Matching Items (102)
Description
The future will be replete with Artificial Intelligence (AI) based agents closely collaborating with humans. Although it is challenging to construct such systems for real-world conditions, the Intelligent Tutoring System (ITS) community has proposed several techniques to work closely with students. However, there is a need to extend these systems outside the controlled environment of the classroom. More recently, Human-Aware Planning (HAP) community has developed generalized AI techniques for collaborating with humans and providing personalized support or guidance to the collaborators. In this thesis, the take learning from the ITS community is extend to construct such human-aware systems for real-world domains and evaluate them with real stakeholders. First, the applicability of HAP to ITS is demonstrated, by modeling the behavior in a classroom and a state-of-the-art tutoring system called Dragoon. Then these techniques are extended to provide decision support to a human teammate and evaluate the effectiveness of the framework through ablation studies to support students in constructing their plan of study (\ipos). The results show that these techniques are helpful and can support users in their tasks. In the third section of the thesis, an ITS scenario of asking questions (or problems) in active environments is modeled by constructing questions to elicit a human teammate's model of understanding. The framework is evaluated through a user study, where the results show that the queries can be used for eliciting the human teammate's mental model.
ContributorsGrover, Sachin (Author) / Kambhampati, Subbarao (Thesis advisor) / Smith, David (Committee member) / Srivastava, Sidhharth (Committee member) / VanLehn, Kurt (Committee member) / Arizona State University (Publisher)
Created2022
Description
Written corrective feedback (WCF) has received considerable attention in secondlanguage (L2) writing research. The conducive role of WCF in developing L2 writing and
second language acquisition has been corroborated by a number of theoretical frameworks,
and the findings of empirical studies, meta-analyses, and research syntheses. WCF research
has predominantly addressed its effectiveness in improving learners’ syntactic, lexical, and
orthographic knowledge. This dissertation project extends the scope of this line of research
to formulaic aspects of language and investigates the relative effectiveness of WCF
targeting formulaic vs. non-formulaic constructions in L2 writing. The text-analytic
descriptive aspect of this research design aimed at investigating the extent of L2 learners’
non-target-like use of formulaic vs. non-formulaic forms in L2 writing and writing
teachers’ WCF treatment of non-target (non)formulaic language use. A total of 480 first
drafts of essays written by 33 advanced adult English-as-a-foreign language (EFL) learners
during one semester and 480 drafts of essays corrected through WCF by three EFL teachers
constituted the corpus in this study. Advancing the field of learner corpus research, the
findings demonstrated that whereas learners’ non-target formulaic forms outnumbered that
of non-formulaic ones in their writing assignments, all three teachers provided WCF more
often for erroneous use of non-formulaic forms. The quasi-experimental aspect of the
research design attempts to add new empirical evidence on the L2 learning potential of
accessing and processing WCF provided for formulaic vs. non-formulaic constructions in
L2 writing. To this end, a total of 66 EFL learners in a Test of English as a Foreign
Language preparation course participated in a pretest-posttest design, with 5 experimental groups (those who were provided with direct, indirect, direct plus metalinguistic, and
indirect plus metalinguistic WCF) and a control group (those who were not provided with
WCF). Maintaining a division between formulaic vs. non-formulaic forms, the findings
provide empirical evidence on the interactions between types of WCF, types of linguistic
targets, and the effectiveness of WCF in terms of enhancing L2 learners’ accuracy and
acquisition in their revised writing and new writings in the short and long term.
ContributorsGholami, Leila (Author) / Smith, David (Thesis advisor) / Matsuda, Paul K (Committee member) / James, Mark A (Committee member) / Arizona State University (Publisher)
Created2022
Description
Transitioning into civilian life after military service is a challenging prospect. It can be difficult to find employment and maintain good mental health, and up to 70 percent of veterans experience homelessness or alcoholism. Upon discharge, many veterans pursue higher education as a way to reintegrate into civilian society. However, many studies have shown that veterans encounter multiple challenges during their attempt to reintegrate into civilian life, including anxiety, a lack of relevant skills, post-traumatic stress disorder (PTSD), and other issues that may lead to communication and interaction challenges in the higher education environment. Student veterans also face challenges in the lack of common language and culture clashes due to differences between military and college culture. This study used a mixed-methods approach to examine the challenges military veterans face related to language use in civilian life. The data was collected from 149 student veterans who completed a questionnaire and 11 student veterans who participated in interviews. Detailed analysis of collected data showed that student veterans experienced some challenges in language use, especially when they initially enrolled in their courses, but they seemed to have overcome challenges after spending time in the university setting. The veterans who had prior college education before joining the military seemed to have a slight advantage, having had experience using the academic language. The study also explored how student veterans chose to share their veteran status with other people in their university community. The findings showed that they strongly identified with their veteran identity and was comfortable sharing their status with others, but they also sometimes were reluctant to share their military experience in details because they were afraid that their peers would not understand.
