CU Dissertations

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Monostatic all-fiber LADAR systems
Degree Awarded: Ph.D. Electrical Engineering and Computer Science. The Catholic University of America, Many applications require a LADAR system smaller in size and more power efficient than those using a polygon, galvo, or Risley-prism beam scanner. A fiber-coupled, monostatic LADAR system which transmits and receives through the same aperture has many advantages. These advantages include low cost, easy optical alignment, small size, and low weight. Optical alignment of the system is greatly simplified since there is no parallax between transmitted and received beam paths. The direction of the received light is inherently aligned with that of the transmitted beam. Multiple alignment steps of bulk optical components are one of the major reasons many laser systems are expensive. Using an all-fiber approach the optical alignment is simplified by automated splicing of the fibers. A 1-D LADAR consisting of a stationary monostatic rangefinder with real-time pulse processing is first demonstrated. Then a 3-D scanning LADAR is demonstrated. A vibrating fiber cantilever tip that is used to scan the laser beam is mounted on a resonant piezo-electric lead zirconium titanate (PZT) stripe actuator that requires very little power. A position sensing detector (PSD) is needed to sense the fiber position since the motion of the scanned fiber may not be fully predictable. The PSD operates in a two-photon absorption mode to accurately measure the fiber tip position for each laser pulse, with very low insertion loss.
Experimental Study of the Effect of Grain Size and Grain Size Distribution Curve on Creep and Stress Relaxation in a Beach Sand
Degree Awarded: D.Engr. Civil Engineering. The Catholic University of America, In order to obtain a greater qualitative understanding of the mechanisms behind the inverse phenomena of creep and stress relaxation in sand as well as yield parametric data for the future calibration of models that quantitatively predict their scope, intensity and magnitude, 9 24-hour creep and 9 24-hour relaxation studies were conducted on various blends of Virginia Beach sand. The artificially formulated blends were purposefully varied along two independent variable dimensions consisting of 3 different maximum grain sizes and 3 different degrees of gradation uniformity thereby forming a 3x3 blend matrix consisting of 9 different blend type elements. The experimental results are validated against 8 regular triaxial compression tests conducted separately, one on each blend. By conducting comparative analysis along the blend matrix meridians and parallels, the effects of varying each independent variable on creep and relaxation phenomena were demonstrated and fresh insights on both phenomena were gained.
Development and Use of Novel Transverse Magnetic Tweezers for Single-Molecule Studies of DNA-Protein Interactions
Degree Awarded: Ph.D. Biomedical Engineering. The Catholic University of America, I describe several contributions to single molecule experiments. A transverse magnetic tweezers is presented that enables in-plane micromechanical manipulation of a single DNA molecule. This includes a new method for tethering DNA utilizing two labeled beads and a functionalized glass micro-rod. The attachment chemistry reported here enables rapid capture of multiple DNA tethers in parallel, overcomes the difficulties associated with bead aspiration, and preserves the ability to perform differential extension measurements from the bead centroids. Combined with micro-injection pipettes, a new sample cell design, and a buffer exchange system, the components increase the ease-of-use and experimental throughput of the magnetic tweezers device. On the software side, several unique computational methods for interrogating single molecule data are described. First, a technique that uses the diffraction pattern of beads to perform sub-pixel, ~10 nm-level localization of the bead centroids is explained. Second, a novel method for automatically detecting steps in DNA extension data is presented. This algorithm is well-suited for analyzing experiments involving binding and force-induced unbinding of DNA-protein complexes, which produce flat extension regions - steps - corresponding to the times between individual protein association or dissociation events. Finally, a new algorithm for tracking densely-populated, fast spawning, indistinguishable objects moving unidirectionally at high-velocities is developed and its performance thoroughly characterized. Together, these results should improve single molecule micromanipulation techniques by providing a hardware and software combination that can be implemented and used relatively easily, while enabling near-Brownian-noise limit force and extension measurements on DNA and DNA-protein complexes.
