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Description
The intracellular motility seen in the cytoplasm of angiosperm plant pollen tubes is known as reverse fountain cytoplasmic streaming (i.e., cyclosis). This effect occurs when organelles move anterograde along the cortex of the cell and retrograde down the center of the cell. The result is a displacement of cytoplasmic volume causing a cyclic motion of organelles and bulk liquid. Visually, the organelles appear to be traveling in a backwards fountain hence the name. The use of light microscopy bioimaging in this study has documented reverse fountain cytoplasmic streaming for the first time in fungal hyphae of Rhizopus oryzae and other members in the order Mucorales (Mucoromycota). This is a unique characteristic of the mucoralean fungi, with other fungal phyla (e.g., Ascomycota, Basidiomycota) exhibiting unidirectional cytoplasmic behavior that lacks rhythmic streaming (i.e., sleeve-like streaming). The mechanism of reverse fountain cytoplasmic streaming in filamentous fungi is currently unknown. However, in angiosperm plant pollen tubes it’s correlated with the arrangement and activity of the actin cytoskeleton. Thus, the current work assumes that filamentous actin and associated proteins are directly involved with the cytoplasmic behavior in Mucorales hyphae. From an evolutionary perspective, fungi in the Mucorales may have developed reverse fountain cytoplasmic streaming as a method to transport various organelles over long and short distances. In addition, the mechanism is likely to facilitate driving of polarized hyphal growth.
ContributorsShange, Phakade Mdima (Author) / Roberson, Robert W. (Thesis advisor) / Gile, Gillian (Committee member) / Baluch, Debra (Committee member) / Arizona State University (Publisher)
Created2020
Description
The current study assessed whether the interrater reliability and predictive validity of fidelity ratings differed significantly across the modalities of audio and video recordings. As empirically supported programs are moving to scale, attention to fidelity, the extent to which a program is delivered as intended, is essential because high fidelity is needed for positive program effects. Consequently, an important issue for prevention science is the development of feasible and acceptable methods for assessing fidelity. Currently, fidelity monitoring is rarely practiced, as the typical way of measuring fidelity, which uses video of sessions, is expensive, time-consuming, and intrusive. Audio recording has multiple advantages over video recording: 1) it is less intrusive; 2) equipment is less expensive; 3) recording procedures are simpler; 4) files are smaller so it takes less time to upload data and storage is less expensive; 5) recordings contain less identifying information; and 6) both clients and providers may be more willing to have sensitive interactions recorded with audio only. For these reasons, the use of audio recording may facilitate the monitoring of fidelity and increase the acceptability of both the intervention and implementation models, which may serve to broaden the scope of the families reached and improve the quality of the services provided. The current study compared the reliability and validity of fidelity ratings across audio and video rating modalities using 77 feedback sessions drawn from a larger randomized controlled trial of the Family Check-Up (FCU). Coders rated fidelity and caregiver in-session engagement at the age 2 feedback session. The composite fidelity and caregiver engagement scores were tested using path analysis to examine whether they predicted parenting behavior at age 3. Twenty percent of the sessions were double coded to assess interrater reliability. The interrater reliability and predictive validity of fidelity scores and caregiver engagement did not significantly differ across rating modality. However, caution must be used in interpreting these results because the interrater reliabilities in both conditions were low. Possible explanations for the low reliability, limitations of the current study, and directions for future research are discussed.
