2,847 research outputs found
Molecular dynamics of O(1D) + CCl4 ? ClO + CCl3 probed by cavity-enhanced sub-THz spectroscopy
The UV photodissociation of ozone in the atmosphere is known to result in highly reactive oxygen atoms in their excited O(1D) electronic state. Subsequent collisions of these atomic radicals with other atmospheric constituents frequently occur without a barrier. Matsumi and Shamsuddin have previously studied the dynamics of these reactions with chlorinated compounds using vacuum-ultraviolet laser-induced fluorescence spectroscopy. In this thesis, we discuss our recent efforts to revisit these experiments by probing the rovibronic distribution of ClO products in hyperfine detail using a recently developed millimeter wavelength cavity enhanced confocal Fabry-Pe´rot molecular beam spectrometer. In the experiment, ozone is generated and passed over carbon tetrachloride and then the vapor is co-expanded through a pulsed nozzle. The resulting supersonic jet expansion is passed through the beam waste of the Fabry-Pe´rot while a counter propagating 266 nm photolysis laser initiates the formation O(1D) atoms and their subsequent intra-beam collision and reaction with CCl4. The resulting rovibronic state distribution of the ClO products in this PHOTOLOC-like experiment are then used to confirm whether the reaction occurs via a direct abstraction mechanism, as inferred in the earlier studies. The results have only shown ClO in the ground vibrational state (v=0) except for a single signal an excited vibrational state (v=3). As it stands, with no other signals being present in the excited vibrational states, we cannot infer the mechanism or molecular dynamics are involved in the reaction to produce ClO from O(1D) and CCl4. [This abstract has been edited to remove characters that will not display in this system. Please see the PDF for the full abstract.]]]>
2020
Molecular dynamics
Molecular emission cavity analysis
Submillimeter waves
Spectrum analysis
English
http://libres.uncg.edu/ir/uncg/f/ONeal_uncg_0154M_13087.pdf
oai:libres.uncg.edu/33270
2020-09-30T14:35:00Z
UNCG
Three essays on the microeconomic analysis of long-acting reversible contraception
NC DOCKS at The University of North Carolina at Greensboro
Pagan, Lorissa Charis
<![CDATA[In this dissertation I use a variety of methods to study the effect of and choice to use long-acting reversible contraceptives (LARCs) using data from the National Survey of Family Growth. Effective contraception may increase women’s welfare by allowing better control of the timing of fertility. However, many contraceptives rely on consistent use to achieve low failure rates, potentially leaving benefits of fertility control forgone due to user error. As LARCs do not rely on contraceptive adherence, they may be welfare improving through eliminating the gap between the “perfect use” and “typical use” failure rates. How much LARCs can reduce the risk of unintended pregnancies depends on the degree to which LARC users would have used other methods consistently and correctly, how sensitive the other methods would be to inconsistent use, and how long LARCs are used. In my first essay, I implement survival analysis techniques to analyze which reversible methods women used before transitioning to a long-acting method and the duration of LARC use. Consistent with the literature, I find that LARC use is associated with high continuation rates. I also find that contraceptive spells of methods that are more sensitive to inconsistent use are not at a greater risk of ending due to switching into LARC use, which may dampen the effect of increased LARC use on pregnancies among contracepting women. Evaluating the additional effectiveness of using a LARC compared to other methods on pregnancy is difficult as women may select into LARC use due to their risk of pregnancy. In my second essay, I use an exogenous change in provider recommendations to get around the selection issue and evaluate the causal effect of LARC use on pregnancies and births using an instrumental variables approach. First, I show that the release of the recommendation had a differential effect for younger mothers of one child compared to older mothers of one child. Then using this exogenous variation, I find that LARC use decreases the probability of pregnancies in the current year, in the following year, and births in the following year compared to other methods, at least among young mothers who were affected by the recommendation. Using a correlated random coefficients model, I find evidence that women who choose LARCS would have been more likely to experience pregnancy in the following year. Finally, LARCs can only be welfare improving if women choose them over other alternatives. As with any product, each contraceptive can be thought of as a bundle of its different characteristics such as its maximum duration of use, its effectiveness, if it is hormonal, and if the method requires the insertion of a device. In my third essay, I use discrete choice models to estimate how attributes of contraceptives affect method choice. I find that the LARC-specific attribute of being a physical device may discourage some women from choosing a LARC method
