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- All Subjects: Biomedical Engineering
- Creators: Arizona State University
Description
A dual-channel directional digital hearing aid (DHA) front-end using a fully differential difference amplifier (FDDA) based Microphone interface circuit (MIC) for a capacitive Micro Electro Mechanical Systems (MEMS) microphones and an adaptive-power analog font end (AFE) is presented. The Microphone interface circuit based on FDDA converts the capacitance variations into voltage signal, achieves a noise of 32 dB SPL (sound pressure level) and an SNR of 72 dB, additionally it also performs single to differential conversion allowing for fully differential analog signal chain. The analog front-end consists of 40dB VGA and a power scalable continuous time sigma delta ADC, with 68dB SNR dissipating 67u¬W from a 1.2V supply. The ADC implements a self calibrating feedback DAC, for calibrating the 2nd order non-linearity. The VGA and power scalable ADC is fabricated on 0.25 um CMOS TSMC process. The dual channels of the DHA are precisely matched and achieve about 0.5dB gain mismatch, resulting in greater than 5dB directivity index. This will enable a highly integrated and low power DHA
ContributorsNaqvi, Syed Roomi (Author) / Kiaei, Sayfe (Thesis advisor) / Bakkaloglu, Bertan (Committee member) / Chae, Junseok (Committee member) / Barnby, Hugh (Committee member) / Aberle, James T., 1961- (Committee member) / Arizona State University (Publisher)
Created2011
Description
Demand for biosensor research applications is growing steadily. According to a new report by Frost & Sullivan, the biosensor market is expected to reach $14.42 billion by 2016. Clinical diagnostic applications continue to be the largest market for biosensors, and this demand is likely to continue through 2016 and beyond. Biosensor technology for use in clinical diagnostics, however, requires translational research that moves bench science and theoretical knowledge toward marketable products. Despite the high volume of academic research to date, only a handful of biomedical devices have become viable commercial applications. Academic research must increase its focus on practical uses for biosensors. This dissertation is an example of this increased focus, and discusses work to advance microfluidic-based protein biosensor technologies for practical use in clinical diagnostics. Four areas of work are discussed: The first involved work to develop reusable/reconfigurable biosensors that are useful in applications like biochemical science and analytical chemistry that require detailed sensor calibration. This work resulted in a prototype sensor and an in-situ electrochemical surface regeneration technique that can be used to produce microfluidic-based reusable biosensors. The second area of work looked at non-specific adsorption (NSA) of biomolecules, which is a persistent challenge in conventional microfluidic biosensors. The results of this work produced design methods that reduce the NSA. The third area of work involved a novel microfluidic sensing platform that was designed to detect target biomarkers using competitive protein adsorption. This technique uses physical adsorption of proteins to a surface rather than complex and time-consuming immobilization procedures. This method enabled us to selectively detect a thyroid cancer biomarker, thyroglobulin, in a controlled-proteins cocktail and a cardiovascular biomarker, fibrinogen, in undiluted human serum. The fourth area of work involved expanding the technique to produce a unique protein identification method; Pattern-recognition. A sample mixture of proteins generates a distinctive composite pattern upon interaction with a sensing platform consisting of multiple surfaces whereby each surface consists of a distinct type of protein pre-adsorbed on the surface. The utility of the "pattern-recognition" sensing mechanism was then verified via recognition of a particular biomarker, C-reactive protein, in the cocktail sample mixture.