ContributorsRudo-Stern, Jenna Simone (Author) / Wolchik, Sharlene A (Thesis advisor) / Mauricio, Anne M (Committee member) / Grimm, Kevin J. (Committee member) / González, Nancy (Committee member) / Arizona State University (Publisher)
Created2019
Description
Background. Hundreds of studies have linked maternal depression to negative child outcomes. However, these studies have been correlational, so they cannot rule out alternative explanations such as that child characteristics evoke maternal depression or that confounding variables are causes of both phenomena. Design. I applied a propensity score approach to data from the Early Steps Multisite Trial, a sample of 731 low-income families tracked approximately annually from ages 2 through 16. Families were equated on propensity scores based on a large set of baseline characteristics, producing two groups that were similar across all measured characteristics except for the presence of clinically significant symptoms of maternal depression during toddlerhood. Children’s longitudinal behavioral outcomes from parent-, teacher-, and self-report measures were compared across the equated groups in order to estimate the causal effects of maternal depression. Results. Both matching and weighting were successful in equating families with depressed and non-depressed mothers on a set of 89 potential confounding variables measured at child age 2. Prior to any adjustment for confounding, the effect of maternal depression was statistically significant for 41 of 48 mother-, secondary-caregiver-, and teacher-reported outcomes. Effect sizes were consistent with the larger literature and in the small to medium range. After matching or weighting to equate families with depressed versus non-depressed mothers, the effects of maternal depression at age 2 was statistically significant for 6 of 48 mother-, secondary-caregiver-, and teacher-reported outcomes. Adjusted effect sizes were in the very small to small range. Conclusions. Findings are consistent with the claim that there is a very small causal effect of exposure to maternal depression at child age 2 on child externalizing and internalizing behavior in early childhood, middle childhood, and adolescence. While awaiting replication, results suggest (a) that treatment of maternal depression should not be expected to substantially reduce child externalizing and internalizing behavior problems; (b) that very large sample sizes are needed to adequately investigate causal developmental processes that link maternal depression to child behavior; and (c) that causal inference methods can be an important addition to the toolbox of developmental psychopathologists.
ContributorsPELHAM III, WILLIAM E (Author) / West, Stephen G. (Thesis advisor) / Crnic, Keith A (Thesis advisor) / LEMERY-CHALFANT, KATHY (Committee member) / Goodman, Sherryl H. (Committee member) / Arizona State University (Publisher)
Created2020
Description
Familism values have been shown to have a multitude of benefits for Mexican American youth. Understanding different pathways of the adoption of familism values from adolescence and young adulthood, and predictors of these pathways, is critical. The current study assessed different classes of change in familism values across five waves from fifth grade to young adulthood, and fifth-grade predictors of these profiles, among a sample of 749 Mexican American youth. Univariate and growth mixture modeling was used to determine classes of familism change and found two classes—one class that showed small, insignificant declines across adolescence that accelerated into young adulthood and one class that showed significant declines across adolescence that stabilized and increased into young adulthood. The three-step procedure was then used to examine the following fifth-grade predictors of familism classes: family conflict, family cohesion, harsh parenting, parental acceptance, economic hardship, and perceived ethnic discrimination. Family conflict and perceived ethnic discrimination were significant predictors of familism class membership. Greater family conflict predicted a greater probability of being in the class of significant declines in familism across adolescence that stabilized and increased into young adulthood. Greater perceived ethnic discrimination predicted a greater probability of being in the class of small, insignificant decreases across adolescence that accelerated into young adulthood. Gender moderated the impact of family cohesion. For females, greater father-reported family cohesion predicted a greater probability of being in the class with significant declines during adolescence that stabilized and increased into young adulthood. For males, greater father-reported family cohesion predicted a greater probability of being in the class with slight, insignificant declines in adolescence that accelerated into young adulthood. Youth nativity moderated the impact of maternal acceptance. For youth born in the U.S., greater mother-reported acceptance predicted a greater probability of being in the class of slight, insignificant declines across adolescence that accelerated into young adulthood. For youth born in Mexico, greater mother-reported acceptance predicted a greater probability of being in the class of significant declines in familism across adolescence that stabilized and increased into young adulthood. Limitations and implications for prevention and future research are discussed.
ContributorsJenchura, Emily C. (Author) / Gonzales, Nancy A. (Thesis advisor) / Knight, George P (Committee member) / Grimm, Kevin J. (Committee member) / Perez, Marisol (Committee member) / Arizona State University (Publisher)
Created2019
Description
Over 25% of children in the United States suffer from a chronic illness, and close to 70% of all childhood deaths are due to chronic illness. Prevalence of childhood chronic illness continues to increase, and as a result, the pervasiveness of parents faced with stress associated with caregiving for their child with a chronic illness is also rising. The Stress Process Model (SPM) conceptualizes the caregiving experience as a multidimensional process influenced by the caregiving context, primary and secondary stressors, resources, and caregiver outcomes. Utilizing the SPM, the goals of this study were to examine the relations between caregiving stress (role overload and role strain) and resources (instrumental support, social support, and positive attitudes) and psychological outcomes (depression and anxiety) to determine whether resources moderated the associations between caregiving stress and psychological outcomes.
