2,826 research outputs found
A Ground Water Quality Summary for Alaska: a Termination Report
The expanding economic activity throughout the State of Alaska
has created an urgent demand for water resource data. Ground water
quality information is of particular interest since this is the most
used source for domestic and industrial supplies.
Many agencies and individuals have accumulated large quantities
of data but their value has been marginal due to a lack of distribution
to potential users. It was the original intent of the work reported
herein to gather, collate, and publish all ground water quality data
available in the files of university, state, and federal laboratories.
Soon after the inception of the project the major contributor, the
U.S. Geological Survey, found it was administratively impossible to
contribute either the monies or the data necessary to accomplish the
ultimate goals of the project -- An Atlas on Alaskan Ground Water
Qualities.
At the time the above decision was made the Institute felt too
much information was on hand to allow it to lay fallow. Therefore,
this report was prepared, In a more limited scope than originally
planned, to fill the need for a readily available source of information.The work upon which this report is based was supported by
funds provided by the U.S. Department of the Interior, Office of
Water Resources Research, Project Number A-024-ALAS and Agreement
Number 14-01-0001-1070
A QUALITATIVE CHOICE ANALYSIS OF FACTORS INFLUENCING POST-CRP LAND USE DECISIONS
The future use of Conservation Reserve Program (CRP) lands is an important agricultural policy issue. To examine the effects of factors that influence landowners' post-contract use of CRP lands, a survey of Texas High Plains CRP contract holders was conducted in 1992. This study analyzes the results of the survey using a qualitative choice model. It was found that the presence of a livestock enterprise in the current contract holder's operation increases the probability of these acres remaining in the established cover. Contract holders who value the commodity base have an increased probability of returning their acres to crop production.Agricultural policy, Conservation Reserve Program, Ordered probit model, Land Economics/Use,
New Modeling Approaches for the Prediction of Combustion Pollutants
Combustion processes are ubiquitous to human technological development and provide many benefits such as large-scale power generation for electricity and transportation along with residential and commercial heating for manufacturing, cooking, and warmth. However, these various processes can also have harmful effects on human health and the environment via emission of CO2 and other pollutants such as NOx and particulate matter (PM; often in the form of soot). For these reasons, there is a continued need for controlling, improving, and optimizing combustion processes. Modeling of these processes provides powerful insights into system-level dynamics and their control. Due to the size and complexity of industrial-scale combustion systems, there is a pressing need for the development of computationally-inexpensive models that can accurately predict gaseous and PM emissions. The research described in this dissertation addresses this need by: 1) careful evaluation of existing soot formation models for application in oxygen-enriched flames, 2) development of new, robust soot modeling capabilities with improved accuracy for flames outside of the normal fuel/air condition, and 3) production of a large data set for the development of machine learning-based algorithms for predicting pollutant emissions under a wide range of combustion operating conditions.
Over the past decades, several semi-empirical soot models have been developed for specific applications with unique characteristic timescales and/or validated only under fuel-air combustion conditions. Hence, their universal use, especially under oxygen-enriched combustion conditions, could lead to highly inaccurate predictions. Twelve semi-empirical models (1-step or 2-step) are evaluated based on their ability to respond to changes in stoichiometric mixture fraction (Zst) and strain in a series of ethylene counterflow flames spanning across the sooting-to-non-sooting (yellow to blue) transition. Results show that no existing model is able to predict a blue flame when Zst is increased beyond the experimentally-measured sooting limit.
Motivated by this finding, a novel modeling approach is presented to account for the unique flame characteristics at elevated-Zst environments and their effect on soot formation. This modeling approach is designed to capture both the formation and the reversible processes that occur on the fuel-side of a diffusion flame in a robust yet simple manner and can be utilized in many industrial combustion applications. A new semi-empirical formulation is presented that achieves this goal. In addition, extensions are presented for two widely-used semi-empirical models (Leung-Lindstedt and Moss-Brookes) which would otherwise be inaccurate at these conditions. Upon application of this approach to counterflow flame systems, the predicted soot volume fraction profiles agree well with experimental findings reported by previous studies under low Zst. This improved approach also resulted in the prediction of blue (soot-free) limit conditions in a non-premixed counterflow flame for the first time. Thus, the performance of semi-empirical soot formation models can be dramatically improved when the reversible nature of soot formation at high temperature is considered.
