Directed forgetting in a proactive interference paradigm

"One explanation of the benefit of directed forgetting is the reduction of proactive interference (PI) from the first list during encoding of the next list. To explore this possibility, I used a forget instruction in a release from PI paradigm. The forget instruction did not reduce the PI on subsequent lists as measured by the immediate tests usually given in this paradigm in Experiments 1-3. The other variable manipulated in this study was the recall tests. A reverse test effect was found on a final recall measure in Experiment 2. Immediate recall tests in a PI paradigm may already serve as an implicit forget cue to the participants. This finding has implications for both directed forgetting and proactive interference research."--Abstract from author supplied metadata

Reasoning about recognizability in security protocols

Although verifying a message has long been recognized as an important concept, which has been used explicitly or implicitly in security protocol analysis, there is no consensus on its exact meaning. Such a lack of formal treatment of the concept makes it extremely difficult to evaluate the vulnerability of security protocols. This dissertation offers a precise answer to the question: What is meant by saying that a message can be "verified''? The core technical innovation is a third notion of knowledge in security protocols -- recognizability. It can be considered as intermediate between deduction and static equivalence, two classical knowledge notions in security protocols. We believe that the notion of recognizability sheds important lights on the study of security protocols. More specifically, this thesis makes four contributions. First, we develop a knowledge model to capture an agent's cognitive ability to understand messages. Thanks to a clear distinction between de re/dicto interpretations of a message, the knowledge model unifies both computational and symbolic views of cryptography gracefully. Second, we propose a new notion of knowledge in security protocols -- recognizability -- to fully capture one's ability or inability to cope with potentially ambiguous messages. A terminating procedure is given to decide recognizability under the standard Dolev-Yao model. Third, we establish a faithful view of the attacker based on recognizability. This yields new insights into protocol compilations and protocol implementations. Specifically, we identify two types of attacks that can be thawed through adjusting the protocol implementation; and show that an ideal implementation that corresponds to the intended protocol semantics does not always exist. Overall, the obtained attacker's view provides a path to more secure protocol designs and implementations. Fourth, we use recognizability to provide a new perspective on type-flaw attacks. Unlike most previous approaches that have focused on heuristic schemes to detect or prevent type-flaw attacks, our approach exposes the enabling factors of such attacks. Similarly, we apply the notion of recognizability to analyze off-line guessing attacks. Without enumerating rules to determine whether a guess can be "verified'', we derive a new definition based on recognizability to fully capture the attacker's guessing capabilities. This definition offers a general framework to reason about guessing attacks in a symbolic setting, independent of specific intruder models. We show how the framework can be used to analyze both passive and active guessing attacks

Medium access control for inter-gateway handoff support in multi-hop wireless mesh networks

Wireless mesh networks (WMNs) have emerged to be a key wireless technology to support large-scale wireless Internet access. Seamless inter-gateway handoff support is an essential issue to ensure continuous communications in multi-hop WMNs. When the movement of a mobile mesh node (MN) causes its attachment point change in the Internet, the complete handoff process may include two steps: the link-layer handoff and the network-layer handoff. During the network-layer handoff, network- layer signaling packets need to be transmitted between the MN and the Internet via the multi-hop wireless mesh backbone. Due to the multi-hop transmission of network- layer handoff signaling packets, the handoff performance in WMNs can be largely degraded by the long queueing delay and medium access delay at each mesh router, especially when the backbone traffic volume is high. However, this critical issue is ignored in existing handoff solutions of multi-hop WMNs. In addition, the channel contention between data packets and handoff signaling packets is not considered in existing medium access control (MAC) designs. In this research, the seamless handoff support is addressed from a different perspec- tive. By eliminating channel contentions between data and handoff signaling pack- ets, the queueing delay and channel access delay of signaling packets are reduced, while data throughput is maintained. Since various WMNs have different channel resources and hardware cost requirements, four MAC schemes are proposed to im- prove the multi-hop handoff performance in single-channel single-radio, single-channel multi-radio, multi-channel single-radio, and multi-channel multi-radio WMNs. With the proposed MAC schemes, the inter-gateway handoff performance can be improved significantly in multi-hop WMNs

