Matching Items (72)
Description
PURPOSE: Lean hypertension (HTN) is characterized by a mechanistically different HTN when compared to obese HTN. The purpose of this study is to assess whether body phenotype influences blood pressure (BP) responses following both acute and chronic exercise. METHODS: Obese (body mass index (BMI) > 30 kg/m2) and lean (BMI < 25 kg/m2) men with pre-hypertension (PHTN) (systolic BP (SBP) 120 - 139 or diastolic BP (DBP) 80 - 89 mm Hg) were asked to participate in a two-phase trial. Phase 1 assessed differences in post-exercise hypotension between groups in response to an acute exercise bout. Phase 2 consisted of a two-week aerobic exercise intervention at 65-70% of heart rate (HR) max on a cycle ergometer. Primary outcome measures were: brachial BP, central (aortic) BP, cardiac output (CO), and systemic vascular resistance (SVR) measured acutely after one exercise session and following two weeks of training. RESULTS: There were no differences between groups for baseline resting brachial BP, central BP, age, or VO2 peak (all P > 0.05). At rest, obese PHTN had greater CO compared to lean PHTN (6.3 ± 1 vs 4.7 ± 1 L/min-1, P = 0.005) and decreased SVR compared to lean PHTN (1218 ± 263 vs 1606 ± 444 Dyn.s/cm5, P = 0.003). Average 60-minute post-exercise brachial and central SBP reduced by 3 mm Hg in Lean PHTN in response to acute exercise (P < 0.005), while significantly increasing 4 mm Hg for brachial and 3 mm Hg for central SBP (P < 0.05). SVR had a significantly greater reduction following acute exercise in lean PHTN (-223 Dyn·s/cm5) compared to obese PHTN (-75 Dyn·s/cm5, P < 0.001). In lean subjects chronic training reduced brachial BP by 4 mm Hg and central BP by 3 mm Hg but training had no effect on the BP’s in obese subjects. Resting BP reduction in response to training was accompanied by reductions in SVR within lean (-169 Dyn·s/cm5, P < 0.001), while obese experienced increased SVR following training (47 Dyn·s/cm5, P < 0.001). CONCLUSION: Hemodynamic response to both acute and chronic exercise training differ between obese and lean individuals.
ContributorsZeigler, Zachary (Author) / Swan, Pamela (Thesis advisor) / Gaesser, Glenn (Committee member) / Buman, Matthew (Committee member) / Angadi, Siddhartha (Committee member) / Farouk, Mookadam (Committee member) / Arizona State University (Publisher)
Created2016
Description
Moore's law has been the most important driving force for the tremendous progress of semiconductor industry. With time the transistors which form the fundamental building block of any integrated circuit have been shrinking in size leading to smaller and faster electronic devices.As the devices scale down thermal effects and the short channel effects become the important deciding factors in determining transistor architecture.SOI (Silicon on Insulator) devices have been excellent alternative to planar MOSFET for ultimate CMOS scaling since they mitigate short channel effects. Hence as a part of thesis we tried to study the benefits of the SOI technology especially for lower technology nodes when the channel thickness reduces down to sub 10nm regime. This work tries to explore the effects of structural confinement due to reduced channel thickness on the electrostatic behavior of DG SOI MOSFET. DG SOI MOSFET form the Qfinfet which is an alternative to existing Finfet structure. Qfinfet was proposed and patented by the Finscale Inc for sub 10nm technology nodes.
As part of MS Thesis we developed electrostatic simulator for DG SOI devices by implementing the self consistent full band Schrodinger Poisson solver. We used the Empirical Pseudopotential method in conjunction with supercell approach to solve the Schrodinger Equation. EPM was chosen because it has few empirical parameters which give us good accuracy for experimental results. Also EPM is computationally less expensive as compared to the atomistic methods like DFT(Density functional theory) and NEGF (Non-equilibrium Green's function). In our workwe considered two crystallographic orientations of Si,namely [100] and [110].
