Matching Items (110)
Description
Filtration for microfluidic sample-collection devices is desirable for sample selection, concentration, preprocessing, and downstream manipulation, but microfabricating the required sub-micrometer filtration structure is an elaborate process. This thesis presents a simple method to fabricate polydimethylsiloxane (PDMS) devices with an integrated membrane filter that will sample, lyse, and extract the DNA from microorganisms in aqueous environments. An off-the-shelf membrane filter disc was embedded in a PDMS layer and sequentially bound with other PDMS channel layers. No leakage was observed during filtration. This device was validated by concentrating a large amount of cyanobacterium Synechocystis in simulated sample water with consistent performance across devices. After accumulating sufficient biomass on the filter, a sequential electrochemical lysing process was performed by applying 5VDC across the filter. This device was further evaluated by delivering several samples of differing concentrations of cyanobacterium Synechocystis then quantifying the DNA using real-time PCR. Lastly, an environmental sample was run through the device and the amount of photosynthetic microorganisms present in the water was determined. The major breakthroughs in this design are low energy demand, cheap materials, simple design, straightforward fabrication, and robust performance, together enabling wide-utility of similar chip-based devices for field-deployable operations in environmental micro-biotechnology.
ContributorsLecluse, Aurelie (Author) / Meldrum, Deirdre (Thesis advisor) / Chao, Joseph (Thesis advisor) / Westerhoff, Paul (Committee member) / Arizona State University (Publisher)
Created2011
Description
Single cell phenotypic heterogeneity studies reveal more information about the pathogenesis process than conventional bulk methods. Furthermore, investigation of the individual cellular response mechanism during rapid environmental changes can only be achieved at single cell level. By enabling the study of cellular morphology, a single cell three-dimensional (3D) imaging system can be used to diagnose fatal diseases, such as cancer, at an early stage. One proven method, CellCT, accomplishes 3D imaging by rotating a single cell around a fixed axis. However, some existing cell rotating mechanisms require either intricate microfabrication, and some fail to provide a suitable environment for living cells. This thesis develops a microvorterx chamber that allows living cells to be rotated by hydrodynamic alone while facilitating imaging access. In this thesis work, 1) the new chamber design was developed through numerical simulation. Simulations revealed that in order to form a microvortex in the side chamber, the ratio of the chamber opening to the channel width must be smaller than one. After comparing different chamber designs, the trapezoidal side chamber was selected because it demonstrated controllable circulation and met the imaging requirements. Microvortex properties were not sensitive to the chambers with interface angles ranging from 0.32 to 0.64. A similar trend was observed when chamber heights were larger than chamber opening. 2) Micro-particle image velocimetry was used to characterize microvortices and validate simulation results. Agreement between experimentation and simulation confirmed that numerical simulation was an effective method for chamber design. 3) Finally, cell rotation experiments were performed in the trapezoidal side chamber. The experimental results demonstrated cell rotational rates ranging from 12 to 29 rpm for regular cells. With a volumetric flow rate of 0.5 µL/s, an irregular cell rotated at a mean rate of 97 ± 3 rpm. Rotational rates can be changed by altering inlet flow rates.
ContributorsZhang, Wenjie (Author) / Frakes, David (Thesis advisor) / Meldrum, Deirdre (Thesis advisor) / Chao, Shih-hui (Committee member) / Wang, Xiao (Committee member) / Arizona State University (Publisher)
Created2011
Description
"Culture talk" figures prominently in the discussions of and about Muslims, both locally and globally. Culture, in these discussions, is considered to be the underlying cause of gender and generational divides giving rise to an alleged "identity crisis." Culture also presumably conceals and contaminates "pure/true Islam." Culture serves as the scaffold on which all that divides Muslim American immigrants and converts is built; furthermore, the fear of a Muslim cultural takeover underpins the "Islamization of America" narrative. This dissertation engages these generational and "immigrant"-"indigenous" fissures and the current narratives that dominate Muslim and public spheres. It does so through the perspectives of the offspring of converts and immigrants. As the children and grandchildren of immigrants and converts come of age, and distant as they are from historical processes and experiences that shaped the parents' generations while having shared a socialization process as both Muslim and American, what role do they play in the current chapter of Islam in post-9/11 America? Will the younger generation be able to cross the divides, mend the fissures, and play a pivotal role in an "American Muslim community"? Examining how younger generations of both backgrounds view each other and their respective roles in forging an American Muslim belonging, agenda and discourse is a timely and much needed inquiry. This project aims to contribute by shedding more light on the identities, perspectives and roles of these younger generations through the four dominant narratives of identity crisis, pure/true Islam vs. Cultural Islam, the Islamization of America, and creation of an American Muslim community/identity/culture. These narratives are both part of public discourse and themes generated from interviews, a questionnaire\survey, and personal observation. This ethnographic study examines how American born and/or raised offspring of both converts to Islam and immigrant Muslims in the Phoenix and Chicago metropolitan areas define self and community, how they negotiate fissures and fault lines (ethnicity, race, class, gender, and religious interpretation) within their communities, and how their faith informs daily life and envisions a future. I utilize participant observation, interviews, and surveys and examine digital, visual and published media to answer these questions.