ContributorsChoi, Seokheun (Author) / Chae, Junseok (Thesis advisor) / Tao, Nongjian (Committee member) / Yu, Hongyu (Committee member) / Forzani, Erica (Committee member) / Arizona State University (Publisher)
Created2011
Description
Alzheimer's Disease (AD) is a debilitating neurodegenerative disease. The disease leads to dementia and loss of cognitive functions and affects about 4.5 million people in the United States. It is the 7th leading cause of death and is a huge financial burden on the healthcare industry. There are no means of diagnosing the disease before neurodegeneration is significant and sadly there is no cure that controls its progression. The protein beta-amyloid or Aâ plays an important role in the progression of the disease. It is formed from the cleavage of the Amyloid Precursor Protein by two enzymes - â and ã-secretases and is found in the plaques that are deposits found in Alzheimer brains. This work describes the generation of therapeutics based on inhibition of the cleavage by â-secretase. Using in-vitro recombinant antibody display libraries to screen for single chain variable fragment (scFv) antibodies; this work describes the isolation and characterization of scFv that target the â-secretase cleavage site on APP. This approach is especially relevant since non-specific inhibition of the enzyme may have undesirable effects since the enzyme has been shown to have other important substrates. The scFv iBSEC1 successfully recognized APP, reduced â-secretase cleavage of APP and reduced Aâ levels in a cell model of Alzheimer's Disease. This work then describes the first application of bispecific antibody therapeutics to Alzheimer's Disease. iBSEC1 scFv was combined with a proteolytic scFv that enhances the "good" pathway (á-secretase cleavage) that results in alternative cleavage of APP to generate the bispecific tandem scFv - DIA10D. DIA10D reduced APP cleavage by â-secretase and steered it towards the "good" pathway thus increasing the generation of the fragment sAPPá which is neuroprotective. Finally, treatment with iBSEC1 is evaluated for reduced oxidative stress, which is observed in cells over expressing APP when they are exposed to stress. Recombinant antibody based therapeutics like scFv have several advantages since they retain the high specificity of the antibodies but are safer since they lack the constant region and are smaller, potentially facilitating easier delivery to the brain
ContributorsBoddapati, Shanta (Author) / Sierks, Michael (Thesis advisor) / Arizona State University (Publisher)
Created2011
Description
The rights of American Indians occupy a unique position within the legal framework of water allocations in the western United States. However, in the formulation and execution of policies that controlled access to water in the desert Southwest, federal and local governments did not preserve the federal reserved water rights that attached to Indian reservations as part of their creation. Consequentially, Indian communities were unable to access the water supplies necessary to sustain the economic development of their reservations. This dissertation analyzes the legal and historical dimensions of the conflict over rights that occurred between Indian communities and non-Indian water users in Arizona during the second half of the twentieth century. Particular attention is paid to negotiations involving local, state, federal, and tribal parties, which led to the Congressional authorization of water rights settlements for several reservations in central Arizona. The historical, economic, and political forces that shaped the settlement process are analyzed in order to gain a better understanding of how water users managed uncertainty regarding their long-term water supplies. The Indian water rights settlement process was made possible through a reconfiguration of major institutional, legal, and policy arrangements that dictate the allocation of water supplies in Arizona.
ContributorsKilloren, Daniel (Author) / Hoerder, Dirk (Thesis advisor) / Hirt, Paul (Committee member) / Smith, Karen (Committee member) / Arizona State University (Publisher)
Created2011
Description
Over the past decades, Colombian society has endured the impact of a longstanding political conflict among different actors and outrageous expressions of violence, especially among left wing guerrillas, right wing paramilitary groups and the state government. Drawing on socio-legal studies in transitional justice and human rights, this research attempts to analyze the recent experience of transitional justice in Colombia. The main purpose of this research is to understand how political, institutional and social actors, especially the government, the courts, the human rights and transitional justice NGOs, and victims associations, frame the mechanisms of transitional justice and use legal instruments to transform the conflict and reach what they consider "justice." It also attempts to understand the relations between politics and law in the context of a hegemonic discourse of security and give account of the expressions of resistance of human rights networks. In doing so, this research advances theory on literature about law and society and transitional justice by means of applying and expanding the theoretical framework of socio-legal research via the process of transitional justice in Colombia. The dissertation presents information gathered in the field in Colombia between July 2009 and July 2010 through a qualitative research design based on document analysis and in-depth interviews with members of different international and domestic human rights organizations, victims' organizations and national institutions. The research explains how these organizations combined political and legal actions in order to contest a project of security, and more specifically a project of impunity that came from negotiations with the paramilitary groups. The research also explains how the human rights networks not only mobilized internationally to gain political support from the international community, but also how these organizations contributed to transform the political debate about victims' rights. The research also explains how the human rights organizations and victims' groups articulated the global discourse on human rights and the local and domestic meanings constructed by the emerging movements of victims. Finally, the research analyses the relevance of legal practices consisting on strategic use of law in order to protect the victims of human rights violations.
