University of Maryland, Baltimore County
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Transcutaneous monitoring of respiratory gases in preterm neonates
No full textThe past decades have seen a widespread application of transcutaneous monitoring in neonatology. The noninvasive approach overcomes the painful nature of blood sampling. Our work focused on the technique of simultaneous noninvasive measurement of tcpO2 (transcutaneous partial pressure of oxygen) and tcpCO2 (transcutaneous partial pressure of carbon dioxide). A small sampling chamber was built connecting the carbon dioxide and oxygen sensors to measure the gases diffusing out of the skin. The measurements were based on the initial diffusion rate instead of the mass-transfer equilibrium which allows for a faster response. By using the new method, physical activities, food intake and breathing patterns were shown to have a strong effect on the amount of carbon dioxide and oxygen evolving from the human skin. The measurement parameters such as sampler area, location, position and procedure timing were optimized using design of experiments. The measurements were validated and correlated against an FDA approved commercial transcutaneous monitor (the Radiometer TCM 4.0). The experimental setup was further modified and automated, and then approved for clinical trials at the University of Maryland, School of Medicine in the Neonatal Intensive Care Unit (NICU). The results obtained from a premature baby in the NICU were correlated to the Arterial Blood Gas (ABG) analysis. The noninvasive and rate-based monitoring technique was also extended to monitoring dissolved oxygen and carbon dioxide in cell cultures. We have shown that by measuring the initial diffusion rate we were able to determine the partial pressures of the two gases in the culture. The technique could be readily automated and measurements could be made in minutes. It was tested in demonstration experiments by growing mammalian cells in a T flask and a spinner flask at 37 degree C.The results were validated using optical sensor systems. A dynamic theoretical model based on a three dimensional unit cell representation of the experimental system that includes a single blood vessel was constructed in order to gain a better fundamental understanding of the factors that determine the performance of the new approach. The model employed the finite element numerical method and accounted for the fluid mechanics, mass transfer and reaction kinetics of the system. The model was implemented using COMSOL Multiphysics engineering simulation software
Corrosion Protection Characterization of an Al/Au/ZnO Anode
No full textEffective protection of power sources from corrosion is critical in the development of abiotic fuel cells, biobatteries and biofuel cells for implantable bioelectronics. Corrosion of these bioelectronic devices result in device inability to generate bioelectricity. Al/Au/ZnO was considered as a possible anode for the development for abiotic fuel cell applications. The protective abilities of corrosive resistant hopeite films formed on the surface of the Al/Au/ZnO anode in various electrolyte environments were examined by electrochemical methods. The presence of phosphate and NaCl in biological fluids allows for the formation of hopeite films that prevent corrosion. Highly protective films formed on the Al/Au/ZnO anode in physiological saline environment resulted in 98.5% corrosion protective efficiency, thereby demonstrating that the formation of hopeite films are effective in the prevention of anode corrosion
Virtual Circuit Provisioning in Challenged Sensor Internetworks, With Application to the Solar System Internet
No full textPlatform heterogeneity, propagation delays, and link disruptions limit the scalability of sensing internetworking architectures. I present a challenged sensor internetwork (CSI) architecture that federates networks behind an overlay abstracted from individual data link layers. The associated delay-tolerant algorithms described in this work allow message exchange over otherwise incompatible networking stacks and enable novel concepts such as the NASA Solar System Internet (SSI). Border monitoring, undersea surveillance, and the SSI exemplify the need for spatially scaling networks. Existing deployments poorly address different physical links and frequent delays/disruptions. Virtual circuits abstracted from differences in the physical, data-link, and transport layers represent a unique solution to the problems of scaling diverse networks. I describe the CSI architecture as the intersection of wireless, delay-tolerant, and heterogeneous networks and describe special characteristics of this architecture that enable useful assumptions to optimize messaging. I define an InterNetwork Routing (INR) framework that decomposes the routing function into discrete logical steps and I provide algorithms for each of these steps. An inferred Contact Graph Routing (iCGR) algorithm populates logical graphs from local nodes. A Contact Graph Routing with Extension Blocks (CGR-EB) algorithm provides a hybrid source-path algorithm for synchronizing link state along network paths. A Predictive Capacity Consumption (PCC) algorithm exploits CGR-EB data to build a congestion model. Payload Aggregation/Fragmentation (PAF) and Traffic-Shaping Contacts (TSC) algorithms condition data and place limits on the amount of internetwork traffic carried over local