VictorJuiz/thesis huggingface dataset:
Signal Processing Methodologies for Resource-efficient and Secure Communications in Wireless Networks

Future-generation wireless and mobile networks are expected to support a panoply of multimedia services, ranging from voice to video data. There is also a de facto "anytime anywhere" mentality that reliable communications should be ubiquitously guaranteed, irrespective of temporal or geographical constraints. However, the implicit catch is that these specifications should be achieved with only minimal infrastructure expansion or cost increases. In this thesis, various signal processing methodologies conducive to attaining these goals are presented. First, a system model that takes into account the time-varying nature of the mobile environment is developed. To this end, a mathematically tractable basis-expansion model (BEM) of the communication channel, augmented with multiple-state characterization, is proposed. In the context of the developed system model, strategies for enhancing the quality of service (QoS), while maintaining resource efficiency, are then studied. Specifically, dynamic channel tracking, adaptive modulation and coding, interpolation and random sampling, and spatiotemporal processing are examined as enabling solutions. Next, the question of how to appropriately aggregate these disparate methods is recast as a nonlinear constrained optimization problem. This enables the construction of a flexible framework that can accommodate a wide range of applications, to deliver practical network designs. In particular, the developed methods are well-suited for multi-user communication systems, implemented using spread-spectrum and multi-carrier solutions, such as code division multiple access (CDMA) and orthogonal frequency division multiplexing (OFDM). Moreover, privacy and security requirements are increasingly becoming essential aspects of the QoS paradigm in communications. Combined with the advent of novel security technologies, such as biometrics, the conventional communication infrastructure is expected to undergo fundamental modifications to support these new system components and modalities. Therefore, within the same framework for maximizing resource efficiency, several unique signal processing applications in network security using biometrics are also investigated in this thesis. It is shown that a resource allocation approach is equally appropriate, and productive, in delivering efficient and practical key distribution and biometric encryption solutions for secure communications.

Keywords: signal processing, resource allocation, communication systems, biometric security
Advisor: Hatzinakos, Dimitrios
Substrate Specificity and Regulation of Nedd4 proteins

Nedd4-1 and Nedd4-2 are closely related E3 ubiquitin protein ligases that contain a C2 domain, 3-4 WW domains, and a catalytic ubiquitin ligase HECT domain. The WW domains of Nedd4 proteins recognize substrates for ubiquitination by binding the sequence L/PPxY (the PY-motif) found in target proteins. Nedd4-2 functions as a suppressor of the epithelial Na+ channel (ENaC), which interacts with Nedd4-2 WW domains via PY-motifs located at its C-terminus. The importance of Nedd4-2 mediated ENaC regulation is highlighted by the fact that mutations affecting the ENaC PY-motifs cause Liddle syndrome, a hereditary hypertension. Since all Nedd4 family members recognize the same core sequence in their target proteins, the question was raised of how substrate specificity for Nedd4 family members is achieved. Using intrinsic tryptophan florescence to measure the binding affinity of Nedd4-1/-2 WW domains for their substrate PY-motifs, we demonstrate the importance of both PY-motif and WW domain residues, outside the core binding residues, in determining the specificity of WW domain-ligand interactions. Little was known about regulation of catalytic activity for this family of E3 ligases, and hence was the second focus of my work. Notably, Nedd4-2 contains a PY-motif within its HECT domain, raising the possibility that its catalytic activity is regulated by an interaction between its WW domains and HECT domain. Here I present evidence supporting a model in which a low-affinity interaction between the Nedd4-2 WW domains and its HECT domain regulate Nedd4-2 stability by preventing self-ubiquitination and subsequent degradation. Furthermore, evidence is presented suggesting that interaction between Nedd4-2 and the RING-E3 ligase Rnf11, a Nedd4-2 substrate, may also serve to regulate Nedd4-2 stability, as this interaction leads to decreased Nedd4-2 self-ubiquitination. Collectively, the studies presented here further our understanding of the substrate specificity and regulation of Nedd4-1 and Nedd4-2.

