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Search Results: 1 - 10 of 301079 matches for " Timothy J. Giffney "
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A Surface Acoustic Wave Ethanol Sensor with Zinc Oxide Nanorods
Timothy J. Giffney,Y. H. Ng,K. C. Aw
Smart Materials Research , 2012, DOI: 10.1155/2012/210748
Abstract: Surface acoustic wave (SAW) sensors are a class of piezoelectric MEMS sensors which can achieve high sensitivity and excellent robustness. A surface acoustic wave ethanol sensor using ZnO nanorods has been developed and tested. Vertically oriented ZnO nanorods were produced on a ZnO/128° rotated Y-cut LiNbO3 layered SAW device using a solution growth method with zinc nitrate, hexamethylenetriamine, and polyethyleneimine. The nanorods have average diameter of 45?nm and height of 1?μm. The SAW device has a wavelength of 60?um and a center frequency of 66?MHz at room temperature. In testing at an operating temperature of 270 with an ethanol concentration of 2300?ppm, the sensor exhibited a 24?KHz frequency shift. This represents a significant improvement in comparison to an otherwise identical sensor using a ZnO thin film without nanorods, which had a frequency shift of 9?KHz. 1. Introduction Sensing of ethanol vapour has important applications in industry and society. At high temperatures (200°C to 300°C) zinc oxide absorbs ethanol vapour, causing a significant change in conductivity [1, 2] and also leading to a change in mass. This change in properties can be used to create an ethanol sensor. Surface acoustic wave (SAW) sensors are a class of piezoelectric MEMS sensor which can achieve high sensitivity and excellent robustness. Since their discovery by Rayleigh in 1885 [3] surface acoustic waves have been extensively researched. The energy of a surface acoustic wave is concentrated within several wavelengths of the surface [4, 5]. For this reason, the propagation characteristics of surface acoustic waves are highly sensitive to any change in the properties of the surface on which they travel. Due to the sensitivity of SAW devices to small changes in mass loading and surface conductivity, SAW devices have been extensively studied as gas sensors [6–8]. A typical SAW gas sensor uses an interdigital transducer (IDT) to generate a surface acoustic wave in a piezoelectric substrate. The surface acoustic wave propagates along a delay line coated in some material which absorbs the target gas. A second IDT at the end of the delay line is then used to transduce the SAW to an electrical signal. Absorption of gas onto the sensing layer causes a change in the propagation velocity of the surface acoustic wave, resulting in a shift in the resonant frequency of the device. The majority of existing SAW gas sensors have used thin film sensing layers, with limited surface area. The application of nanostructured sensing layers, such as ZnO nanorods can potentially lead to
Powder River Basin Coal: Powering America  [PDF]
Timothy J. Considine
Natural Resources (NR) , 2013, DOI: 10.4236/nr.2013.48063
Abstract:

Powder River Basin (PRB) coal in Wyoming and Montana is used to produce 18 percent of the electricity consumed in the United States. Coal production from the PRB more than doubled between 1994 and 2009. PRB coal companies produced greater amounts of coal at declining real prices over much of this period through investment in equipment and production systems that achieved massive economies of scale. The bulk of PRB coal is shipped to the middle part of America from Texas in the south to Michigan in the north and New York in the east. States that consume significant amounts of PRB coal have electricity rates well below the national average. The largest industrial users of electricity are in these regions. Replacing PRB coal would require almost 5.5 trillion cubic feet of natural gas per year, representing a 26 percent increase in demand. Such an increase in gas consumption would increase prices for natural gas by roughly 76 percent. In such a world, U.S. energy users would pay $107 billion more each year for electricity and natural gas. Hence, by using PRB coal, the U.S. economy avoids $107 billion per year in higher energy costs. Estimates reported in the literature indicate that the gross environmental damages from PRB coal production are $27 billion. Hence, the net social benefits of PRB coal are $80 billion per year. Given the large size and low cost of these reserves, PRB coal will likely supply societal energy needs well into the future as long as the public and their elected officials are willing to accept the environmental impacts in return for the substantial economic benefits from using PRB coal.

