Matching Items (475)
Description
Membrane proteins are very important for all living cells, being involved in respiration, photosynthesis, cellular uptake and signal transduction, amongst other vital functions. However, less than 300 unique membrane protein structures have been determined to date, often due to difficulties associated with the growth of sufficiently large and well-ordered crystals. This work has been focused on showing the first proof of concept for using membrane protein nanocrystals and microcrystals for high-resolution structure determination. Upon determining that crystals of the membrane protein Photosystem I, which is the largest and most complex membrane protein crystallized to date, exist with only a hundred unit cells with sizes of less than 200 nm on an edge, work was done to develop a technique that could exploit the growth of the Photosystem I nanocrystals and microcrystals. Femtosecond X-ray protein nanocrystallography was developed for use at the first high-energy X-ray free electron laser, the LCLS at SLAC National Accelerator Laboratory, in which a liquid jet would bring fully hydrated Photosystem I nanocrystals into the interaction region of the pulsed X-ray source. Diffraction patterns were recorded from millions of individual PSI nanocrystals and data from thousands of different, randomly oriented crystallites were integrated using Monte Carlo integration of the peak intensities. The short pulses ( 70 fs) provided by the LCLS allowed the possibility to collect the diffraction data before the onset of radiation damage, exploiting the diffract-before-destroy principle. At the initial experiments at the AMO beamline using 6.9- Å wavelength, Bragg peaks were recorded to 8.5- Å resolution, and an electron-density map was determined that did not show any effects of X-ray-induced radiation damage. Recently, femtosecond X-ray protein nanocrystallography experiments were done at the CXI beamline of the LCLS using 1.3- Å wavelength, and Bragg reflections were recorded to 3- Å resolution; the data are currently being processed. Many additional techniques still need to be developed to explore the femtosecond nanocrystallography technique for experimental phasing and time-resolved X-ray crystallography experiments. The first proof-of-principle results for the femtosecond nanocrystallography technique indicate the incredible potential of the technique to offer a new route to the structure determination of membrane proteins.
ContributorsHunter, Mark (Author) / Fromme, Petra (Thesis advisor) / Wolf, George (Committee member) / Levitus, Marcia (Committee member) / Arizona State University (Publisher)
Created2011
Description
When people pick up the phone to call a telephone quitline, they are taking an important step towards changing their smoking behavior. The current study investigated the role of a critical cognition in the cessation process--self-efficacy. Self-efficacy is thought to be influential in behavior change processes including those involved in the challenging process of stopping tobacco use. By applying basic principles of self-efficacy theory to smokers utilizing a telephone quitline, this study advanced our understanding of the nature of self-efficacy in a "real-world" cessation setting. Participants received between one and four intervention calls aimed at supporting them through their quit attempt. Concurrent with the initiation of this study, three items (confidence, stress, and urges) were added to the standard telephone protocol and assessed at each call. Two principal sets of hypotheses were tested using a combination of ANCOVAs and multiple regression analyses. The first set of hypotheses explored how self-efficacy and changes in self-efficacy within individuals were associated with cessation outcomes. Most research has found a positive linear relation between self-efficacy and quit outcomes, but this study tested the possibility that excessively high self-efficacy may actually reflect an overconfidence bias, and in some cases be negatively related to cessation outcomes. The second set of hypotheses addressed several smoking-related factors expected to affect self-efficacy. As predicted, higher baseline self-efficacy and increases in self-efficacy were associated with higher rates of quitting. However, contrary to predictions, there was no evidence that overconfidence led to diminished cessation success. Finally, as predicted, shorter duration of quit attempts, shorter time to relapse, and stronger urges all were associated with lower self-efficacy. In conclusion, understanding how self-efficacy and changes in self-efficacy affect and are affected by cessation outcomes is useful for informing both future research and current quitline intervention procedures.
ContributorsGoesling, Jenna (Author) / Barrera, Manuel (Thesis advisor) / Shiota, Lani (Committee member) / Enders, Craig (Committee member) / Presson, Clark (Committee member) / Arizona State University (Publisher)
Created2011
Description
Surveys have shown that several hundred billion weather forecasts are obtained by the United States public each year, and that weather news is one of the most consumed topics in the media. This indicates that the forecast provides information that is significant to the public, and that the public utilizes details associated with it to inform aspects of their life. Phoenix, Arizona is a dry, desert region that experiences a monsoon season and extreme heat. How then, does the weather forecast influence the way Phoenix residents make decisions? This paper aims to draw connections between the weather forecast, decision making, and people who live in a desert environment. To do this, a ten-minute survey was deployed through Amazon Mechanical Turk (MTurk) in which 379 respondents were targeted. The survey asks 45 multiple choice and ranking questions categorized into four sections: obtainment of the forecast, forecast variables of interest, informed decision making based on unique weather variables, and demographics. This research illuminates how residents in the Phoenix metropolitan area use the local weather forecast for decision-making on daily activities, and the main meteorological factors that drive those decisions.