Advisor: Rotin, Daniela
Approximation and Refinement Techniques for Hard Model-checking Problems

Formal verification by model checking verifies whether a system satisfies some given correctness properties, and is intractable in general. We focus on several problems originating from the usage of model checking and from the inherent complexity of model checking itself. We propose approximation and iterative refinement techniques and demonstrate that they help in making these problems tractable on practical cases. Vacuity detection is one of the problems, relating to the trivial satisfaction of properties. A similar problem is query solving, useful in model exploration, when properties of a system are not fully known and are to be discovered rather than checked. Both of these problems have solution spaces structured as lattices and can be solved by model checking using those lattices. The lattices, in the most general formulation of these problems, are too complex to be implemented efficiently. We introduce a general approximation framework for model checking with lattices and instantiate this framework for the two problems, leading to algorithms and implementations that can obtain efficiently partial answers to the problems. We also introduce refinement techniques that consider incrementally larger lattices and compute even the partial answers gradually, to further abate the size explosion of the problems. Another problem we consider is the state-space explosion of model checking. The size of system models is exponential in the number of state variables and that renders model checking intractable. We consider systems composed of several components running concurrently. For such systems, compositional verification checks components individually to avoid composing an entire system. Model checking an individual component uses assumptions about the other components. Smaller assumptions lead to smaller verification problems. We introduce iterative refinement techniques that improve the assumptions generated by previous automated approaches. One technique incrementally refines the interfaces between components in order to obtain smaller assumptions that are sufficient to prove a given property. The smaller assumptions are approximations of the assumption that would be obtained without our interface refinement. Another technique computes assumptions as abstractions of components, as an alternative to current approaches that learn assumptions from counterexamples. Our abstraction refinement has the potential to compute smaller nondeterministic assumptions, in contrast to the deterministic assumptions learned by current approaches. We confirm experimentally the benefits of our new approximation and refinement techniques.

Keywords: formal methods
model checking
software verification
hardware verification
Advisor: Chechik, Marsha
Probing Mesocorticolimbic Dopamine Function in Alcohol Dependence Using Dextroamphetamine: Behavioural and FMRI Studies

Background: A dysfunctional mesocorticolimbic dopamine system has been reported in alcohol dependence and major depressive disorder. Probing mesocorticolimbic dopamine function in severe depression using dextroamphetamine revealed an altered behavioural response and a disrupted mesocorticolimbic circuitry in behavioural and functional magnetic resonance imaging (fMRI) studies. The purpose of this study was to use a similar approach in alcohol dependence. Behavioural Study: to assess dextroamphetamine subjective effects in alcohol-dependent and depressed alcohol-dependent participants. FMRI Study: to assess how the mesocorticolimbic circuitry would respond to a dextroamphetamine challenge in alcohol-dependent participants exposed to alcohol cues. Methods: In both studies, a single oral 30 mg dose of dextroamphetamine was the pharmacological intervention. Behavioural Study: randomized, double-blind, placebo-controlled, between-subject study. Eighteen alcohol-dependent and 22 depressed alcohol-dependent participants were compared using validated self-report drug effect tools (e.g. Addiction Research Center Inventory). FMRI Study: single-blind, between-subject study. FMRI blood oxygen level–dependent (BOLD) activation was measured in 14 alcohol-dependent and 9 healthy control participants during an alcohol-cue exposure task pre- and post-drug. Results: Behavioural Study: DRUG (F1,40=18.6; p<0.001) and GROUP (F1,40=16.6; p<0.001) main effects but no GROUPxDRUG interaction effects (F1,40=0.02; p=0.88) were detected, even when only severely depressed alcohol-dependent individuals were included (F1,30=0.04; p=0.84). FMRI Study: Alcohol-dependent participants exhibited greater ventral striatal activation compared to controls pre-drug and post-drug effect (F1,40=20.1; z=3.8; p<0.001; k>10; (x=10;y=-2;z=-14)). A GROUPxDRUG interaction effect was detected in the medial orbitofrontal cortex (mOFC) (F1,40=21.5; z=4.0; p<0.001; k>10; (x=-12;y=28;z=-20). The alcohol-dependent group exhibited a negligible mOFC response across both pre- and post-drug scanning sessions. In contrast, controls exhibited attenuation of mOFC response post-drug. Conclusion: The lack of significant GROUPxDRUG interaction effects in the Behavioural Study may suggest different neurobiological mechanisms underlying alcohol dependence and depression mesocorticolimbic dysfunction. Alcohol dependence appeared to mitigate the impact of depression severity on participants’ behavioural responses to dextroamphetamine. The FMRI Study data suggest there may be ventral striatal and mOFC disruption in alcohol-dependent participants. We suggest the mOFC may be involved in the reported loss of prefrontal modulation of dopamine cell activity in alcohol dependence. This supports a key role for the mOFC in mesocorticolimbic dysfunction in alcohol dependence.

