Substance Use and Academic Outcomes among High School Seniors: Examining the Influence of Emotional Academic Engagement

Substance use is prevalent among adolescents, with two-thirds trying alcohol and half trying an illicit drug by twelfth grade (Miech et al., 2015). Substance use is known to affect academic performance. This study utilized nationally representative data from the 2013 Monitoring the Future twelfth grade survey to examine the relationships between substance use, skipping school, grades, and academic engagement. One-quarter of respondents (26%) had never used a substance. The majority (67%) had used at least one substance during the past year. Substance use during their lifetime but not during the past year was uncommon (7%). Lifetime non-users were less likely than past-year users to skip school during the past month and to have low grades. Lifetime non-users also had greater academic self-efficacy and emotional academic engagement relative to past-year users. These findings underscore the importance of screening and intervention for substance use to promote academic achievement and adolescent wellbeing.

Estimating Population Trends in American Woodcock (Scolopax Minor) Using Population Reconstruction Models

The American woodcock (Scolopax minor) population index in North America has declined 0.9% a year since 1968 prompting managers to identify priority information and management needs for the species (Sauer et al 2008). Managers identified a need for a population model that better informs on the status of American woodcock populations (Case et al. 2010). Population reconstruction techniques use long-term age-at-harvest data and harvest effort to estimate abundances with error estimates. Four new models were successfully developed using survey data (1999 to 2013). The optimal model estimates sex specific harvest probability for adult females at 0.148 (SE = 0.017) and all other age-sex cohorts at 0.082 (SE = 0.008) for the most current year 2013. The model estimated a yearly survival rate of 0.528 (SE = 0.008). Total abundance ranged from 5,206,000 woodcock in 2007 to 6,075,800 woodcock in 1999. This study represents the first population estimates of woodcock populations.

Joint Optimization for Social Content Delivery in Wireless Networks

Over the last decade, success of social networks has significantly reshaped how people consume information. Recommendation of contents based on user profiles is well-received. However, as users become dominantly mobile, little is done to consider the impacts of the wireless environment, especially the capacity constraints and changing channel. In this dissertation, we investigate a centralized wireless content delivery system, aiming to optimize overall user experience given the capacity constraints of the wireless networks, by deciding what contents to deliver, when and how. We propose a scheduling framework that incorporates content-based reward and deliverability. Our approach utilizes the broadcast nature of wireless communication and social nature of content, by multicasting and precaching. Results indicate this novel joint optimization approach outperforms existing layered systems that separate recommendation and delivery, especially when the wireless network is operating at maximum capacity. Utilizing limited number of transmission modes, we significantly reduce the complexity of the optimization. We also introduce the design of a hybrid system to handle transmissions for both system recommended contents ('push') and active user requests ('pull'). Further, we extend the joint optimization framework to the wireless infrastructure with multiple base stations. The problem becomes much harder in that there are many more system configurations, including but not limited to power allocation and how resources are shared among the base stations ('out-of-band' in which base stations transmit with dedicated spectrum resources, thus no interference; and 'in-band' in which they share the spectrum and need to mitigate interference). We propose a scalable two-phase scheduling framework: 1) each base station obtains delivery decisions and resource allocation individually; 2) the system consolidates the decisions and allocations, reducing redundant transmissions. Additionally, if the social network applications could provide the predictions of how the social contents disseminate, the wireless networks could schedule the transmissions accordingly and significantly improve the dissemination performance by reducing the delivery delay. We propose a novel method utilizing: 1) hybrid systems to handle active disseminating requests; and 2) predictions of dissemination dynamics from the social network applications. This method could mitigate the performance degradation for content dissemination due to wireless delivery delay. Results indicate that our proposed system design is both efficient and easy to implement.

