Matching Items (43,913)
Description
The increased use of commercial complementary metal-oxide-semiconductor (CMOS) technologies in harsh radiation environments has resulted in a new approach to radiation effects mitigation. This approach utilizes simulation to support the design of integrated circuits (ICs) to meet targeted tolerance specifications. Modeling the deleterious impact of ionizing radiation on ICs fabricated in advanced CMOS technologies requires understanding and analyzing the basic mechanisms that result in buildup of radiation-induced defects in specific sensitive regions. Extensive experimental studies have demonstrated that the sensitive regions are shallow trench isolation (STI) oxides. Nevertheless, very little work has been done to model the physical mechanisms that result in the buildup of radiation-induced defects and the radiation response of devices fabricated in these technologies. A comprehensive study of the physical mechanisms contributing to the buildup of radiation-induced oxide trapped charges and the generation of interface traps in advanced CMOS devices is presented in this dissertation. The basic mechanisms contributing to the buildup of radiation-induced defects are explored using a physical model that utilizes kinetic equations that captures total ionizing dose (TID) and dose rate effects in silicon dioxide (SiO2). These mechanisms are formulated into analytical models that calculate oxide trapped charge density (Not) and interface trap density (Nit) in sensitive regions of deep-submicron devices. Experiments performed on field-oxide-field-effect-transistors (FOXFETs) and metal-oxide-semiconductor (MOS) capacitors permit investigating TID effects and provide a comparison for the radiation response of advanced CMOS devices. When used in conjunction with closed-form expressions for surface potential, the analytical models enable an accurate description of radiation-induced degradation of transistor electrical characteristics. In this dissertation, the incorporation of TID effects in advanced CMOS devices into surface potential based compact models is also presented. The incorporation of TID effects into surface potential based compact models is accomplished through modifications of the corresponding surface potential equations (SPE), allowing the inclusion of radiation-induced defects (i.e., Not and Nit) into the calculations of surface potential. Verification of the compact modeling approach is achieved via comparison with experimental data obtained from FOXFETs fabricated in a 90 nm low-standby power commercial bulk CMOS technology and numerical simulations of fully-depleted (FD) silicon-on-insulator (SOI) n-channel transistors.
ContributorsSanchez Esqueda, Ivan (Author) / Barnaby, Hugh J (Committee member) / Schroder, Dieter (Thesis advisor) / Schroder, Dieter K. (Committee member) / Holbert, Keith E. (Committee member) / Gildenblat, Gennady (Committee member) / Arizona State University (Publisher)
Created2011
Description
Despite the extensive research on the consequences of migration, little is known about the effects of seasonal migration on fertility, contraception and sexually transmitted diseases in the countries of former Soviet Union, that have undergone vast demographic changes in the last two decades. Using cross-sectional data from two surveys conducted in Armenia in 2005 and 2007, this dissertation is exploring the effects of seasonal migration on reproductive behavior and outcomes, as well as sexual health among women left-behind. The dissertation is constructed of three independent studies that combined draw the broad picture of the consequences of seasonal migration in this part of the world. The first study, "Seasonal migration and fertility in low-fertility areas of origin" looks at the effect of seasonal migration on yearly pregnancy rates, lifetime fertility, and fertility preferences among women and their husbands. The models are fitted using discrete-time logistic regression, and random-intercept logistic regression for negative binomial and binary outcomes, correspondingly. The findings show that seasonal migration in low-fertility settings does not further disrupt fertility levels in a short-, or long-run, contradicting to the findings from high-fertility settings. However, the study provides some evidence that seasonal migration is associated with increased fertility preferences among migrant men. The second study, "Seasonal migration and contraception among women left-behind", examines the associations between migration and modern contraceptive use, by looking at current contraceptive use and the history of abortions. A series of random-intercept logistic regression models reveal that women with migrant partners are significantly less likely to use modern contraceptives, than women married to non-migrants. They also have higher rates of abortions; however this effect is moderated by the socioeconomic status of the household. The third study, "Seasonal migration and risks of sexually transmitted diseases (STDs) among women left-behind", looks at the effects of seasonal migration on the diagnosed STDs in the last three years, and self reported STD-like symptoms in the last twelve months. The results of random-intercept logistic regression for negative binomial and binary outcomes provide strong evidence of increased STD risks among migrants' wives; however, this effect is also moderated by the household income.