Participants included 200 parent caregivers of a child with a chronic illness. Participants responded to an online survey that measured demographics, role overload (Role Overload scale), role strain (The Revised Caregiver Burden Measure), instrumental support and social support (Medical Outcomes Survey), positive attitudes about caregiving (Brief Assessment Scale for Caregivers), depression (Patient Health Questionnaire-9), and anxiety (Generalized Anxiety Disorder scale-7). Pearson correlations and six hierarchical regression models were tested to examine caregiving stress, resources, and psychological outcomes.
Consistent with the study hypotheses, positive correlations between caregiving stress (role overload and role strain) and depression and anxiety were found. Negative correlations were found between resources (instrumental support, social support, positive attitudes) and depression and anxiety. Both instrumental support and social support had negative moderating effects on the relations between role overload and psychological outcomes (depression and anxiety). Positive attitudes also negatively moderated the relations between role strain and psychological outcomes. Thus, when participants reported high instrumental and social support, they also reported low depression and anxiety, even when role overload was high. Participants also reported low anxiety and depression when they reported high positive attitudes, even when role strain was high. Implications of these findings are discussed.
Participants included 200 parent caregivers of a child with a chronic illness. Participants responded to an online survey that measured demographics, role overload (Role Overload scale), role strain (The Revised Caregiver Burden Measure), instrumental support and social support (Medical Outcomes Survey), positive attitudes about caregiving (Brief Assessment Scale for Caregivers), depression (Patient Health Questionnaire-9), and anxiety (Generalized Anxiety Disorder scale-7). Pearson correlations and six hierarchical regression models were tested to examine caregiving stress, resources, and psychological outcomes.
Consistent with the study hypotheses, positive correlations between caregiving stress (role overload and role strain) and depression and anxiety were found. Negative correlations were found between resources (instrumental support, social support, positive attitudes) and depression and anxiety. Both instrumental support and social support had negative moderating effects on the relations between role overload and psychological outcomes (depression and anxiety). Positive attitudes also negatively moderated the relations between role strain and psychological outcomes. Thus, when participants reported high instrumental and social support, they also reported low depression and anxiety, even when role overload was high. Participants also reported low anxiety and depression when they reported high positive attitudes, even when role strain was high. Implications of these findings are discussed.
ContributorsJohnson, Courtney Kerber (Author) / Kurpius, Sharon (Thesis advisor) / Dillon, Frank (Committee member) / Tracey, Terence (Committee member) / Arizona State University (Publisher)
Created2020
Description
This study investigated low regulatory flexibility as a mechanism of the associations of rumination with affect, internalizing symptoms, and substance use and problems. 403 first-year college students completed an online baseline survey assessing rumination, regulatory flexibility, internalizing symptoms, alcohol use, cannabis use, alcohol problems, and cannabis problems. Roughly 2.67 months later, 261 of these participants completed a follow-up survey assessing internalizing symptoms and substance use and problems. Additionally, 71 of the 403 participants completed an experimental study. Thirty-three participants were randomly assigned to undergo a rumination induction, and 38 were assigned to a control condition. All lab participants underwent an interpersonal stress task during which regulatory flexibility was observed and completed pre-test and post-role-play measures of positive and negative affect. Experimental study results showed regulatory flexibility did not mediate effects of rumination induction on positive (indirect effect: standardized beta (β)=-0.01, unstandardized beta (b)=-0.12, 95% Confidence Interval (CI) [-0.64, 0.41], p=.66) or negative affect (indirect effect: β=0.01, b=0.17, 95% CI [-0.29, 0.63], p=.48). Longitudinal study results showed regulatory flexibility did not mediate associations between baseline rumination and follow-up internalizing symptoms (indirect effect: b=0.01, 95% CI [-0.03, 