Characterization of the Atmosphere as a Random Bit-Stream Generator in a Weak Turbulence Regime
The purpose of this dissertation is to investigate the extent to which atmospheric turbulence can be exploited as a robust random number generator. Atmospheric turbulence is considered an inherently random process, due to the complex non-homogeneous system composition and its sensitivity to changes in pressure, temperature, humidity, wind speed and direction. This work describes the background theory on atmospheric turbulence, which attempts to describe its dynamic behavior, as well as experimental work. A Mach-Zehnder interferometer was designed, built, and used to characterize the work in this dissertation; this sensor system enables the collection of empirical data of the phase fluctuation in the temporal domain introduced to an optical beam propagating through the atmosphere. The recorded phase fluctuations were converted into bit streams that were further analyzed in order to search for evidence of non-random properties. Empirical data and results, which attempt to characterize the degree of randomness in the noise introduced into the temporal phase component of an optical wave propagating through the atmosphere as a function of the atmospheric turbulence in the weak turbulence regime, are presented here for the first time., Degree awarded: Ph.D. Electrical Engineering and Computer Science. The Catholic University of America
A Functional Medical Imaging System for the Measurement of Oxygen Saturation in the Superficial Retina Vasculature
The retinal vasculature's oxygen saturation (SO2) is a valuable indicator of disease, in particular for patients with diabetic retinopathy (DR) who may experience changes in retinal oxygen saturation during their lifetime. Although numerous experimental systems aimed at measuring retinal SO2 have been developed in the last thirty years, a reliable, robust model for in vivo monitoring is still lacking.This dissertation explores the feasibility of using Two Dimensional Spatial Fourier Domain Imaging (2D-SFDI) and its related physics-based models for observation of the human retina. Two dimensional SFDI is based on spatially modulated light in two perpendicular axes. The most significant benefit of the 2D-SFDI technique compared with the current SFDI technique is to decrease the number of snapshots to one. The proposed proof of concept instrument was one in which spatially modulated illumination was achieved using two dimensional sinusoidal mechanical patterns positioned at a conjugate plane of the patient's retina. In additional to implementing 2D-SFDI, this dissertation employs Extended Modified Beer-Lambert Law (EMBLL) to obtain the optical properties of a two-layered structure. EMBLL is a modified version of MBLL that is used to measure the optical properties of the top layer in a two-layered structure using an imaging technique. Thus, this dissertation is focused on the structure of the vessels on top of the optic disc. Since the goal is determining the optical properties and ultimately measuring the oxygen saturation of vessels on top of the optic disc, in this dissertation the ophthalmic system (fundus camera) was modified to implement the presented algorithm in the eye. The system was tested using optical phantoms of known optical properties as well as a cow's optical disc. In the end, the optical properties of the human optic disc and oxygen saturation of the vein and artery on top of the optic disc were obtained. The tests' results show less than 6% error for phantoms. Also, vascular results are comparable with other reports. In summary, the proposed concepts provide an algorithm that is capable of determining the optical properties of the top layer in a two-layered media, using a single snapshot., Degree awarded: D.Engr. Electrical Engineering and Computer Science. The Catholic University of America
Effects of Near-Fault Translational and Torsional Ground Motions on Dynamic Response of Single-Story Buildings
Rotational components of ground motions, torsion about the vertical axis and rocking about the horizontal axes, have caused significant damage to engineering structures and failures to bridges. Several analytical and experimental studies have been conducted to investigate the effect of these components on structures. Rotational components of ground motions cannot be measured directly and have been measured by rotational sensors only for explosions and by strong motion arrays only for far-field seismic events. Therefore, in the absence of near-fault records of differential ground motions, the characterization, parameterization, modeling and simulation of strain, rocking, and torsional ground motions in the vicinity of the fault, as well as the systematic investigation of their effects on the dynamic response of engineering structures becomes an important issue.In this study, the dynamic ground deformations generated by Mavroeidis and Papageorgiou (2010a) for two well-documented seismic events (i.e. 1979 Imperial Valley and 1999 Izmit earthquakes) based on the discrete wavenumber representation method (Bouchon and Aki, 1977; Bouchon, 1979a) are utilized to obtain torsional and rocking ground motions and their associated distributions on the gridded region in the vicinity of each earthquake. These synthetic ground deformations are used in this study to investigate