Using feedback enhanced visual metronomes to manipulate gait dynamics
Recent literature suggests that gait dynamics plays a role in establishing healthy, adaptive gait behavior, and that illness or injury can alter the dynamic patterns of gait (termed fractal patterns). So called “dynamical diseases” change the fractal patterns in gait, hereby reducing adaptive gait ability and increasing fall-risk. Previous research has shown that fractal patterns in gait can be strengthened through the use of a fractal metronome stimulus. However, in previous research participants have consistently presented weaker fractal patterns than prescribed by the metronome, despite improvements from their baseline. One postulate is that this gap between the stimulus and the participants’ response is due to the prescriptive nature of the stimulus – that is, the metronome is presented with no interaction with the user. If so, the introduction of real-time feedback regarding synchrony with the stimulus may be beneficial to strengthening fractal patterns. The purpose of this study was to examine the role of feedback in increasing synchrony with a fractal metronome stimulus, and in entraining fractal gait patterns. There were three hypotheses: First, feedback would elicit a stronger coupling between participants’ gait dynamics and the dynamics of the stimulus relative to a non-feedback condition. Second, the addition of feedback to the visual metronome would lead to a stronger fractal pattern during the training and post-training (retention) phases. Third, participants with the strongest coupling during training would exhibit the strongest fractal patterns during training and post training. Results showed no difference in coupling between feedback and non-feedback conditions. The addition of feedback to the fractal metronome lead to no significant difference in fractal strength from baseline to training and baseline to retention. While greater coupling was correlated to stronger fractal patterns during training, there was no relationship between coupling and retention. This study provided further evidence supporting the use of metronomes to alter gait dynamics, and was one of the first to examine feedback in conjunction with fractal gait training
The Old Lady and Old Beardless: Gender, Emotion, and Legitimate Violence in Njal's Saga
2017 University Libraries Undergraduate Research Award Winner---The purpose of this research paper is to analyze the confluence of the concepts of gendered language, emotional display, and legitimate attributions of violence as they interacted during feud in Njal's Saga. This Icelandic saga tells the tale of two feuding families, led by the warrior Gunnar and the lawyer Njal. Interestingly enough, much of the feud is not perpetrated by them, but primarily by their family members, with specific attention being paid to their wives. Much has been written about how these concepts interacted in medieval Iceland, but few articles exist where the body of the work has been analyzed and where the evidence is so abundant. By analyzing scenes that had a large impact on the feud, the argument is made that the displays of emotions and performance of gender informed the sort of violence perpetrated and whether or not it was seen as legitimate
Expression levels of immune-genes in developing workers of Apis mellifera in response to reproductive timing and infestation level by the parasitic mite Varroa destructor
The parasitic mite Varroa destructor is one of the biggest health problems of the Western Honey Bee, Apis mellifera. It feeds from the bees' hemolymph and vectors several honey bee pathogens. V. destructor has also been reported to compromise honey bee immunity but available data are insufficient to support this claim. This study was designed to assess the effect of mite infestation on honey bee immune-gene expression during the biologically relevant host developmental stages. In my experiment, mites were manually introduced into honey bee larval cells at three different levels. Control groups were either left unmanipulated or wounded. Developing bees were collected with any retrievable mites daily from the experimental cells for ten days. Mite reproduction was assessed and bee hosts were analyzed for expression levels of ten immune genes using quantitative RT-PCR. This experiment showed effects of developmental time and experimental treatment on gene expression that generally contradict the previously hypothesized immunosuppression of bees by V. destructor. However, mites might temporarily suppress the honey bees' normal response to cuticle wounding based on reproductive timing. The artificial wounding group exhibited an increased viral load, suggesting that wounding may trigger or enable virus replication. Overall, my results indicate the importance of physical trauma caused by wounding and suggest complex temporal dynamics in the relationships between bee host, mite parasite, and vectored pathogens
Leptaxis and the constructed body: an exploration of poetic queer cyborg prosthesis.