ContributorsAli, Muna (Author) / Eder, James (Thesis advisor) / Jackson, Sherman (Committee member) / Hjorleifur Jonsson (Committee member) / Tsuda, Takeyuki (Committee member) / Arizona State University (Publisher)
Created2013
Description
Food system and health characteristics were evaluated across the last Waorani hunter-gatherer group in Amazonian Ecuador and a remote neighboring Kichwa indigenous subsistence agriculture community. Hunter-gatherer food systems like the Waorani foragers may not only be nutritionally, but also pharmaceutically beneficial because of high dietary intake of varied plant phytochemical compounds. A modern diet that reduces these dietary plant defense phytochemicals below levels typical in human evolutionary history may leave humans vulnerable to diseases that were controlled through a foraging diet. Few studies consider the health impact of the recent drastic reduction of plant phytochemical content in the modern global food system, which has eliminated essential components of food because they are not considered "nutrients". The antimicrobial and anti-inflammatory nature of the food system may not only regulate infectious pathogens and inflammatory disease, but also support beneficial microbes in human hosts, reducing vulnerability to chronic diseases. Waorani foragers seem immune to certain infections with very low rates of chronic disease. Does returning to certain characteristics of a foraging food system begin to restore the human body microbe balance and inflammatory response to evolutionary norms, and if so, what implication does this have for the treatment of disease? Several years of data on dietary and health differences across the foragers and the farmers was gathered. There were major differences in health outcomes across the board. In the Waorani forager group there were no signs of infection in serious wounds such as 3rd degree burns and spear wounds. The foragers had one-degree lower body temperature than the farmers. The Waorani had an absence of signs of chronic diseases including vision and blood pressure that did not change markedly with age while Kichwa farmers suffered from both chronic diseases and physiological indicators of aging. In the Waorani forager population, there was an absence of many common regional infectious diseases, from helminthes to staphylococcus. Study design helped control for confounders (exercise, environment, genetic factors, non-phytochemical dietary intake). This study provides evidence of the major role total phytochemical dietary intake plays in human health, often not considered by policymakers and nutritional and agricultural scientists.
ContributorsLondon, Douglas (Author) / Tsuda, Takeyuki (Thesis advisor) / Beezhold, Bonnie L (Committee member) / Hruschka, Daniel (Committee member) / Eder, James (Committee member) / Arizona State University (Publisher)
Created2012
Description
This dissertation examines incidents of conflict and violence amid communities of the Maya Tzotzil Chamula in Chiapas, Mexico. Despite ostensible homogeneity, or more social and cultural resemblances than differences, conflicts arise between many Chamula because of how they acquire desire according to others who mediate what is desirable. These conflicts relate well to Rene Girard's hypothesis that mimetic desire influences identity yet generates conflict as imitation fosters rivalry. Qualitative methods of participant observation, interviews, and document research depict how desire, identity, and conflict interrelate. Ethnographic cases show how conflict emerges "interdividually" as rivals compete to obtain objects imputed desirable. The study begins with how young Tzotzils today appropriate the desires of others, becoming lawyer, spiritual guide, rock and roll singer, or anthropologist. Complex examples exhibit groups struggling for power and privilege within or between members of communities as they vie over "objects of desire" such as status, land, water, or representations of power and pecuniary interests. For some Chamula, mimetic rivalry works to deny resemblances with others despite being alike as neighbor, relative, farmer, carpenter, or member of the same political or religious affiliation. The study also highlights mimetic interactions that have shaped Maya struggles in the past, such as the uprisings of 1712, 1867, and 1911. Interpretive analysis explores how identity formation (structures), imitative desire (motivated interaction), and practice (habitual agency) together galvanize material and psychosocial variables for conflict. Imitative desire is worth observing because of its long-term implications for human adaptation and social change. As a contribution to social conflict theory, this dissertation offers a critical perspective to current research on mimetic desire as a significant force in human relations.