ContributorsMarturano, Julia (Author) / Middel, Ariane (Thesis director) / Schneider, Florian (Committee member) / School of Geographical Sciences and Urban Planning (Contributor, Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
Fibromyalgia (FM) is a chronic musculoskeletal disorder characterized by widespread pain, fatigue, and a variety of other comorbid physiological and psychological characteristics, including a deficit of positive affect. Recently, the focus of research on the pathophysiology of FM has considered the role of a number of genomic variants. In the current manuscript, case-control analyses did not support the hypothesis that FM patients would differ from other chronic pain groups in catechol-O-methyltransferase (COMT) and mu-opioid receptor (OPRM1) genotype. However, evidence is provided in support of the hypothesis that functional single nucleotide polymorphisms on the COMT and OPRM1 genes would be associated with risk and resilience, respectively, in a dual processing model of pain-related positive affective regulation in FM. Forty-six female patients with a physician-confirmed diagnosis of FM completed an electronic diary that included once-daily assessments of positive affect and soft tissue pain. Multilevel modeling yielded a significant gene X environment interaction, such that individuals with met/met genotype on COMT experienced a greater decline in positive affect as daily pain increased than did either val/met or val/val individuals. A gene X environment interaction for OPRM1 also emerged, indicating that individuals with at least one asp allele were more resilient to elevations in daily pain than those homozygous for the asn allele. In sum, the findings offer researchers ample reason to further investigate the contribution of the catecholamine and opioid systems, and their associated genomic variants, to the still poorly understood experience of FM.
ContributorsFinan, Patrick Hamilton (Author) / Zautra, Alex (Thesis advisor) / Davis, Mary (Committee member) / Lemery-Chalfant, Kathryn (Committee member) / Presson, Clark (Committee member) / Arizona State University (Publisher)
Created2011
Description
The use of synthetic cathinones or "bath salts" has risen dramatically in recent years with one of the most popular being Methylendioxypyrovalerone (MDPV). Following the temporary legislative ban on the sale and distribution of this compound , a multitude of other cathinone derivatives have been synthesized. The current study seeks to compare the abuse potential of MDPV with one of the emergent synthetic cathinones 4-methylethcathinone (4-MEC), based on their respective ability to lower current thresholds in an intracranial self-stimulation (ICSS) paradigm. Following acute administration (0.1, 0.5, 1 and 2 mg/kg i.p.) MDPV was found to significantly lower ICSS thresholds at all doses tested (F4,35=11.549, p<0.001). However, following acute administration (0.3,1,3,10,30 mg/kg i.p) 4-MEC produced no significant ICSS threshold depression (F5,135= 0.622, p = 0.684). Together these findings suggest that while MDPV may possess significant abuse potential, other synthetic cathinones such as 4-MEC may have a drastically reduced potential for abuse.
ContributorsWegner, Scott Andrew (Author) / Olive, M. Foster (Thesis director) / Presson, Clark (Committee member) / Sanabria, Federico (Committee member) / Barrett, The Honors College (Contributor) / Department of Chemistry and Biochemistry (Contributor) / Department of Psychology (Contributor)
Created2013-05
Description
This thesis focuses on the erotic depictions of Lucretia and Susanna in Renaissance art. Both noted for displaying exemplary chastity, Lucretia and Susanna gained popularity as Christian and secular role models for women in the late Middle Ages and Renaissance. My examination of the heroines addresses the seductive portrayal of these women in painting, which seemingly contradicts the essence of their celebrity. The images specifically analyzed in this thesis include: Lucas Cranach the Elder's Lucretia from 1525, Lucretia from 1533, and Venus from 1532 as well as Tintoretto's Susanna and the Elders and Annibale Carracci's Susanna and the Elders. The scope of my thesis includes both textual and visual analyses of the myths/figures and the disparity that arises between them. Employing Lucretia and Susanna as examples, my aim is to demonstrate a subtle subversion occurring within images of powerful women that ultimately strips them of their power.
