Matching Items (41)
Description
Nonlinear dispersive equations model nonlinear waves in a wide range of physical and mathematics contexts. They reinforce or dissipate effects of linear dispersion and nonlinear interactions, and thus, may be of a focusing or defocusing nature. The nonlinear Schrödinger equation or NLS is an example of such equations. It appears as a model in hydrodynamics, nonlinear optics, quantum condensates, heat pulses in solids and various other nonlinear instability phenomena. In mathematics, one of the interests is to look at the wave interaction: waves propagation with different speeds and/or different directions produces either small perturbations comparable with linear behavior, or creates solitary waves, or even leads to singular solutions. This dissertation studies the global behavior of finite energy solutions to the $d$-dimensional focusing NLS equation, $i partial _t u+Delta u+ |u|^{p-1}u=0, $ with initial data $u_0in H^1,; x in Rn$; the nonlinearity power $p$ and the dimension $d$ are chosen so that the scaling index $s=frac{d}{2}-frac{2}{p-1}$ is between 0 and 1, thus, the NLS is mass-supercritical $(s>0)$ and energy-subcritical $(s<1).$ For solutions with $ME[u_0]<1$ ($ME[u_0]$ stands for an invariant and conserved quantity in terms of the mass and energy of $u_0$), a sharp threshold for scattering and blowup is given. Namely, if the renormalized gradient $g_u$ of a solution $u$ to NLS is initially less than 1, i.e., $g_u(0)<1,$ then the solution exists globally in time and scatters in $H^1$ (approaches some linear Schr"odinger evolution as $ttopminfty$); if the renormalized gradient $g_u(0)>1,$ then the solution exhibits a blowup behavior, that is, either a finite time blowup occurs, or there is a divergence of $H^1$ norm in infinite time. This work generalizes the results for the 3d cubic NLS obtained in a series of papers by Holmer-Roudenko and Duyckaerts-Holmer-Roudenko with the key ingredients, the concentration compactness and localized variance, developed in the context of the energy-critical NLS and Nonlinear Wave equations by Kenig and Merle. One of the difficulties is fractional powers of nonlinearities which are overcome by considering Besov-Strichartz estimates and various fractional differentiation rules.
ContributorsGuevara, Cristi Darley (Author) / Roudenko, Svetlana (Thesis advisor) / Castillo_Chavez, Carlos (Committee member) / Jones, Donald (Committee member) / Mahalov, Alex (Committee member) / Suslov, Sergei (Committee member) / Arizona State University (Publisher)
Created2011
Description
Hispanic youth have the highest risk for obesity, making this population a key priority for early childhood interventions to prevent the development of adult obesity and its consequences. Involving parents in these interventions is essential to support positive long-term physical activity and nutrition habits. Interventions in the past have engaged parents by providing information about nutrition and fruit and vegetable intake through written materials or text such as newsletters and text messages. The Sustainability via Active Garden Education (SAGE) intervention used gardening and interactive activities to teach preschool children ages 3-5 about healthy eating and physical activity. It aimed to increase physical activity and fruit and vegetable intake in preschool children as well as improve related parenting practices. The intervention utilized newsletters to engage parents by promoting opportunities to increase physical activity and fruit and vegetable intake for their children at home. The newsletters also encouraged parents to discuss what was learned during the SAGE lessons with their children. The purpose of this paper is to describe the content of the newsletters and determine the parent perception of the newsletters through parent survey responses. This can help inform future childhood obesity interventions and parent engagement.
ContributorsVi, Vinny (Author) / Lee, Rebecca (Thesis director) / Martinelli, Sarah (Committee member) / Edson College of Nursing and Health Innovation (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
This thesis outlines the development of a vector retrieval technique, based on data assimilation, for a coherent Doppler LIDAR (Light Detection and Ranging). A detailed analysis of the Optimal Interpolation (OI) technique for vector retrieval is presented. Through several modifications to the OI technique, it is shown that the modified technique results in significant improvement in velocity retrieval accuracy. These modifications include changes to innovation covariance portioning, covariance binning, and analysis increment calculation. It is observed that the modified technique is able to make retrievals with better accuracy, preserves local information better, and compares well with tower measurements. In order to study the error of representativeness and vector retrieval error, a lidar simulator was constructed. Using the lidar simulator a thorough sensitivity analysis of the lidar measurement process and vector retrieval is carried out. The error of representativeness as a function of scales of motion and sensitivity of vector retrieval to look angle is quantified. Using the modified OI technique, study of nocturnal flow in Owens' Valley, CA was carried out to identify and understand uncharacteristic events on the night of March 27th 2006. Observations from 1030 UTC to 1230 UTC (0230 hr local time to 0430 hr local time) on March 27 2006 are presented. Lidar observations show complex and uncharacteristic flows such as sudden bursts of westerly cross-valley wind mixing with the dominant up-valley wind. Model results from Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®) and other in-situ instrumentations are used to corroborate and complement these observations. The modified OI technique is used to identify uncharacteristic and extreme flow events at a wind development site. Estimates of turbulence and shear from this technique are compared to tower measurements. A formulation for equivalent wind speed in the presence of variations in wind speed and direction, combined with shear is developed and used to determine wind energy content in presence of turbulence.