networks. High fidelity simulations demonstrate performance in a variety of scenarios. iCGR performs within ~15% of a perfect-knowledge system. CGR-EB has a speedup over standard approaches by 300% in stable topologies, by 3000% in unstable topologies, and by 11000% in unstable topologies with non-monotonic cost functions. PCC delivers 97% more data in congested networks over table-based approaches and 37% more data than the INR framework without the congestion model. PAF/TSC reduces message count by 43% while increasing goodput by 63%. This work enables spatially distributed, scalable internetworks managed behind a consolidated data and control plane. The principals of network semi-structure and path locality should be considered in any new sensor internetwork deployment, and particularly when considering graph-based networking at astronomical scales
Ram Pressure Induced Star Formation in Abell 3266
No full textAn X-ray observation of the merging galaxy cluster Abell 3266 was obtained via the ROSAT PSPC. This information, along with spectroscopic data from the WIde-field Nearby Galaxy-clusters Survey (i.e. WINGS), were used to investigate whether ram pressure is a mechanism that influences star formation. Galaxies exhibiting ongoing star formation are identified by the presence of strong Balmer lines (Hβ), known to correspond to early type stars. Older galaxies where a rapid increase in star formation has recently ceased, known as E+A galaxies, are identified by strong Hβ absorption coupled with little to no [OII] emission. The correlation between recent star formation and high ram pressure, as defined by Kapferer et al. (2009) as ≥ 5 x 10-11 dyn cm-2, was tested and lead to a contradiction of the previously held belief that ram pressure influences star formation on the global cluster scale
Female color preferences, ecological selection, and the evolution of male coloration in darters (Percidae: Etheostomatinae)
No full textSince Charles Darwin's initial observations and hypotheses, the evolution of elaborate male coloration in sexually dichromatic species has been the subject of great interest. Of particular recent interest is how sexual and ecological selection interact to shape variation in male coloration between closely-related species. Using darters (Percidae: Etheostomatinae), a group of fishes that vary in male coloration as a model system, my goal is to determine how sexual and ecological selection interact to shape variation in male coloration between as well as within species lineages. In Chapter 1, I used reflectance spectrophotometry to examine correlations between spectral properties of orange and blue pigmentation in the rainbow darter, Etheostoma caeruleum, with parasite load and observed a correlation between the chroma of orange bars with parasite counts. In Chapter 2, I quantified color preferences in the darter genus Etheostoma to determine if the strengths of attraction to different colors coincided with variation in male coloration between species. The females of most achromatic species exhibited no significant color preferences, while chromatic species varied in preferences, with a positive association between the presence of red or orange on the flanks and preference for red detected across all species. In Chapter 3 I utilized phylogenetic comparative approaches and a laboratory experiment of predator color preferences to quantify the role of ecological variables in shaping variation in male coloration in darters. Compared to achromatic species, chromatic darters tend to inhabit environments where predation risk would be lower; specifically, shallower, faster-flowing upland streams with a lower number of overlapping predatory species. Additionally, a common darter predator, largemouth bass (Micropterus salmoides), exhibited significant preferences for red stimuli in a color choice experiment. Finally, in Chapter 4 I investigated color and size correlations, as well as male and female preferences for different sized and colored mates, in the Roanoke darter, Percina roanoka. Using digital photography I found correlations between size and color, but no preferences for larger or more colorful mates were observed in either sex. The results of this dissertation suggest that sexual and ecological selection do interact to shape color variation between darter species
Performance Evaluation of Probabilistic Latent Semantic Analysis for Unstructured Social Media Data
No full textBig data analytics is being applied in many fields today to mine unstructured data such as social media blogs or medical records. We focus this thesis on two popular analysis techniques, the methods of Latent Semantic Analysis(LSA) and Probabilistic Latent Semantic Analysis(PLSA), both used for interpreting or extracting concepts and relationships from data. As a use case, we propose to compare their performances in identifying communities from Twitter data sets during natural disasters such as Hurricanes. Latent semantic analysis uses statistical computations, typically singular value decomposition, to find semantic or contextual meaning from the data. It finds relationships between terms and concepts in an unstructured data set. Probabilistic latent semantic analysis or indexing is another method based on Bayesian analysis that typically is used for two-mode data. The objective is to compare these two methods on a large set of social media documents related to Hurricane Sandy in order to form clusters of similar concepts. We then compare the performance of these two methods to determine their relative performance in determining communities and hidden topics, e.g. finding clusters of similar topics like power outages, floods, gas outages, etc. We apply two clustering methods, K-Means and Affinity Propagation to form clusters in the data. Finally, we present the results by applying external methods of evaluation after creating a test data-set to compare the performance of these two methods. Metrics like Precision, Recall, confusion matrix are used to evaluate the performance of our system. The evaluation showed us that in almost all the scenarios, PLSA works better than LSA in finding out hidden relationships and structures. Whereas LSA is slightly faster than PLSA