As part of MS Thesis we developed electrostatic simulator for DG SOI devices by implementing the self consistent full band Schrodinger Poisson solver. We used the Empirical Pseudopotential method in conjunction with supercell approach to solve the Schrodinger Equation. EPM was chosen because it has few empirical parameters which give us good accuracy for experimental results. Also EPM is computationally less expensive as compared to the atomistic methods like DFT(Density functional theory) and NEGF (Non-equilibrium Green's function). In our workwe considered two crystallographic orientations of Si,namely [100] and [110].
ContributorsLaturia, Akash (Author) / Vasileska, Dragica (Thesis advisor) / Ferry, David (Committee member) / Goodnick, Stephen (Committee member) / Arizona State University (Publisher)
Created2016
Description
Thermal effects in nano-scaled devices were reviewed and modeling methodologies to deal with this issue were discussed. The phonon energy balance equations model, being one of the important previous works regarding the modeling of heating effects in nano-scale devices, was derived. Then, detailed description was given on the Monte Carlo (MC) solution of the phonon Boltzmann Transport Equation. The phonon MC solver was developed next as part of this thesis. Simulation results of the thermal conductivity in bulk Si show good agreement with theoretical/experimental values from literature.
ContributorsYoo, Seung Kyung (Author) / Vasileska, Dragica (Thesis advisor) / Ferry, David (Committee member) / Goodnick, Stephen (Committee member) / Arizona State University (Publisher)
Created2015
Description
The purpose of this study was to examine whether a workplace environmental intervention would improve work-related outcomes including productivity, presenteeism and cognition. The secondary aim was to investigate whether work-related outcomes are correlated to observed changes in sitting time, physical activity, and sleep. The study was introduced as part of a naturalistic environmental change in which university staff and faculty were relocated into a new building (n=23). The comparison group consisted of university staff within the same college with no imminent plans to re-locate during the intervention period; there were no environmental changes to this workplace (n =10). Participants wore two behavioral monitoring devices, activPAL and GeneActiv, for 7 consecutive days at two time points (immediately prior and 16 weeks following the office relocation). Measures of productivity and presenteeism were obtained via four validated questionnaires and participants underwent cognitive performance testing. Baseline adjusted analysis of covariance statistical analyses were used to examine differences between groups in work-related outcomes. A residual analysis in regression was conducted to determine the differences between observed changes in sitting time, physical activity and sleep, and work-related outcomes. The results showed that a reduction in work hour sitting time was not detrimental to work related outcomes. Decreased sitting was observed to potentially improve presenteeism and absenteeism. Additionally, physical activity was shown to modestly improve productivity, presenteeism and absenteeism. Poor sleep patterns were associated with work impairment and increased absenteeism.
ContributorsPark, Anna (Author) / Buman, Matthew (Thesis advisor) / Crespo, Noe (Committee member) / Chisum, Jack (Committee member) / Arizona State University (Publisher)
Created2014
Description
From 2D planar MOSFET to 3D FinFET, the geometry of semiconductor devices is getting more and more complex. Correspondingly, the number of mesh grid points increases largely to maintain the accuracy of carrier transport and heat transfer simulations. By substituting the conventional uniform mesh with non-uniform mesh, one can reduce the number of grid points. However, the problem of how to solve governing equations on non-uniform mesh is then imposed to the numerical solver. Moreover, if a device simulator is integrated into a multi-scale simulator, the problem size will be further increased. Consequently, there exist two challenges for the current numerical solver. One is to increase the functionality to accommodate non-uniform mesh. The other is to solve governing physical equations fast and accurately on a large number of mesh grid points.