Keywords: Alcohol Dependence
Mesocorticolimbic
Dopamine
Dextroamphetamine
fMRI
Advisor: Naranjo, Claudio
Sproule, Beth
Reshaping an Enduring Sense of Self: The Process of Recovery from a First Episode of Schizophrenia

Although many advances in the treatment of schizophrenia have been made over the past decade, little is known about the process of recovery from a first episode of schizophrenia (FES). To date, the study of recovery in the field of mental health has focused on long-term mental illness. This in depth qualitative study drew upon Charmaz’s (1990) constructivist grounded theory methodology to address the following questions: How do individuals who have experienced a FES describe their process of recovery? How does an identified individual (e.g. friend, family member, teacher, or clinician) describe their role during the participant’s process of recovery, and their perception of the recovery process? Ten primary participants (who self-identified as recovering from a FES) had two interviews; in addition, there was a one-time interview with a secondary participant, for a total of 30 interviews. Data collection sources included participant semi-structured interviews, participant selected personal objects that symbolized their recovery, and clinical records. The results provide a substantive theory of the process of recovery from a FES. The emergent process of recovery model for these participants is comprised of the following phases: ‘Lives prior to the illness’, ‘Lives interrupted: Encountering the illness’, ‘Engaging in services and supports’, ‘Re-engaging in life’, ‘Envisioning the future’; and the core category, ‘Re-shaping an enduring sense of self,’ that occurred through all phases. A prominent distinctive feature of this model is that participants’ enduring sense of self were reshaped versus reconstructed throughout their recovery. The emergent model of recovery from a FES is unique, and as such, provides implications for clinical care, future research, and policy development specifically for these young people and their families.

Keywords: First Episode Schiophrenia
Recovery
Sense of Self
Process of Recovery
Advisor: Goering, Paula N.
McCay, Elizabeth
The Immunoregulatory Role of FGL2 as a Novel Effector Molecule of Treg Cells

