ANALYSIS AND IMPLEMENTATION OF SIGNAL PROCESSING STRATEGIES FOR A 3-D DOPPLER LIDAR WIND PROFILER
Year of Dissertation:
2012
A heterodyne detection fiber optic based wind lidar system has been developed and tested, which benefits from unique field programmable gate array (FPGA) signal processing techniques and leverages devices from the telecommunication industry to make it particularly cost efficient. A narrow band stabilized fiber laser, polarization maintaining fiber amplifiers, acousto-optic modulators and an optical circulator comprise the transmitter which is coupled to free space using refractive optics. The collinear propagating lidar return signal that scatters off of atmospheric aerosols and in a heterodyne arrangement beats with a local oscillator and is then detected using a shot noise limited polarization maintaining balanced receiver. The system, which operates at a 20 kHz pulse repetition rate and acquires lidar return signals at 400 MSample/second, accumulates signals that are as much as 20 dB lower than the receiver noise power by using embedded programming techniques. For this reason two FPGA embedded programming approaches are considered and compared. In the first approach, the acquired return signal is gated in time and the square modulus of the fast Fourier transform is accumulated for each range gate, producing a series of power spectra as a function of range. Wind speed estimates based on numerical estimators can then be made after transferring the range gated accumulated power spectra to a host computer, enabling line of sight wind speed to be calculated as a function of range gate and stored for additional processing. In the second FPGA approach, a digital IQ demodulator and down sampler reduces the data flow requirements so that an autocorrelation matrix representing a pre-selected number of lags can be accumulated, allowing for the process of range gating to be explored on the host computer. The Fourier transform of the autocorrelation produces the power spectrum and, in the same manner as the first approach, estimates can then be made regarding the line of sight wind speed. The added feature of the second approach is that it allows for an additional capability to adjust the range gate period dynamically as the state of the atmospheric boundary layer (e.g. backscatter coefficient and stability condition) changes. A simple manual beam scanning technique is used to sample three line of sight directions and, by making suitable assumptions regarding the coherence of the averaged wind fields, the three dimensional wind field vector (representing both the horizontal wind speed and direction and the vertical wind speed and direction) is calculated and graphically displayed on time-height cross section plots. Precision in the velocity measurements is estimated to be on the order of 0.08 m/sec and the precision in the measured horizontal wind direction is estimated to be to be about 2 degrees, where both of these estimates are made assuming a relatively short 3-beam cycle time (less than 2 minutes) and a typical backscatter coefficient and atmospheric stability condition. A comparison to other observed wind information is presented which indicates that this lidar will open new doors for the practical characterization of microscale meteorology.
Prosodic Phrasing and Modifier Attachment in Standard Arabic Sentence Processing
Year of Dissertation:
2010
This dissertation investigates the syntax-prosody interface in Standard Arabic, focusing on the ambiguity of a modifier (relative clause or adjective phrase) in relation to the two nouns in a complex noun phrase. Ambiguity resolution tendencies for this construction differ across languages, contrary to otherwise universal parsing tendencies. One explanation proposed is Fodor's (2000) Implicit Prosody Hypothesis: that readers mentally project onto a text a default prosodic phrasing (possibly different between languages), which then influences their syntactic ambiguity resolution.