Lucretius: the Wonderer

I seek to create a Lucretius text useful for a high school classroom including a commentary on four sections of the poem. The passages include 2.998 – 1047 which explains how the Epicurean atomic theory, 3.912—979 the famous passage that denies the underworld and its tortures, 5.855 – 923 the semi-Darwinian passage detailing the sorts of creatures that can exist in this world, and 5.1194– 1240 about the detrimental effects of humans fearing gods. In addition to writing a commentary on these passages, I will explore the perception of Lucretius though the present day, in hopes of discovering how and why this important and influential author has been so systematically excluded from secondary latin literary studies. My discussion will include an overview of how modern Latin textbooks do or do not mention Lucretius and how his presence in these textbooks compares to his role in university-level Latin course offerings. In addition to writing a commentary on these passages, I will explore the perception of Lucretius though the present day, in hopes of discovering how and why this important and influential author has been so systematically excluded from secondary latin literary studies. My discussion will include an overview of how modern Latin textbooks do or do not mention Lucretius and how his presence in these textbooks compares to his role in university-level Latin course offerings. I am hoping this research will be useful both pedagogically and for learning how decisions about literary content are made in American secondary and higher education in Latin.

An Exploration of Auditory Brainstem Encoding of Stop Consonants in Infants and Implications for Language Outcomes

Current trends in speech-language pathology focus on early intervention as the preferred tool for promoting the best possible outcomes in children with language disorders. Neuroimaging techniques are being studied as promising tools for flagging at-risk infants. In this study, the auditory brainstem response (ABR) to the syllables /ba/ and /ga/ was examined in 41 infants between 3 and 12 months of age as a possible tool to predict language development in toddlerhood. The MacArthur-Bates Communicative Development Inventory (MCDI) was used to assess language development at 18 months of age. The current study compared the periodicity of the responses to the stop consonants and phase differences between /ba/ and /ga/ in both at-risk and low-risk groups. The study also examined whether there are correlations among ABR measures (periodicity and phase differentiation) and language development. The study found that these measures predict language development at 18 months.

THE DISTRIBUTION AND FUNCTION OF DENITRIFICATION GENES: EXPLORING AGRICULTURAL MANAGEMENT AND SOIL CHEMICAL IMPLICATIONS

Denitrification is a microbially-mediated process that converts nitrate (NO3-) to dinitrogen (N2) gas and has implications for soil fertility, climate change, and water quality. Using PCR, qPCR, and T-RFLP, the effects of environmental drivers and land management on the abundance and composition of functional genes were investigated. Environmental variables affecting gene abundance were soil type, soil depth, nitrogen concentrations, soil moisture, and pH, although each gene was unique in its spatial distribution and controlling factors. The inclusion of microbial variables, specifically genotype and gene abundance, improved denitrification models and highlights the benefit of including microbial data in modeling denitrification. Along with some evidence of niche selection, I show that nirS is a good predictor of denitrification enzyme activity (DEA) and N2O:N2 ratio, especially in alkaline and wetland soils. nirK was correlated to N2O production and became a stronger predictor of DEA in acidic soils, indicating that nirK and nirS are not ecologically redundant.

Fighting Evasive Malware with DVasion

Malware is a foundational component of cyber crime that enables an attacker to modify the normal operation of a computer or access sensitive, digital information. Despite the extensive research performed to identify such programs, existing schemes fail to detect evasive malware, an increasingly popular class of malware that can alter its behavior at run-time, making it difficult to detect using today’s state of the art malware analysis systems. In this thesis, we present DVasion, a comprehensive strategy that exposes such evasive behavior through a multi-execution technique. DVasion successfully detects behavior that would have been missed by traditional, single-execution approaches, while addressing the limitations of previously proposed multi-execution systems. We demonstrate the accuracy of our system through strong parallels with existing work on evasive malware, as well as uncover the hidden behavior within 167 of 1,000 samples.

Development of a Real-Time Hierarchical 3D Path Planning Algorithm for Unmanned Aerial Vehicles

Unmanned aerial vehicles (UAVs) frequently operate in partially or entirely unknown environments. As the vehicle traverses the environment and detects new obstacles, rapid path replanning is essential to avoid collisions. This thesis presents a new algorithm called Hierarchical D* Lite (HD*), which combines the incremental algorithm D* Lite with a novel hierarchical path planning approach to replan paths sufficiently fast for real-time operation. Unlike current hierarchical planning algorithms, HD* does not require map corrections before planning a new path. Directional cost scale factors, path smoothing, and Catmull-Rom splines are used to ensure the resulting paths are feasible. HD* sacrifices optimality for real-time performance. Its computation time and path quality are dependent on the map size, obstacle density, sensor range, and any restrictions on planning time. For the most complex scenarios tested, HD* found paths within 10% of optimal in under 35 milliseconds.

