8,887 research outputs found
The Application of Text Mining and Data Visualization Techniques to Textual Corpus Exploration
Unstructured data in the digital universe is growing rapidly and shows no evidence of slowing anytime soon. With the acceleration of growth in digital data being generated and stored on the World Wide Web, the prospect of information overload is much more prevalent now than it has been in the past. As a preemptive analytic measure, organizations across many industries have begun implementing text mining techniques to analyze such large sources of unstructured data. Utilizing various text mining techniques such as n -gram analysis, document and term frequency analysis, correlation analysis, and topic modeling methodologies, this research seeks to develop a tool to allow analysts to maneuver effectively and efficiently through large corpuses of potentially unknown textual data. Additionally, this research explores two notional data exploration scenarios through a large corpus of text data, each exhibiting unique navigation methods analysts may elect to take. Research concludes with the validation of inferential results obtained through each corpus’s exploration scenario
An application of multiattribute decision analysis to the Space Station Freedom program. Case study: Automation and robotics technology evaluation
The results are described of an application of multiattribute analysis to the evaluation of high leverage prototyping technologies in the automation and robotics (A and R) areas that might contribute to the Space Station (SS) Freedom baseline design. An implication is that high leverage prototyping is beneficial to the SS Freedom Program as a means for transferring technology from the advanced development program to the baseline program. The process also highlights the tradeoffs to be made between subsidizing high value, low risk technology development versus high value, high risk technology developments. Twenty one A and R Technology tasks spanning a diverse array of technical concepts were evaluated using multiattribute decision analysis. Because of large uncertainties associated with characterizing the technologies, the methodology was modified to incorporate uncertainty. Eight attributes affected the rankings: initial cost, operation cost, crew productivity, safety, resource requirements, growth potential, and spinoff potential. The four attributes of initial cost, operations cost, crew productivity, and safety affected the rankings the most
Neighbors Matter: Causal Community Effects and Stock Market Participation
This paper establishes a causal relation between an individual's decision of whether to own stocks and average stock market participation decision of the individual's community. We instrument for the average ownership of an individual's community with lagged average ownership of the states in which one's non-native neighbors were born. Combining this instrumental variables approach with controls for individual and community fixed effects, a broad set of time-varying individual and community controls, and state-by-year effects, rules out alternative explanations. To further establish that word-of-mouth communication drives this causal effect, we show that the results are stronger in more sociable communities.
The Geography of Stock Market Participation: The Influence of Communities and Local Firms
This paper is the first to investigate the importance of geography in explaining equity market participation. We provide evidence to support two distinct local area effects. The first is a community ownership effect, that is, individuals are influenced by the investment behavior of members of their community. Specifically, a ten percentage-point increase in equity market participation of the members of one's community makes it two percentage points more likely that the individual will invest in stocks. We find further evidence that the influence of community members is strongest for less financially sophisticated households and strongest within peer groups' as defined by age and income categories. The second is that proximity to publicly-traded firms also increases equity market participation. In particular, the presence of publicly-traded firms within 50 miles and the share of U.S. market value headquartered within the community are significantly correlated with equity ownership of individuals. These results are quite robust, holding up in the presence of a wide range of individual and community controls, instrumental variables estimation, the inclusion of individual fixed effects, and specification checks to rule out that the relations are driven solely by ownership of the stock of one's employer.
Biochemical and genetic analyses of a catalase from the anaerobic bacterium Bacteroides fragilis.
A single catalase enzyme was produced by the anaerobic bacterium Bacteroides fragilis when cultures at late
log phase were shifted to aerobic conditions. In anaerobic conditions, catalase activity was detected in
stationary-phase cultures, indicating that not only oxygen exposure but also starvation may affect the production
of this antioxidant enzyme. The purified enzyme showed a peroxidatic activity when pyrogallol was used
as an electron donor. It is a hemoprotein containing one heme molecule per holomer and has an estimated
molecular weight of 124,000 to 130,000. The catalase gene was cloned by screening a B. fragilis library for
complementation of catalase activity in an Escherichia coli catalase mutant (katE katG) strain. The cloned gene,
designated katB, encoded a catalase enzyme with electrophoretic mobility identical to that of the purified
protein from the B. fragilis parental strain. The nucleotide sequence of katB revealed a 1,461-bp open reading
frame for a protein with 486 amino acids and a predicted molecular weight of 55,905. This result was very close
to the 60,000 Da determined by denaturing sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the
purified catalase and indicates that the native enzyme is composed of two identical subunits. The N-terminal
amino acid sequence of the purified catalase obtained by Edman degradation confirmed that it is a product of
katB. The amino acid sequence of KatB showed high similarity to Haemophilus influenzae HktE (71.6% identity,
66% nucleotide identity), as well as to gram-positive bacterial and mammalian catalases. No similarities to
bacterial catalase-peroxidase-type enzymes were found. The active-site residues, proximal and distal hemebinding
ligands, and NADPH-binding residues of the bovine liver catalase-type enzyme were highly conserved
in B. fragilis KatB. Originally published Journal of Bacteriology, Vol. 117, No. 11, June 199
Analysis of Economic Depreciation for Multi-Family Property
This paper uses a hedonic pricing model and National Council of Real Estate Investment Fiduciaries data to estimate economic depreciation for multi-family real estate. The findings indicate that investment grade multi-family housing depreciates approximately 2.7% per year in real terms based on total property value. This implies a depreciation rate for just the building of about 3.25% per year. With 2% inflation, this suggests a nominal depreciation rate of about 5.25% per year. Converted into a straight-line depreciation rate that has the same present value, this suggests a depreciable life of 30.5 years - as compared to 27.5 years allowed under the current tax laws. Thus, these laws are slightly favorable to multi-family properties by providing a tax depreciation rate that exceeds economic depreciation, which is in part due to inflation that has been less than expected during the past decade.