This research rst discusses a 2D planar MOSFET simulator and its numerical solver, pointing out its performance limit. By analyzing the algorithm complexity, Multigrid method is proposed to replace conventional Successive-Over-Relaxation method in a numerical solver. A variety of Multigrid methods (standard Multigrid, Algebraic Multigrid, Full Approximation Scheme, and Full Multigrid) are discussed and implemented. Their properties are examined through a set of numerical experiments. Finally, Algebraic Multigrid, Full Approximation Scheme and Full Multigrid are integrated into one advanced numerical solver based on the exact requirements of a semiconductor device simulator. A 2D MOSFET device is used to benchmark the performance, showing that the advanced Multigrid method has higher speed, accuracy and robustness.
This research rst discusses a 2D planar MOSFET simulator and its numerical solver, pointing out its performance limit. By analyzing the algorithm complexity, Multigrid method is proposed to replace conventional Successive-Over-Relaxation method in a numerical solver. A variety of Multigrid methods (standard Multigrid, Algebraic Multigrid, Full Approximation Scheme, and Full Multigrid) are discussed and implemented. Their properties are examined through a set of numerical experiments. Finally, Algebraic Multigrid, Full Approximation Scheme and Full Multigrid are integrated into one advanced numerical solver based on the exact requirements of a semiconductor device simulator. A 2D MOSFET device is used to benchmark the performance, showing that the advanced Multigrid method has higher speed, accuracy and robustness.
ContributorsGuo, Xinchen (Author) / Vasileska, Dragica (Thesis advisor) / Goodnick, Stephen (Committee member) / Ferry, David (Committee member) / Arizona State University (Publisher)
Created2015
Description
Background and purpose: Regular physical activity (PA) provides benefits for cognitive health and helps to improve or maintain quality of life among older adults. Objective PA measures have been increasingly used to overcome limitations of self-report measures. The purpose of this study was to investigate the association of objectively measured PA and sedentary time with cognitive function among older adults.
Methods: Participants were recruited from the parent REasons for Geographic and Racial Differences in Stroke (REGARDS) Study. ActicalTM accelerometers provided estimates of PA variables, including moderate-to-vigorous PA (MVPA), high light PA (HLPA), low light PA (LLPA) and sedentary time, for 4-7 consecutive days. Prevalence and incidence of cognitive impairment were defined by the Six-Item Screener. Letter fluency, animal fluency, word list learning and Montreal Cognitive Assessment (orientation and recall) were conducted to assess executive function and memory.
Results: Of the 7,339 participants who provided accelerometer wear data > 4 days (70.1 ± 8.6 yr, 54.2% women, 31.7% African American), 320 participants exhibited impaired cognition. In cross-sectional analysis, participants in the highest MVPA% quartile had 39% lower odds of cognitive impairment than those in the lowest quartile (OR: 0.61, 95% C.I.: 0.39-0.95) after full adjustment. Further analysis shows most quartiles of MVPA% and HLPA% were significantly associated with executive function and memory (P<0.01). During 2.7 ± 0.5 years of follow-up, 3,385 participants were included in the longitudinal analysis, with 157 incident cases of cognitive impairment. After adjustments, participants in the highest MVPA% quartile had 51% lower hazards of cognitive impairment (HR: 0.49, 95% C.I.: 0.28-0.86). Additionally, MVPA% was inversely associated with change in memory z-scores (P<0.01), while the highest quartile of HLPA% was inversely associated with change in executive function and memory z-scores (P<0.01).
Conclusion: Higher levels of objectively measured MVPA% were independently associated with lower prevalence and incidence of cognitive impairment, and better memory and executive function in older adults. Higher levels of HLPA% were also independently associated with better memory and executive function. The amount of MVPA associated with lower risk of cognitive impairment (259 min/week) is >70% higher than the minimal amount of MVPA recommended by PA guidelines.
Methods: Participants were recruited from the parent REasons for Geographic and Racial Differences in Stroke (REGARDS) Study. ActicalTM accelerometers provided estimates of PA variables, including moderate-to-vigorous PA (MVPA), high light PA (HLPA), low light PA (LLPA) and sedentary time, for 4-7 consecutive days. Prevalence and incidence of cognitive impairment were defined by the Six-Item Screener. Letter fluency, animal fluency, word list learning and Montreal Cognitive Assessment (orientation and recall) were conducted to assess executive function and memory.