ContributorsGomez Sanchez, Gabriel (Author) / Lauderdale, Pat (Thesis advisor) / Vanna, Gonzales (Committee member) / Ladawn, Haglund (Committee member) / Jeffrey, Juris (Committee member) / Arizona State University (Publisher)
Created2011
Description
Psychology of justice research has demonstrated that individuals are concerned with both the process and the outcomes of a decision-making event. While the literature has demonstrated the importance of formal and informal aspects of procedural justice and the relevancy of moral values, the present study focuses on introducing a new form of justice: Substantive justice. Substantive justice focuses on how the legal system uses laws to constrain and direct human behavior, specifically focusing on the function and the structure of a law. The psychology of justice literature is missing the vital distinction between laws whose function is to create social opportunities versus threats and between laws structured concretely versus abstractly. In the present experiment, we found that participant evaluations of the fairness of the law, the outcome, and the decision-maker all varied depending on the function and structure of the law used as well as the outcome produced. Specifically, when considering adverse outcomes, individuals perceived laws whose function is to create liability (threats) as being fairer when structured as standards (abstract guidelines) rather than rules (concrete guidelines); however, the opposite is true when considering laws whose function is to create eligibility (opportunities). In juxtaposition, when receiving a favorable outcome, individuals perceived laws whose function is to create liability (threats) as being fairer when defined as rules (concrete guidelines) rather than standards (abstract guidelines).
ContributorsLovis-McMahon, David (Author) / Schweitzer, Nicholas J. (Thesis advisor) / Saks, Michael (Thesis advisor) / Kwan, Sau (Committee member) / Arizona State University (Publisher)
Created2011
Description
In this work, a novel method is developed for making nano- and micro- fibrous hydrogels capable of preventing the rejection of implanted materials. This is achieved by either (1) mimicking the native cellular environment, to exert fine control over the cellular response or (2) acting as a protective barrier, to camouflage the foreign nature of a material and evade recognition by the immune system. Comprehensive characterization and in vitro studies described here provide a foundation for developing substrates for use in clinical applications. Hydrogel dextran and poly(acrylic acid) (PAA) fibers are formed via electrospinning, in sizes ranging from nanometers to microns in diameter. While "as-electrospun" fibers are continuous in length, sonication is used to fragment fibers into short fiber "bristles" and generate nano- and micro- fibrous surface coatings over a wide range of topographies. Dex-PAA fibrous surfaces are chemically modified, and then optimized and characterized for non-fouling and ECM-mimetic properties. The non-fouling nature of fibers is verified, and cell culture studies show differential responses dependent upon chemical, topographical and mechanical properties. Dex-PAA fibers are advantageously unique in that (1) a fine degree of control is possible over three significant parameters critical for modifying cellular response: topography, chemistry and mechanical properties, over a range emulating that of native cellular environments, (2) the innate nature of the material is non-fouling, providing an inert background for adding back specific bioactive functionality, and (3) the fibers can be applied as a surface coating or comprise the scaffold itself. This is the first reported work of dex-PAA hydrogel fibers formed via electrospinning and thermal cross-linking, and unique to this method, no toxic solvents or cross-linking agents are needed to create hydrogels or for surface attachment. This is also the first reported work of using sonication to fragment electrospun hydrogel fibers, and in which surface coatings were made via simple electrostatic interaction and dehydration. These versatile features enable fibrous surface coatings to be applied to virtually any material. Results of this research broadly impact the design of biomaterials which contact cells in the body by directing the consequent cell-material interaction.