This written portion of the M.F.A. thesis describes the both aesthetic experience of
the artwork leptaxis and the critical intent, political perspective, and conceptual motivations
behind the construction of the work. The artwork leptaxis consists of a series of objects
worn by participating viewers in conjunction with a reactive audio installation space.
Framed as a space of play outside of traditional art spaces, viewers are invited to
participate in the installation space by wearing the prosthetic objects and interacting with
each other and elements of the installation. These worn objects are framed as queer
cyborg prosthesis in the way that they intend to disrupt heteronormative perspectives on
how gender and the human body is defined. The prosthesis interface with each other and
the installation space via physical computing technology and digital audio signals. The
audio component of installation is modulated and effected through the viewers' social
interactions with the prosthesis. A key element within the artwork is the use of the concept
of as pleasure functioning as a communicative vehicle for the radical queer cyborg political
perspective
Noise and vibration from building-mounted micro wind turbines Part 2: Results of measurements and analysis
Description
To research the quantification of vibration from a micro turbine, and to develop a method of prediction of vibration and structure borne noise in a wide variety of installations in the UK.
Objective
The objectives of the study are as follows:
1) Develop a methodology to quantify the amount of source vibration from a building mounted micro wind turbine installation, and to predict the level of vibration and structure-borne noise impact within such buildings in the UK.
2) Test and validate the hypothesis on a statically robust sample size
3) Report the developed methodology in a form suitable for widespread adoption by industry and regulators, and report back on the suitability of the method on which to base policy decisions for a future inclusion for building mounted turbines in the GPDO
The Adaptive Nature of Cytochrome P4502E1-Mediated Ethanol Oxidation: Implications on the Overall Catalytic Scheme
The Cytochrome P450 family is a class of enzymes responsible for the breakdown of about 75% of the drugs that are administered (18). The 2E1 isoform of this family is known as the "ethanol-inducible" member, because ethanol has demonstrated the capacity to affect the metabolism of other 2E1 substrates (15, 16). It has been proposed that elevated concentrations of ethanol in the liver are responsible for the activation of acetaminophen and nitrosamine constituents found in cigarette smoke into hepatotoxic byproducts, and that an increase in polarity in a very hydrophobic active site may have a significant role in perpetuating these toxic effects (2-3, 23). In the present study, the objective was to probe the influence of ethanol and subsequently, increased active site polarity, on the catalytic scheme of other P4502E1 substrates. Additionally, due to the fact that many other P450 isoforms contain hydrophobic active sites and therefore, may also be affected by changing polarity in the active site environment, the implications of these studies were evaluated in the context of the P450 family as a whole. Potential evidence regarding the existence of an effector site adjacent to the catalytic site, and its role in 2E1 catalysis, was also probed. Designed to examine the effect of ethanol on the previously observed substrate inhibition pattern in p-nitrophenol oxidation, results from current studies indicated that ethanol potentially disrupts ligand-ligand interactions between the catalytic and effector sites. The ability of ethanol to potentially alter rate-limiting steps in 2E1-mediated benzyl alcohol oxidation was explored through intrinsic isotope effect studies. Despite being limited by the purity of the benzyl alcohol substrate, an apparent shift or "unmasking" of the isotope effect was observed when ethanol was added. Finally, reversibility studies were carried out to evaluate the capacity of ethanol to interfere with 2E1 inactivation by 4-nitrobenzaldehyde, a potent irreversible inhibitor of the 2B4 isoform (7). When ethanol was present in low concentrations, a synergistic effect was exhibited, where the activity of 2E1 was reduced to an even greater degree than reactions containing the aldehyde alone. An increase in enzyme activity was observed in reactions containing the aldehyde and higher concentrations of ethanol, relative to those containing only the aldehyde, suggesting that ethanol exerted a pseudo-protective effective in this case
Executive succession and competitive advantage in U.S. hospitals: simulating a randomized control trial