the effect of the biaxial action of recorded translational ground motions and synthetic torsional ground motions on the response of symmetric and asymmetric structures. In the current seismic deign codes and standards, this torsional ground motion accounts by the shifting of the center of mass to produce the desired results. In order to investigate the effects of torsional motions on the structural responses, a software has been developed to study the linear and nonlinear response of buildings under biaxial and torsional seismic ground excitation. The program is able to perform nonlinear time history analysis based on the force- and displacement-based formulation methods developed by Spacone (1992). The biaxial and uniaxial Smooth Hysteresis Models developed Simeonov et al. (2000) are employed to model the hysteresis behavior of elements in the context of the moment-curvature relationship. The uniaxial and biaxial smooth hysteresis behaviors of the material, similar to the widely used Bouc-Wen model are employed in this research. Various numerical approaches such as the implicit Runge-Kutta, Newton-Raphson and Newmark methods are used to solve the differential equations that govern the dynamic response of the system.Finally, parametric linear and nonlinear analyses are performed for a series of symmetric and asymmetric single-story buildings to investigate the influence of the natural and accidental torsional eccentricity on the response of structures. The structural models are subjected to bidirectional recorded translational motions and synthetic low-frequency angular accelerations from the 1979 Imperial Valley and 1999 Izmit earthquakes. In order to examine the response of structures subjected to synthetic torsional motions containing high-frequency components, the bidirectional translational records from the 1986 Taiwan earthquake at FAT-1 station and the associated synthetic torsional motion, generated by the Surface Distribution Method, are also used to conduct parametric nonlinear analysis. The equivalent accidental eccentricity is developed through the mathematical formula for structures subjected to the combination of the bidirectional translational motions and torsional ground motions. The torsional amplifications developed in structures either by accidental torsion or by synthetic ground differential deformations are not significant for the lower periods. The nonlinear behavior of the structure imposed by strength eccentricity is also explored, while the results are displayed in the biaxial Base Shear and Torque (BST) Surface, inferred for the possible collapse mechanisms regardless of the analysis results., Degree awarded: Ph.D. Civil Engineering. The Catholic University of America
The Role of Consultative Alliance in Early Childhood Mental Health Consultation
Young children’s social and emotional development is powerfully shaped by their early environments, which for many young children includes early childhood education (ECE) settings. Early Childhood Mental Health Consultation (ECMHC) is an intervention that pairs educators and mental health consultants (MHCs) to promote educators’ capacity to foster positive social-emotional development in ECE. While the outcomes of ECMHC have been well studied, little research has investigated how this model impacts educators and children. It has been theorized that the quality of the relationship between educators and MHCs – which is here termed Consultative Alliance (CA) – is a key mechanism of change, but this construct has yet to be thoroughly studied.Across two papers, this dissertation presents findings from multilevel models analyzing the role of Consultative Alliance on outcomes at the classroom and child levels after six months of consultation. Participants were 316 children, 289 educators, and 62 MHCs engaged in a statewide implementation of ECMHC at childcare centers in the Southwest.Paper 1 investigated the potential parallel process initiated in consultation, such that the strength of the CA may predict the extent of improvement in the teacher-child relationship. The findings suggest that a stronger CA was related to greater improvements to teacher-child closeness and teacher-rated child attachment behaviors. In addition, moderation analyses demonstrated that these effects were strongest for MHC-teacher dyads in which the MHC was more experienced or the teacher was less experienced.Paper 2 parsed the role of CA on educator and classroom level outcomes. Multilevel models demonstrated that a strong CA was related to greater improvement in classroom climate, teacher self-efficacy, and teacher perceptions of her job. Furthermore, preliminary support for the indirect effects of ECMHC was found. Mediation analyses indicated that CA was indirectly related to improved child-level outcomes (specifically, self-control and teacher-child conflict) via the classroom climate, though the cross-sectional data could not establish whether classroom-level changes preceded child-level changes.Taken together, this work upholds the centrality of relationship-building in mental health consultation. These findings should be considered exploratory in light of relevant limitations, including missing data, measurement concerns, and potential confounds. Nevertheless, these findings advance understanding of the mechanisms of change for ECMHC, with potentially salient implications for policy and practice., Clinical psychology, Consultative Alliance, Early Childhood, Mental Health Consultation, Social-Emotional Development, Psychology, Degree Awarded: Ph.D. Psychology. The Catholic University of America