ContributorsChoukulkar, Aditya (Author) / Calhoun, Ronald (Thesis advisor) / Mahalov, Alex (Committee member) / Kostelich, Eric (Committee member) / Huang, Huei-Ping (Committee member) / Phelan, Patrick (Committee member) / Arizona State University (Publisher)
Created2013
Description
It is possible in a properly controlled environment, such as industrial metrology, to make significant headway into the non-industrial constraints on image-based position measurement using the techniques of image registration and achieve repeatable feature measurements on the order of 0.3% of a pixel, or about an order of magnitude improvement on conventional real-world performance. These measurements are then used as inputs for a model optimal, model agnostic, smoothing for calibration of a laser scribe and online tracking of velocimeter using video input. Using appropriate smooth interpolation to increase effective sample density can reduce uncertainty and improve estimates. Use of the proper negative offset of the template function has the result of creating a convolution with higher local curvature than either template of target function which allows improved center-finding. Using the Akaike Information Criterion with a smoothing spline function it is possible to perform a model-optimal smooth on scalar measurements without knowing the underlying model and to determine the function describing the uncertainty in that optimal smooth. An example of empiric derivation of the parameters for a rudimentary Kalman Filter from this is then provided, and tested. Using the techniques of Exploratory Data Analysis and the "Formulize" genetic algorithm tool to convert the spline models into more accessible analytic forms resulted in stable, properly generalized, KF with performance and simplicity that exceeds "textbook" implementations thereof. Validation of the measurement includes that, in analytic case, it led to arbitrary precision in measurement of feature; in reasonable test case using the methods proposed, a reasonable and consistent maximum error of around 0.3% the length of a pixel was achieved and in practice using pixels that were 700nm in size feature position was located to within ± 2 nm. Robust applicability is demonstrated by the measurement of indicator position for a King model 2-32-G-042 rotameter.
ContributorsMunroe, Michael R (Author) / Phelan, Patrick (Thesis advisor) / Kostelich, Eric (Committee member) / Mahalov, Alex (Committee member) / Arizona State University (Publisher)
Created2012
Description
Acne scarring can negatively affect individuals’ lives long after active acne has resolved. An online survey analyzed the public’s acne history and knowledge of acne scar prevention to determine acne scar risk factors and public awareness of acne scar prevention and yielded 209 complete data sets. Though types of acne scars vary in how long they persist on one’s skin, all forms were found to be equal in the negative psychological impact they inflict. Acne severity, acne duration, individual age, and family history of scarring were found to have associations with atrophic scarring The findings suggest a need for implementing a structured and standardized way for communicating acne scar prevention information to the general public. Practical implications of these findings are discussed further for increasing public awareness of acne scarring and prevention knowledge.
ContributorsJone, Jillian Louise (Author) / Lee, Rebecca (Thesis director) / Redden, Tamara (Committee member) / Edson College of Nursing and Health Innovation (Contributor) / College of Health Solutions (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Cultural Perceptions of Leisure and Well-being in Rock Climbing Communities of Peru and Arizona, USA
Description
In December of 2015, I made my way to rural Peru for a few weeks, my first visit to South America. While I was there, I observed a devotion to family and leisure activity, topics that were not heavily prioritized in my experience in Arizona. Upon my return, I became more involved in leisure activities, particularly running, hiking, yoga, and climbing. These involvements noticeably benefitted my health and well-being. The way the Peruvians I met prioritized these subjects fascinated me, and I wanted to study this difference between Arizona and Peru. In July of 2017, I returned to Peru for a semester abroad with my bags packed and the following research questions: 1) Are differences in motivation for rock climbing between Arizona and Peruvian climbers associated with cultural values? 2) Do leisure activities and the amount of time spent on them have an effect on quality of life? 3) Does the degree of climbing specialization impact perceptions of well-being? 4) What characteristics impact perceptions of quality of life among climbers? Are these characteristics affected by country of origin? My prediction was that Peruvians had higher quality of life due to their emphasis on leisure. Through this study, I learned that this conclusion was not as simple as I anticipated.