ContributorsObaid, Naji (Author) / Matsuda, Aya (Thesis advisor) / Smith, David (Committee member) / James, Mark (Committee member) / Arizona State University (Publisher)
Created2022
Description
Studying the so-called ”hidden” phases of quantum materials—phases that do not exist under equilibrium conditions, but can be accessed with light—reveals new insights into the broader field of structural phase transitions. Using terahertz irradiation as well as hard x-ray probes made available by x-ray free electron lasers (XFELs) provides unique capabilities to study phonon dispersion in these materials. Here, we study the cubic peak of the quantum paraelectric strontium titanate (SrTiO3, STO) below the 110 K cubic-to-tetragonal tran- sition. Our results reveal a temperature and field strength dependence of the transverse acoustic mode in agreement with previous work on the avoided crossing occurring at finite wavevector, as well as evidence of anharmonic coupling between transverse optical phonons and a fully symmetric A1g phonon. These results elucidate previous optical studies on STO and hold promise for future studies on the hidden metastable phases of quantum materials.
ContributorsStanton, Jade (Author) / Teitelbaum, Samuel (Thesis director) / Smith, David (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Department of Physics (Contributor)
Created2023-05
Description
In this dissertation, the surface interactions of fluorine were studied during atomic layer deposition (ALD) and atomic layer etching (ALE) of wide band gap materials. To enable this research two high vacuum reactors were designed and constructed for thermal and plasma enhanced ALD and ALE, and they were equipped for in-situ process monitoring. Fluorine surface interactions were first studied in a comparison of thermal and plasma enhanced ALD (TALD and PEALD) of AlF3 thin films prepared using hydrogen fluoride (HF), trimethylaluminum (TMA), and H2-plasma. The ALD AlF3 films were compared ¬in-situ using ellipsometry and X-ray photoelectron spectroscopy (XPS). Ellipsometry showed a growth rate of 1.1 Å/ cycle and 0.7 Å/ cycle, at 100°C, for the TALD and PEALD AlF3 processes, respectively. XPS indicated the presence of Al-rich clusters within the PEALD film. The formation of the Al-rich clusters is thought to originate during the H2-plasma step of the PEALD process. The Al-rich clusters were not detected in the TALD AlF3 films. This study provided valuable insight on the role of fluorine in an ALD process.
Reactive ion etching is a common dry chemical etch process for fabricating GaN devices. However, the use of ions can induce various defects, which can degrade device performance. The development of low-damage post etch processes are essential for mitigating plasma induced damage. As such, two multistep ALE methods were implemented for GaN based on oxidation, fluorination, and ligand exchange. First, GaN surfaces were oxidized using either water vapor or O2-plasma exposures to produce a thin oxide layer. The oxide layer was addressed using alternating exposures of HF and TMG, which etch Ga2O3 films. Each ALE process was characterized using in-situ using ellipsometry and XPS and ex-situ transmission electron microscopy (TEM). XPS indicated F and O impurities remained on the etched surfaces. Ellipsometry and TEM showed a slight reduction in thickness. The very low ALE rate was interpreted as the inability of the Ga2O3 ALE process to fluorinate the ordered surface oxide on GaN (0001).
Overall, these results indicate HF is effective for the ALD of metal fluorides and the ALE of metal oxides.
