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Photoexcitation and nonradiative relaxation in molecular systems: methodology, optical properties, and dynamics
No full text2019-02-21Computational modeling of photoexcited molecules provides a fundamental understanding of processes such as photodissociation, photoisomerization, and charge and energy transfer. To model these processes requires the development and utilization of theories in electronic structure and quantum dynamics. One of the most popular methods for modeling nuclear-electronic dynamics is surface hopping. In this dissertation, surface hopping will be presented in different spotlights. We describe the method along with its advantages, disadvantages, and the contributions we make to improve its reliability and applicability. These efforts are carried out with simple Hamiltonians that can be solved exactly, thus allowing for an assessment of this approximate method. While this is an important step in methods development, modeling the large number of degrees of freedom in realistic systems requires efficient software. We present a software that combines surface hopping with numerically efficient methods for calculating ground and excited state potential energy surfaces—a necessary feature for modeling systems made up of hundreds of atoms and processes lasting up to tens of picoseconds. As part of our contribution to this software, we implement and benchmark an implicit solvent model, including investigating its effects during the nonradiative relaxation in organic conjugated molecules. The ultimate goal is to improve and assess the accuracy of these theoretical tools with the intention of progressing real-life applications. Having said that, a portion of this dissertation explores the early stages of an application called photoactive energetic materials—a field seeking to discover mechanically and electrically insensitive materials that undergo detonation through optical initiation. Our work investigates the optical properties in energetic materials, identified through an experimental collaboration, and is aimed at unveiling design principles to enhance control over the initiation threshold. In summary, we provide a comprehensive view of atomistic simulations of photoexcited molecules, starting from the methods used to describe electronic transitions through a manifold of excited states as a result of photoexcitation, followed by the development of software used to model realistic systems, and finally the use of such tools to discover how desired photophysical properties can be attained for practical use. The final part of this dissertation explores a new and booming field of research in the computational sciences called machine learning. Machine learning is a clever way of attaining calculations of ab initio accuracy at a tiny fraction of the computational cost through the use of statistically trained models. We present an application using machine learning and discuss how the use of this method can change the scope of nonadiabatic molecular dynamics
Integration of behavioral health outcomes into electric health records to improve patient care
No full text2019-02-27This study describes the use of innovative technology to develop behavioral health outcome measures and integrate them into electronic health records (EHR) across a large healthcare organization (HMO) Behavioral Health departments in Southern California. An evidence-based implementation model, the Quality Implementation Framework consisting of four phases (i.e., the host setting consideration, implementation structure, support strategies and improving application) are used along with the Reach, Effectiveness, Adoption, Implementation, and Maintenance approach as a means of implementation of the innovation. The study demonstrates how a behavioral health organization can promote capacity to implement a new innovation while accelerating impact in the provision of behavioral health services. As more health care organizations consider their options in improving patient care through the development of technological behavioral health outcome measures, the promotion of this project can serve as a blue-print for other large health and human service organizations to accelerate impact in client/patient outcomes while harnessing the power of innovation
Role and influence of globalization, multinational corporations, and foreign direct investment on educational policy and science, technology, engineering, mathematics, and inquiry-based instructional practices in schools such as Central Catholic Secondary School of Ireland
No full text2019-04-25Today, countries must deliberately develop educational systems and economic policies that can prepare themselves to be competitive around the globe. As such, Ireland has evolved into a nation that endeavors to create internal structures necessary to influence multinational corporations (MNCs) to place headquarters in the country. These efforts are anchored in proactive economic policies aimed at creating favorable business environments for MNCs to conduct business and educational policies that place emphasis on creating science, technology, engineering, and mathematics (STEM) learning environments necessary to develop the requisite knowledge-based workforce that Ireland and their MNC partners need. ❧ However, students in Ireland are currently in a paradox regarding academic expectations being placed upon them. While the nation understands the critical importance of developing an innovative knowledge-based workforce with STEM skillsets, it also immerses students in a mandated structural environment that requires them to take a high stakes summative assessment called the Leaving Certificate Exam (LCE), which is central to a student's academic experiences from the perspective of determining which students are placed in universities and colleges. Stress that students and teachers feel as a result of preparing for this test may reduce their willingness to explore subject matter and content for growth experiences because they cannot risk the chance of not sufficiently preparing themselves for core subjects that are measured on the LCE. ❧ This study examined the influence of globalization and educational policy on the development of 21st-century skills in Irish students through the implementation of STEM education, instructional practices, and student participation in the SciFest science competition. The principal findings of this predominantly qualitative study indicated that STEM-related content, 21st-century skills, and school leadership are important in Irish schools to ensure that students have access to real-world, inquiry based learning experiences necessary to prepare them to compete in a globalized economy. The findings indicated that female students' participation in science fair competitions such as SciFest was beneficial to their self-efficacy in relation to their confidence and authentic interest in enrolling into STEM-related coursework