Contactless Spectral-Dependent Measurement of Bulk Lifetime and Surface Recombination Velocity in Silicon Photovoltaic Materials

Charge carrier lifetime measurements in bulk or unfinished photovoltaic (PV) materials allow for a more accurate estimate of power conversion efficiency in completed solar cells. In this work, carrier lifetimes in PV- grade silicon wafers are obtained by way of quasi-steady state photoconductance measurements. These measurements use a contactless RF system coupled with varying narrow spectrum input LEDs, ranging in wavelength from 460 nm to 1030 nm. Spectral dependent lifetime measurements allow for determination of bulk and surface properties of the material, including the intrinsic bulk lifetime and the surface recombination velocity. The effective lifetimes are fit to an analytical physics-based model to determine the desired parameters. Passivated and non-passivated samples are both studied and are shown to have good agreement with the theoretical model.

Experimental Modeling of Twin-Screw Extrusion Processes to Predict Properties of Extruded Composites

Twin-screw extrusion is used to compound fillers into a polymer matrix in order to improve the properties of the final product. The resultant properties of the composite are determined by the operating conditions used during extrusion processing. Changes in the operating conditions affect the physics of the melt flow, inducing unique composite properties. In the following work, the Residence Stress Distribution methodology has been applied to model both the stress behavior and the property response of a twin-screw compounding process as a function of the operating conditions. The compounding of a pigment into a polymer melt has been investigated to determine the effect of stress on the degree of mixing, which will affect the properties of the composite. In addition, the pharmaceutical properties resulting from the compounding of an active pharmaceutical ingredient are modeled as a function of the operating conditions, indicating the physical behavior inducing the property responses.

“NYAM CHIEM” RECONSTRUCTING AND PERFORMING NIGHTMARE: A DANCE RESEARCH IN PERFORMANCE OF SLEEP PARALYSIS.

This paper is a documentation of a practice-based dance work of the creative process, research and performance presentation of the piece “Nyam chiem.” This thesis examines the phenomenon of sleep paralysis through a personal reflexive research. The work challenges the notion that sleep paralysis is evil, revealing the phenomenon as a part of the human experience. The research is in two parts, practical and theory. The practical component includes; dance rehearsals, and staging of the piece as presentation. The theoretical component includes the documentation of the work in a written format capturing my personal stories, and salient issues arising from the process into a scholarly paper.

Computational Foundations for Safe and Efficient Human-Robot Collaboration in Assembly Cells