ContributorsSevoyan, Arusyak (Author) / Agadjanian, Victor (Thesis advisor) / Haas, Steven (Committee member) / Yabiku, Scott (Committee member) / Arizona State University (Publisher)
Created2011
Description
ABSTRACT The purpose of this study is to demonstrate that stable lipid bilayers can be set up on an array of silicon micropores and can be used as sites for self-inserting ion-channel proteins which can be studied independently of each other. In course of this study an acrylic based holder was designed and machined to ensure leak-free fluidic access to the silicon micropores and physical isolation of the individual array channels. To measure the ion-channel currents, we simulated, designed and manufactured low-noise transimpedance amplifiers and support circuits based on published patch clamp amplifier designs, using currently available surface-mount components. This was done in order to achieve a reduction in size and costs as well as isolation of individual channels without the need for multiplexing of the input. During the experiments performed, stable bilayers were formed across an array of four vertically mounted 30 µm silicon micropores and OmpF porins were added for self insertion in each of the bilayers. To further demonstrate the independence of these bilayer recording sites, the antibiotic Ampicillin (2.5 mM) was added to one of the fluidic wells. The ionic current in each of the wells was recorded simultaneously. Sub-conductance states of Ompf porin were observed in two of the measurement sites. In addition, the conductance steps in the site containing the antibiotic could be clearly seen to be larger compared to those of the unmodified site. This is due to the transient blocking of ion flow through the porin due to translocation of the antibiotic. Based on this demonstration, ion-channel array reconstitution is a potential method for efficient electrophysiological characterization of different types of ion-channels simultaneously as well as for studying membrane permeation processes.
ContributorsRamakrishnan, Shankar (Author) / Goryll, Michael (Thesis advisor) / Thornton, Trevor J (Committee member) / Blain Christen, Jennifer M (Committee member) / Arizona State University (Publisher)
Created2011
Description
The discipline of rhetoric and composition established the Writing Program Administrators Outcomes Statement (WPA OS) to fulfill a general expectation about the skills and knowledge students should be able to demonstrate by the end of first-year composition. Regardless of pedagogy used, academic preparation of the teacher, or preference of particular topics or types of assignments, the WPA OS is versatile. This dissertation employs a problem-solution argument showcasing methods to improve assignments through intentional use of the WPA OS for a fluid conversation throughout first-year composition and a more clear articulation of course goals. This dissertation includes summation, analysis, and synthesis of documents that inform first-year composition curriculum from foundational organizations within the field, including National Council of Teachers of English, Council of Writing Program Administrators, National Writing Project, and Conference on College Composition and Communication. This study uses the WPA OS as a lens to examine and revise writing assignments that aid in students' comprehension of the WPA OS with particular focus on the areas of rhetorical knowledge and critical thinking, reading, and writing. Framing assignment design with theoretically grounded content and the use of common topics throughout first-year composition is one way to operationalize the WPA OS. Using common topics throughout course content presents opportunities for teachers to include detailed scaffolding in assignments that expand students' literate practices and engage students as critical thinkers and writers. This study explores how using the topic of family, a common topic to all students, provides a rich bank of social, historical, and cultural elements for research and writing. The topic of family seamlessly employs multimodal composition, which presents students with opportunities for developing rhetorical knowledge and expanding students' literacies. This dissertation displays evidence of praxis of the WPA OS from assignment development to presentation of student samples. This study recommends the use of common topics and intentional application of the WPA OS to construct assignments that clearly articulate learning goals in first-year composition.
ContributorsRankins-Robertson, Sherry, 1976- (Author) / Roen, Duane H. (Thesis advisor) / Miller, Keith (Committee member) / Lauer, Claire (Committee member) / Arizona State University (Publisher)
Created2011
Description
In recent years, the field of nanomedicine has progressed at an astonishing rate, particularly with respect to applications in cancer treatment and molecular imaging. Although organic systems have been the frontrunners, inorganic systems have also begun to show promise, especially those based upon silica and magnetic nanoparticles (NPs). Many of these systems are being designed for simultaneous therapeutic and diagnostic capabilities, thus coining the term, theranostics. A unique class of inorganic systems that shows great promise as theranostics is that of layered double hydroxides (LDH). By synthesis of a core/shell structures, e.g. a gold nanoparticle (NP) core and LDH shell, the multifunctional theranostic may be developed without a drastic increase in the structural complexity. To demonstrate initial proof-of-concept of a potential (inorganic) theranostic platform, a Au-core/LDH-shell nanovector has been synthesized and characterized. The LDH shell was heterogeneously nucleated and grown on the surface of silica coated gold NPs via a coprecipitation method. Polyethylene glycol (PEG) was introduced in the initial synthesis steps to improve crystallinity and colloidal stability. Additionally, during synthesis, fluorescein isothiocyanate (FITC) was intercalated into the interlayer spacing of the LDH. In contrast to the PEG stabilization, a post synthesis citric acid treatment was used as a method to control the size and short-term stability. The heterogeneous core-shell system was characterized with scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), dynamic light scattering (DLS), and powder x-ray diffraction (PXRD). A preliminary in vitro study carried out with the assistance of Dr. Kaushal Rege's group at Arizona State University was to demonstrate the endocytosis capability of homogeneously-grown LDH NPs. The DLS measurements of the core-shell NPs indicated an average particle size of 212nm. The PXRD analysis showed that PEG greatly improved the crystallinity of the system while simultaneously preventing aggregation of the NPs. The preliminary in vitro fluorescence microscopy revealed a moderate uptake of homogeneous LDH NPs into the cells.