An Integrative Socio-Technical Enterprise Approach to Urban Design/Planning for Sustainable Development  [PDF]
Timothy J. Downs
Open Journal of Civil Engineering (OJCE) , 2018, DOI: 10.4236/ojce.2018.82015
Abstract: Human society locally and globally needs to better understand and respond to ever-more complex, interwoven problems: environmental degradation; climate instability; persistent poverty; disparities in human health; growing income/wealth inequality; economies and infrastructures vulnerable to climate shock; and mounting socio-political unrest. Cities are where most people live, urbanization is a strong upward global trend, and cities bring all these problems into sharp, compelling focus. Since outcomes stem from processes and systems, we argue transformative changes depend on re-imagining the Urban Design, Urban Planning and Urban Development Practice (UD/UP/UDP) process. While there has been insufficient attention to process innovation— with technological aspects tending to dominate UD/UP/UDP work—emerging systems views of cities, and disenchantment with existing modes are enabling. We propose an empirically based integrative frame to tackle recognized conundrums, and inform an adaptive UD/UP/UDP process—from concept through design, assessment, planning, implementation, project functioning and monitoring. The frame contemplates six domains (6-D): 1) Project ethos, concept, and framing; 2) sectors, topics, and issues; 3) Varying spatial and temporal scales; 4) Stakeholder interests, relationships and capacities; 5) Knowledge types, modes and methods; and 6) Socio-technical capacities and networks. The frame, process and outcomes constitute a socio-technical enterprise (STE) approach to UD/UP/UDP work, with implications for education, training, and professional practice. We highlight the pivotal role Integrators and Universities play, and the scalability of STE knowledge/capacity networks. The case of Greater Mexico City/Central Mexico Urban Region illustrates the utility of the approach in a hyper-complex, climate-change vulnerable regional context.
The Economic Impacts of Restrictions on the Transportation of Petroleum Coke  [PDF]
Timothy J. Considine
Natural Resources (NR) , 2019, DOI: 10.4236/nr.2019.103005
Abstract: Petroleum coke is the?third?leading refined petroleum product export from the US behind distillate fuel oil. Legal challenges and proposals could either increase the cost or restrict the transportation of petroleum coke. This paper develops an econometric model of world markets for refined petroleum markets to estimate the effects of such restrictions. The model is used to estimate how supply, demand, trade flows, and prices would adjust under a shutdown of US petroleum coke production. The market impacts are significant, withsubstantially higher prices for jet fuel and petroleum coke, significantly higher prices for gasoline and other products, and sharply lower prices for residual fuel oil. Over a four-year simulation of the model, the US petroleum trade balance deteriorates by $85 billion and consumers pay over $187 and $376 billion more for refined petroleum products in the US and the rest of the world respectively.
The Sociological Determination: A Reflexive Look at Conducting Local Disaster Research after Hurricane Katrina  [PDF]
Timothy J. Haney, James R. Elliott
Sociology Mind (SM) , 2013, DOI: 10.4236/sm.2013.31002
Abstract:

This paper examines the process of collecting data on New Orleanians affected by Hurricane Katrina. It does so by focusing upon the experiences of local researchers who were simultaneously conducting research on and within the disaster. It also documents one research team’s attempt to generate a random sample of residents from several New Orleans neighborhoods, stratified both by racial composition and level of damage. Further, it describes the challenges associated with navigating complex bureaucracies that are themselves affected by the disaster. Results demonstrate that our methods for drawing samples from six New Orleans neighborhoods yielded highly representative samples, even in heavily damaged neighborhoods where the long-term displacement required a multi-pronged strategy that involved contact by mail, telephone, and visits to local churches. The paper concludes by making recommendations for facilitating future research by locally affected researchers.

 

System for High Throughput Water Extraction from Soil Material for Stable Isotope Analysis of Water  [PDF]
Timothy S. Goebel, Robert J. Lascano
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2012, DOI: 10.4236/jasmi.2012.24031
Abstract:

A major limitation in the use of stable isotope of water in ecological studies is the time that is required to extract water from soil and plant samples. Using vacuum distillation the extraction time can be less than one hour per sample. Therefore, assembling a distillation system that can process multiple samples simultaneously is advantageous and necessary for ecological or hydrological investigations. Presented here is a vacuum distillation apparatus, having six ports, that can process up to 30 samples per day. The distillation system coupled with the Los Gatos Research DLT-100 Liquid Water Isotope Analyzer is capable of analyzing all of the samples that are generated by vacuum distillation. These two systems allow larger sampling rates making investigations into water movement through an ecological system possible at higher temporal and spatial resolution.

