University of Maryland, Baltimore County
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UNDERSTANDING NATALITY DATA USERS' PERCEPTIONS AND PREFERENCES TOWARDS a QUERY BASED NOISE ADDITION APPROACH BASED ON DIFFERENTIAL PRIVACY
No full textThis study aims to understand natality data users' perceptions towards the noise-added query answering approach. To this end, a web-based query interface has been developed to allow natality researchers to issue queries and receive noise-added results based on the differential privacy approach. A survey instrument has been developed to understand data users' perceptions and preferences towards this web-based querying system. To design the survey, the goal question metric paradigm is followed to define a measurement framework for differential privacy acceptance, in which, the survey questions are purposeful and quantitatively measurable. The pilot survey has provided a useful feedback. In the light of this feedback, a training tool is suggested to improve the study instrument in the full-scale project. The purpose of this tool is to set the context for the survey questions and provide in-depth information about differential privacy. In the long run, this survey will be controlled by the traditional statistical disclosure control in a comparative study, so that users will be given the chance to determine their preferences based on their research requirements
IDENTIFICATION OF NOVEL C. ELEGANS WNT SIGNALING TARGETS FUNCTIONING IN THE SPECIFICATION AND DIFFERENTIATION OF LARVAL SEAM CELLS AND VULVAL PRECURSOR CELLS
No full textThe Wnt signaling pathway is one of the key extracellular pathways involved in many developmental processes in vertebrates and invertebrates. In the nematode C. elegans, the two Wnt pathways named the Wnt/BAR-1 canonical (WBC) pathway and the Wnt/β-catenin asymmetry (WBA) pathway function in cell fate specification, polarity and migration. We and others have shown that the WBC pathway functions in the specification of the vulval precursor cells (VPCs) that form the hermaphrodite vulva, and the WBA pathway functions in the specification of epithelial seam cells during their larval asymmetric stem cell-like divisions. My research project has focused on the identification of Wnt signaling targets functioning in the VPCs and seam cells using microarray analysis. The Wnt pathway was over-activated in worms using a heat shock inducible stable variant of BAR-1/β-catenin, and under-activated using a dominant negative variant of POP-1/TCF. The transcript pools from the VPCs and seam cells were enriched by the `mRNA tagging' method and I used microarray analysis to identify 240 putative Wnt pathway targets showing an average fold change of ≥ 1.5 in the Wnt pathway over-activation samples compared to the under-activation samples. Of these, expression analysis and phenotypic characterization was conducted for 50 genes. I found 29 genes are expressed in the seam cells, hypodermis and/or vulval cells during larval development. RNA interference and mutant analysis revealed five genes with defects in terminal seam cell number. This work has also uncovered a previously unexplored role of Wnt signaling and of eight putative Wnt targets in influencing the lateral fusion of differentiated seam cells, and formation of the cuticular structure called alae. Additionally, 12 putative Wnt targets showed defects in vulval induction, differentiation and morphogenesis. I have also identified the GATA transcription factor encoding genes egl-18 and elt-6, which are known embryonic regulators of seam cell specification, as putative Wnt targets in larval seam cells. Genetic and epistasis analysis suggests that these factors act reiteratively downstream of the Wnt pathway in specifying seam cell fate during larval asymmetric seam cell divisions, unraveling a novel connection between two important regulators of seam cell fate specification. Finally, I have defined for the first time, the L2/L3 larval transcriptome of the seam cells and VPCs. This work has filled a significant gap in our understanding of C. elegans Wnt targets functioning in seam cell and vulval development
COMPLETELY NON-INVASIVE MONITORING OF DISSOLVED OXYGEN IN DISPOSABLE SMALL SCALE CELL CULTURE DEVICES
No full textIncreased emphasis on Process Analytical Technology (PAT) requires that process be monitored at every scale. However, even though large scale systems are equipped with monitoring capabilities, small scale vessels are usually not monitored. Minimally invasive, disposable fluorescence based sensing patches which can be placed inside small scale vessels to monitor Dissolved Oxygen(DO) are now available but concerns regarding the effect of patches on cell cultures has limited their use. A new, completely non-invasive, method of monitoring DO has been suggested and implemented here. Sensor patch is placed and sealed outside gas permeable cell culture device and oxygen diffusing through its wall is detected by the patch. This is implemented for two types of vessels: T-flask and Vuelife� FEP bag. It has been shown that the outside patch follows the inside patches quite well and is capable of detecting DO concentrations in the range of interest for a mammalian cell culture