MIDDLEWARE ROUTING ALGORITHMS COMPONENTS FOR MOBILE AD-HOC WIRELESS NETWORKS
Year of Dissertation:
2010
In this research, we introduce middleware routing algorithms components for Mobile
Clustering Categorical Data Using Data Summaries and Spectral Techniques
Year of Dissertation:
2009
Cluster analysis is an active area of research with applications in various fields including information retrieval, social sciences, bioinformatics, object recognition, and image segmentation (Jain et al., 1999). However, most algorithms are intended for numerical (continuous) data where proximity among data objects is naturally defined by virtue of their numerical properties. Although these algorithms can be used on categorical data, they are not designed to handle data properties typically found in this data type such as high dimensionality and lack of inherent relationships among attribute values. During the past decade, several algorithms have been designed for categorical data such as K-modes (Huang, 1998), STIRR (Gibson et al., 1998), CACTUS (Ganti et al., 1999), ROCK (Guha et al., 1999), COOLCAT (Barbara et al., 2002), LIMBO (Andritsos et al., 2004), CLICKS (Zaki et al., 2007), and others. Some of these algorithms exploit attribute relationships through data summaries such as attributes occurrence and co-occurrence frequencies while others use information entropy and links among data objects. In this thesis, we focus on using data summaries and spectral analysis to detect clustering structure in categorical data. Spectral techniques provide a relaxed solution to the discrete clustering problem which has been shown to be NP-hard (Drineas et al., 2004). Formulating the clustering problem as a graph partitioning problem and then finding the minimum normalized cut leads to a solution based on eigenvectors of the similarity matrix (i.e. Laplacian matrix). Spectral methods have been used in various algorithms and have been shown to find non-linearly separable clusters. Equally important, spectral analysis encompasses techniques for handling high-dimensional data since input data is projected into a lower-dimensional space where all computation/comparisons can be performed. Our approach is to extend spectral techniques to data summaries which are relatively less expensive to compute than data object similarity matrix for very large data sets. Our goal is to combine the benefits of spectral analysis with the relative low cost of computing data summaries. We have developed three algorithms for clustering categorical data using data summaries. Two of them use spectral techniques. Our test results on standard data sets and synthetic data sets show that our algorithms are competitive with current spectral and non-spectral algorithms for categorical data. Our algorithms provide a solution to the categorical data clustering problem that produces quality clustering and is scalable to large data sets.
Psychophysical and electrophysiological assessment of early visual processing and emotion recognition deficits in schizophrenia
Year of Dissertation:
2011
Previous data suggest that patients with schizophrenia have preferential magnocellular (M) versus parvocellular (P) visual dysfunction. The goal of Experiment 1 was to characterize M–stream impairment in the patient population using a novel approach. Contrast thresholds at varying luminance levels were investigated. M– and P–biased responses were examined by using scotopic and photopic luminance conditions, respectively. Patients exhibited contrast threshold deficits during scotopic conditions, indicative of M–stream dysfunction. Further, the pattern of contrast threshold responses at photopic levels indicated relatively preserved patient P–pathway functionality.
THE MARITAL STATE: PERSONAL STATUS LAWS, DISCOURSES OF REFORM, AND SECULARISM IN LEBANON
Year of Dissertation:
2012
An important aspect of the modern Lebanese state is the arrangement of personal status laws, which consigns matters of marriage and its consequences to the several Islamic, Christian, and Jewish religious authorities. With the absence of civil jurisdictions, some individuals choose to get married under the civil laws of countries, such as France, Cyprus, and Turkey. Recurrent attempts to make civil marriage in Lebanon legal have proven to be controversial and ended ultimately in failure. The problem of marriage has accompanied the system of personal status since the formation of the Lebanese state under French Mandate after the collapse of the Ottoman Empire. This dissertation aims to offer an account of what is at stake in marriage. Based on ethnographic and archival research in Lebanon, it analyzes the terms of the controversies over legal reform, opinions about civil marriage, as well as the decisions of the Maronite Catholic, Sunni Islamic, and civil courts in matters of personal status. It argues that at stake in marriage is the very assumption upon which the modern Lebanese state rests, namely, that Lebanon consists essentially of a variety of religious communities each possessing a distinctive personal status. The formal articulation of that status is the several religious personal status jurisdictions that oversee marriage. This assumption gives rise to a specific configuration whereby marriage, religious communities, and the state, are interconnected. Rather than adopt a perspective that sees in the problem of marriage an opposition between secularism and religion, this study seeks its conditions in tensions internal to the secular itself, in the ambiguities between moral autonomy and religious belonging, freedom and equality, religion and law.
Real-time Measurement of Glial Progenitor Chemotactic Migration
Year of Dissertation:
2012
Gliomas are the most commonly diagnosed form of central nervous system tumors, occurring primarily in adults. Like many malignant cancers, gliomas pathologically exhibit very aggressive spreading and lead to an average diagnosed survival expectancy of twelve months. This prognosis is due in large part to the uncontrolled division and migration of malignant tumor cells within healthy brain, which makes complete surgical resection impossible. Gliomas are known to contain numerous genotypic and phenotypic alterations that affect cell proliferation and survival. Previous research has indicated that both gliomas and their precursor cells exhibit distinct migration patterns in brain tissue, which may be induced by specific cytokines and their concentration gradients. Here, we investigated the migration of four brain tumor cell (BTCs) lines (U-87 MG; U-251 MG; Daoy; and XFMPDGF) and three RCAS-infected glial progenitor cell (GPCs) populations (GPCLacZ, GPCPDGF, and GPCkRas) toward various growth factors, including but not limited to: EGF, HGF/SF, PDGF-BB, and TGF-α.