0.05], p=.57), alcohol use (indirect effect: b=-0.03, 95% CI [-0.09, 0.04], p=.39), cannabis use (indirect effect: b=0.10, 95% CI [-0.06, 0.26], p=.21), alcohol problems (indirect effect: b=-0.05, 95% CI [-0.18, 0.07], p=.40), or cannabis problems (indirect effect: b=-0.10, 95% CI [-0.36, 0.16], p=.43). However, rumination predicted greater internalizing symptoms (Incidence Rate Ratio (IRR)=1.26, b=0.23, 95% CI [0.08, 0.37], p=.003) and cannabis problems (IRR=1.73, b=0.55, 95% CI [0.23, 0.87], p=.001). Regulatory flexibility predicted fewer alcohol use days (IRR=0.76, b=-0.27, 95% CI [-0.49, -0.05], p=.015) and problems (IRR=0.58, b=-0.55, 95% CI [-0.95, -0.15], p=.007), and less cannabis use for women (IRR=0.59, b=-0.53, 95% CI [-0.92, -0.14], p=.007) and fewer cannabis problems for men (IRR=0.21, b=-1.55, 95% CI [-2.50, -0.60], p=.001). Lack of agreement about how best to measure regulatory flexibility makes it unclear whether null associations were due to measurement problems or actual null effects. Research on how best to measure this construct is a priority. Findings indicate rumination and regulatory flexibility may be promising intervention targets.
ContributorsHill, Melanie Laurel (Author) / Meier, Madeline H (Thesis advisor) / Karoly, Paul (Committee member) / Luecken, Linda J. (Committee member) / Infurna, Frank J. (Committee member) / Arizona State University (Publisher)
Created2020
Description
Alcohol use among romantic partners is known to be related to a variety of detrimental outcomes, such as decreased relationship satisfaction and increases in conflict. However, discrepant drinking among partners may be a stronger predictor of relationship outcomes over and above the amount of alcohol use. Currently, little is known about potential differences in the within- and between-person effects and discrepancy’s effect on mood, particularly among community samples. The current study investigated the effects of both individual and partner alcohol use, as well as discrepant drinking, on mood and relationship functioning. Data were obtained from 280 heterosexual romantic couples using a measurement burst daily dairy design over the course of one year. Actor Partner Interdependence Model and Dyadic Score Model analyses were used to investigate the effect of alcohol use and discrepant drinking on mood and relationship functioning, both at the within- and between- person levels. Specifically, analyses investigated the effects of no drinking versus moderate drinking, no drinking versus binge drinking, and moderate drinking versus binge drinking. Results revealed that while binge drinking may be related to positive outcomes proximally, the cumulative effects at the between-person level are detrimental. Moreover, discrepant drinking appears most detrimental when women outdrink their partners. These findings have important implications for refining and improving upon couples-based interventions aimed at alcohol-use problems among non-clinical couples.
ContributorsChampion, Charlie (Author) / Corbin, William (Thesis advisor) / Ha, Thao (Committee member) / Iida, Masumi (Committee member) / Randall, Ashley (Committee member) / Arizona State University (Publisher)
Created2020
Description
The term Poly-Limb stems from the rare birth defect syndrome, called Polymelia. Although Poly-Limbs in nature have often been nonfunctional, humans have had the fascination of functional Poly-Limbs. Science fiction has led us to believe that having Poly-Limbs leads to augmented manipulation abilities and higher work efficiency. To bring this to life however, requires a synergistic combination between robot manipulation and wearable robotics. Where traditional robots feature precision and speed in constrained environments, the emerging field of soft robotics feature robots that are inherently compliant, lightweight, and cost effective. These features highlight the applicability of soft robotic systems to design personal, collaborative, and wearable systems such as the Soft Poly-Limb.
This dissertation presents the design and development of three actuator classes, made from various soft materials, such as elastomers and fabrics. These materials are initially studied and characterized, leading to actuators capable of various motion capabilities, like bending, twisting, extending, and contracting. These actuators are modeled and optimized, using computational models, in order to achieve the desired articulation and payload capabilities. Using these soft actuators, modular integrated designs are created for functional tasks that require larger degrees of freedom. This work focuses on the development, modeling, and evaluation of these soft robot prototypes.
