Matching Items (241)
Description
HIV/AIDS is the sixth leading cause of death worldwide and the leading cause of death among women of reproductive age living in low-income countries. Clinicians in industrialized nations monitor the efficacy of antiretroviral drugs and HIV disease progression with the HIV-1 viral load assay, which measures the copy number of HIV-1 RNA in blood. However, viral load assays are not widely available in sub-Saharan Africa and cost between 50-$139 USD per test on average where available. To address this problem, a mixed-methods approach was undertaken to design a novel and inexpensive viral load diagnostic for HIV-1 and to evaluate barriers to its adoption in a developing country. The assay was produced based on loop-mediated isothermal amplification (LAMP). Blood samples from twenty-one individuals were spiked with varying concentrations of HIV-1 RNA to evaluate the sensitivity and specificity of LAMP. Under isothermal conditions, LAMP was performed with an initial reverse-transcription step (RT-LAMP) and primers designed for HIV-1 subtype C. Each reaction generated up to a few billion copies of target DNA within an hour. Presence of target was detected through naked-eye observation of a fluorescent indicator and verified by DNA gel electrophoresis and real-time fluorescence. The assay successfully detected the presence of HIV in samples with a broad range of HIV RNA concentration, from over 120,000 copies/reaction to 120 copies/reaction. In order to better understand barriers to adoption of LAMP in developing countries, a feasibility study was undertaken in Tanzania, a low-income country facing significant problems in healthcare. Medical professionals in Northern Tanzania were surveyed for feedback regarding perspectives of current HIV assays, patient treatment strategies, availability of treatment, treatment priorities, HIV transmission, and barriers to adoption of the HIV-1 LAMP assay. The majority of medical providers surveyed indicated that the proposed LAMP assay is too expensive for their patient populations. Significant gender differences were observed in response to some survey questions. Female medical providers were more likely to cite stigma as a source problem of the HIV epidemic than male medical providers while males were more likely to cite lack of education as a source problem than female medical providers.
ContributorsSalamone, Damien Thomas (Author) / Jacobs, Bertram L (Thesis advisor) / Marsiglia, Flavio (Committee member) / Stout, Valerie (Committee member) / Johnson, Crista (Committee member) / Arizona State University (Publisher)
Created2011
Description
With the advent of the X-ray free-electron laser (XFEL), an opportunity has arisen to break the nexus between radiation dose and spatial resolution in diffractive imaging, by outrunning radiation damage altogether when using single X-ray pulses so brief that they terminate before atomic motion commences. This dissertation concerns the application of XFELs to biomolecular imaging in an effort to overcome the severe challenges associated with radiation damage and macroscopic protein crystal growth. The method of femtosecond protein nanocrystallography (fsPNX) is investigated, and a new method for extracting crystallographic structure factors is demonstrated on simulated data and on the first experimental fsPNX data obtained at an XFEL. Errors are assessed based on standard metrics familiar to the crystallography community. It is shown that resulting structure factors match the quality of those measured conventionally, at least to 9 angstrom resolution. A new method for ab-initio phasing of coherently-illuminated nanocrystals is then demonstrated on simulated data. The method of correlated fluctuation small-angle X-ray scattering (CFSAXS) is also investigated as an alternative route to biomolecular structure determination, without the use of crystals. It is demonstrated that, for a constrained two-dimensional geometry, a projection image of a single particle can be formed, ab-initio and without modeling parameters, from measured diffracted intensity correlations arising from disordered ensembles of identical particles illuminated simultaneously. The method is demonstrated experimentally, based on soft X-ray diffraction from disordered but identical nanoparticles, providing the first experimental proof-of-principle result. Finally, the fundamental limitations of CFSAXS is investigated through both theory and simulations. It is found that the signal-to-noise ratio (SNR) for CFSAXS data is essentially independent of the number of particles exposed in each diffraction pattern. The dependence of SNR on particle size and resolution is considered, and realistic estimates are made (with the inclusion of solvent scatter) of the SNR for protein solution scattering experiments utilizing an XFEL source.