Results: Of the 7,339 participants who provided accelerometer wear data > 4 days (70.1 ± 8.6 yr, 54.2% women, 31.7% African American), 320 participants exhibited impaired cognition. In cross-sectional analysis, participants in the highest MVPA% quartile had 39% lower odds of cognitive impairment than those in the lowest quartile (OR: 0.61, 95% C.I.: 0.39-0.95) after full adjustment. Further analysis shows most quartiles of MVPA% and HLPA% were significantly associated with executive function and memory (P<0.01). During 2.7 ± 0.5 years of follow-up, 3,385 participants were included in the longitudinal analysis, with 157 incident cases of cognitive impairment. After adjustments, participants in the highest MVPA% quartile had 51% lower hazards of cognitive impairment (HR: 0.49, 95% C.I.: 0.28-0.86). Additionally, MVPA% was inversely associated with change in memory z-scores (P<0.01), while the highest quartile of HLPA% was inversely associated with change in executive function and memory z-scores (P<0.01).
Conclusion: Higher levels of objectively measured MVPA% were independently associated with lower prevalence and incidence of cognitive impairment, and better memory and executive function in older adults. Higher levels of HLPA% were also independently associated with better memory and executive function. The amount of MVPA associated with lower risk of cognitive impairment (259 min/week) is >70% higher than the minimal amount of MVPA recommended by PA guidelines.
ContributorsZhu, Wenfei (Author) / Hooker, Steven P (Thesis advisor) / Wadley, Virginia (Committee member) / Ainsworth, Barbara (Committee member) / Der Ananian, Cheryl (Committee member) / Buman, Matthew (Committee member) / Arizona State University (Publisher)
Created2015
Description
Research provides increasing support of self-worth, non-physical motives, and body image for predicting physical activity in women. However, no empirical tests of these associations have been conducted. Ecological momentary assessment (EMA) has been recognized as useful for understanding correlates of physical activity. This study tested the feasibility of a novel EMA protocol and explored temporal relationships between daily self-worth and physical activity in middle-aged women. Women aged 35-64 years (N=63; M age=49.2±8.2 years) received text message prompts to an Internet-based mobile survey three times daily for 28 days. The survey assessed momentary activity, self-worth (knowledge, emotional, social, physical, general), and self-efficacy. Women concurrently wore an accelerometer on their non-dominant wrist. Feasibility was assessed via accelerometer wear-time estimates, survey completion rates, and participant feedback. Multilevel models examined the predictive influence of self-worth on daily activity counts. Self-efficacy was also tested due to known relationships with self-worth and physical activity in women. Wear time was high (952.92 ± 100.99 min per day), with only 141 observations lost to non-wear. However, 449 were lost to accelerometer malfunction. Women completed 80.8% of surveys. After excluding missing physical activity data, 67.5% of observations (N=3573) were analyzed. Although women thought the survey was easy to complete, perceptions of the accelerometer were mixed. Approximately 34% of the variance in daily counts was within individuals (ICC=0.66). Average self-efficacy (β=0.005, p=0.009), daily fluctuations in self-efficacy (β=0.001, p<0.001), and daily fluctuations in general self-worth (β=0.04, p=0.003) predicted daily activity. There were significant individual differences in relationships between daily fluctuations in emotional (β=0.006, p=0.02) and general self-worth (β=0.005, p=0.02) and daily activity. The use of text message prompts and an Internet-based mobile survey was feasible for conducting EMA in middle-aged women. Research identifying optimal methods of behavior monitoring in longitudinal studies is needed. Results provide support for small but significant associations among daily fluctuations in self-efficacy and general self-worth and daily activity in middle-aged women. The impact of emotional self-worth may differ across women. Further research examining the transient natures of self-efficacy and general self-worth, improving self-worth scales, and testing momentary strategies to increase women's self-worth and physical activity is warranted.