The Exploration of Stimulate Raman Processes in Rb85 using Dual Amplitude Pulses
No full textAtom interferometers are at the heart of the next generation of sensor device technology. Currently, atom interferometers are at the center of an atomic clock as well as atomic gryoscopes. In applications at the Naval Air Station in Patuxent River, MD, atom interferometers will be used in creating atomic magnetic field gradiometers. The research done in the atomic Physics lab in Patuxent River, MD is to develop this new technology for magnetic field gradiometers. To develop such technology, pulse shapes and pulse sequences are explored. This thesis will explore theory of atom interferometers as well as a specific pulse shape (the dual amplitude pulse) and its implications in atom interferometry
Finding trust in relational vulnerability: Interpersonal and intrapersonal influences on the intimacy process
No full textTheory suggests that intimacy in romantic relationships increases when one's vulnerability exposure is validated and decreases when one's partner is invalidating. Relational vulnerabilities increase vulnerable feelings for both partners and thus should be less likely to create intimacy. The present study examines whether interpersonal (vulnerability occurrence) and intrapersonal (attachment and mindfulness) factors influence couples' intimacy/distance during relational vulnerability discussions. Attachment style and mindfulness were hypothesized to moderate the effect of vulnerability occurrence on intimacy/distance during a discussion of that vulnerability. Hypotheses, tested with 81 newly married couples, were not supported. Main effects for avoidant attachment and mindfulness were found. Higher avoidant attachment predicted lower intimacy for both spouses and wives higher mindfulness predicted higher intimacy. Exploratory analysis suggested level of trust in one's partner regarding the vulnerability topic is a better indicator of vulnerability than occurrence. This research highlights the roles of mindfulness, attachment, and relational vulnerabilities in intimacy processes
A Mother's Inheritance: Women, Interracial Identity, and Emancipation in Maryland, 1664-1820
No full textInspired by my work at a local historic house museum in Maryland, I began this project with the intention of rejuvenating the interpretation of slavery at the particular site through the use of a scripted monologue that will be accompanied by a lecture. This public history thesis project is divided into three parts: an overview of museum theatre and public interpretation of slavery; a historical essay that will serve as a companion to the scripted monologue; and then the monologue itself. The monologue is designed to challenge audiences to reevaluate their preconceptions about the history of race and slavery, as well as the relationships that enslaved people had with the justice system. The historical essay is designed to provide the performer with the historical context for the production. From the late seventeenth- to early nineteenth-centuries, a series of laws were passed in Maryland that strengthened the institution of slavery as the prominent labor system. These laws held an equal influence over the concept of race, as it evolved from a fluid to a fixed model. Despite these changes, enslaved people often demonstrated cunning as they learned to use the legal system for their own purposes. Utilizing the story of one enslaved family of women, freedom petitions demonstrate not only how, over six generations, the law came to define race, but also the local impact of such changes through the examination of witness, plaintiffs, defendants, judges, and lawyers
Engaging Community: Art and Food in Baltimore City
No full textA Full Plate marks the culmination of three years of actions in Southwest Baltimore. Through my work, I seek to generate a critical dialogue about food justice, which is defined as a community's right to access healthy food. The installation in the CADVC is a three-walled grid comprised of 317 ceramic dinner plates painted by attendees of workshops focused on personal food histories and our role in food systems. My artistic practice, which is defined by direct engagement with community groups and an emphasis on dialogical forms, has a long legacy within the history of art. The form itself is defined by flexibility in process and in semantics; both the creative practices and the vocabulary we use to define and critique them are changing constantly. This paper analyzes socially engaged artist projects, and describes my own artistic practice, positioning it within the contemporary sphere of socially engaged art