In Situ ATR-SEIRAS of Carbon Dioxide Reduction at a Plasmonic Silver Cathode.
Illumination of a voltage-biased plasmonic Ag cathode during CO2 reduction results in a suppression of the H2 evolution reaction while enhancing CO2 reduction. This effect has been shown to be photonic rather than thermal, but the exact plasmonic mechanism is unknown. Here, we conduct an in situ ATR-SEIRAS (attenuated total reflectance-surface-enhanced infrared absorption spectroscopy) study of a sputtered thin film Ag cathode on a Ge ATR crystal in CO2-saturated 0.1 M KHCO3 over a range of potentials under both dark and illuminated (365 nm, 125 mW cm-2) conditions to elucidate the nature of this plasmonic enhancement. We find that the onset potential of CO2 reduction to adsorbed CO on the Ag surface is -0.25 VRHE and is identical in the light and the dark. As the production of gaseous CO is detected in the light near this onset potential but is not observed in the dark until -0.5 VRHE, we conclude that the light must be assisting the desorption of CO from the surface. Furthermore, the HCO3- wavenumber and peak area increase immediately upon illumination, precluding a thermal effect. We propose that the enhanced local electric field that results from the localized surface plasmon resonance (LSPR) is strengthening the HCO3- bond, further increasing the local pH. This would account for the decrease in H2 formation and increase the CO2 reduction products in the light
UAS Service Supplier Specification
Within the Unmanned Aircraft Systems (UAS) Traffic Management (UTM) system, the UAS Service Supplier (USS) is a key component. The USS serves several functions. At a high level, those include the following: Bridging communication between UAS Operators and Flight Information Management System (FIMS) Supporting planning of UAS operations Assisting strategic deconfliction of the UTM airspace Providing information support to UAS Operators during operations Helping UAS Operators meet their formal requirements This document provides the minimum set of requirements for a USS. In order to be recognized as a USS within UTM, successful demonstration of satisfying the requirements described herein will be a prerequisite. To ensure various desired qualities (security, fairness, availability, efficiency, maintainability, etc.), this specification relies on references to existing public specifications whenever possible
The Redox-Sensitive Transcriptional Activator OxyR Regulates the Peroxide Response Regulon in the Obligate Anaerobe Bacteroides fragilis
The peroxide response-inducible genes ahpCF, dps, and katB in the obligate anaerobe Bacteroides fragilis are
controlled by the redox-sensitive transcriptional activator OxyR. This is the first functional oxidative stress
regulator identified and characterized in anaerobic bacteria. oxyR and dps were found to be divergently
transcribed, with an overlap in their respective promoter regulatory regions. B. fragilis OxyR and Dps proteins
showed high identity to homologues from a closely related anaerobe, Porphyromonas gingivalis. Northern blot
analysis revealed that oxyR was expressed as a monocistronic 1-kb mRNA and that dps mRNA was approximately
500 bases in length. dps mRNA was induced over 500-fold by oxidative stress in the parent strain and
was constitutively induced in the peroxide-resistant mutant IB263. The constitutive peroxide response in strain
IB263 was shown to have resulted from a missense mutation at codon 202 (GAT to GGT) of the oxyR gene
[oxyR(Con)] with a predicted D202G substitution in the OxyR protein. Transcriptional fusion analysis revealed
that deletion of oxyR abolished the induction of ahpC and katB following treatment with hydrogen
peroxide or oxygen exposure. However, dps expression was induced approximately fourfold by oxygen exposure
in DoxyR strains but not by hydrogen peroxide. This indicates that dps expression is also under the control of
an oxygen-dependent OxyR-independent mechanism. Complementation of DoxyR mutant strains with wildtype
oxyR and oxyR(Con) restored the inducible peroxide response and the constitutive response of the ahpCF,
katB, and dps genes, respectively. However, overexpression of OxyR abolished the catalase activity but not katB
expression, suggesting that higher levels of intracellular OxyR may be involved in other physiological processes.
Analysis of oxyR expression in the parents and in DoxyR and overexpressing oxyR strains by Northern
blotting and oxyR*::xylB fusions revealed that B. fragilis OxyR does not control its own expression. Originally published Journal of Bacteriology, Vol. 182, No. 18, Sep. 200
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