In the first steps to understand whether humans have the capability of collaborating with a wearable Soft Poly-Limb, multiple versions of the Soft Poly-Limb are developed for assisting daily living tasks. The system is evaluated not only for performance, but also for safety, customizability, and modularity. Efforts were also made to monitor the position and orientation of the Soft Poly-Limbs components through embedded soft sensors and first steps were taken in developing self-powered compo-nents to bring the system out into the world. This work has pushed the boundaries of developing high powered-to-weight soft manipulators that can interact side-by-side with a human user and builds the foundation upon which researchers can investigate whether the brain can support additional limbs and whether these systems can truly allow users to augment their manipulation capabilities to improve their daily lives.
This dissertation presents the design and development of three actuator classes, made from various soft materials, such as elastomers and fabrics. These materials are initially studied and characterized, leading to actuators capable of various motion capabilities, like bending, twisting, extending, and contracting. These actuators are modeled and optimized, using computational models, in order to achieve the desired articulation and payload capabilities. Using these soft actuators, modular integrated designs are created for functional tasks that require larger degrees of freedom. This work focuses on the development, modeling, and evaluation of these soft robot prototypes.
In the first steps to understand whether humans have the capability of collaborating with a wearable Soft Poly-Limb, multiple versions of the Soft Poly-Limb are developed for assisting daily living tasks. The system is evaluated not only for performance, but also for safety, customizability, and modularity. Efforts were also made to monitor the position and orientation of the Soft Poly-Limbs components through embedded soft sensors and first steps were taken in developing self-powered compo-nents to bring the system out into the world. This work has pushed the boundaries of developing high powered-to-weight soft manipulators that can interact side-by-side with a human user and builds the foundation upon which researchers can investigate whether the brain can support additional limbs and whether these systems can truly allow users to augment their manipulation capabilities to improve their daily lives.
ContributorsNguyen, Pham Huy (Author) / Zhang, Wenlong (Thesis advisor) / Sugar, Thomas G. (Committee member) / Santello, Marco (Committee member) / Arizona State University (Publisher)
Created2020
Description
Recent improvements in energy resolution for electron energy-loss spectroscopy in the scanning transmission electron microscope (STEM-EELS) allow novel effects in the low-loss region of the electron energy-loss spectrum to be observed. This dissertation explores what new information can be obtained with the combination of meV EELS energy resolution and atomic spatial resolution in the STEM. To set up this up, I review nanoparticle shape effects in the electrostatic approximation and compare the “classical” and “quantum” approaches to EELS simulation. Past the electrostatic approximation, the imaging of waveguide-type modes is modeled in ribbons and cylinders (in “classical" and “quantum" approaches, respectively), showing how the spatial variations of such modes can now be imaged using EELS. Then, returning to the electrostatic approximation, I present microscopic applications of low-loss STEM-EELS. I develop a “classical” model coupling the surface plasmons of a sharp metallic nanoparticle to the dipolar vibrations of an adsorbate molecule, which allows expected molecular signal enhancements to be quantified and the resultant Fano-type asymmetric spectral line shapes to be explained, and I present “quantum” modelling for the charged nitrogen-vacancy (NV-) and neutral silicon-vacancy (SiV0) color centers in diamond, including cross-sections and spectral maps from density functional theory. These results are summarized before concluding.
Many of these results have been previously published in Physical Review B. The main results of Ch. 2 and Ch. 4 were packaged as “Enhanced vibrational electron energy-loss spectroscopy of adsorbate molecules” (99, 104110), and much of Ch. 5 appeared as “Prospects for detecting individual defect centers using spatially resolved electron energy loss spectroscopy” (100, 134103). The results from Ch. 3 are being prepared for a forthcoming article in the Journal of Chemical Physics.
Many of these results have been previously published in Physical Review B. The main results of Ch. 2 and Ch. 4 were packaged as “Enhanced vibrational electron energy-loss spectroscopy of adsorbate molecules” (99, 104110), and much of Ch. 5 appeared as “Prospects for detecting individual defect centers using spatially resolved electron energy loss spectroscopy” (100, 134103). The results from Ch. 3 are being prepared for a forthcoming article in the Journal of Chemical Physics.