Background and Aim: CD4+CD25+ regulatory T (Treg) cells are important in the maintenance of self-tolerance, regulation of T cell homeostasis, prevention of allograft rejection and in the modulation of immune responses to pathogens. Several groups have recently reported an increased expression of fgl2 in Treg cells by microarray analysis. FGL2, a member of the fibrinogen-like family, was previously shown to act as an immunomodulator by inhibiting DC maturation and T cell proliferation. Based on these findings, the immunoregulatory role of FGL2 as a novel effector molecule of Treg cells was investigated. Results: In agreement with previous studies, high levels of fgl2 transcripts were detected in Treg cells by real-time PCR. In fgl2-/- mice, an increased number and percentage of Treg cells were found with a greater expression of Foxp3 compared with fgl2+/+ Treg cells; however, the suppressive activity of fgl2-/- Treg cells was significantly impaired. Antibody to FGL2 completely inhibited the activity of fgl2+/+ Treg cells in vitro. Consistent with FGL2 contribution to Treg cell activity, targeted deletion of the gene led to an increased immune reactivity of DC, T cells and B cells, and the manifestation of glomerular autoimmunity in aged fgl2-/- mice. The importance of FGL2 as an effector of Treg cells was also demonstrated in MHV-3-induced fulminant hepatitis. Uninfected susceptible BALB/cJ mice had increased numbers of Treg cells and expression of FGL2 compared to uninfected resistant A/J mice. Following MHV-3 infection, plasma levels of FGL2 in BALB/cJ mice were significantly increased, correlating with an increased percentage of Treg cells. Treatment with anti-FGL2 antibody completely inhibited Treg cell activity and protected susceptible BALB/cJ mice against MHV-3-induced liver injury and mortality. Adoptive transfer of fgl2+/+ Treg cells into resistant fgl2-/- mice increased their mortality following MHV-3 infection. Finally, FGL2 treatment led to prolonged skin graft survival in a murine allotransplant model. The suppressive activity of FGL2 was mediated through binding to the inhibitory FcγRIIB receptor expressed on APCs, resulting in inhibition of DC maturation and induction of B cell apoptosis. Conclusion: These studies indicate that FGL2 plays an important immunoregulatory role as an effector cytokine of Treg cells; targeting FGL2 may provide a novel therapeutic approach for the treatment of patients with viral hepatitis, autoimmunity and transplant rejection.

Keywords: Immunology
Regulation
Treg cells
FGL2
Advisor: Levy, Gary A.
Perceptions of Chinese International Students in Singapore: Adjustment Issues and Support

The number of students choosing to engage in international education is increasing. Typically, the United States has been the number one destination for international students but that has declined in recent years (2002 to 2006). This implies that international students choose to study in other English speaking countries or in countries that may be more similar in culture. The purpose of this study was to explore the thoughts, opinions, and experiences of undergraduate Mainland Chinese international students who were studying at a university in Singapore. The focus was to understand their perceptions of the adjustments issues they faced as international students. Twenty-one (21) students were interviewed using a semi-structured face-to-face technique. A review of the literature was conducted. The three major areas of difficulty identified were learning to speak English, weather, and food. The most helpful support reported by the Chinese international students was the ‘English Bridging course’. Overall, general adaptation to life and study in Singapore presented no major obstacles for the Chinese international students and this resulted in low utilization of and need for existing support services. The respondents reported that learning to speak English was the most difficult adaptation they encountered due to the widespread use of Mandarin and Singlish by the local population. Interestingly the issues identified in other research studies such as difficulty with general living adjustment, personal psychological adjustment, social adjustment, and culture shock were not supported in this research. Also, loneliness, homesickness, anxiety, lack of social support, and difficulty with finances were not identified as major issues for this group of Chinese international students. This led the researcher to conclude that the more similar a host country is to the home country in culture and language, the easier the general adjustment of the international student. Also, the researcher concluded that the similarity in language (Mandarin) from the home country (China) to the host country (Singapore) is both a negative and a positive – it can greatly and positively facilitate general adjustment of an international student but it can hinder the English language adjustment and learning. Suggestions for future research were included in this study.