ContributorsRolland, Michael (Author) / Chance, John K. (Thesis advisor) / Eder, James (Committee member) / Hjorleifur Jonsson (Committee member) / Rus Iii, Jan (Committee member) / Arizona State University (Publisher)
Created2012
Description
Laboratory automation systems have seen a lot of technological advances in recent times. As a result, the software that is written for them are becoming increasingly sophisticated. Existing software architectures and standards are targeted to a wider domain of software development and need to be customized in order to use them for developing software for laboratory automation systems. This thesis proposes an architecture that is based on existing software architectural paradigms and is specifically tailored to developing software for a laboratory automation system. The architecture is based on fairly autonomous software components that can be distributed across multiple computers. The components in the architecture make use of asynchronous communication methodologies that are facilitated by passing messages between one another. The architecture can be used to develop software that is distributed, responsive and thread-safe. The thesis also proposes a framework that has been developed to implement the ideas proposed by the architecture. The framework is used to develop software that is scalable, distributed, responsive and thread-safe. The framework currently has components to control very commonly used laboratory automation devices such as mechanical stages, cameras, and also to do common laboratory automation functionalities such as imaging.
ContributorsKuppuswamy, Venkataramanan (Author) / Meldrum, Deirdre (Thesis advisor) / Collofello, James (Thesis advisor) / Sarjoughian, Hessam S. (Committee member) / Johnson, Roger (Committee member) / Arizona State University (Publisher)
Created2012
Description
The children of immigrants who arrived in the United States in the 1980s now make up one of the fastest growing components of American society. They face unique and interesting pressures as they incorporate aspects of their parents' heritage into their contemporary American lives. The purpose of this dissertation is to offer an in-depth look at the 1.5 and second generation by examining how the immigrant descendants negotiate assimilative pressures, transnational practices, and ethnic identification. Using ethnographic research methods, such as participant observation and in-depth interviews, I researched the children of immigrants, ages 18-30, living in northwest Arkansas, who have at least one immigrant parent from Latin America. This research is important because non-traditional receiving towns, especially more rural localities, are often overlooked by scholarly studies of migration in favor of larger metropolitan centers (e.g., Los Angeles, Chicago). Studying immigrant descendants in smaller towns that are becoming increasingly populated by Hispanic/Latinos will create a better understanding of how a new generation of immigrants is assimilating into American society and culture. To increase awareness on the Hispanic/Latino 1.5 and second generation living in small town America and to offer potential solutions to facilitate an upwardly mobile future for this population, my dissertation explores a number of research questions. First, how is this population assimilating to the U.S.? Second, are members of the 1.5 and second generation transnational? How active is this transnational lifestyle? Will transnationalism persist as they grow older? Third, how does this population identify themselves ethnically? I also pay particular attention to the relationships among assimilation, transnationalism, and ethnic identity. My dissertation documents the lived experiences of the 1.5 and second generation in northwest Arkansas. The children of immigrants are one of the fastest growing groups nationwide. To understand their world and the lives they lead is to understand the new fabric of American society. I anticipate that the results from this research can be used to facilitate easier transitions to the U.S. among current and prospective immigrant generations, ensuring a brighter outlook for the future of the newest members of U.S. society.
ContributorsSmith, Claire M. (Author) / Tsuda, Takeyuki (Thesis advisor) / Eder, James (Committee member) / Chance, John K. (Committee member) / Arizona State University (Publisher)
Created2014
Description
The dissertation is based on 15 months of ethnographically-informed qualitative research at a liberal arts college in the Himalayan nation of Bhutan. It seeks to provide a sense of daily life and experience of schooling in general and for female students in particular. Access to literacy and the opportunities that formal education can provide are comparatively recent for most Bhutanese women. This dissertation will look at how state-sponsored schooling has shaped gender relations and experiences in Bhutan where non-monastic, co-educational institutions were unknown before the 1960s. While Bhutanese women continue to be under-represented in politics, upper level government positions and public life in general, it is frequently claimed at a variety of different levels (for instance in local media and government reports), that Bhutan, unlike it South Asian neighbors, has a high degree of gender equity. It is argued that any under-representation does not reflect access or opportunity but is instead the result of women's decision not to "come up" and participate. However this dissertation will dispute the claim that female students could choose to be more visible, vocal and mobile in classrooms and on campus without being challenged or discouraged. I will show that school is a gendered context, in which female students are consistently reminded of their "limitations" and their "appropriate place" through the use of familiar social practices such as teasing, gossip, and harassment. Schooling, particularly in developing nations like Bhutan, is usually implicitly and uncritically understood to be a neutral resource, often evaluated in relation to development aims such as creating a more educated and skilled workforce. While Bhutanese schools do seem to promote new kind of opportunity and new understandings of success, they also continue to recognize, maintain and reproduce conventional values around hierarchy, knowledge transmission, cooperation (or group identity) and gender norms. This dissertation will also show how emergent disparities in wealth and opportunity in the nation at large are beginning to be reflected and reproduced in both the experience of schooling and the job market in ways that Bhutanese development policy is not yet able to adequately address.