High Dimensional Time Series: Mean Vector Testing and Testing for Autocorrelation Matrices
No full textMultivariate analysis has undergone radical changes in the recent past with the advent of the so-called ultra high-dimensional data sets. Standard procedures cannot be applied for analysis of such data sets as they are all developed based on the assumption that the sample size is larger than the dimension of the data. Two different families of tests have been proposed so far for mean vector testing in high-dimensional case, but they work only when the observations are assumed to be independently and identically distributed. We propose a new testing procedure when the observations are dependent. Asymptotic normality of the proposed test statistic is derived under the assumption that the data is a realization of a M-dependent strictly stationary process. The proposed test is also extended to the two sample case. Another aspect of multivariate analysis is testing independence of the variates. Likelihood ratio based tests for testing independence of variates assume independence amongst the observations. An extension of this problem to the time series setting is considered, with emphasis on testing the equality of correlation matrices at lag zero. A Wald-type test statistic is proposed for testing equality of correlation matrices between two dependent groups. Construction of a MANOVA model for Resting State Networks(RSN) in brain imaging is discussed. The derived results are applied to validate the reproducibility and reliability of RSNs and compare several data pre-processing techniques. In multiple testing, estimation of the number of hypotheses accepted is of importance in certain problems. Measuring the proportion of accepted nulls gives a measure of sparsity of the noise. When the number of hypotheses to be tested is in millions, testing each hypothesis can be disregarded to estimate the proportion of accepted hypotheses. We study the properties of an empirical characteristic function based estimator for exponentially distributed signals. An iterative bias correction procedure is applied to improve the performance of the estimator. A non-parametric approach based on level set estimators is proposed
Toward Mid-Infrared Photonic Integration
No full textThe mid-infrared (Mid-IR) wavelength range is important for applications including medical and security imaging, environmental trace gas sensing and free space communications. However, photonic integrated circuits (PICs) in the mid-IR range are under-developed which significantly slows the possible reduction of mid-IR system size, weight, and coupling losses and limits the development of highly functional mid-IR photonic modules with lower cost. In this dissertation, a solution to mid-IR photonic integration was demonstrated using a compact, widely tunable mid-IR transmitter and a mid-IR amplifying photo-detector, both which can be integrated with the mid-IR source. This integrated widely tunable mid-IR source is fabricated by incorporating a super structure grating (SSG) to a mid-IR quantum cascade laser (QCL) waveguide. The emission wavelength of the fabricated SSG-DBR QCL can be well controlled by varying the injection currents to the two grating sections of the device. The wavelength can be tuned from 4.58 um to 4.77 um (90 cm-1) with a supermode spacing of 30 nm. This SSG-DBR QCL can be a compact replacement for the external cavity QCL used in current mid-IR sensors. Mid-IR amplification and detection was achieved using the same material as the mid-IR source. This QCL amplifier has an adjustable bandwidth and tunable gain peak, so it can function as a tunable mid-IR filter. By biasing the QCL just below its threshold, we demonstrated more than 11-dB optical gain and over 28-dB electrical gain at specified wavelengths. In the electrical gain measurement process, the resonant amplifier also functioned as a detector. This indicates that intersubband-based gain materials are ideal candidates for mid-IR photonic integrations. Beside the optimized fabrication processes, a new characterization technique based on the electrical derivative of the QCL I-V curves is used to quickly acquire the QCL threshold and leakage current, and explore the device carrier transport. The leakage currents present in different QCL waveguide structures are also studied and compared using this technique. Finally, we report on the wavelength induced optical quenching effects on mid-IR QCLs when the QCLs are operated well above their threshold. The quenching effect is a result of intersubband band bending and it depends on the coupled near-IR intensity, wavelength, and the QCL voltage bias. The quenching effects not only can be used for mid-IR QCL optical switching and modulation but they also reveal that the mid-IR QCLs can function as converters to convert the telecom optical signal into the mid-IR optical signal at the near-IR fiber end. A coherent mid-IR transceiver with both transmitting and receiving functions can be realized based on each integrated component introduced in this dissertation. This compact transceiver includes an integrated widely tunable mid-IR source, a mid-IR filter, amplifier, and detector based on the same material system