Characterization of the Acoustic Field in Marine Environments with Anthropogenic Noise
Most animals inhabit the aquatic environment are acoustical-oriented, due to the physical characteristics of water that favors sound transmission. Many aquatic animals depend on underwater sound to navigate, communicate, find prey, and avoid predators. The degradation of underwater acoustic environment due to human activities is expected to affected these animals' well-being and survival at the population level. This dissertation presents three original studies on the characteristics and behavior of underwater sound fields in three unique marine environments with anthropogenic noises.The first study examines the soundscape of the Chinese white dolphin habitat in Taiwan. Acoustic recordings were made at two coastal shallow water locations, Yunlin and Waisanding, in 2012. Results show that croaker choruses are dominant sound sources in the 1.2-2.4 kHz frequency band for both locations at night, and noises from container ships in the 150-300 Hz frequency band define the relative higher broadband sound levels at Yunlin. Results also illustrate interrelationships among different biotic, abiotic, and anthropogenic elements that shape the fine-scale soundscape in a coastal environment.The second study investigates the inter-pulse sound field during an open-water seismic survey in coastal shallow waters of the Arctic. The research uses continuous acoustic recordings collected from one bottom-mounted hydrophone deployed in the Beaufort Sea in summer 2012. Two quantitative methods were developed to examine the inter-pulse sound field characteristics and its dependence on source distances. Results show that inter-pulse sound field could raise the ambient noise floor by as much as 9 dB, depending on ambient condition and source distance.The third study examines the inter-ping sound field of simulated mid-frequency active sonar in deep waters off southern California in 2013 and 2014. The study used drifting acoustic recorder buoys to collect acoustic data during sonar playbacks. The results show strong band-limited elevation (13-24 dB) of sound pressure levels for over half of the inter-ping intervals above the natural background levels.These three studies provide insights on the dynamics of marine soundscape and how anthropogenic activities can change the acoustic habitat by elevating the overall sound field levels., Degree awarded: Ph.D. Mechanical Engineering. The Catholic University of America
Quantitative Assessment of Optical Coherence Tomography Imaging Performance with Phantom-Based Test Methods and Computational Modeling
Optical coherence tomography (OCT) is a powerful medical imaging modality that uniquely produces high-resolution cross-sectional images of tissue using low energy light. Its clinical applications and technological capabilities have grown substantially since its invention about twenty years ago, but efforts have been limited to develop tools to assess performance of OCT devices with respect to the quality and content of acquired images. Such tools are important to ensure information derived from OCT signals and images is accurate and consistent, in order to support further technology development, promote standardization, and benefit public health. The research in this dissertation investigates new physical and computational models which can provide unique insights into specific performance characteristics of OCT devices.Physical models, known as phantoms, are fabricated and evaluated in the interest of establishing standardized test methods to measure several important quantities relevant to image quality. (1) Spatial resolution is measured with a nanoparticle-embedded phantom and model eye which together yield the point spread function under conditions where OCT is commonly used. (2) A multi-layered phantom is constructed to measure the contrast transfer function along the axis of light propagation, relevant for cross-sectional imaging capabilities. (3) Existing and new methods to determine device sensitivity are examined and compared, to better understand the detection limits of OCT.A novel computational model based on the finite-difference time-domain (FDTD) method, which simulates the physics of light behavior at the sub-microscopic level within complex, heterogeneous media, is developed to probe device and tissue characteristics influencing the information content of an OCT image. This model is first tested in simple geometric configurations to understand its accuracy and limitations, then a highly realistic representation of a biological cell, the retinal cone photoreceptor, is created and its resulting OCT signals studied.The phantoms and their associated test methods have successfully yielded novel types of data on the specific performance parameters of interest, which can feed standardization efforts within the OCT community. The level of signal detail provided by the computational model is unprecedented and gives significant insights into the effects of subcellular structures on OCT signals. Together, the outputs of this research effort serve as new tools in the toolkit to examine the intricate details of how and how well OCT devices produce information-rich images of biological tissue., Degree awarded: Ph.D. Electrical Engineering and Computer Science. The Catholic University of America