ContributorsLouie, Katherine BoYook (Author) / Massia, Stephen P (Thesis advisor) / Bennett, Kevin (Committee member) / Garcia, Antonio (Committee member) / Pauken, Christine (Committee member) / Vernon, Brent (Committee member) / Arizona State University (Publisher)
Created2011
Description
This thesis explores the implications that the outcome of a certain U.S. lawsuit involving antiquities could have on practices and programs in the United States, related to cultural heritage and history. This paper examines the Rubin et al case, which sought to attach a collection of ancient Persian artifacts (known as The Persepolis Tablets) as a source of legal compensation. Presented as a case study, and using primary and secondary research sources, this paper analyzes the Rubin et al lawsuit and the factors that led to its initiation, and seeks to determine how and why adverse consequences could result from its final ruling. This thesis demonstrates that the final decision in the lawsuit could leave a negative impact on a number of practices related to cultural heritage in the United States, especially with regards to cultural and academic institutions such as museums and universities.
ContributorsAhouraiyan, Taraneh (Author) / Warren-Findley, Jannelle (Thesis advisor) / Warrren-Findley, Jannelle (Committee member) / Thompson, Victoria (Committee member) / Smith, Louis (Committee member) / Arizona State University (Publisher)
Created2011
Description
The PPP Loan Program was created by the CARES Act and carried out by the Small Business Administration (SBA) to provide support to small businesses in maintaining their payroll during the Coronavirus pandemic. This program was approved for $350 billion, but this amount was expanded by an additional $320 billion to meet the demand by struggling businesses, since initial funding was exhausted under two weeks.<br/><br/>Significant controversy surrounds the program. In December 2020, the Department of Justice reported 90 individuals were charged for fraudulent use of funds, totaling $250 million. The loans, which were intended for small business, were actually approved for 450 public companies. Furthermore, the methods of approval are<br/>shrouded in mystery. In an effort to be transparent, the SBA has released information about loan recipients. Conveniently, the SBA has released information of all recipients. Detailed information was released for 661,218 recipients who have received a PPP loan in excess of $150,000. These recipients are the central point of this research.<br/><br/>This research sought to answer two primary questions: how did the SBA determine which loans, and therefore which industries are approved, and did the industries most affected by the pandemic receive the most in PPP loans, as intended by Congress? It was determined that, generally, PPP Loans were approved on the basis of employment percentages relative to the individual state. Furthermore, in general, the loans approved were approved fairly, with respect to the size of the industry. The loans, when adjusted for GDP and Employment factors, yielded a clear ranking that prioritized vulnerable industries first.<br/><br/>However, significant questions remain. The effectiveness of the PPP has been hindered by unclear incentives and negative outcomes, characterized by a government program that has essentially been rushed into service. Furthermore, limitations of available data to regress and compare the SBA's approved loans are not representative of small business.
ContributorsMaglanoc, Julian (Author) / Kenchington, David (Thesis director) / Cassidy, Nancy (Committee member) / Department of Finance (Contributor) / Dean, W.P. Carey School of Business (Contributor) / School of Accountancy (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
Music streaming services have affected the music industry from both a financial and legal standpoint. Their current business model affects stakeholders such as artists, users, and investors. These services have been scrutinized recently for their imperfect royalty distribution model. Covid-19 has made these discussions even more relevant as touring income has come to a halt for musicians and the live entertainment industry. <br/>Under the current per-stream model, it is becoming exceedingly hard for artists to make a living off of streams. This forces artists to tour heavily as well as cut corners to create what is essentially “disposable art”. Rapidly releasing multiple projects a year has become the norm for many modern artists. This paper will examine the licensing framework, royalty payout issues, and propose a solution.
ContributorsKoudssi, Zakaria Corley (Author) / Sadusky, Brian (Thesis director) / Koretz, Lora (Committee member) / Dean, W.P. Carey School of Business (Contributor) / Department of Finance (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05