Research linking executive succession and competitive advantage has produced inconsistent findings. Definitive empirical evidence is not available to reconcile how executive leadership succession influences competitive advantage and more specifically whether organizational insiders or outsiders perform better. Two significant concerns exist about the methods used to explore the executive succession-organizational performance phenomenon. First, improved study designs are needed allowing for more robust causal inferences to be made about succession's competitive impact. Second, disagreements about competitive advantage's measurement have contributed to inconsistent results. This study suggests design improvements for executive succession-organizational performance studies with an empirical example using a sample of U.S. hospitals. Propensity score matching was used to simulate a randomized control trial with executive succession as the intervention. Stochastic frontier estimation was used to measure organizations' competitive performances before and after executive succession occurred. The results provided empirical evidence from a simulated random sample indicating that change in leadership and specifically outside succession led to increased competitive capabilities. In general, executive leadership changes led to increased competitive capabilities in this study and outsiders were able to close the performance gap faster in the sampled hospitals. Insiders performed no better than the control group creating a relative reduction in gains to the frontier as compared to outsiders
The effects of kudzu (Pueraria lobata) on various cytochrome P450s
The significant impact that this project is desired to have is to provide fundamental knowledge regarding the use of kudzu products for medicinal purposes, as it relates to antioxidant and anti-inflammatory effects. This is anticipated to be achieved by studying how the plant may alter the activity of several cytochrome P450 enzymes with known effects on human health. Different human cytochrome P450 isoforms were selected for this study based on their ability to convert relatively inert foreign chemical species into toxic metabolites. These include P450 2E1, 2A6, and 1A2. To analyze the selected enzymes in crude liver tissue each isoform had a unique substrate that was metabolized selectively. Several different kudzu extracts were prepared for analysis, including an ethanolic and a chloroform extract, and each was tested for inhibition of the enzymes, along with the pure compound puerarin. The most inhibitory effects were observed with the interaction between cytochrome P450 1A2 and the ethanolic kudzu root extract and cytochrome P450 2C9 and the ethanolic kudzu root extract
Postmodern materialism: things, people, and the remaking of the social in contemporary American narrative
This dissertation reexamines the critical orthodoxies of postmodern American literature by attending to the everyday objects that populate the worlds of narrative texts written from the 1960s to the first decade of the new millennium. Whereas the majority of literary and cultural critics, from Fredric Jameson to Linda Hutcheon to K. Anthony Appiah, argue that postmodernism can be best understood in terms of a commitment to the demystification of social arrangements that seem natural, this project proposes that what makes literature postmodern is a dedication to the ongoing material construction of the social. Beginning with the most mundane items in works of fiction by Leslie Marmon Silko, Don DeLillo, John Barth, Toni Morrison, and others, "Postmodern Materialism" charts the complex interactions of vast arrays of subjects and objects in the assembly of social groups. The resulting inquiry offers two important benefits: 1) a new approach to postmodernism in general through a rereading of postmodern fiction; 2) a unique methodology for assessing the relationship between things and people that reveals the fluidity of, and thus the possibility for remaking, our social structures. By showcasing the simplest components of the social, the project of postmodernism can be seen, I maintain, as calling our attention not so much away from ourselves and our preoccupations as toward the material world that we all share. Such a shift in consideration does necessitate, however, a theoretical movement away from human essence as the gravitational center of our social relations, thus precluding an overly reductive comparison between people that more often than not results in the exclusion, alienation, or marginalization of individuals and groups based on actual or perceived differences. Along these lines, I conclude that postmodern fiction is especially well-suited for a critical remaking of the social because it is attuned to the ways in which the social is constantly being fashioned by the world of material objects
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