ContributorsRearick, Colton (Author) / Dey, Sandwip K (Thesis advisor) / Krause, Stephen (Committee member) / Ramakrishna, B (Committee member) / Arizona State University (Publisher)
Created2011
Description
This study treats in some depth a contemporary solo piano work, "Arirang Variations" (2006) by Edward "Teddy" Niedermaier (b. 1983). Though Niedermaier is an American composer and pianist, he derives his inspiration for that work from four types of Korean arirang: "Arirang," "Raengsanmopan Older Babe Arirang," "Gangwondo Arirang" and "Kin Arirang." The analysis of "Arirang Variations" focuses primarily on how the composer adapts arirang in each variation and develops them into his own musical language. A salient feature of Niedermaier's composition is his combination of certain contradictions: traditional and contemporary styles, and Western and Eastern musical styles. In order to discuss in detail the musical elements of arirang used in "Arirang Variations," scores of all the arirang Niedermaier references are included with the discussion of each. Unfortunately, sources concerning three of these were limited to a single book by Yon-gap Kim, Pukhan Arirang Yongu (A Study of North Korean Arirang), because "Raengsanmopan Older Babe Arirang," "Gangwondo Arirang" and "Kin Arirang"are North Korean versions of arirang. Since arirang are the most important Korean folk song genre, basic information concerning such features of Korean traditional musical elements as scales, vocal techniques, rhythms and types of folk songs are provided along with an overview of the history and origins of arirang. Given that each arirang has distinctive characteristics that vary by region, the four best-known types of arirang are introduced to demonstrate these differences.
ContributorsPark, Hyunjin (Author) / Meir, Baruch (Thesis advisor) / Campbell, Andrew (Committee member) / Levy, Benjamin (Committee member) / Thompson, Janice (Committee member) / Arizona State University (Publisher)
Created2011
Description
One necessary condition for the two-pass risk premium estimator to be consistent and asymptotically normal is that the rank of the beta matrix in a proposed linear asset pricing model is full column. I first investigate the asymptotic properties of the risk premium estimators and the related t-test and Wald test statistics when the full rank condition fails. I show that the beta risk of useless factors or multiple proxy factors for a true factor are priced more often than they should be at the nominal size in the asset pricing models omitting some true factors. While under the null hypothesis that the risk premiums of the true factors are equal to zero, the beta risk of the true factors are priced less often than the nominal size. The simulation results are consistent with the theoretical findings. Hence, the factor selection in a proposed factor model should not be made solely based on their estimated risk premiums. In response to this problem, I propose an alternative estimation of the underlying factor structure. Specifically, I propose to use the linear combination of factors weighted by the eigenvectors of the inner product of estimated beta matrix. I further propose a new method to estimate the rank of the beta matrix in a factor model. For this method, the idiosyncratic components of asset returns are allowed to be correlated both over different cross-sectional units and over different time periods. The estimator I propose is easy to use because it is computed with the eigenvalues of the inner product of an estimated beta matrix. Simulation results show that the proposed method works well even in small samples. The analysis of US individual stock returns suggests that there are six common risk factors in US individual stock returns among the thirteen factor candidates used. The analysis of portfolio returns reveals that the estimated number of common factors changes depending on how the portfolios are constructed. The number of risk sources found from the analysis of portfolio returns is generally smaller than the number found in individual stock returns.