ContributorsRoder, Dolma Choden (Author) / Eder, James (Thesis advisor) / Hjorleifur Jonsson (Committee member) / Mccarty, Teresa (Committee member) / Arizona State University (Publisher)
Created2012
Description
This dissertation is intended to tie together a body of work which utilizes a variety of methods to study applied mathematical models involving heterogeneity often omitted with classical modeling techniques. I posit three cogent classifications of heterogeneity: physiological, behavioral, and local (specifically connectivity in this work). I consider physiological heterogeneity using the method of transport equations to study heterogeneous susceptibility to diseases in open populations (those with births and deaths). I then present three separate models of behavioral heterogeneity. An SIS/SAS model of gonorrhea transmission in a population of highly active men-who-have-sex-with-men (MSM) is presented to study the impact of safe behavior (prevention and self-awareness) on the prevalence of this endemic disease. Behavior is modeled in this examples via static parameters describing consistent condom use and frequency of STD testing. In an example of behavioral heterogeneity, in the absence of underlying dynamics, I present a generalization to ``test theory without an answer key" (also known as cultural consensus modeling or CCM). CCM is commonly used to study the distribution of cultural knowledge within a population. The generalized framework presented allows for selecting the best model among various extensions of CCM: multiple subcultures, estimating the degree to which individuals guess yes, and making competence homogenous in the population. This permits model selection based on the principle of information criteria. The third behaviorally heterogeneous model studies adaptive behavioral response based on epidemiological-economic theory within an $SIR$ epidemic setting. Theorems used to analyze the stability of such models with a generalized, non-linear incidence structure are adapted and applied to the case of standard incidence and adaptive incidence. As an example of study in spatial heterogeneity I provide an explicit solution to a generalization of the continuous time approximation of the Albert-Barabasi scale-free network algorithm. The solution is found by recursively solving the differential equations via integrating factors, identifying a pattern for the coefficients and then proving this observed pattern is consistent using induction. An application to disease dynamics on such evolving structures is then studied.
ContributorsMorin, Benjamin (Author) / Castillo-Chavez, Carlos (Thesis advisor) / Hiebeler, David (Thesis advisor) / Hruschka, Daniel (Committee member) / Suslov, Sergei (Committee member) / Arizona State University (Publisher)
Created2012
Description
Single cell analysis has become increasingly important in understanding disease onset, progression, treatment and prognosis, especially when applied to cancer where cellular responses are highly heterogeneous. Through the advent of single cell computerized tomography (Cell-CT), researchers and clinicians now have the ability to obtain high resolution three-dimensional (3D) reconstructions of single cells. Yet to date, no live-cell compatible version of the technology exists. In this thesis, a microfluidic chip with the ability to rotate live single cells in hydrodynamic microvortices about an axis parallel to the optical focal plane has been demonstrated. The chip utilizes a novel 3D microchamber design arranged beneath a main channel creating flow detachment into the chamber, producing recirculating flow conditions. Single cells are flowed through the main channel, held in the center of the microvortex by an optical trap, and rotated by the forces induced by the recirculating fluid flow. Computational fluid dynamics (CFD) was employed to optimize the geometry of the microchamber. Two methods for the fabrication of the 3D microchamber were devised: anisotropic etching of silicon and backside diffuser photolithography (BDPL). First, the optimization of the silicon etching conditions was demonstrated through design of experiment (DOE). In addition, a non-conventional method of soft-lithography was demonstrated which incorporates the use of two positive molds, one of the main channel and the other of the microchambers, compressed together during replication to produce a single ultra-thin (<200 µm) negative used for device assembly. Second, methods for using thick negative photoresists such as SU-8 with BDPL have been developed which include a new simple and effective method for promoting the adhesion of SU-8 to glass. An assembly method that bonds two individual ultra-thin (<100 µm) replications of the channel and the microfeatures has also been demonstrated. Finally, a pressure driven pumping system with nanoliter per minute flow rate regulation, sub-second response times, and < 3% flow variability has been designed and characterized. The fabrication and assembly of this device is inexpensive and utilizes simple variants of conventional microfluidic fabrication techniques, making it easily accessible to the single cell analysis community.
ContributorsMyers, Jakrey R (Author) / Meldrum, Deirdre (Thesis advisor) / Johnson, Roger (Committee member) / Frakes, David (Committee member) / Arizona State University (Publisher)
Created2012