ContributorsMatta, Samantha Tania (Author) / Hultsman, Wendy (Thesis director) / Sampson, David (Committee member) / Lee, Rebecca (Committee member) / College of Integrative Sciences and Arts (Contributor) / School of Molecular Sciences (Contributor) / Division of Teacher Preparation (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
This is the study of Acute Impact of Ujjayi Yogic Pranayama vs Aerobic Exercise on Cognitive Performance and Short Term Memory. The purpose of this research was to compare two forms of exercise and their effects on someone's cognitive performance and short term memory. The research was performed in an acute setting were both exercises was conducted in under 15 minutes of active participation. The research question was; will aerobic exercise or the Pranayama breathing exercise provide better results and demonstrate a more effective way to increase the cognitive performance and short term memory for a college student aged 18-30. This was accomplished by using an aerobic exercise on an elliptical machine and then participating in the breathing exercise for 10 minutes in both scenarios. This study had two scenarios. Each scenario had a preliminary cognitive performance and short-term memory, post-Ujjayi exercise had a cognitive performance and short-term memory and a post-aerobic exercise had a cognitive performance and short-term memory. There was an hour break between Ujjayi exercise and aerobic exercise in both scenarios to prevent any type of bias. Scenario 1 had these three settings but the students were not given a breakfast supplement. In Scenario 2 the students were given a break supplement and followed the same procedures as scenario 1. There were 25 students for scenario 1 and 25 students for scenario 2. The students were allowed to participate in scenario 1 and 2 but it had to be a week after their first participation. All participants were originally signed up for scenario 1 and they could come back to perform scenario 2 a week later. The first scenario was completing the tests in the absence of food. Scenario two was completing the tests after having been given a Clif Bar to consume. The results of both of these scenarios showed that for cognitive performance and short term memory aerobic exercise had a beneficial impact on their performance. However, students who had a breakfast performed better on the preliminary tests and scored better after the yogic Ujjayi Pranayama exercise on their cognitive performance and short term memory tests. There was also a negligible difference between the test results after the preliminary tests and yogic Ujjayi Pranayama. However, in scenario one the overall tests scores for preliminary and yogic Ujjayi Pranayama were less than those in scenario two. Students who recorded that they were more actively engaging in regular physical exercise 3-7 days a week also did worse in scenario 1, but when presented with scenario 2 they scored equal with those who did not perform regular exercise. The overall purpose for this research was to find out how to increase cognitive performance and short term memory ability in college age students 18-30 in a short amount of time. The results of this study will be impactful for the future studies that will be focused on when comparing aerobic exercise and yogic pranayama.
ContributorsKopecky, Zachary (Co-author) / Enright, Roan (Co-author) / McILwraith, Heide (Thesis director) / Lee, Rebecca (Committee member) / College of Integrative Sciences and Arts (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
This study confirms that there is stigma attached to how Somali-Americans perceive mental and emotional impairments compared to the perception of physical disabilities and impairments. More Somali-Americans are willing to seek help regarding their mental and physical health which is a positive step in improving the perceptions of Somali-Americans towards mental or emotional impairments and physical disabilities. Findings can contribute to the knowledge of health care professionals (i.e. nurses) in caring for patients identifying as Somali to promote culturally competent care.
ContributorsAden, Amina (Author) / Hosley, Brenda (Thesis director) / Lee, Rebecca (Committee member) / Lyles, Annmarie (Committee member) / Arizona State University. College of Nursing & Healthcare Innovation (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
A numerical study of wave-induced momentum transport across the tropopause in the presence of a stably stratified thin inversion layer is presented and discussed. This layer consists of a sharp increase in static stability within the tropopause. The wave propagation is modeled by numerically solving the Taylor-Goldstein equation, which governs the dynamics of internal waves in stably stratified shear flows. The waves are forced by a flow over a bell shaped mountain placed at the lower boundary of the domain. A perfectly radiating condition based on the group velocity of mountain waves is imposed at the top to avoid artificial wave reflection. A validation for the numerical method through comparisons with the corresponding analytical solutions will be provided. Then, the method is applied to more realistic profiles of the stability to study the impact of these profiles on wave propagation through the tropopause.
ContributorsCole, Alexandra Shea (Author) / Moustaoui, Mohamed (Thesis director) / Kostelich, Eric (Committee member) / Mahalov, Alex (Committee member) / School of International Letters and Cultures (Contributor) / School of Geographical Sciences and Urban Planning (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Research supports that music therapy can be used in multiple aspects of care for patients living within different environments. There is a gap in the literature when it comes to the impact of music sessions for older adults who do not have a diagnosed disease, therefore this study analyzes this population specifically. This study examines music therapy and its effects on anxiety and depression in adults aged 65 or older living in independent living homes. The adults participated in a mixed-methods study over the span of one month examining music as an intervention to decrease anxiety and depression. Each subject consented into the study, completed a demographic survey, answered open-ended questions regarding their experience with anxiety/sadness and ways to cope, as well as Profile of Moods Scale (POMS) during the first session. On the last week of the study, the participants were asked to fill out the same POMS scale to evaluate whether music influenced anxiety and depression. There was limited evidence found in this study to support the use of music therapy as an intervention to decrease anxiety and depression in adults over the age of 65.
ContributorsWolfus, Sarah Ilyssa (Author) / Lee, Rebecca (Thesis director) / Larkey, Linda (Committee member) / Arizona State University. College of Nursing & Healthcare Innovation (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05