The dark matter distributions in low-mass disk galaxies
No full text2019-04-24The ΛCDM model has been successful at describing the structure and evolution of our universe, however there are still small discrepancies in our understanding. Dark matter-only simulations predict that dark matter halos have steep, cuspy inner density profiles, while observations of dwarf galaxies find a range of inner slopes that are often much shallower. It is still not well established whether this discrepancy can be explained by baryonic feedback or if it may require modified dark matter models. To better understand the diversity of dark matter profiles in dwarf galaxies, we undertook a survey of 26 low-mass galaxies (log M*/M☉ = 8.4 − 9.8, vₘₐₓ = 50 − 140 km s⁻¹) within 30 Mpc. We obtained high-resolution integral field Hα observations using the Palomar Cosmic Web Imager, making this work among the largest integral field spectroscopic surveys of its type. In this work, we derive Hα velocity fields for the full sample with a typical spatial resolution of ∼160 pc. We present a method for improving the velocity precision obtained from image slicing spectrographs using narrowband Hα images. For 11 galaxies, we compare the Hα velocity fields to CO kinematics measured using CARMA, finding the maps to be in good agreement. The standard deviation of the difference is typically ∼7 km s⁻¹, comparable to the level of turbulence in the interstellar medium, showing that the two tracers have substantially the same bulk kinematics. We extract rotation curves from the Hα velocity fields and verify their robustness to several choices in the analysis, which are then used to construct mass models. We model the total mass distribution as the sum of a generalized Navarro-Frenk-White (NFW) dark matter halo and the stellar and gaseous components, modeled from optical and infrared photometry and the CO observations from CARMA respectively. Our analysis of the slope of the dark matter density profile focuses on the inner 300-800 pc, chosen based on the resolution of our data and the region that can be resolved by modern hydrodynamical simulations. The inner slope measured using ionized and molecular gas tracers is remarkably consistent, and it is additionally robust to the choice of stellar mass-to-light ratio. We find a range of dark matter profiles, including both cored and cuspy slopes, with an average slope of ρ_DM ∼ r^0.75±0.07, shallower than expect for the NFW profile. We find dark matter profiles that are typically steeper than those observed for lower mass galaxies with M* ∼ 10^7.5 M☉. Simulations that reproduce the observed shallow slopes in these lower mass galaxies also produce slopes that are too shallow for galaxies in our mass range. We therefore conclude that supernova feedback models do not yet provide a fully satisfactory explanation for the observed trend in dark matter slopes. Future work will explore whether mass models constructed with a self-interacting dark matter model are able to adequately describe our sample
Investigating voltage activated potassium and proton channels
No full text2019-04-25Simulating the nature of voltage activated systems is a problem of major current interest, covering the action of voltage gated ion channels to energy storage batteries. However, fully microscopic converging molecular simulations of external voltage effects present a major challenge and macroscopic models are associated with major uncertainties about the dielectric treatment and the underlying physical basis. Recently, we developed a coarse-grained (CG) model that represents explicit the electrodes, the electrolytes and the membrane / protein system. The CG model provides a semi-macroscopic way for capturing the microscopic physics of voltage activated systems. Our method was originally validated by reproducing macroscopic and analytical results for key test cases and then used in modeling voltage activated ion channels and related problems. In this work, we further establish the reliability of the CG voltage model by comparing it to the results of Monte Carlo (MC) simulations with a microscopic electrolyte model. The comparison explores different aspects of membrane, electrolytes, electrodes systems ranging from the Gouy-Chapman model to the determination of the electrolyte charge distribution in the solution between two electrodes (without and with separating membrane), as well as the evaluation of gating charges. In addition to this work, we explored our voltage-activated ion channel study to proton transport proteins, Hv1, found in diverse cells in humans and other organisms. Our study focuses on evaluating the free energy of transporting a proton through the channel, as well as the effect of the proton transfer through D112, in both the closed and open channel conformations. It is found that D112 allows a transported proton to bypass the electrostatic barrier of the open channel, while not being able to help in passing the barrier in the closed form. This reflects the change in position of the gating-related arginine residues relative to D112, upon voltage-activation. Significantly, the effect of D112 accounts for the observed trend in selectivity by overcoming the electrostatic barrier at its highest point. Thus, the calculations provide a structure/function correlation for the Hv1 system. The present work also clarifies that the action of Hv1 is not controlled by a Grotthuss mechanism but, as is always the case, by the protein electrostatic potential at the rate limiting barriers
The future of games and health: towards responsible interaction design
