Matching Items (57)
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
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
Infectious diseases have been a major threat to survival throughout human history. Humans have developed a behavioral immune system to prevent infection by causing individuals to avoid people, food, and objects that could be contaminated. This current project investigates how ambient temperature affects the activation of this system. Because temperature is positively correlated with the prevalence of many deadly diseases, I predict that temperature moderates the behavioral immune system, such that a disease prime will have a stronger effect in a hot environment compared to a neutral environment and one's avoidant behaviors will be more extreme. Participants were placed in a hot room (M = 85F) or a neutral room (M = 77F) and shown a disease prime slide show or a neutral slide show. Disgust sensitivity and perceived vulnerability surveys were used to measure an increased perceived risk to disease. A taste test between a disgusting food item (gummy bugs) and a neutral food item (gummy animals) measured food avoidance. There was no significant avoidance of the gummy and no significant difference in ratings of disgust sensitivity or perceived vulnerability as a function of temperature conditions. There were no significant interactions between temperature and disease. The conclusion is that this study did not provide evidence that temperature moderates the effect of disease cues on behavior.
ContributorsOsborne, Elizabeth (Author) / Cohen, Adam B. (Thesis advisor) / Kwan, Sau (Committee member) / Neuberg, Steven (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
Description
The present study explored the relationship between desired purchasing behavior and individual differences using two nationally-representative, longitudinal samples of the U.S. population early in the COVID-19 pandemic. Past research has shown that individual differences provide information about how one might respond to threat. Therefore, we predicted changes in desired purchasing behavior across different sociodemographic variables that might reflect those differences. Specifically, we investigated hypotheses related to political orientation, age, sexual orientation, socioeconomic status, and whether or not the participant had children. We measured participants’ reported desired purchasing behavior across eleven categories of goods and investigated the connection between specific demographic variables and desired purchasing behavior. We found that conservatives desired to purchase more basic protection goods (guns/ammunition, cash, gas) and that older people desired to purchase more cleaning supplies and toiletries. These findings illustrate possible explanations for purchasing behavior during the COVID-19 pandemic and reveal directions for marketing designed to influence purchasing behavior.
ContributorsZeider, Justyn (Author) / Varnum, Michael (Thesis director) / Neuberg, Steven (Committee member) / Department of Psychology (Contributor) / School of International Letters and Cultures (Contributor) / School of Social Transformation (Contributor) / Sandra Day O'Connor College of Law (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description
Regular instances of employee and petty theft seem to suggest that stealing is common. Certain situations make stealing an advantageous opportunity, and studies show that most people will steal under the right conditions. However, these "right conditions" vary widely among individuals and are a combination of biological, social, psychological, and situational factors. In an attempt to better understand the rationality of stealing, our research team applied evolutionary psychology principles to a social experiment involving gift card theft. To find trends in how people will steal when given the opportunity, we attempted to create these "right conditions" (which we believed would encourage theft by minimizing cost) so that we could measure how a random sample of subjects (male students on the Tempe campus of Arizona State University) responded to variation in benefit. We predicted that if the cost was kept low, and if some gift cards conferred greater advantages than others (by possession greater value or utility), then the more advantageous gift cards would be stolen at a higher frequency from the sample pool than less advantageous ones. The results show that our assumptions were wrong. Theft almost never occurred and the few cards that were stolen were not the more "rational" choices as predicted. The experimental design indicates a flawed understanding of how the subjects weighed the benefits and costs of stealing gift cards. One major issue is that we failed to consider pro-social behavior as the norm. We also neglected the evolutionary benefits of cooperative behavior while overemphasizing the evolutionary benefits of theft. A more thorough and nuanced examination of the literature must be performed to avoid these fundamental flaws in the experiment in the future. The experiment also suffered from issues which might have inadvertently discouraged theft including the location, population, presence of other students, and time given to contemplate theft. If we wish to truly examine trends in theft to see if there is a trend towards the rational theft model we proposed, we must work with a population in which individuals already have a propensity to steal, the benefit is sufficiently high, and social pressures to be cooperative are low.