ContributorsEhlers, Diane K. (Author) / Huberty, Jennifer L (Thesis advisor) / Todd, Michael (Committee member) / Vreede, Gert-Jan de (Committee member) / Hooker, Steven (Committee member) / Buman, Matthew (Committee member) / Arizona State University (Publisher)
Created2014
Description
Understanding the interplay between the electrical and mechanical properties of single molecules is of fundamental importance for molecular electronics. The sensitivity of charge transport to mechanical fluctuations is a key problem in developing long lasting molecular devices. Furthermore, harnessing this response to mechanical perturbation, molecular devices which can be mechanically gated can be developed. This thesis demonstrates three examples of the unique electromechanical properties of single molecules.
First, the electromechanical properties of 1,4-benzenedithiol molecular junctions are investigate. Counterintuitively, the conductance of this molecule is found to increase by more than an order of magnitude when stretched. This conductance increase is found to be reversible when the molecular junction is compressed. The current-voltage, conductance-voltage and inelastic electron tunneling spectroscopy characteristics are used to attribute the conductance increase to a strain-induced shift in the frontier molecular orbital relative to the electrode Fermi level, leading to resonant enhancement in the conductance.
Next, the effect of stretching-induced structural changes on charge transport in DNA molecules is studied. The conductance of single DNA molecules with lengths varying from 6 to 26 base pairs is measured and found to follow a hopping transport mechanism. The conductance of DNA molecules is highly sensitive to mechanical stretching, showing an abrupt decrease in conductance at surprisingly short stretching distances, with weak dependence on DNA length. This abrupt conductance decrease is attributed to force-induced breaking of hydrogen bonds in the base pairs at the end of the DNA sequence.
Finally, the effect of small mechanical modulation of the base separation on DNA conductance is investigated. The sensitivity of conductance to mechanical modulation is studied for molecules of different sequence and length. Sequences with purine-purine stacking are found to be more responsive to modulation than purine-pyrimidine sequences. This sensitivity is attributed to the perturbation of &pi-&pi stacking interactions and resulting effects on the activation energy and electronic coupling for the end base pairs.
First, the electromechanical properties of 1,4-benzenedithiol molecular junctions are investigate. Counterintuitively, the conductance of this molecule is found to increase by more than an order of magnitude when stretched. This conductance increase is found to be reversible when the molecular junction is compressed. The current-voltage, conductance-voltage and inelastic electron tunneling spectroscopy characteristics are used to attribute the conductance increase to a strain-induced shift in the frontier molecular orbital relative to the electrode Fermi level, leading to resonant enhancement in the conductance.
Next, the effect of stretching-induced structural changes on charge transport in DNA molecules is studied. The conductance of single DNA molecules with lengths varying from 6 to 26 base pairs is measured and found to follow a hopping transport mechanism. The conductance of DNA molecules is highly sensitive to mechanical stretching, showing an abrupt decrease in conductance at surprisingly short stretching distances, with weak dependence on DNA length. This abrupt conductance decrease is attributed to force-induced breaking of hydrogen bonds in the base pairs at the end of the DNA sequence.
Finally, the effect of small mechanical modulation of the base separation on DNA conductance is investigated. The sensitivity of conductance to mechanical modulation is studied for molecules of different sequence and length. Sequences with purine-purine stacking are found to be more responsive to modulation than purine-pyrimidine sequences. This sensitivity is attributed to the perturbation of &pi-&pi stacking interactions and resulting effects on the activation energy and electronic coupling for the end base pairs.