No full text2019-04-30The role of technology in our lives has outpaced our understanding of its impact. Digital artifacts are irreplaceable elements of the lives we live. Post-cognitive thought has embraced the possibility that these artifacts should be granted a more important status than mere property. Instead, they might be considered extensions, or even expressions, of agency. Game designers are in the business of creating interactive systems that have significant degrees of meaning to us, so they are in a unique position to command a shift towards responsible interaction design. In this piece, I try to chart out how the sensibilities of game designers can assist in creating digital artifacts that maintain the dignity of users. The solution I offer is to take insights from the field of narrative medicine and use phenomenological reflection as a legitimate source of qualitative data. These reflections can help disclose the relationships we have to technology and reorient design frameworks away from an overly formal approach
Effects of teacher autonomy support with structure on marginalized urban student math achievement
No full text2019-04-29Self-determination theory asserts that, in order to experience well-being, all human beings must possess three basic psychological needs: relatedness, perceived competence, and autonomy (Ryan & Deci, 2000). In school contexts, autonomous students are self-managed and intrapersonally motivated to achieve (Ryan & Deci, 2000). The study purpose was to demonstrate that teacher autonomy support with structure could increase math achievement in urban marginalized students served in a public elementary school. The study school serves students who are 93 percent low-SES, 54 percent English language learners, 92 percent Hispanic immigrants, 5 percent African American, and 1.5 percent white (CALP ADS, 2018). The study implemented a Teacher Autonomy Support with structure intervention across all academic content areas in grades two through four. It was hypothesized that marginalized student exposure to a 12-week teacher autonomy support with structure classroom intervention would lead to increased student academic autonomy, motivation, and achievement compared with students in control classrooms. Measurement instruments of established validity were administered. Outcome measures were student: (a) math performance, (b) academic motivation, (c) academic autonomy, and (d) learning climate. Data were collected prior to and immediately following the 12-week classroom intervention. Independent t-test analyses examining the relative effectiveness of the intervention on student dependent variables revealed no statistically significant pretest/posttest differences or by experimental condition. Bivariate correlational analyses found statistically significant correlations between student academic motivation and perceived learning climate and between student autonomy and motivation
Affluent teens and school stress: an evaluation study
No full text2019-04-30Stress in adolescence is not a new or uncommon concept. However, for high-achieving, affluent teens, the anxieties and pressures associated with high school academic success and being accepted to a highly selective college can lead to unmanageable levels of stress. This study sought to understand the knowledge and motivation of faculty members at an independent high school in southern California as well as organizational influences within the school related to reducing school-related stress. Clark and Estes’ (2008) gap analysis served as the general conceptual and methodological framework for the study. A mixed methods explanatory sequential study was conducted using surveys, interviews, and document analysis. The findings of the study revealed that there is a gap in the faculty’s knowledge and motivation related to reducing student stress and there are organizational influences inhibiting the school’s ability to be successful in their goal if reducing student school-related stress. The study concludes with recommendations for context-specific solutions grounded in literature and the New World Kirkpatrick Model (Kirkpatrick & Kirkpatrick, 2016), as well as an integrated implementation and evaluation plan, strengths and weaknesses of the study, limitations and delimitations, and recommendations for future study
Transposable element suppression in basal-like breast cancer
No full text2019-05-08The Cancer Genome Atlas (TCGA) described many large-scale transcriptomes in cancer, but did not examine transposable elements. In order to further understand transposable elements in breast-cancer, we analyzed the transcriptome of 484 subjects using TCGA, and compared the repeatomes from each subtype classification. Despite Basal-like hypo-methylation, transposable elements had suppressed expression, whereas Luminal types showed increased levels
The impact of teacher perceptions about underrepresented students
No full text2019-03-15Teachers have the ability to greatly impact student learning outcomes. However, teacher perceptions about underrepresented students have influenced the expectations that teachers have about students’ academic ability, which can jeopardize their ability to succeed in and out of the classroom. The researcher conducted an evaluation study that analyzed the knowledge, motivation, and organizational influences that affect teachers’ ability to gain an understanding of implicit bias, equity-based classrooms, and how their relationships and academics can be impacted by the assumptions that they make about underrepresented (Black and Latinx) students. Through a qualitative study, data was collected and analyzed that validated the influences that impact teachers’ perceptions and implicit biases as they relate to teaching Black and Latinx students. The influences involved educating teachers about the impact of their perceptions and assisting them in recognizing their own implicit biases, along with providing professional development on the importance of building relationships with their students, and additional time to reflect on their practices in a collaborative school environment. Finally, the New World Kirkpatrick Model was implemented as a means to evaluate the recommendations related to the improvement program to assist teachers in understanding the impact of their perceptions about underrepresented students