Human and robots have complementary strengths in performing assembly operations. Humans are very good at perception tasks in unstructured environments. They are able to recognize and locate a part from a box of miscellaneous parts. They are also very good at complex manipulation in tight spaces. The sensory characteristics of the humans, motor abilities, knowledge and skills give the humans the ability to react to unexpected situations and resolve problems quickly. In contrast, robots are very good at pick and place operations and highly repeatable in placement tasks. Robots can perform tasks at high speeds and still maintain precision in their operations. Robots can also operate for long periods of times. Robots are also very good at applying high forces and torques. Typically, robots are used in mass production. Small batch and custom production operations predominantly use manual labor. The high labor cost is making it difficult for small and medium manufacturers to remain cost competitive in high wage markets. These manufactures are mainly involved in small batch and custom production. They need to find a way to reduce the labor cost in assembly operations. Purely robotic cells will not be able to provide them the necessary flexibility. Creating hybrid cells where humans and robots can collaborate in close physical proximities is a potential solution. The underlying idea behind such cells is to decompose assembly operations into tasks such that humans and robots can collaborate by performing sub-tasks that are suitable for them. Realizing hybrid cells that enable effective human and robot collaboration is challenging. This dissertation addresses the following three computational issues involved in developing and utilizing hybrid assembly cells: - We should be able to automatically generate plans to operate hybrid assembly cells to ensure efficient cell operation. This requires generating feasible assembly sequences and instructions for robots and human operators, respectively. Automated planning poses the following two challenges. First, generating operation plans for complex assemblies is challenging. The complexity can come due to the combinatorial explosion caused by the size of the assembly or the complex paths needed to perform the assembly. Second, generating feasible plans requires accounting for robot and human motion constraints. The first objective of the dissertation is to develop the underlying computational foundations for automatically generating plans for the operation of hybrid cells. It addresses both assembly complexity and motion constraints issues. - The collaboration between humans and robots in the assembly cell will only be practical if human safety can be ensured during the assembly tasks that require collaboration between humans and robots. The second objective of the dissertation is to evaluate different options for real-time monitoring of the state of human operator with respect to the robot and develop strategies for taking appropriate measures to ensure human safety when the planned move by the robot may compromise the safety of the human operator. In order to be competitive in the market, the developed solution will have to include considerations about cost without significantly compromising quality. - In the envisioned hybrid cell, we will be relying on human operators to bring the part into the cell. If the human operator makes an error in selecting the part or fails to place it correctly, the robot will be unable to correctly perform the task assigned to it. If the error goes undetected, it can lead to a defective product and inefficiencies in the cell operation. The reason for human error can be either confusion due to poor quality instructions or human operator not paying adequate attention to the instructions. In order to ensure smooth and error-free operation of the cell, we will need to monitor the state of the assembly operations in the cell. The third objective of the dissertation is to identify and track parts in the cell and automatically generate instructions for taking corrective actions if a human operator deviates from the selected plan. Potential corrective actions may involve re-planning if it is possible to continue assembly from the current state. Corrective actions may also involve issuing warning and generating instructions to undo the current task.

Machtverhältnisse und die Problematik des postkolonialen Blicks in Uwe Timms Morenga (1978) und Gerhard Seyfrieds Herero (2003)

Using a postcolonial methodology within a German Cultural Studies framework, this thesis applies a close reading to Uwe Timm’s 1978 novel Morenga and Gerhard Seyfried’s 2003 novel Herero. Both novels narrate the colonial experience in German Southwest Africa during the 1904-1907 Herero and Nama uprising through the eyes of a German male protagonist. I investigate how notions of the ‘other’ become ingrained in the collective cultural imaginary of a nation and manifest themselves as inherent truths used to justify methods of subjugation. I also examine the conflicts that arise due to the clash between these drastically different cultures in the “contact zone”, a term I borrow from Mary Louise Pratt. Emphasis is placed on analyzing the ways in which the natives’ use of mimicry allows for the creation of a cultural hybridity in which power relations are constantly negotiated and re-evaluated. I also problematize the difficulty both protagonists demonstrate in their quest to abandon the colonial gaze in favor of adopting a postcolonial perspective, an attempt that often appears ambivalent at best.

"Let Us Sing as We Go": The Role of Music in the United States Suffrage Movement

Music played a prominent role in the United States women’s suffrage movement (1848–1920). Suffragists left behind hundreds of compositions supporting their cause and historical accounts indicate that musical performances were common at suffrage events. With only a few exceptions, scholars have disregarded the music used in this movement, and have underemphasized its significance. This study examines the use of music in the suffrage movement from three perspectives: music with lyrics, titles, and images that espouse women’s enfranchisement; music performed at national suffrage conventions held by the National American Woman Suffrage Association; and music accompanying suffrage parades. Though the music used varies in each case, it is clear that music played an important role in unifying suffragists and underscoring the ideals and goals of the movement.

Invoking Justice

Invoking Justice, a performative work of dance-theater, is a social commentary, both on the failure of the American justice system to balance the scales, and on our individual and collective failings to balance our communities, and ourselves, while recognizing our inherent unity and interconnectedness. The show was performed on March 10th and 11th, 2016 in the Clarice Smith Performing Arts Center, at the University of Maryland, College Park. This document is a survey of the creative process through which this project was realized and serves as a record of the many obstacles and successes that one might encounter in directing a work of dance-theater.