ContributorsWilliamson, Jennifer Marie (Author) / Schleif, Corine (Thesis director) / Geschwind, Rachel (Committee member) / Pratt, Rebekah (Committee member) / Barrett, The Honors College (Contributor) / School of Social Transformation (Contributor) / School of Human Evolution and Social Change (Contributor) / School of Art (Contributor)
Created2013-05
Description
Science fiction themed video games, specifically Role Playing Games (RPGs) like Deus Ex: Human Revolution (DX:HR), that focus on an emerging technology, contain features that help to better inform anticipatory governance. In a game like DX:HR, players vicariously experience human-enhancement technology and its societal effects through their in-game character. Acting as the character, the player explores the topic of human-enhancement technology in various ways, including dialogue with non-player characters (NPCs) and decisions that directly affect the game's world. Because Deus Ex: Human Revolution and games similar to it, allow players to explore and think about the technology itself, the stances on it, and its potential societal effects, they facilitate the anticipatory governance process. In this paper I postulate a theory of anticipatory gaming, which asserts that video games inform the anticipatory governance process for an emerging technology. To demonstrate this theory I examine the parts of the anticipatory governance process and demonstrate RPG's ability to inform it, through a case study of Deus Ex: Human Revolution.
ContributorsShedd, Jesse Bernard (Author) / Wetmore, Jameson (Thesis director) / Fisher, Erik (Committee member) / McKnight, John Carter (Committee member) / Barrett, The Honors College (Contributor) / School of Human Evolution and Social Change (Contributor)
Created2013-05
Description
This study looked at the gender roles of individuals in the LGBT community, who hold gender-inverting and gender-conforming queer identities. The specific identities looked at were twinks (gender-inverted) and bears (gender-conforming) for men, and lipsticks (gender-conforming) and butches (gender-inverting) for women. The hypothesis was that individuals with gender-inverting identities would react effectively to a masculine gender role selecting prime, as well as a feminine gender role selecting prime.
ContributorsBlankenship, Benjamin Tyrus (Author) / Nagoshi, Craig (Thesis director) / Presson, Clark (Committee member) / Grzanka, Patrick (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor)
Created2013-05
Description
This research is focused on two separate but related topics. The first uses an electroencephalographic (EEG) brain-computer interface (BCI) to explore the phenomenon of motor learning transfer. The second takes a closer look at the EEG-BCI itself and tests an alternate way of mapping EEG signals into machine commands. We test whether motor learning transfer is more related to use of shared neural structures between imagery and motor execution or to more generalized cognitive factors. Using an EEG-BCI, we train one group of participants to control the movements of a cursor using embodied motor imagery. A second group is trained to control the cursor using abstract motor imagery. A third control group practices moving the cursor using an arm and finger on a touch screen. We hypothesized that if motor learning transfer is related to the use of shared neural structures then the embodied motor imagery group would show more learning transfer than the abstract imaging group. If, on the other hand, motor learning transfer results from more general cognitive processes, then the abstract motor imagery group should also demonstrate motor learning transfer to the manual performance of the same task. Our findings support that motor learning transfer is due to the use of shared neural structures between imaging and motor execution of a task. The abstract group showed no motor learning transfer despite being better at EEG-BCI control than the embodied group. The fact that more participants were able to learn EEG-BCI control using abstract imagery suggests that abstract imagery may be more suitable for EEG-BCIs for some disabilities, while embodied imagery may be more suitable for others. In Part 2, EEG data collected in the above experiment was used to train an artificial neural network (ANN) to map EEG signals to machine commands. We found that our open-source ANN using spectrograms generated from SFFTs is fundamentally different and in some ways superior to Emotiv's proprietary method. Our use of novel combinations of existing technologies along with abstract and embodied imagery facilitates adaptive customization of EEG-BCI control to meet needs of individual users.
Contributorsda Silva, Flavio J. K (Author) / Mcbeath, Michael K (Thesis advisor) / Helms Tillery, Stephen (Committee member) / Presson, Clark (Committee member) / Sugar, Thomas (Committee member) / Arizona State University (Publisher)
Created2013
Description
This paper studies the change in social diversity and interaction space from the Classic to Postclassic periods in the Mimbres Valley and East Mimbres Area. Between the Classic and Postclassic periods the Mimbres region of the American Southwest exhibits an increase in diversity of ceramic wares. Previous research suggests that increased diversity of ceramics indicates a more diverse community, which could pose challenges to local social interaction (Nelson et al. 2011). I am interested in whether the architecture of plazas, focal points of communities' social structures, change in response to the growing social diversity. To examine this, I quantify the diversity of painted ceramics at Classic and Postclassic villages as well as the extent of the enclosure of plazas. I find that there is a definite shift towards greater plaza enclosure between the Classic and Postclassic periods. I conclude this paper with a discussion of possible interpretations of this trend regarding the social reactions of Mimbres communities to the changes which reshaped the region between the Classic and Postclassic periods.
ContributorsHarkness, Rebecca Jean (Author) / Nelson, Margaret (Thesis director) / Hegmon, Michelle (Committee member) / Barrett, The Honors College (Contributor) / School of Human Evolution and Social Change (Contributor) / School of Historical, Philosophical and Religious Studies (Contributor)
Created2015-05