Time for cotton to uptake water of a known isotopic signature as measured in leaf petioles  [PDF]
Timothy S. Goebel, Robert J. Lascano
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.52021
Abstract:

While stable isotopes of water have been used to study water movement through the environment, they generally have not been used to examine shorter, more transient events, e.g., rainfall of <25 mm. With the development of robust methods that use isotope ratio infrared spectrometry, evaluating samples has become faster and simpler, allowing more soil and plant samples to be collected and analyzed. Using larger sampling rates can therefore increase the resolution of changes in stable isotopes within an ecosystem, and allows for a better understanding of how quickly rainwater that enters the soil by infiltration is transpired by a plant via root-water uptake. Quantifying rainwater uptake by plants is essential to increase crop production in rainfed agriculture. Thus the objective of this study was to measure the time required by a plant to transpire water from a source of water with a different isotopic signature than the water that the plant was irrigated. To this end, cotton (Gossypium hirsutum (L.)) plants were grown in a greenhouse and the time required for the enriched water added the soil to show up in the meristematic petioles of cotton leaves was measured. The initial divergence from the irrigation water signature occurred as quickly as 4 hours. The water from the sampled petioles then reached equilibrium with the new source water within 12 hours.

Changes in the Threshold Uncertainty in a Simultaneous Subscription Game  [PDF]
Timothy J. Gronberg, Hui-Chun Peng
Theoretical Economics Letters (TEL) , 2014, DOI: 10.4236/tel.2014.44036
Abstract:

This paper considers a discrete public good subscription game under threshold uncertainty and private information on valuations and analyzes the effect of change in cost uncertainty on the private contribution equilibrium under a simultaneous institution. Comparative statics with respect to the changes in the cost distribution are derived. We find that if the cost distribution becomes more dispersed, in the sense of a mean-preserving spread, the expected total contributions to the public good will decrease. Our proposition provides a policy implication that if the suppliers are able to reduce the uncertainty of the cost distribution, the private contribution to the public good will increase.

A Review of Immune System Components, Cytokines, and Immunostimulants in Cultured Finfish Species  [PDF]
Timothy J. Bruce, Michael L. Brown
Open Journal of Animal Sciences (OJAS) , 2017, DOI: 10.4236/ojas.2017.73021
Abstract: Aquaculture is a rapidly growing global agriculture sector and the importance of fish health has become of upmost importance as production levels and stocking densities increase. Over the past few decades, there have been a large number of immunological investigations on commonly cultured finfish species. Further, new technologies and strategies that embody use of fish immunostimulants, probiotics, and vaccinology rely heavily upon a comprehensive understanding of teleost immune system mechanics. The teleost immune system works in concert to properly recognize, control, and clear aquatic pathogens. Recent findings have exemplified the cooperative efforts of the nonspecific and adaptive branches, and have put forth an emphasis on the importance of the mucosal immune response in all aspects of a mounted immune response. This review provides a generalized overview of the innate and adaptive arms of the fish immune system, and provides highlights of recently published work in the areas of signaling networks and mucosal immune interactions.
Effects of Timber Harvest on River Food Webs: Physical, Chemical and Biological Responses
J. Timothy Wootton
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0043561
Abstract: I compared physical, chemical and biological characteristics of nine rivers running through three timber harvest regimes to investigate the effects of land use on river ecosystems, to determine whether these corresponded to changes linked with downstream location, and to compare the response of different types of indicator variables. Physical variables changed with downstream location, but varied little with timber harvest. Most chemical variables increased strongly with timber harvest, but not with downstream location. Most biological variables did not vary systematically with either timber harvst or downstream location. Dissolved organic carbon did not vary with timber harvest or downstream location, but correlated positively with salmonid abundance. Nutrient manipulations revealed no general pattern of nutrient limitation with timber harvest or downstream location. The results suggest that chemical variables most reliably indicate timber harvest impact in these systems. The biological variables most relevant to human stakeholders were surprisingly insensitive to timber harvest, however, apparently because of decoupling from nutrient responses and unexpectedly weak responses by physical variables.
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