The next goal was to develop a machine-learning based modelling approach for combustion systems. As part of this collaborative effort, a series of experiments were performed using a lab-scale (25 kW) combustor that was operated under varying the fuel and air ratios. Measurements were made of temperature profiles along the reactor wall and gas composition and pollutants (CO, NOx, PM) in the exhaust. A series of tests were performed totaling 60 hours of runtime and 140,000 data points corresponding to each parameter. Findings from these experiments highlight a series of trends in the reactor: low and high primary air flows lead to elevated PM and NOx emission levels, respectively; NOx levels correlate with varying swirl ratios under fixed fuel / air ratio. Based on the generated data set, a model may be developed to accurately predict pollutant levels and subsequently recommend optimized operating conditions for the combustion system
Elemental and Technological Analyses of Basalt Adze Manufacture on Tutuila, Amerika Samoa: Economic Intensification and Specialization During the Monument Building Period
This dissertation research presents the elemental and technological analyses of basalt adze quarries from the Samoan Island of Tutuila. Both Instrumental Neutron Activation Analysis (INAA) and Energy Dispersive X-ray Fluorescence (EDXRF) were utilized in the chemical characterization of basalt samples and artifacts. Elemental concentration data derived from both INAA and EDXRF successfully differentiated between multiple Tutuilan basalt adze quarries, and these data were utilized to determine the most efficacious elemental analysis technique for Tutuilan basalt adze provenance study.
Elemental concentration data from the Lau’agae quarry were utilized with technological attribute analysis of artifacts recovered from that archaeological site to investigate the potential for economic specialization in the manufacture of basalt adzes. Analysis of both the technological attribute data and the elemental concentration data provided evidence for potential specialization at the Lau’agae quarry. When these data were compared to similar data from other Polynesian archaeological sites it further supported the potential for specialized production at Lau’agae. Ultimately, it was determined that multiple skilled producers created various types of basalt adzes at Lau’agae with the intent to export and exchange their products
NFκB and AP-1 Drive Human Myometrial IL8 Expression
The uterine expression of the chemokine IL8 increases dramatically with the onset of labour both at term and preterm. The IL8 promoter contains binding sites for the transcription factors nuclear factor-kappa B (NFκB), activator protein-1 (AP-1), and CCAAT/enhancer-binding protein (CEBP). In this study we investigated the roles of these transcription factors in IL1B regulation of the IL8 gene in human myometrium. Using chromatin immune precipitation (ChIP) assay, we showed that each of NFκB, CEBP, and AP-1 binds to the IL8 promoter upon IL1B stimulation. To examine the relative importance of each site in IL8 gene expression, site-directed mutagenesis of each of these sites was performed. We found that the NFκB site was essential for basal and IL1B-stimulated gene expression. Mutation of the AP-1 site reduced both basal and IL1B-stimulated expression but to a lesser extent. Mutation of the CEBP site had no effect upon basal expression but eliminated the IL1B response. Small interfering RNA (siRNA) silencing of NFκB abolished the IL8 response to IL1B significantly; siRNA against AP-1 reduced it to a lesser extent whilst knockdown of CEBP enhanced the response. Our data confirms a central and essential role for NFκB in regulation of IL8 in human myometrium
PAYLEAN® Improves Growth and Carcass Merit of Pigs with 25% and 50% Nebraska Index Line Genes
The Nebraska Index Line excels in reproduction and is being used in industry breeding programs. However, because it has been selected only for litter size since 1981, growth and carcass merit of pure-line pigs are below industry standards. The objectives of this experiment were 1) to compare growth and carcass traits of Index cross pigs with either 50% or 25% Line I genes in a crossbreeding system typical of how the line is used in the industry and 2) to determine the effects of feeding 18 g PAYLEAN® per ton during the last 28 days of the feeding period on Index cross pigs. Line I was crossed with Danbred® USA Landrace (L) boars and Duroc-Hampshire terminal boars to produce F1 pigs with 50% Line I genes and terminal cross pigs with 25% Line I genes. Pigs with 25% Line I genes grew faster (2.03 vs. 1.97 lb/d) from 65 days of age to approximately 240 lb than pigs with 50% Line I genes (P \u3c 0.05). They also ate more feed per day although the difference was not significant (5.82 vs 5.76 lb per d). Thus, the difference between groups in feed conversion was small and not significant. Terminal cross pigs with 25% Line I genes had only 0.02 in less backfat at the end of the experiment than F1 pigs with 50% Line I genes, but they had significantly larger longissimus muscle area (6.42 vs 6.10 in2) and greater percentage carcass lean (52.4 vs 51 %). Pigs of both genetic groups and both barrows and gilts responded similarly to a diet with 18 g PAYLEAN® per ton. Feeding PAYLEAN® at 18 g/ton for 28 days significantly increased growth rate (2.19 vs. 1.80 lb/d), reduced feed intake (6.49 vs. 6.81 lb/d) improved efficiency of growth (0.33 vs 0.26 gain/ feed ratio, corresponding with 3.03 and 3.85 feed/gain ratios), increased carcass weight (185.4 vs 177.2 lb), increased dressing percentage (75.2 vs 74.3%), and increased carcass lean (53.6 vs 49.9%). Performance and carcass merit of pigs with 25% Line I genes were greater than for F1 pigs with 50% Line I genes, and feeding PAYLEAN® at the rate of 18 g per ton produced similar increases in performance and carcass merit of both groups
The ion-induced charge-exchange X-ray emission of the Jovian Auroras: Magnetospheric or solar wind origin?