The effects of estrogen on carrageenan-induced nociceptive behaviors and inflammatory mediators in ovariectomized female mice
Year of Dissertation:
2010
Advisor:
Vanya Quinones-Jenab
Epidemiological studies have shown that pain perception is sexually dimorphic; females tend to experience greater sensitivity to painful stimuli and more chronic pain compared to males. Researchers believe that this dichotomy is caused by the distinct endocrinological profile of females. 17beta -estradiol has been shown to attenuate inflammatory behaviors in both the formalin and carrageenan (Cg) models of inflammation. Research also shows that estrogen affects many inflammatory mediators, including proinflammatory cytokines and prostaglandins (PG). Estrogen plays an important, yet complicated role, in inflammation, and little is known about the specific biochemical mechanisms involved. The objective of this study is to determine if, similar to rats, estrogen attenuates Cg-induced thermal hyperalgesia by altering cytokine or PG release. To that end, female OVX mice were pretreated with various doses of estradiol and injected with 1% Cg. Paw withdrawal latency was recorded prior to, 1 hour, and 5 hours after Cg-treatment in response to a low, medium, and high heat stimuli. Additional animals were treated with indomethacin, a COX blocker. High doses of estradiol caused an increase in nociceptive responses prior to and subsequent to Cg administration. This increase in these pain behaviors was not directly caused by an increase in proinflammatory cytokine levels or a decrease in anti-inflammatory cytokines levels. However, estradiol caused increases in cytokine levels in the untreated paw. Furthermore, treatment with indomethacin caused an attenuation of hyperalgesia. Additionally, indomethacin negated the difference between estradiol- and vehicle-treated mice, indicating that estrogen may interact with prostanoid synthesis. This effect, however, was not seen in the Cg-treated paw, suggesting that estradiol may be increasing hyperalgesia via another pathway as well. Taken together, our results suggest that estrogen's hyperalgesic effects are partly mediated through cytokine up-regulation and prostanoid synthesis, but the main mechanism of action still needs further investigation.
Registered Sex Offenders in the Community: A Test of Agnew's General Strain Theory
Year of Dissertation:
2009
Over the past two decades, sexual offending and offenders have become a topic of interest among researchers, policymakers, and the public. Since the inception of Registration and Community Notification Laws (RCNLS), researchers have assessed the negative consequences associated with the laws and how they affect sex offenders in the community; however, no study has utilized a criminological framework to do so. Agnew's General Strain Theory, which should be able to account for all crime, suggests that when individuals do not achieve desired goals, have negative stimuli placed on them or positive stimuli taken away, they are more likely to engage in crime. These are conditioned by certain factors, such as coping strategies and self-esteem. This study will synthesize these two distinct fields of research to determine whether the negative consequences of RCNLSs lead to recidivism. In all, surveys were mailed to 4,500 sex offenders with (N=997) in Nebraska, (N=2086) and (N=1417) sex and violent offenders in Kansas and Montana, respectively. These states are similar in population and demographic aspects, though they differ in RCNLSs. Findings lend partial support to GST and suggest that, consistently, anger influences recidivism.
Building the New American Nation: The U.S. Army and Economic Development, 1787-1860
Year of Dissertation:
2011
Program:
Political Science
This dissertation examines the Army's integral role in the early American political economy. Notwithstanding its small size, the Army proved to be a powerful instrument for promoting economic expansion and guiding the pattern and direction of development. The Army spurred development through two lines of activity: first, the traditional application of coercion and, second, by providing public goods that neither private actors nor state governments could supply. Considering the Army leads me to reconceptualize the early American state as a bifurcated entity: a state of the periphery, dominated by the Army, and a state of the center, in which the Army still influenced economic development but other public institutions also performed key development functions.