Keywords: Higher Education
Advisor: Hildyard, Angela
Testing the Maternal Response Hypothesis in Cases of Suspected or Substantiated Child Sexual Abuse: Secondary Data Analysis of the Canadian Incidence Study of Reported Child Abuse and Nelect, 1998

This dissertation’s analyses examined the association of caregiver, child, abuse and investigation characteristics with maternal response and emotional harm among families for whom child sexual abuse (CSA) was suspected or substantiated. Method This study was based on secondary analysis of data collected in the Canadian Incidence Study of Report Child Abuse and Neglect 1998. The current analysis was limited to 373 CSA investigations for which there was a female non-offending caregiver and complete data on maternal response. Bivariate and hierarchical logistic regression analysis was conducted for two outcomes; maternal response and emotional harm. Results According to social worker assessment, the majority of female non-offending caregivers (87.1%) of children investigated for suspected or substantiated child sexual abuse responded with belief of the abuse disclosure, emotional support and protection of the child victim. The overall maternal response model was significant and accounted for 40.8% of the variance (Nagelkerke R2). Factors significantly associated with maternal response in the multivariate model included maternal mental health, age of the child, child’s manifestation of sexualized behavior, child’s relationship to the perpetrator, duration of abuse and co-occurring maltreatment. The overall emotional harm model was significant and accounted for 18.3% of the variance (Nagelkerke R2). Age of the child at the time of investigation, inappropriate sexualized behavior and substantiation level were significant predictors in the final block of the emotional harm regression equation. Maternal response was no longer significantly associated with emotional harm when the analysis adjusted for child characteristics. Conclusion Consistent with previous research, the majority of non-offending mothers investigated as part of the CIS-98 responded to CSA disclosure with belief, emotional support and protection as determined by the social worker’s assessment. The current study supports the cumulative evidence that caregiver mental health, age of the child and the child’s relationship with the offender are significant predictors of negative maternal response and emotional harm. Although negative maternal response failed to predict emotional harm among children investigated for CSA, continued examination of the risk factors associated with maternal response is warranted to ensure the safety of a small, yet vulnerable segment of children.

Keywords: Child sexual abuse
Maternal response
Advisor: Fuller-Thomson, Esme
Multi-factor Energy Price Models and Exotic Derivatives Pricing

The high pace at which many of the world's energy markets have gradually been opened to competition have generated a significant amount of new financial activity. Both academicians and practitioners alike recently started to develop the tools of energy derivatives pricing/hedging as a quantitative topic of its own. The energy contract structures as well as their underlying asset properties set the energy risk management industry apart from its more standard equity and fixed income counterparts. This thesis naturaly contributes to these broad market developments in participating to the advances of the mathematical tools aiming at a better theory of energy contingent claim pricing/hedging. We propose many realistic two-factor and three-factor models for spot and forward price processes that generalize some well known and standard modeling assumptions. We develop the associated pricing methodologies and propose stable calibration algorithms that motivate the application of the relevant modeling schemes.

Keywords: Mathematical finance
Energy derivatives
Option pricing and hedging
Singular perturbation
Advisor: Jaimungal, Sebastian
What's Expected? Anticipation of Education and School and Peer Contexts in a National Longitudinal Study of Youth

This dissertation examines the relationships among school structure, climate, and peer networks and adolescents’ college expectations using the first wave of the American National Longitudinal Study of Adolescent Health (Add Health). Hierarchical linear models are applied to examine the direct, intervening, and cross-level interaction effects of school context and peer networks. This dissertation applies perspectives of school socialization and peer social capital to explain the relationship between contextual-level characteristics and youths’ intentions to attend college. With controls for individual-level compositional factors, findings indicate that higher school SES and lower percentages of high school dropouts are positively associated with adolescents’ college expectations. Contingencies of gender provide evidence of moderating effects between school context and expectations, particularly for male adolescents. With regard to peer networks, adolescents who expect to attend college are more likely to be involved with prosocial and academically goal-oriented peers. Cross-level interactions between school and peer networks reveal that higher SES schools mediate the potential impact of peers on youths’ college expectations. In contrast to previous studies, this dissertation research indicates that prosocial peer behaviors mediate but do not moderate the effects on adolescents’ own expectations. The findings of this research suggest that future studies and interventions should continue to explore the multiple effects of social contexts to assess fully the impact of schools and peer networks on adolescents’ educational future outcomes.

Advisor: Hagan, John