ContributorsKordahl, David Daniel (Author) / Dwyer, Christian (Thesis advisor) / Rez, Peter (Committee member) / Spence, John C.H. (Committee member) / Sukharev, Maxim (Committee member) / Arizona State University (Publisher)
Created2020
Description
Volcanic eruptions are serious geological hazards; the aftermath of the explosive eruptions produced at high-silica volcanic systems often results in long-term threats to climate, travel, farming, and human life. To construct models for eruption forecasting, the timescales of events leading up to eruption must be accurately quantified. In the field of igneous petrology, the timing of these events (e.g. periods of magma formation, duration of recharge events) and their influence on eruptive timescales are still poorly constrained.
In this dissertation, I discuss how the new tools and methods I have developed are helping to improve our understanding of these magmatic events. I have developed a method to calculate more accurate timescales for these events from the diffusive relaxation of chemical zoning in individual mineral crystals (i.e., diffusion chronometry), and I use this technique to compare the times recorded by different minerals from the same Yellowstone lava flow, the Scaup Lake rhyolite.
I have also derived a new geothermometer to calculate magma temperature from the compositions of the mineral clinopyroxene and the surrounding liquid. This empirically-derived geothermometer is calibrated for the high FeOtot (Mg# = 56) and low Al2O3 (0.53–0.73 wt%) clinopyroxene found in the Scaup Lake rhyolite and other high-silica igneous systems. A determination of accurate mineral temperatures is crucial to calculate magmatic heat budgets and to use methods such as diffusion chronometry. Together, these tools allow me to paint a more accurate picture of the conditions and tempo of events inside a magma body in the millennia to months leading up to eruption.
Additionally, I conducted petrological experiments to determine the composition of hypothetical exoplanet partial mantle melts, which could become these planets’ new crust, and therefore new surface. Understanding the composition of an exoplanet’s crust is the first step to understanding chemical weathering, surface-atmosphere chemical interactions, the volcanic contribution to any atmosphere present, and biological processes, as life depends on these surfaces for nutrients. The data I have produced can be used to predict differences in crust compositions of exoplanets with similar bulk compositions to those explored herein, as well as to calibrate future exoplanet petrologic models.
In this dissertation, I discuss how the new tools and methods I have developed are helping to improve our understanding of these magmatic events. I have developed a method to calculate more accurate timescales for these events from the diffusive relaxation of chemical zoning in individual mineral crystals (i.e., diffusion chronometry), and I use this technique to compare the times recorded by different minerals from the same Yellowstone lava flow, the Scaup Lake rhyolite.
I have also derived a new geothermometer to calculate magma temperature from the compositions of the mineral clinopyroxene and the surrounding liquid. This empirically-derived geothermometer is calibrated for the high FeOtot (Mg# = 56) and low Al2O3 (0.53–0.73 wt%) clinopyroxene found in the Scaup Lake rhyolite and other high-silica igneous systems. A determination of accurate mineral temperatures is crucial to calculate magmatic heat budgets and to use methods such as diffusion chronometry. Together, these tools allow me to paint a more accurate picture of the conditions and tempo of events inside a magma body in the millennia to months leading up to eruption.
Additionally, I conducted petrological experiments to determine the composition of hypothetical exoplanet partial mantle melts, which could become these planets’ new crust, and therefore new surface. Understanding the composition of an exoplanet’s crust is the first step to understanding chemical weathering, surface-atmosphere chemical interactions, the volcanic contribution to any atmosphere present, and biological processes, as life depends on these surfaces for nutrients. The data I have produced can be used to predict differences in crust compositions of exoplanets with similar bulk compositions to those explored herein, as well as to calibrate future exoplanet petrologic models.
ContributorsBrugman, Karalee (Author) / Till, Christy B. (Thesis advisor) / Bose, Maitrayee (Committee member) / Desch, Steven J (Committee member) / Hervig, Richard L (Committee member) / Shock, Everett L (Committee member) / Arizona State University (Publisher)
Created2020