Polarimetric Radar Scattering Analysis in a Maritime Environment
This dissertation evaluates multiple effects that will cause a satellite borne radar to observe transformation of the transmitted polarization by an ocean surface. Knowing the surface conditions over large swaths of ocean is very important for both global weather prediction and for safety of navigation at sea. Fully polarimetric linearly polarized ocean observation radars use the linear cross-polarized ocean response to obtain an assessment of the surface wind vectors. However, radar technology is evolving. More compact hybrid polarization radars that transmit a single circular polarization, and then simultaneously receive two orthogonal linear polarizations are expected to obtain near fully polarimetric capability with a significant savings in weight, volume, and complexity. The models used by fully polarimetric linearly polarized radars to obtain the surface wind vectors are empirical, and not usable for hybrid compact polarimetric radars. The literature survey indicated two areas needed investigation to develop ocean observation capabilities for hybrid compact polarimetric radar. The first is for antenna cross-polarization isolation models specific to hybrid polarization radars. The second is for improved understanding of the nature of the ocean's polarimetric response to hybrid polarizations. Conclusions include that hybrid polarizations provide opportunities to polarimetrically isolate surface features, including surface roughness, the surface specular response, and breaking waves. These features should provide insight into surface winds, wave steepness, and sea state., Degree awarded: Ph.D. Electrical Engineering and Computer Science. The Catholic University of America
Employing pFUS for Treatment of Peripheral Arterial Disease via Homing of Infused Bone Marrow Stromal Cells
Peripheral artery disease (PAD) manifests from vascular blockage or trauma to a region causing restricted flow of oxygen-rich blood to tissues and organs Treatment options for PAD include lifestyle modification, pharmacotherapy, and revascularization, but they often fail. Clinical data shows that administration of bone marrow stromal cells (BMSC) can provide therapeutic benefits to!promote regeneration of damaged tissue, treat inflammation, and induce angiogenesis. However <<3% of IV-infused cells arrive at the target site. Pulsed focused ultrasound (pFUS) has been used as a noninvasive and nondestructive modality to enhance tissue permeability and retention in drug delivery through physical alterations in tissue. The goal of the proposed research is to employ pFUS exposures to elicit local molecular responses for enhancing homing and retention of BMSC in PAD tissues to improve vascularization and reestablish perfusion blood flow. Hamstrings of healthy mice were treated with pFUS and harvested at various time points to characterize the biological response of tissue. The results demonstrated significant elevations in chemoattractants (homing factor) as early as 10min and subsided by 60hrs post-pFUS. From this data, an optimal time window for maximal BMSC homing to pFUS treated site was suggested. Maximum homing of IV-infused BMSC occurred pre-pFUS and up to 16 post-pFUS demonstrating enhance homing of cells by pFUS. After creation and validation of the PAD model using laser Doppler perfusion imaging, the ischemic limb was treated and harvested at various days after ischemic induction to demonstrate the feasibility of generating a transient inflammatory response outside innate inflammatory response of the disease. Fourteen days after the induction of PAD, the innate inflammatory response had subsided and pFUS was used to stimulate an inflammatory response and enhance cell homing to pFUS treated site. When therapeutic efficacy was tested for 7 weeks in aged (≥12 months) mice with PAD and treatment,(BMSC+pFUS), given 14days after ischemic induction, perfusion blood flow was significantly enhanced in the treatment group versus control. The results demonstrated the therapeutic benefits of combining pFUS and cells that can be translated in other vascular disease models. The implications of this research have the potential to enhance regenerative medicine., Degree awarded: Ph.D. Biomedical Engineering. The Catholic University of America
Ultrasound Mediated lntracellular Drug Delivery in 2D Biological Scaffolds