ContributorsBruot, Christopher, 1986- (Author) / Tao, Nongjian (Thesis advisor) / Lindsay, Stuart (Committee member) / Mujica, Vladimiro (Committee member) / Ferry, David (Committee member) / Arizona State University (Publisher)
Created2014
Description
PURPOSE: This study aimed to identify whether increased Pokémon GO use resulted in increased daily steps, compared to days when an individual did not play. In addition, this study examined Pokémon GO as a use case for for the study of gamification, particularly whether traditionally identified game mechanics in gamification literature were successfully identified as elements players enjoy when playing Pokémon GO. METHODS: A mixed methods approach, with 17 participants taking part in a daily physical activity tracking study and 14 participants participating in semi-structured interviews. In the use study, participant steps were tracked for one week using the Apple Health Kit application, and participants were also asked to provide daily answers to a variety of questions assessing game preferences and daily use of Pokémon GO - using the application called PACO. The semi-structured interviews examined self-reported physical activity, and asked questions pertaining to use of Pokémon GO, such as motivation to play. RESULTS: Results assessed by t-test indicate a small but non-significant trend towards increased steps taken on days when a participant played vs. did not play (t(72)=- .56, p=.57, mplay=5,0153220, mnonplay=4,5152,959). This was confirmed with a mixed model test showing that when controlling for time and participant’s baseline level of steps, there was no significant effect on steps/day. Results from the daily surveys and also the semi-structured interviews, indicated that nostalgia (i.e., catching ones’ favorite childhood Pokémon), was a strong motivator for many to play the game, which was counter to theoretical expectations. In line with previous theory, results suggested that operant conditioning principles appeared to be at work in terms of fostering game play use. DISCUSSION: Results of this study, which was a primarily hypothesis generating endeavor, indicated possible trends toward increased steps on days when a person plays Pokémon G), but - with such a small sample, and short-term length of study - no firm conclusions can be drawn. Further, results indicate the particular value of nostalgia as a driver towards game play for Pokémon GO.
ContributorsBiel, Alexander M (Author) / Hekler, Eric (Thesis advisor) / Ainsworth, Barbara (Committee member) / Buman, Matthew (Committee member) / Arizona State University (Publisher)
Created2016
Description
Pitchers are a vital part of the game of baseball and may account for up to two-thirds of the variance in win percentage. As they rise through the ranks of competition, physical skill set becomes less of a factor when compared to mentality. Pitchers are the “first line of defense” for keeping opponents from having an opportunity to score, as well as for holding onto their own team’s lead. Baseball pitchers not only face pressure to perform, but also experience stress from factors such as low pay, adjusting to higher levels of competition, and internal team competition for a limited number of spots. Athletes are often resistant to seeking aid from sport psychologists and often turn to unfavorable means to cope (i.e. drugs/alcohol, excessive exercise) with stress instead. Meditation has been shown to have beneficial effects on psychological factors associated with performance including emotional regulation, anxiety, confidence, focus, and mindfulness. Mobile applications have become a popular means of delivering mindfulness. The purpose of this study was to determine the feasibility and preliminary effectiveness of delivering a mindful meditation intervention using a mobile meditation application to improve psychological factors associated with performance (i.e. emotional regulation, anxiety (somatic and cognitive), confidence, focus, mindfulness) to minor league baseball pitchers. Pitchers in instructional league (Phase one) and off season (Phase two) were asked to meditate daily for 10-minutes each day for three weeks (Phase one) and eight weeks (Phase two). Pitchers were asked to complete self-report questionnaires and satisfaction surveys at pre- and post-intervention. Pitchers in phase one reported enjoying meditation, had improvements in self-confidence and sport confidence, and reported moderate decreases in cognitive anxiety and concentration disruption. Pitchers in phase two also enjoyed meditating (94.7%) and had improvements in self-confidence and moderate decreases in somatic anxiety. Low adherence due to timing (off-season) of intervention may have been a contributing factor to fewer outcomes. Future research should explore the feasibility and effectiveness of implementing meditation during the baseball season.
ContributorsDowling, Tiffany (Author) / Huberty, Jennifer (Thesis advisor) / Ransdell, Lynda (Committee member) / Buman, Matthew (Committee member) / Michel, Jesse (Committee member) / Arizona State University (Publisher)
Created2018