EVOLUTION AND DYNAMICS OF TRANSCRIPTIONAL REGULATION IN BACTERIA

Although transcription is one of the most important biological functions of cells, our understanding of its regulation is still limited. In this dissertation, we have studied the transcriptional regulation in prokaryotes in three aspects. First, we investigated the extent to which cis-regulatory elements are conserved during the course of evolution using the LexA regulons in cyanobacteria as an example. We found that in most cyanobacterial genomes analyzed, LexA appears to function as the transcriptional regulator of the key SOS response genes. The loss of lexA in some genomes might lead to the degradation of its binding sites. Second, directional RNA-seq techniques have recently become the workhorse for transcriptome profiling in prokaryotes, however, it is a challenging task to accurately assemble highly labile prokaryotic transcriptomes for further analyses. To fill this gap, we have developed a hidden Markov model based transcriptome assembler which outperforms the state-of-the-art assemblers. Using our tool, we characterized alternative operon structures in E. coli K12 under various growth conditions and growth phases, and found that they are more complex and dynamic than previously anticipated. Lastly, we determined anti-sense and non-coding transcription patterns in E. coli K12 under various growth conditions and time points. We found that a large portion of genes have antisense transcription in a condition-dependent manner. Most antisense transcripts are initiated and restricted to the 5?-end of the gene on the sense strand, and their expression levels are correlated with those of the genes on the sense strand, suggesting that these antisense transcripts might play an important role in transcriptional regulation

TESTING PREDICTABILITY OF ASSET RETURNS

In this paper, a L2 type nonparametric test is developed to test a specific nonlinear parametric regression model with near-integrated regressors. The asymptotic distri- butions of the proposed test statistic under both null and alternative hypotheses are established. The finite sample performance is also examined by conducting Monte Carlo simulation. The test statistic is applied to testing the linear prediction model of asset return and the predictability of asset return is shown at last

OPTICAL CHARACTERIZATION OF INHOMOGENEITIES IN BLUE-EMITTING INGAN/GAN MQWS

The growth of blue-emitting InGaN/GaN MQWs, the system setup of a low temperature PL/EL/IV system for temperature dependent PL/EL/IV spectroscopy, and the system setup of a CLSM with nanometer-scale spectrum measurement and TRPL measurement abilities are described. A range of temperature-dependent PL experimental work, CLSM imaging experimental work and TRPL experimental work on blue-emitting InGaN/GaN MQWs are presented. In temperature-dependent PL measurements, the decreasing of spectrum- integrated PL intensity with increasing temperature is explained with a two-nonradiative- channel model, in which the two nonradiative channels correspond to the thermal activation of carriers out of the strongly localized states and the weakly localized states, respectively. The ‘S-shaped’ red-blue-red shift of PL peak energy and the ‘inverse S- shaped’ change of PL FWHM when temperature increases from 10 K to 300 K are explained with carrier localization and carrier dynamics. CLSM imaging and nanometer-scale PL spectral measurements show that the PL intensity fluctuates in micrometer scale, and that the bandgap energy in bright region is tens of meV smaller than that in dark region. The small-bandgap-energy regions are localization centers which limit the diffusion of the carriers and prevent carriers from diffusing to the NRRCs. Nanometer-scale TRPL measurements are conducted on blue-emitting InGaN/GaN MQWs for the first time, as far as the author knows. The measurements show that both bright region and dark region are characterized by two lifetimes: fast decay lifetime t1 is smaller than 3 ns and slow decay lifetime t2 is longer than 10 ns. The fast decay with shorter lifetime t1 corresponds to the carrier localization in weakly localized states, where the radiative recombination is more quenched by NRRCs and also competes with carrier transfer intro strongly localized states. And the slow decay with longer lifetime t2 corresponds carrier localization in strongly localized states. The fact that both fast decay and slow decay exist in both bright region and dark region indicates that both bright region and dark region has small bandgap energy fluctuation in themselves. Measurements show that the slow decay lifetime t2 in bright region is longer than that in dark region, indicating a higher probability of nonradiative recombination in dark region or carrier transporting from dark region to bright region. Measurements show that larger bandgap energy difference between small- bandgap-energy regions and large-bandgap-energy regions provides stronger carrier localization effect, via the presence of higher CLSM image average intensity, larger PL intensity ratio and longer smaller-bandgap-energy slow decay lifetime t2 when larger bandgap energy difference occurs. The effect of MOCVD growth parameters on MQW bandgap energy fluctuations and average intensity was analyzed. It was found out that by increasing growth pressure, decreasing growth rate, increasing growth temperature, increasing effective V/III ratio, and increasing gas speed, the bandgap energy difference between bright region and dark region increases, leading to higher average PL intensity

A stochastic segmentation method for interesting region detection and image retrieval