Successful intracellular drug and gene delivery represents a major goal for medical researchers. Sonoporation (i.e. the formation of pores using sound) is considered one of the most promising techniques, especially since it is non-destructive and as it can be carried out deep inside the body under image guidance. The mechanism of sonoporation is not fully understood. Presently, the vast majority of in vitro sonoporation investigations are carried out on cells in monolayer in plastic dishes. These systems are problematic from a variety of aspects. Ultrasound interaction with the wells, themselves acoustically incompatible, can result in unwanted phenomena such as mode conversion, heat generation, and standing waves. These factors combined can lead to uncertainties of up to 700% in the actual ultrasound exposure experienced by cells. Biological scaffolds can serve as an artificial extra cellular matrix to support different cell processes. Compared to plastic dishes, they more realistically resemble the in vivo environment in terms of how ultrasound interacts with cells and the extracellular matrix. The goal of this project was to develop a more biologically and acoustically compatible platform for investigating the process of sonoporation. I have developed a prototypical 2D biological scaffold, based on chitosan and gelatin. Scaffolds formulation was optimized for both cell adhesion and proliferation. I have also designed and custom built an acoustically compatible treatment chamber, where problematic issues of current setup were minimized. The acoustic activity inside the chamber was verified. The acoustic compatibility of the scaffolds was demonstrated using B-mode diagnostic ultrasound imaging and transmission test, compared to traditional culture dish. To study cell survival, sonoporation experiments were carried out over a range of ultrasound intensities and durations in this novel system. High cell survival (i.e. 83%) was achieved at 0.8 w/cm2 for 30 sec. Fluorescent imaging revealed successful intracellular delivery of nanoparticles at this ultrasound exposure. At the same ultrasound exposure, when carried out in a well plate, lower cell survival and higher variability was obtained. Acoustic incompatibility of culture plates produces less predictable results. This new platform was more acoustically compatible, allowing more predictable ultrasound exposures, and more consistent results., Degree awarded: Ph.D. Biomedical Engineering. The Catholic University of America
The Titan Laboratory: Studies of Hazy and Reducing Atmospheres Near and Far
Titan is one of the most unique terrestrial worlds, besides our own planet, in our solar system. Orbiting Saturn at 9.5 AU from the Sun it is the only moon with an appreciable haze and so cold that instead of liquid water, there is liquid methane that forms when the methane condenses and rains out. The puffy extended atmosphere (1400 km high) hides the surface with a shroud of haze that forms from the photolysis of methane high up in the atmosphere which produce aggregates of tar-like particles. With almost 6% methane near the surface and 1.4% in the stratosphere this world is far more reducing (hydrogen rich) than the oxidized (oxygen rich) Archean eon of Earth and the Modern Earth. With such an alien world right here in our back yard it is paramount that we understand the processes that control it while comparing it to our own planet as we search the galaxy for terrestrial exoplanets.In this dissertation I focus on answering three main questions. The first one is: Using the Titan-Enceladus cryovolcano oxygen exchange as a starting point, can external material entering a terrestrial atmosphere trigger a methane-oxygen false-positive biosignature observation? Methane and oxygen are a strong biosignature pair due to the way the two gases destroy one another unless a constant source is provided. Using a 1D-photochemical model I produce atmospheres with abiotic and biotic levels of oxygen and water entering a terrestrial world and then observe the spectra of the planet with a synthetic spectrum generator to look for the presence of the methane-oxygen pair. Simulating observations with next generation and future generation space-based telescopes, my results show that a false positive biosignature will not be triggered unless unphysically high external fluxes of material are used and even than the signal-to-noise-ratios of the spectra are not strong enough to be considered reliable. The second question I answer is: Can Titan-like exoplanets be characterized with next-generation space-based observatories and what role if any does haze play? In this work Titan-like means a rocky body that is along the snow-line of its system where it is assumed to be cold enough for methane to condense, be highly reducing and have a hazy atmosphere. An exoplanet 6 light years away was recently detected by the radial velocity method, orbiting Barnard’s Star. The planet, Barnard’s Star b, is along the snow-line of its system with a minimum mass of 3.2 Earth masses. Using a 1D-photochemical model and synthetic spectrum generator I model this exoplanet as a Titan-like super Earth and apply a mass-radii relation to arrive at a minimum radius of 11053 km. With these parameters I simulated the observation of the exoplanet with LUVOIR-A, the 15 m mirror future-generation space-based telescope. My results show strong signals for methane in the visible and near-infrared and the suppression of the Rayleigh tail in the ultra-violet, that mirror the spectral methane windows seen in observations of Titan. The third and final question is focused on how atmosphere transitions behave on rocky planets as they move from reducing to oxidized atmosphere conditions and whether or not Great Oxidation Event similarities occur. The Great Oxidation Event (GOE) was a period in Earth’s past, during the Proterozoic eon, when the planet quickly transitioned from a reducing to highly oxygenated atmosphere. One of the hallmarks of the GOE was a sharp spike and stepwise behavior in the abundance of atmospheric oxygen. Titan is on the far end