ContributorsKirian, Richard A (Author) / Spence, John C. H. (Committee member) / Doak, R. Bruce (Committee member) / Weierstall, Uwe (Committee member) / Bennett, Peter (Committee member) / Treacy, Michael M. J. (Committee member) / Arizona State University (Publisher)
Created2011
Description
One of the most important issues in femtosecond free electron laser X-ray diraction is to reconstruct the 3D charge density of molecule from a mass of diraction snapshots. In order to determine the orientation of single molecule from diraction patterns, we rst determine the moments and products of inertia of this from 2D experiment data (diraction patterns or EM images to obtain the elements of the inertia tensor. If diraction patterns from uniformly random orientations or some preferred orientations are collected, the principal axes of the molecule can be extracted, together with the Euler angles which relate the principal axes of the molecule to the laboratory frame axes. This is achieved by nding the maximum and minimum values for the measured moments from many single-molecule patterns. Simulations for GroEL protein indicates that the calculation of the autocorrelation help eliminate the Poisson noise in Cryo- EM images and can make correct orientation determination. The eect of water jacket surrounding the protein molecule is studied based on molecular dynamics simulation result. The intensities from water and interference is found to suppress those from protein itself. A method is proposed and applied to the simulation data to show the possibility for it to overcome the water background problem. The scattering between Bragg re ections from nanocrystals is used to aid solution of the phase problem. We describe a method for reconstructing the charge density of a typical molecule within a single unit cell, if suciently nely-sampled diraction data are available from many nanocrystals of dierent sizes lying in the same orientations without knowledge of the distribution of particle size or requiring atomic-resolution data. Triple correlation of the diraction patterns are made use of to reconiii
ContributorsWang, Xiaoyu (Author) / Spence, John C.H. (Thesis advisor) / Schmidt, Kevin (Committee member) / Doak, R. Bruce (Committee member) / Weierstall, Uwe (Committee member) / Ros, Robert (Committee member) / Arizona State University (Publisher)
Created2011
Description
The purpose of our study was to examine the effectiveness of a cycling intervention on body composition in adolescents with Down syndrome (DS). Participants completed one of three interventions over eight consecutive weeks. The interventions were: 1) Voluntary Cycling (VC), in which participants cycled at their self-selected pedaling rate 2) Assisted Cycling (AC), in which the participants' voluntary pedaling rates were assisted with a motor to ensure the maintenance of 80 rpms. 3) No cycling (NC), in which the participants acted as controls. Participants in the AC intervention did not decrease body fat or increase lean body mass however they did maintain these measures during the intervention as compared to the VC and NO participants who increased body fat and decreased lean body mass. These statistics were not exactly as expected nor were they statistically significant. Future research will try to replicate this data with statistically significant values for more cycling adolescents with DS using more randomized intervention groups.
ContributorsBennett, Kristen Leigh (Author) / Ringenbach, Shannon (Thesis director) / Brown, Steven (Committee member) / Barrett, The Honors College (Contributor) / School of Nutrition and Health Promotion (Contributor)
Created2015-05
Description
This research study examined the effects of assisted cycling using a stationary recumbent bicycle that had an internal motor to help participants pedal at a desired cadence. The participants were either placed in an Assisted Cycling (AC), Voluntary Cycling (VC), or No Cycling (NC) intervention group. Those placed in the AC of VC groups then came to a laboratory setting 3 days a week for 8 weeks to cycle for 30 minutes. This research specifically analyzes the Vineland Adaptive Behavior Scale II to analyze the changes in daily living skills and maladaptive behaviors pre and post the exercise intervention. After analyzing the VABS II scores it was found that those in the VC intervention had statistically significant improvements in maladaptive behaviors. An interpretation of this finding is that the VC intervention had an increased heart rate over the span of the intervention and had a larger power output than those in the AC group. A limitation of this research is that it was a self-reported questionnaire that was given to the caregivers of the participant. The caregivers were not always controlled for, so in some cases two different caregivers were given the questionnaire for a single participant. A suggestion for future research would be to use the participant's mental age versus their chronological age when using the VABS-II and to use the Adaptive Behaviors Assessment System III (ABAS-III).