The explosively increasing digital photo urges for an efficient image retrieval sys- tem so that digital images can be organized, shared, and reused. Current content based image retrieval (CBIR) systems face multiple challenges in all aspects: image representation, classification and indexing. Image representation of current CBIR system is of such low quality that the background is often mixed with the objects which makes the signature of an image less distinguishable or even misleading. An image classifier connects the low level feature with the high level concept and the low quality feature will only make the effort of bridging of the semantic gap harder. A new system to tackle these challenges more efficiently has been developed. My contribution consists of: (a) A stochastic image segmentation algorithm that is able to achieve better balance on integrity/oversegmentation. The algorithm estimates the average contour conformation and obtains more accurate results and is very at- tractive for feature extraction for customer photos as well as for tissue segmentation in 3D medical images. (b) A new interesting region detection method which can seamlessly integrate GMM and SVM in one scheme. It proves that the pattern of the common interests can be efficiently learned using the interesting region classifier. (c) The popularity and useability of the metadata of the +200 different models sold on market is explored and metadata is used both for interesting region detection and image classification. This incorporation of camera metadata has been missed in the computer vision community for decades. (d) A new high dimensional GMM estimator that tackles the oscillation of principle dimensionality of GMM in high dimension in real world dataset by estimating the average conformation along the evolution history. (e) An image retrieval system that can support query by keyword, query by example, and ontology browsing alternatively

FINITE ELEMENT MODELING AND SIMULATION OF OCCUPANT RESPONSES IN HIGHWAY CRASHES

Roadside barrier systems play an important role in reducing the number of fatalities and the severity of injuries in highway crashes. After decades of work by researchers and engineers, roadside barriers have been improved and are generally effective in preventing head-on collisions and thus crash fatalities. To further improve the performance of highway safety devices and develop new systems, a good understanding of occupant injuries is required. Although incorporating occupant responses and/or injuries into the design of safety devices is highly recommended by the current safety regulations, there are currently no studies that can be used to develop official guidelines or standards. Despite its usefulness in understanding the crash mechanism and improving vehicle crashworthiness, crash testing is very expensive and restricted by the crash scenarios that can be investigated. In addition, no crash test dummy is incorporated in majority of the crash testing of roadside barriers. With the recent advances in high performance computing and numerical codes, computer modeling and simulation are playing an important role in crash analysis and roadside safety research. In this study, the finite element model of a Hybrid III 50th percentile male dummy was developed for studying the driver’s responses in vehicular crashes into highway barriers. After validation by standard crash tests, the dummy model was combined with the finite element model of a 2006 Ford F250 pickup truck and used in simulations of the vehicle impacting a concrete barrier and a W-beam guiderail under different impact speeds and angles. Finally, the dummy responses in these simulations were analyzed by correlating with existing human injury criteria so as to correlate impact severity to vehicular responses and ultimately to barrier performances

Parents and Teachers' Beliefs about Preschool Inclusion in P.R. China

The primary purpose of this study was to examine parents of typically developing children and preschool teachers' beliefs about early inclusion in P. R. China, from the perspectives of Bronfenbrenner's Bioecological Theory, Vygotsky's Social-Cultural Theory, and Goodenough's Belief Theory. Parents and teachers' previous experience with individuals with disabilities, parents' socioeconomic status, teachers' age, education, and sense of teaching efficacy, preschool quality, and average socioeconomic status of families in each preschool were considered in relation to parents and teachers' beliefs about preschool inclusion. Participants included 346 teachers and 597 parents across 16 preschools in Northern China. Their participation included completing an online survey to assess their general beliefs about inclusion and perceived benefits and risks of inclusion on children with and without disabilities. The results revealed that parents and teachers reported moderately positive beliefs about inclusion and perceived benefits for children with and without disabilities. Teachers who had prior experiences with children or adults with disabilities had higher overall positive beliefs about inclusion, higher perceived benefits of inclusion for children with and without disabilities, lower negative beliefs about inclusion, and lower perceived risks of inclusion for children with and without disabilities. Teachers with higher sense of teaching efficacy had more positive beliefs about inclusion and perceived benefits for children with and without disabilities. Teachers with a higher level of education had more positive beliefs about inclusion than teachers with a lower education level. The results also indicated that parents whose children were in preschools with higher quality had higher overall and positive beliefs about inclusion, higher perceived benefits of inclusion for children with and without disabilities, lower negative beliefs about inclusion, and lower perceived risks of inclusion for children with and without disabilities than parents with children in moderate quality programs. In addition, parents from a preschool in which the socioeconomic status (SES) of families was higher had higher perceived benefits of inclusion on children with disabilities. Teachers from a preschool in which the SES of families was higher had lower reported negative beliefs of inclusion and higher reported perceived benefits for children with and without disabilities than teachers from a lower SES preschool. Implications of these findings for quality inclusive preschool programs, teacher preparation programs, and future research are discussed

Sequence: for clarinets, electric guitar, double bass and drum set

This thesis, Sequence, is a composition for clarinet (doubling bass clarinet), electric guitar, double bass, and drum set. Working within the boundaries of a minimalist musical style, my goal for this piece was to create structural motion by means of rhythm, registration, and color in the context of static harmonies. I modeled my music on works by Steve Reich and Hans Zimmer, who composed Electric Counterpoint (1997), and Supermarine (2017), respectively. This paper focuses on procedures