the age of 16. While no study explicitly used the PYD approach, over 90% of studies described camps that deployed both active leadership and sustained positive relationships, while only 59% of studies described camps providing the opportunity to learn life skills. Although no study utilized the PYD 5 Cs framework for outcome measurement, 47% addressed outcomes related to Competence, 44% addressed Confidence, 33% addressed Connection, 4% addressed Compassion, and 2% addressed Character. This review highlights opportunities for camp leadership to align their programming with the PYD framework, to incorporate older adolescents and young adults and, ultimately, to improve positive adult outcomes for youth with COCI. It provides a starting point for future research evaluating illness-specific camps using a PYD approach

    Pathogenic huntingtin inhibits fast axonal transport by activating JNK3 and phosphorylating kinesin

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    Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Nature America for personal use, not for redistribution. The definitive version was published in Nature Neuroscience 12 (2009): 864-871, doi:10.1038/nn.2346.Selected vulnerability of neurons in Huntington’s disease (HD) suggests alterations in a cellular process particularly critical for neuronal function. Supporting this idea, pathogenic Htt (polyQ-Htt) inhibits fast axonal transport (FAT) in various cellular and animal HD models (mouse and squid), but the molecular basis of this effect remains unknown. Here we show that polyQ-Htt inhibits FAT through a mechanism involving activation of axonal JNK. Accordingly, increased activation of JNK was observed in vivo in cellular and animal HD models. Additional experiments indicate that polyQ-Htt effects on FAT are mediated by the neuron-specific JNK3, and not ubiquitously expressed JNK1, providing a molecular basis for neuron-specific pathology in HD. Mass spectrometry identified a residue in the kinesin-1 motor domain phosphorylated by JNK3, and this modification reduces kinesin-1 binding to microtubules. These data identify JNK3 as a critical mediator of polyQ-Htt toxicity and provides a molecular basis for polyQ-Htt-induced inhibition of FAT.This work was supported by 2007/2008 MBL summer fellowship to GM; an HDSA grant to GM; NIH grants MH066179 to GB; and ALSA, Muscular Dystrophy Association, and NIH (NS23868, NS23320, NS41170) grants to STB

    Plio-Pleistocene phylogeography of the Southeast Asian Blue Panchax killifish, Aplocheilus panchax

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    The complex climatic and geological history of Southeast Asia has shaped this region’s high biodiversity. In particular, sea level fluctuations associated with repeated glacial cycles during the Pleistocene both facilitated, and limited, connectivity between populations. In this study, we used data from two mitochondrial and three anonymous nuclear markers to determine whether a fresh/brackish water killifish, Aplocheilus panchax, Hamilton, 1822, could be used to further understand how climatic oscillations and associated sea level fluctuations have shaped the distribution of biota within this region, and whether such patterns show evidence of isolation within palaeodrainage basins. Our analyses revealed three major mitochondrial clades within A. panchax. The basal divergence of A. panchax mitochondrial lineages was approximately 3.5 Ma, whilst the subsequent divergence timings of these clades occurred early Pleistocene (~2.6 Ma), proceeding through the Pleistocene. Continuous phylogeographic analysis showed a clear west-east dispersal followed by rapid radiation across Southeast Asia. Individuals from Krabi, just north of the Isthmus of Kra, were more closely related to the Indian lineages, providing further evidence for a freshwater faunal disjunction at the Isthmus of Kra biogeographic barrier. Our results suggest that Sulawesi, across the Wallace Line, was colonised relatively recently (~30 ka). Nuclear DNA is less geographically structured, although Mantel tests indicated that nuclear genetic distances were correlated with geographic proximity. Overall, these results imply that recent gene flow, as opposed to historical isolation, has been the key factor determining patterns of nuclear genetic variation in A. panchax, however, some evidence of historical isolation is retained within the mitochondrial genome. Our study further validates the existence of a major biogeographic boundary at the Kra Isthmus, and also demonstrates the use of widely distributed fresh/brackishwater species in phylogeographic studies, and their ability to disperse across major marine barriers in relatively recent time periods

    Diagnostics of Carbon Nanotube Formation in a Laser Produced Plume

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    This research has involved the analysis and interpretation of spectroscopic data taken over a two year period from 1998 to 1999 at the Johnson Space Center. The data was taken in an attempt to perform diagnostic studies of the formation of carbon nanotubes in a laser produced plume. Carbon nanotubes hold great promise for the development of new materials with exciting properties. Current production processes are not sufficient to meet research and development needs. A better understanding of the chemical processes involved in carbon nanotube formation will suggest better production processes that would be more able to meet the demands of research and development. Our work has focused on analysis of the emission spectra and laser induced fluorescent spectra of the carbon dimer, C2, and the laser induced fluorescence spectra of the nickel atom, which is a necessary reagent in th formation of carbon nanotubes

    MANAGING PHOSPHOROUS SOIL DYNAMICS OVER SPACE AND TIME

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    Understanding the relationship between soil fertility dynamics and crop response is conceptually appealing. Even more appealing is comprehension of the spatial and temporal heterogeneity of these connections over a production surface and across seasons. Knowledge of these interactions is complicated because nutrient carryover dynamics and crop response to inputs are determined simultaneously on the one-hand, and sequentially on the other. A second problem enters when crops are rotated, for example, in the corn-soybean system commonly practiced in the Corn Belt. This paper examines the nutrient carryover-crop response nexus using data from a corn-soybean, variable-rate nitrogen (N) and phosphorous (P) experiment conducted over five years. Site-specific corn response to N and P and soybean response to P are simultaneously estimated with a P carryover equation. These estimates are used in a dynamic programming model to map site-specific optimal N and P fertilizer policies, soil P evolution, and profitability. The net present value of managing N and P site-specifically is compared to a strategy where these inputs are managed uniformly following extension guidelines. The results suggest that when P-carryover is managed, site-specific returns to the variable-rate strategies are higher than returns to a conventional, uniform strategy
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