ContributorsWang, Na (Author) / Ahn, Seung C. (Thesis advisor) / Kallberg, Jarl G. (Committee member) / Liu, Crocker H. (Committee member) / Arizona State University (Publisher)
Created2011
Description
This thesis explores the ways two contemporary artists engage the archive to challenge ideas calcified through visual culture. Steven Yazzie and Lorna Simpson respond to constructions of history through art making strategies and practices. Yazzie's photogravure Tsosido Sweep Dancer (2009) presents a carefully constructed image of a ceremony drawing on symbols of Indianness to provoke a critical dialogue that questions the role of the American Indian stereotype in the United States imaginary. Simpson's Counting (1991) is a multilayered work that juxtaposes text and image to address the capriciousness of memory, power and other issues found at the intersection of race and gender. These photography-based works draw on the histories of ethnographic and criminal photography to deconstruct the same knowledge that photography helped to construct. Throughout the thesis I examine the relationship of the photographic archive to colonial histories by considering whose history is represented through photography. These thoughtful and challenging artworks contribute to a growing body of work that proposes new narratives drawing on embodied knowledge and experience to create a counter-archive.
ContributorsWaitoller, Lekha Hileman (Author) / Malagamba-Ansótegui, Amelia (Thesis advisor) / Lineberry, Heather S (Committee member) / Mesch, Ulrike C (Committee member) / Arizona State University (Publisher)
Created2011
Description
Spotlight mode synthetic aperture radar (SAR) imaging involves a tomo- graphic reconstruction from projections, necessitating acquisition of large amounts of data in order to form a moderately sized image. Since typical SAR sensors are hosted on mobile platforms, it is common to have limitations on SAR data acquisi- tion, storage and communication that can lead to data corruption and a resulting degradation of image quality. It is convenient to consider corrupted samples as missing, creating a sparsely sampled aperture. A sparse aperture would also result from compressive sensing, which is a very attractive concept for data intensive sen- sors such as SAR. Recent developments in sparse decomposition algorithms can be applied to the problem of SAR image formation from a sparsely sampled aperture. Two modified sparse decomposition algorithms are developed, based on well known existing algorithms, modified to be practical in application on modest computa- tional resources. The two algorithms are demonstrated on real-world SAR images. Algorithm performance with respect to super-resolution, noise, coherent speckle and target/clutter decomposition is explored. These algorithms yield more accu- rate image reconstruction from sparsely sampled apertures than classical spectral estimators. At the current state of development, sparse image reconstruction using these two algorithms require about two orders of magnitude greater processing time than classical SAR image formation.
ContributorsWerth, Nicholas (Author) / Karam, Lina (Thesis advisor) / Papandreou-Suppappola, Antonia (Committee member) / Spanias, Andreas (Committee member) / Arizona State University (Publisher)
Created2011
Description
Dust devils have proven to be commonplace on Mars, although their occurrence is unevenly distributed across the surface. They were imaged or inferred by all six successful landed spacecraft: the Viking 1 and 2 Landers (VL-1 and VL-2), Mars Pathfinder Lander, the Mars Exploration Rovers Spirit and Opportunity, and the Phoenix Mars Lander. Comparisons of dust devil parameters were based on results from optical and meteorological (MET) detection campaigns. Spatial variations were determined based on comparisons of their frequency, morphology, and behavior. The Spirit data spanning three consecutive martian years is used as the basis of comparison because it is the most extensive on this topic. Average diameters were between 8 and 115 m for all observed or detected dust devils. The average horizontal speed for all of the studies was roughly 5 m/s. At each site dust devil densities peaked between 09:00 and 17:00 LTST during the spring and summer seasons supporting insolation-driven convection as the primary formation mechanism. Seasonal number frequency averaged ~1 dust devils/ km2/sol and spanned a total of three orders of magnitude. Extrapolated number frequencies determined for optical campaigns at the Pathfinder and Spirit sites accounted for temporal and spatial inconsistencies and averaged ~19 dust devils/km2/sol. Dust fluxes calculated from Pathfinder data (5x10-4 kg/m2/s and 7x10-5 kg/m2/s) were well with in the ranges calculated from Spirit data (4.0x10-9 to 4.6x10-4 kg/m2/s for Season One, 5.2x10-7 to 6.2x10-5 kg/m2/s during Season Two, and 1.5x10-7 to 1.6x10-4 kg/m2/s during Season Three). Based on the results a campaign is written for improvements in dust devil detection at the Mars Science Laboratory's (MSL) site. Of the four remaining candidate MSL sites, the dusty plains of Gale crater may potentially be the site with the highest probability of dust devil activity.
ContributorsWaller, Devin (Author) / Greeley, Ronald (Thesis advisor) / Christensen, Philip R. (Philip Russel) (Committee member) / Cerveny, Randall (Committee member) / Arizona State University (Publisher)
Created2011