Social Media Analytics - Digital Footprints
No full textIn this work we describe an approach to distinguish real and impostor/compromised accounts on social media. Compromising a user's social media account is not only a breach of security, but can also lead to dissemination of misinformation at a fast pace on social media. There have been several such high profile attacks recently, including on Twitter feeds of AP, CBS, and Delta Airlines. A fake account for the Prime Minister's Office (PMO) in India was used to spread malicious rumors last year. Our approach builds a digital social footprint of users using both the content of their tweets and the structure of their social network. We analyze the real time content of users' tweets and compare it with information about them from reliable sources on the web (newspapers / news channels etc.)to compute a similarity metric. We also compute a metric based on the social network analysis of the users -- who connects to them, who they are connected with, and how central they are in their network. We have shown how these metrics combined judiciously can detect fake accounts for not just well known people such as President Obama, but also for lesser known people and organizations. We also show promising initial results on how this approach can be used to detect an account which has been hacked
Emergency Medical Services Innovation: Comparison of Outcomes for Access and Referral in Two North Carolina Systems
No full textToo many patients with low acuity medical problems access Emergency Medical Services (EMS) and Emergency Departments (EDs) for care. EMS is a key component of the health care system. Historically, its function was to provide care for people who experience emergencies, transporting them to hospital EDs for further definitive diagnosis and treatment. Over the last two decades, EMS is caring for a growing percentage of people accessing 9-1-1 for less than serious emergency conditions. This phenomenon is an element of a health care crisis that includes rapidly escalating costs, increasing numbers of uninsured, poor access to consistent primary care and comparatively mediocre health outcomes. With crowded EDs, EMS innovators have been exploring alternatives to relieve these structural pressures by diverting patients from EDs to other venues, particularly primary care providers (PCPs). This study compares two alternatives in North Carolina. There are two models that have been piloted. The first found in Orange County involves an EMS response to every 911 request. Once a paramedic evaluates a patient, it is decided if transport to the ED is warranted or whether the patient can be treated on-scene and referred to their PCP. The second model employs a telephone triage system in which requests for service of a low severity type are diverted from the 911 call center to nurse call centers. Nurses use an evidenced-based, medically approved protocol to make the determination if the patient does not need an EMS response and, if not, provides advice to the patient and refers them to their PCP. More significant emergencies receive the normal EMS response that results in care and transport to the ED. Using primary data from the two service quality improvement programs, the primary question is whether there is a significant difference in effectiveness between the Evaluate, Treat and Refer (ETR) intervention and the Telephone Triage and Refer (TTR) intervention as measured by patient follow through with instructions for the referral to primary care and patient satisfaction. Major findings were that there was a significant difference between the two alternatives in that odds were greater that low acuity callers in Mecklenburg County would follow instructions for referral/and or self-care than the low acuity patients evaluated in person in Orange County. Patient satisfaction was high for both alternatives with only slightly higher odds that patients in Orange County would be satisfied. The Orange County ETR alternative used the ETR on a broader spectrum of patient conditions as compared to more conservative criteria used in the Mecklenburg County TTR alternative. This factor may explain the significant difference in following instructions. The high patient satisfaction rates for both alternatives is an indication people with low acuity but urgent medical problems are willing to accept alternatives to transport and treatment in the ED and high percentages follow the instructions given. While the Mecklenburg TTR model was less costly and had higher odds that patients would follow instructions, it entered a narrower range of patient problems into its alternative pathway. More research is needed to explore the difference in outcomes and patient behaviors of these alternatives and to examine hybrid systems that combine both TTR and ETR