ContributorsKumar, Davina Sangitha (Author) / Angilletta, Michael (Thesis director) / Neuberg, Steven (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
Contextual cues can impact how statements are perceived. Specifically, they may be perceived as more aggressive than they otherwise would be. For the study, both medium of communication (in-person versus online) as well as how competitive the context was (non-competitive or competitive) were examined, with a bit of focus on gender. 130 Arizona State University students enrolled in Psychology 101 were surveyed; the mean age was 19.32 (SD = 1.43). A 2x2 factorial design was used, consisting of four possible conditions: In-person/Competitive, Online/Competitive, In-person/Non-Competitive, and Online/Non-Competitive. Participants read two scenarios, each featuring a target character who says an ambiguous statement, and each scenario with one of the four conditions at random. One scenario involved earning a promotion, and the other involved trying to win a voucher via mini-golf. After, participants answered questions regarding how they felt about the intent of the ambiguous statement, how the participant would feel in the scenario, and what kind of person the participant felt the target character was. Exploratory Factor Analysis with Principal Axis Factoring and Direct Oblimin Rotation was used to find outcome variables. We hypothesized that Perceived Aggression and Participant Negative Emotion would be higher in both the competitive condition as well as the online condition, and that Perceived Agreeableness would be higher in both the non-competitive condition as well as the in-person condition; this applied for both scenarios. The results were mostly not statistically significant, and contrary to the hypotheses, Perceived Aggression and Participant Negative Emotion were higher in the in-person condition than the online condition. However, as predicted, Perceived Agreeableness was higher for the in-person condition, and the competitive led to higher levels of Perceived Aggression and Participant Negative Emotion, along with lower levels of Perceived Agreeableness, as opposed to the non-competitive condition. Limitations included a small age range and only one type of online communication (instant messaging), along with the fact that the study was a survey. Future studies are needed to examine what factors affect perception of aggression, as very few have been conducted.
ContributorsRobins, Alexander Eric (Author) / Shiota, Michelle (Lani) (Thesis director) / Neuberg, Steven (Committee member) / Danvers, Alexander (Committee member) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
In the current study, the author investigated whether sociosexual orientation interacted with an experimental manipulation of sex ratios previously used by Li et al. (2010) which showed that men and women report greater religiosity after viewing profiles of attractive members of their own sex. The author predicted that only people of restricted sociosexual orientation would be reporting greater religiosity after viewing profiles of attractive members of their own sex. A sample of 171 undergraduate students (85 men, Mage = 19.5) from a large Southwestern university participated in the study for course credit. Participants were first administered the Sociosexual Orientation Index (Simpson & Gangestad, 1991). Then, under the pretense of assisting psychology faculty in designing a dating website for incoming students, participants viewed a set of profiles (photo and description) of either attractive men or attractive women, after which they answered a series of questions on a religiosity scale developed for the current study. Results showed that sociosexual orientation did not interact significantly with the experimental manipulation. Additionally, the results of the current study failed to replicate those of Li et al. (2010). The author discusses possibilities for why the results of the current study failed to replicate the results of Li et al., and for alternative explanations of the potential role of sociosexual orientation in responding to shifting sex ratios.
ContributorsCottengaim, Isaiah John (Author) / Cohen, Adam (Thesis director) / Neuberg, Steven (Committee member) / Barrett, The Honors College (Contributor) / School of Social and Behavioral Sciences (Contributor)
Created2014-05
Description
The aim of this thesis was to explore whether major life changes can have a visual, perceptible impact on facial changes. The proposed mediation model suggested that changes in personality serve as a mediating factor between life experiences and facial changes throughout the lifetime. The proposed model was tested by examining (1) perceived personality changes, (2) perceived physical changes, and (3) major life changes in photos of individuals' old-aged faces compared to their respective younger faces. Participants in the current study viewed old and young photos of 29 Miss America pageant winners and rated how much each older face changed from its respective younger face on the following criteria: age change, overall change, personality change, and physical change. Responses were aggregated across participants for each target, and personality and physical items were separately composited into single measures of overall perceived personality change and overall perceived physical change. Results did not support the proposed model; however, some marginally significant correlations were found between the number of times the targets experienced a change in marital status and the appearance of being calm, feminine, and less changed in older age. However, these correlations were in the reverse direction from what was expected; further research is needed to understand how marital changes influence, and are influenced by, personality and physical changes. As a form of face perception, the processes underlying the proposed model are discussed in terms of possible social consequences. Further research is needed to explore whether changes in life events, such as the ones presented here, are related to specific facets of personality and physical changes, and how these perceptions translate to important social outcomes. Suggestions for future research pertaining to these issues are discussed.
ContributorsMichael, Kendra (Author) / Kwan, Virginia (Thesis director) / Knight, George (Committee member) / Neuberg, Steven (Committee member) / Barrett, The Honors College (Contributor) / College of Liberal Arts and Sciences (Contributor)
Created2012-12