A new and more comprehensive model of charge-exchange induced X-ray emission,
due to ions precipitating into the Jovian atmosphere near the poles, has been
used to analyze spectral observations made by the Chandra X-ray Observatory.
The model includes for the first time carbon ions, in addition to the oxygen
and sulfur ions previously considered, in order to account for possible ion
origins from both the solar wind and the Jovian magnetosphere. By comparing the
model spectra with newly reprocessed Chandra observations, we conclude that
carbon ion emission provides a negligible contribution, suggesting that solar
wind ions are not responsible for the observed polar X-rays. In addition,
results of the model fits to observations support the previously estimated
seeding kinetic energies of the precipitating ions (~0.7-2 MeV/u), but infer a
different relative sulfur to oxygen abundance ratio for these Chandra
observations.Comment: 11 pages, 2 figures, 2 tables, submitted to ApJ Lette
Explosive Dust Test Vessel Comparison using Pulverized Pittsburgh Coal
Explosions of coal dust are a major safety concern within the coal mining industry. The explosion and subsequent fires caused by coal dust can result in significant property damage, loss of life in underground coal mines and damage to coal processing facilities. The United States Bureau of Mines conducted research on coal dust explosions until 1996 when it was dissolved. In the following years, the American Society for Testing and Materials (ASTM) developed a test standard, ASTM E1226, to provide a standard test method characterizing the “explosibility” of particulate solids of combustible materials suspended in air. The research presented herein investigates the explosive characteristic of Pulverized Pittsburgh Coal dust using the ASTM E1226-12 test standard. The explosibility characteristics include: maximum explosion pressure, (Pmax); maximum rate of pressure rise, (dP/dt)max; and explosibility index, (Kst). Nine Pulverized Pittsburgh Coal dust concentrations, ranging from 30 to 1,500 g/m3 , were tested in a 20-Liter Siwek Sphere. The newly recorded dust explosibility characteristics are then compared to explosibility characteristics published by the Bureau of Mines in their 20 liter vessel and procedure predating ASTM E1126-12. The information presented in this paper will allow for structures and devices to be built to protect people from the effects of coal dust explosions
Climate Change and Biosphere Response: Unlocking the Collections Vault
Natural history collections (NHCs) are an important source of the long-term data needed to understand how biota respond to ongoing anthropogenic climate change. These include taxon occurrence data for ecological modeling, as well as information that can be used to reconstruct mechanisms through which biota respond to changing climates. The full potential of NHCs for climate change research cannot be fully realized until high-quality data sets are conveniently accessible for research, but this requires that higher priority be placed on digitizing the holdings most useful for climate change research (e.g., whole-biota studies, time series, records of intensively sampled common taxa). Natural history collections must not neglect the proliferation of new information from efforts to understand how present-day ecosystems are responding to environmental change. These new directions require a strategic realignment for many NHC holders to complement their existing focus on taxonomy and systematics. To set these new priorities, we need strong partnerships between NHC holders and global change biologists
Measurement of gut permeability using fluorescent tracer agent technology
Abstract The healthy gut restricts macromolecular and bacterial movement across tight junctions, while increased intestinal permeability accompanies many intestinal disorders. Dual sugar absorption tests, which measure intestinal permeability in humans, present challenges. Therefore, we asked if enterally administered fluorescent tracers could ascertain mucosal integrity, because transcutaneous measurement of differentially absorbed molecules could enable specimen-free evaluation of permeability. We induced small bowel injury in rats using high- (15 mg/kg), intermediate- (10 mg/kg), and low- (5 mg/kg) dose indomethacin. Then, we compared urinary ratios of enterally administered fluorescent tracers MB-402 and MB-301 to urinary ratios of sugar tracers lactulose and rhamnose. We also tested the ability of transcutaneous sensors to measure the ratios of absorbed fluorophores. Urinary fluorophore and sugar ratios reflect gut injury in an indomethacin dose dependent manner. The fluorophores generated smooth curvilinear ratio trajectories with wide dynamic ranges. The more chaotic sugar ratios had narrower dynamic ranges. Fluorophore ratios measured through the skin distinguished indomethacin-challenged from same day control rats. Enterally administered fluorophores can identify intestinal injury in a rat model. Fluorophore ratios are measureable through the skin, obviating drawbacks of dual sugar absorption tests. Pending validation, this technology should be considered for human use
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