Monolithically Integrated Photonic Devices for Reconfigurable Metro-optical Network
No full textThe main focus of this dissertation is to explore the planar lightwave circuitry (PLC) based photonics integration that can be used as optical switching subsystem such as a reconfigurable optical add and drop multiplexer (ROADM) and wavelength selective switch (WSS). Performance evaluations of key optical parameters of ROADM and WSS are also accomplished for a reconfigurable metro mesh optical network. A PLC ROADM or WSS are made of wavelength multiplexer/de-multiplexer and a switching fabric, which are constructed by waveguide couplings, waveguide bends and waveguide crossings. In this dissertation, first, generalized optimization schemes for waveguide crossing and low-insertion loss AWG are proposed, which are applicable to different PLC (index difference) materials. Devices based on silica-on-silicon material (=0.78% and =1.5%) and Silicon Oxynitride materials (=17%) have been made and tested to compare with the theoretical simulation results. Next, monolithically integrated 2-degree ROADM and 8-Degree WSS devices are designed and fabricated. The first 2D-ROADM is to support 4 color-less add drop ports and 40 wavelengths, the 2nd 2D-ROADM is expandable to support 21 wavelengths. The network applications enabled by this expandable design is discussed. The WSS is to support 40 wavelength and 8 network MUX/DEMUX ports. An efficient scheme by multiple path interference (MPI) information in the output signals to pinpoint the defect region for a large scale integrated photonic devices proposed. The last part focuses on the performance evaluation of optical switching system in a reconfigurable metro optical network. A statistical methodology is proposed to evaluate the penalty of the receiver optical signal to noise ratio (R-OSNR). Real device statistical information is employed and the model is verified by the field measurement of OSNR penalty
Optimal Portfolio Withdrawal Strategy for Retirees
No full textIndividual's and couple's entering retirement face an uncertain future. They have to decide how to manage their savings so that they live the fullest life possible from a financial standpoint, while minimizing the risk of outliving their money. To get the best financial growth, retirees should invest their savings in a portfolio consisting of equity and fixed income securities. We use dynamic programming to maximize annual portfolio withdrawals dependent on mortality tables and stochastic models for stock and bond returns. We call our approach the Dynamic Forecasting (DF) approach because it assumes that the retiree's portfolio will repeat its past performances in the future. Two variations on the DF approach are the relaxed DF approach and the alternate DF approach. These provide two opposite withdrawal structures while guaranteeing a 0% probability of failure. Our strategy is compared with the Constant Dollar (CD) approach and the Endowment approach, also known as the Constant Percentage approach (CP), using the Withdrawal Efficiency Rate (WER) metric. The strategies are compared under increasing, decreasing, and constant equity glide paths. The DF and alternate DF approaches outperform the other strategies under the WER metric and are the only strategies evaluated that a probability of failure of zero and are guaranteed to not leave money unspent at the end of the retirement period
GEORGE WASHINGTON'S LABORING WOMEN: AN EXAMINATION OF THE WORK AND LIVES OF THE ENSLAVED FEMALE FIELD WORKERS AT MOUNT VERNON'S OUTLYING PLANTATIONS, 1785-1787
No full textAbstract: The strenuous labor of the enslaved women who worked as unskilled hands on the outlying properties at George Washington's Mount Vernon is the focus of this thesis. Through a close examination of Washington's farm and plantation records from 1785-87 as well as scrutiny of his diary entries, letters, and other writings from this time period, this thesis crafts a detailed picture of the kinds of work women enslaved at Mount Vernon's outlying farms carried out and how they dealt with so-called gang work assignment patterns. Moreover, it sheds light on these women's roles as nursing, pregnant, and caregiving mothers within the context of their demanding work lives. This thesis posits that though enslaved men were certainly pivotal in the transition to diversified agriculture in the eighteenth-century Chesapeake, enslaved women performed many of the tasks that were vital to the success of that transition at Mount Vernon. Finally, this thesis argues that the fact that women did many of the monotonous and difficult tasks that were key this transition paved the way for enslaved men to gain opportunities for skilled labor.