ContributorsJenkins, Cayla Marie (Author) / Ringenbach, Shannon (Thesis director) / Kulinna, Pamela (Committee member) / Barrett, The Honors College (Contributor) / School of Nutrition and Health Promotion (Contributor)
Created2015-05
Description
Communication skills within dating contexts are developed during the adolescent years, and are associated with a lifelong ability to have satisfying, enduring, and non-violent partnerships. As such, they are currently and increasingly implemented into both more general forms of healthy relationship education, as well as that targeting the prevention of teen dating violence specifically. Reaching Mexican American youth with culturally and developmentally appropriate relationship education, including communication skills, may be particularly important given their earlier transitions to marital and parenting relationships, acculturative stressors that present them with unique coupling challenges, and their higher rates of teen dating violence as compared to European American youth. We know very little about how Mexican American dating couples communicate about areas of conflict. This dissertation research utilizes Bell and Naugle's (2008) framework of interpersonal violence to explore how cultural and developmental considerations may be integrated in order to better understand how communication behaviors contribute to Mexican American middle adolescents' experiences with dating conflict. I use an observational study design in order to 1.) Qualitatively explore the communication strategies used by a sample of committed couples, including integration of culturally- and developmentally-relevant contexts, 2.) Quantitatively examine whether couple-level discrepancies in acculturation are associated with observed negativity, including whether this relationship may be mediated by dissimilar gender-related beliefs, and to 3.) Review empirical findings pertaining to the communication behaviors of Mexican American adolescents and to integrate ecodevelopmental theory in said framework as informed by Papers 1, 2, and literature specific to this topic area. The ultimate aim of this dissertation research is to generate findings that may improve the dating health of Mexican American adolescents living in the United States.
ContributorsAdams, Heidi (Author) / Rankin Williams, Lela (Thesis advisor) / Marsiglia, Flavio (Committee member) / Anthony, Elizabeth (Committee member) / Arizona State University (Publisher)
Created2013
Description
Although it has been established that children raised by lesbian and gay (LG) parents are comparable in psychological adjustment to those raised by heterosexuals, there are unique stressors that these families must face as members of a social minority group. For example, chronic exposure to stigma and discrimination has been associated with several poor psychological and behavioral outcomes in children, as well as high levels of stress experienced by LG parents. Thus, the current study sought to examine LG parents' coping actions and parenting strategies as used during and after an act of antigay discrimination which also involved their children, or as these involved an act which their children witnessed. This study also sought to define the parenting needs of LG parents. The research plan utilized an integrative mixed methods approach to examine the qualitative text narratives of 43 LG parents (29 mothers and 14 fathers) ranging in age from 28-56 years old with school-aged children (6-12 years). Results revealed that LG parents' negative emotion-based coping actions predicted higher depressive symptoms (β= .41,t(33) = 3.17, p < .01), LG parents' avoidant/escape coping actions predicted lower parenting self-agency (β = -.34, t(33) = -2.23, p < .05), and LG parents' engagement in understanding and coping with discrimination parenting strategies predicted lower post-traumatic stress problems in their children (β = -.33, t(33) = -1.96, yp = .059). Last, a family needs assessment survey was used to determine the unique parenting needs of these LG parents. The results of this survey indicated that LG parents endorsed the following three topic areas as most important to them: (a) LG Family Community Services, (b) Information about Child Development, and (c) Explaining LG Family to Others. These findings reinforce existing knowledge in terms of the effects of discrimination on LG parents and their children. Indeed, results indicate the importance of providing LG parents with adaptive discrimination coping and parenting strategies, as well as offering valuable information concerning their specific needs.
ContributorsKellison, Joshua G (Author) / Gonzalez Castro, Felipe (Thesis advisor) / Crnic, Keith (Thesis advisor) / Barrera, Jr., Manuel (Committee member) / Marsiglia, Flavio (Committee member) / Wolchik, Sharlene (Committee member) / Arizona State University (Publisher)
Created2014
Description
ABSTRACT The relationships between adaptive and maladaptive aspects of gender roles in predicting substance use were examined in a sample of 955 (450 boys, 505 girls) Mexican American 7th and 8th grade adolescents participating in a school-based substance use intervention. The moderating effect of linguistic acculturation, the mediating effects of antisociality, depressive symptoms, and adaptive and avoidant coping on gender role-substance use relationships were examined. Correlational and path analyses supported the Functional Model of Gender Roles that considers these roles as adaptive or maladaptive social coping strategies. For boys, the path analyses yielded significant direct paths from aggressive masculinity to composite alcohol, cigarette, and marijuana use measures, with all other effects of gender roles on substance use operating through the mediators. Bootstrapped mediation tests yielded significant indirect paths, where for boys the positive relationships between assertive and aggressive masculinity with substance use and the negative relationship of affective femininity with substance use were mediated through antisociality, which is predictive of increased substance use. For girls, the positive relationship between aggressive masculinity with cigarette and alcohol use and the negative relationship of affective femininity with alcohol and cigarette use were also mediated by adaptive coping, which is predictive of decreased substance use. A different set of significant indirect paths through avoidant coping connected assertive masculinity and submissive femininity to alcohol use for boys. For boys, the paths from affective femininity to antisociality and adaptive coping were found to be moderated by linguistic acculturation, with the negative correlation of affective femininity with antisociality and positive correlation of this gender role with adaptive coping being stronger in boys low in acculturation. In turn, the pathway from this acculturation by affective femininity interaction to substance use was found to be mediated by antisociality. The present analyses confirmed the importance of gender roles and their interaction with acculturation in predicting substance use in Mexican American adolescents. The analyses also were important in delineating functional mechanisms through which these gender roles have their effects, with implications for the design of interventions to reduce substance use in this population.