ContributorsMessina, Daniel C (Author) / Nemanich, Robert J (Thesis advisor) / Goodnick, Stephen (Committee member) / Ponce, Fernando A (Committee member) / Smith, David (Committee member) / Arizona State University (Publisher)
Created2021
ContributorsForgey, Sydney (Performer) / Hickman, Miriam, 1955- (Performer) / Smith, David (Performer) / ASU Library. Music Library (Publisher)
Created2020-03-25
Description
Understanding the diversity, evolutionary relationships, and geographic distribution of species is foundational knowledge in biology. However, this knowledge is lacking for many diverse lineages of the tree of life. This is the case for the desert stink beetles in the tribe Amphidorini LeConte, 1862 (Coleoptera: Tenebrionidae) – a lineage of arid-adapted flightless beetles found throughout western North America. Four interconnected studies that jointly increase our knowledge of this group are presented. First, the darkling beetle fauna of the Algodones sand dunes in southern California is examined as a case study to explore the scientific practice of checklist creation. An updated list of the species known from this region is presented, with a critical focus on material now made available through digitization and global aggregation. This part concludes with recommendations for future biodiversity checklist authors. Second, the psammophilic genus Trogloderus LeConte, 1879 is revised. Six new species are described, and the first, multi-gene phylogeny for the genus is inferred. In addition, historical biogeographic reconstructions along with novel hypotheses of speciation patterns within the Intermountain Region are given. In particular, the Kaibab Plateau and Kaiparowitz Formation are found to have promoted speciation on the Colorado Plateau. The Owens Valley and prehistoric Bouse Embayment are similarly hypothesized to drive species diversification in southern California. Third, a novel phylogenomic analysis for the tribe Amphidorini is presented, based on 29 de novo partial transcriptomes. Three putative ortholog sets were discovered and analyzed to infer the relationships between species groups and genera. The existing classification of the tribe is found to be highly inadequate, though the earliest-diverging relationships within the tribe are still in question. Finally, the new phylogenetic framework is used to provide a genus-level revision for the Amphidorini, which previously contained six valid genera and 253 valid species. This updated classification includes more than 100 taxonomic changes and results in the revised tribe consisting of 16 genera, with three being described as new to science.
ContributorsJohnston, Murray Andrew (Author) / Franz, Nico M (Thesis advisor) / Cartwright, Reed (Committee member) / Taylor, Jesse (Committee member) / Pigg, Kathleen (Committee member) / Arizona State University (Publisher)
Created2018
Description
A piezoelectric transducer, comprised of electroded and active pad PZT layer atop a backing PZT layer and protected with an acoustic matching layer, and operating under a pulse-echo technique for longitudinal ultrasonic imaging, acts as both source and detector.
Ultrasonic transducer stacks (modules), which had failed or passed during pulse-echo sensitivity testing, were received from Consortium X. With limited background information on these stacks, the central theme was to determine the origin(s) of failure via the use of thermal and physicochemical characterization techniques.
The optical and scanning electron microscopy revealed that contact electrode layers are discontinuous in all samples, while delaminations between electrodes and pad layer were observed in failed samples. The X-ray diffraction data on the pad PZT revealed an overall c/a ratio of 1.022 ratio and morphotropic boundary composition, with significant variations of the Zr to Ti ratio within a sample and between samples. Electron probe microanalysis confirmed that the overall Zr to Ti ratio of the pad PZT was 52/48, and higher amounts of excess PbO in failed samples, whereas, inductively coupled plasma mass spectrometry revealed the presence of Mn, Al, and Sb (dopants) and presence of Cu (sintering aid) in in this hard (pad) PZT. Additionally, three exothermic peaks during thermal analysis was indicative of incomplete calcination of pad PZT. Moreover, transmission electron microscopy and scanning transmission electron microscopy revealed the presence of parylene at the Ag-pad PZT interface and within the pores of pad PZT (in failed samples subjected to electric fields). This further dilutes the electrical, mechanical, and electromechanical properties of the pad PZT, which in turn detrimentally influences the pulse echo sensitivity.
Ultrasonic transducer stacks (modules), which had failed or passed during pulse-echo sensitivity testing, were received from Consortium X. With limited background information on these stacks, the central theme was to determine the origin(s) of failure via the use of thermal and physicochemical characterization techniques.