of the reduced atmosphere spectrum, in contrast to the Archean and Modern Earth, and in my work I use a 1D-photochemical model to simulate Titan transitioning to an oxidized state. Methane and carbon-dioxide are gradually adjusted to make the atmosphere more oxidized while looking for evidence of stepwise changes in the abundances and column densities of major oxygenated species. The simulations are also performed for G, K and M host star types. However, neither oxygen nor ozone were included in the model at this time. My results do not show signs of pronounced stepwise behavior, but they do show gradual stepwise behavior for atmospheric water in the G and M star cases, while K star simulations made it difficult for the atmospheres to transition very far in the direction of oxidation., Atmospheric sciences, Astronomy, Biosignatures, Exoplanets, Titan, Physics, Degree Awarded: Ph.D. Physics. The Catholic University of America
The Development of the Principle of Subsidiarity in the 1983 Code of Canon Law
The principle of subsidiarity was one of the ten principles that guided the canonical revision process of the 1917 Code of Canon Law. Yet insufficient scholarly attention has been paid to the development of subsidiarity regarding the canonical revision process. This dissertation studies the application of the principle of subsidiarity in the 1983 Code of Canon Law, which requires analyses of the revision process of the 1917 CIC. It examines subsidiarity throughout the pontificates from Pius XI to John Paul II. Three fundamental questions underlined the research: 1) What is the principle of subsidiarity? 2) Where can the principle of subsidiarity be applied? 3) What is the principle of subsidiarity for? The dissertation has three chapters. Chapter one studies the historical origin and development of subsidiarity within the Catholic social doctrine's context, where the principle is formulated initially. It examines the principle's evolution from the encyclical Quadragesimo anno to Vatican II. Chapter two presents the influence of both the theology of Vatican II and the selected synod of bishops in the understanding of the principle of subsidiarity. The bishops' participation in the 1967 synod is described, drawing upon unpublished sources from the Pontifical Council for Legislative Texts archives. Chapter three summarizes the canonical applications of subsidiarity in the revision process of the 1917 CIC by analyzing commissions' acts. The dissertation examines pertinent pontifical, conciliar, curial, and canonical documents and relevant scholarly sources on the question. A proper understanding of the principle of subsidiarity requires recognizing that it is a principle, which must be interpreted in light of the theological and canonical concepts lying beneath it. This dissertation offers an extensive bibliography on subsidiarity in various languages from 1931 to 1985. This bibliography is essential to evaluate the purpose of subsidiarity in the Church accurately. This dissertation presents the evolution of subsidiarity systematically from Catholic Social Doctrine into the 1983 CIC. It also analyses the suppositions, the fundamental issues, and limits of its pastoral application. The principle of subsidiarity promotes spaces where the faithful can exercise their vocations in an adulthood manner and cooperate with the mission of the Church. , Canon law, Canon Law, Degree Awarded: J.C.D. Canon Law. The Catholic University of America
Collaborative Assessment and Management of Suicidality--Integrated Training Model: Impact on Clinician Competency
Effective implementation of evidence-based practices is vital in clinical suicide prevention. Multiple factors influence the implementation of evidence-based practices (EBPs), including mental health care clinicians’ access to training as well as the quality of training they receive. This study investigated the impact of a multi-modal training program for a suicide-specific evidence-based practice: The Collaborative Assessment and Management of Suicidality – Integrated Training Model (CAMS – ITM). Survey data was used to assess the effectiveness of CAMS – ITM in increasing clinical competency to treat suicidal patients, as measured by improvements in clinicians’ self-report of skill in treating suicidal patients, knowledge of suicide-specific best practices, and attitude toward the treatment of suicidality. Pre-training survey responses compared to post-training survey responses were analyzed across groups of clinicians receiving CAMS training in the states of Oklahoma, Ohio, Colorado, and Alaska. The findings of this exploratory study showed good support for CAMS – ITM, as analyses showed improvements in attitude, knowledge, and skill by the end of training. Moreover, there was evidence that the first training, an online video course, was effective in improving competency in and of itself. This study adds to the extant literature on EBP training for mental health clinicians and adds to the body of evidence in support of CAMS as a tool for the dissemination and implementation of suicide specific best practices. , Clinical psychology, CAMS, clinical competency, clinician training, implementation, suicide-specific EBP, training outcome, Psychology, Degree Awarded: Ph.D. Psychology. The Catholic University of America

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