ContributorsNagoshi, Julieann Lynn (Author) / Kulis, Stephen (Thesis advisor) / Marsiglia, Flavio (Committee member) / Gillmore, Mary (Committee member) / Arizona State University (Publisher)
Created2012
Description
This research study examined the bilateral asymmetry found in muscle pairs including the right and left sides of the upper rectus abdominis, lower rectus abdominis, external oblique, and internal oblique in college-aged, apparently fit men and women. Bilateral symmetry was found using surface electromyography (EMG) during three core exercises: 1) ab-slides using paper plates (paper), 2) planks, and 3) ab-slides using a commercial AbSlide® roller device by comparing maximal voluntary contractions (MVCs) of the four muscles previously listed. This research analyzed the percentage of muscle activation during these exercises to each person’s MVC using Noraxon® software. Analysis found that asymmetry for each muscle group was present although there is no measure of clinical significance for symmetry scores of the core muscles yet.
Asymmetry scores were calculated for all three exercises. The exercise that produced the greatest absolute, average asymmetry score was the ab-slide using the roller device. The muscle that the greatest absolute asymmetry was found was the internal oblique. This means that during the three exercises and MVC, the greatest difference between right and left side pair muscles was observed in the internal obliques. The standard deviation of symmetry scores for all exercises and muscles was great as there was much variation in the skill levels in the participants of this study. Bilateral asymmetry was found by visually comparing the asymmetry scores. In conclusion, bilateral asymmetry was found in the core muscles of college-aged individuals during bilateral abdominal exercises.
Asymmetry scores were calculated for all three exercises. The exercise that produced the greatest absolute, average asymmetry score was the ab-slide using the roller device. The muscle that the greatest absolute asymmetry was found was the internal oblique. This means that during the three exercises and MVC, the greatest difference between right and left side pair muscles was observed in the internal obliques. The standard deviation of symmetry scores for all exercises and muscles was great as there was much variation in the skill levels in the participants of this study. Bilateral asymmetry was found by visually comparing the asymmetry scores. In conclusion, bilateral asymmetry was found in the core muscles of college-aged individuals during bilateral abdominal exercises.
ContributorsFavaro, Miguel Angel (Author) / Berger, Christopher (Thesis director) / Lorenz, Kent (Committee member) / Barrett, The Honors College (Contributor) / School of Nutrition and Health Promotion (Contributor)
Created2015-05
Description
This study examines cognitive planning in adolescents with Down syndrome (DS) following an 8-week assisted cycling therapy intervention. Forty-three participants were randomly assigned to assisted cycling (AC) (i.e., at least 30% faster than self-selected cadence accomplished by a motor), voluntary cycling (VC) (self-selected cadence), and no cycling (NC) control group. Both AC and VC rode a stationary bicycle three times/week, 30 minutes/session, for eight weeks in duration. Participants completed cognitive testing that assessed cognitive planning at the beginning (i.e., pretest) and end (i.e., posttest) of the 8-week intervention. Consistent with our hypothesis, the results showed that cognitive planning improved following eight weeks of cycling for the AC group. The same results were not seen for individuals in the VC or NC groups. Our results suggest that assisted cycling therapy may induce permanent changes in the prefrontal cortex in adolescents with DS.
ContributorsMillar, Kelsey Leann (Author) / Ringenbach, Shannon (Thesis director) / Amazeen, Eric (Committee member) / Barrett, The Honors College (Contributor) / School of Nutrition and Health Promotion (Contributor)
Created2015-05