The optical and scanning electron microscopy revealed that contact electrode layers are discontinuous in all samples, while delaminations between electrodes and pad layer were observed in failed samples. The X-ray diffraction data on the pad PZT revealed an overall c/a ratio of 1.022 ratio and morphotropic boundary composition, with significant variations of the Zr to Ti ratio within a sample and between samples. Electron probe microanalysis confirmed that the overall Zr to Ti ratio of the pad PZT was 52/48, and higher amounts of excess PbO in failed samples, whereas, inductively coupled plasma mass spectrometry revealed the presence of Mn, Al, and Sb (dopants) and presence of Cu (sintering aid) in in this hard (pad) PZT. Additionally, three exothermic peaks during thermal analysis was indicative of incomplete calcination of pad PZT. Moreover, transmission electron microscopy and scanning transmission electron microscopy revealed the presence of parylene at the Ag-pad PZT interface and within the pores of pad PZT (in failed samples subjected to electric fields). This further dilutes the electrical, mechanical, and electromechanical properties of the pad PZT, which in turn detrimentally influences the pulse echo sensitivity.
ContributorsPeri, Prudhvi Ram (Author) / Dey, Sandwip (Thesis advisor) / Smith, David (Committee member) / Alford, Terry (Committee member) / Arizona State University (Publisher)
Created2018
Description
Computer assisted language learning (CALL) has become increasingly common as a means of helping learners develop essential skills in a second or foreign language. However, while many CALL programs claim to be based on principles of second language acquisition (SLA) theory and research, evaluation of design and learning outcomes at the level of individual CALL exercises is lacking in the existing literature. The following proposed study will explore the design of computer-based vocabulary matching exercises using both written text and images and the effects of various design manipulations on learning outcomes. The study will use eye-tracking to investigate what users attend to on screen as they work through a series of exercises with different configurations of written words and images. It will ask whether manipulation of text and image features and combinations can have an effect on learners’ attention to the various elements, and if so, whether differences in levels of attention results in higher or lower scores for measures of learning. Specifically, eye-tracking data will be compared to post-test scores for recall and recognition of target vocabulary items to look for a correlation between levels of attention to written forms in-task and post-test gains in scores for vocabulary learning.
ContributorsPatchin, Colleen (Author) / Smith, David (Thesis advisor) / Ross, Andrew (Committee member) / James, Mark (Committee member) / Arizona State University (Publisher)
Created2019
Description
The complex life cycle and widespread range of infection of Plasmodium parasites, the causal agent of malaria in humans, makes them the perfect organism for the study of various evolutionary mechanisms. In particular, multigene families are considered one of the main sources for genome adaptability and innovation. Within Plasmodium, numerous species- and clade-specific multigene families have major functions in the development and maintenance of infection. Nonetheless, while the evolutionary mechanisms predominant on many species- and clade-specific multigene families have been previously studied, there are far less studies dedicated to analyzing genus common multigene families (GCMFs). I studied the patterns of natural selection and recombination in 90 GCMFs with diverse numbers of gene gain/loss events. I found that the majority of GCMFs are formed by duplications events that predate speciation of mammal Plasmodium species, with many paralogs being neutrally maintained thereafter. In general, multigene families involved in immune evasion and host cell invasion commonly showed signs of positive selection and species-specific gain/loss events; particularly, on Plasmodium species is the simian and rodent clades. A particular multigene family: the merozoite surface protein-7 (msp7) family, is found in all Plasmodium species and has functions related to the erythrocyte invasion. Within Plasmodium vivax, differences in the number of paralogs in this multigene family has been previously explained, at least in part, as potential adaptations to the human host. To investigate this I studied msp7 orthologs in closely related non-human primate parasites where homology was evident. I also estimated paralogs’ evolutionary history and genetic polymorphism. The emerging patterns where compared with those of Plasmodium falciparum. I found that the evolution of the msp7 multigene family is consistent with a Birth-and-Death model where duplications, pseudogenization and gene lost events are common. In order to study additional aspects in the evolution of Plasmodium, I evaluated the trends of long term and short term evolution and the putative effects of vertebrate- host’s immune pressure of gametocytes across various Plasmodium species. Gametocytes, represent the only sexual stage within the Plasmodium life cycle, and are also the transition stages from the vertebrate to the mosquito vector. I found that, while male and female gametocytes showed different levels of immunogenicity, signs of positive selection were not entirely related to the location and presence of immune epitope regions. Overall, these studies further highlight the complex evolutionary patterns observed in Plasmodium.
ContributorsCastillo Siri, Andreina I (Author) / Rosenberg, Michael (Thesis advisor) / Escalante, Ananias (Committee member) / Taylor, Jesse (Committee member) / Collins, James (Committee member) / Arizona State University (Publisher)
Created2016