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Title: What it do? : Houston hip hop, ciphers, migration, and borderlands
Creator: Del Hierro, Victor
Date: 2017
Collection: Electronic Theses & Dissertations
Description: In this dissertation, I migrate through Houston Hip Hop culture from 1991-2000 to understand the history and legacy of DJ Screw, Screw Tapes, and Screw and Chopped style. The purpose of this project is to understand the relationship between local communities and the Global Hip Hop Nation (GHHN) by migrating through the borderland spaces that exists both physically and metaphorically. Using Hip Hop practices and knowledges, this dissertation understands Hip Hop as a culture made up of multiple...
Show moreIn this dissertation, I migrate through Houston Hip Hop culture from 1991-2000 to understand the history and legacy of DJ Screw, Screw Tapes, and Screw and Chopped style. The purpose of this project is to understand the relationship between local communities and the Global Hip Hop Nation (GHHN) by migrating through the borderland spaces that exists both physically and metaphorically. Using Hip Hop practices and knowledges, this dissertation understands Hip Hop as a culture made up of multiple Hip Hop Ciphers. Locating borderlands between ciphers by purposefully migrating between them, this study combines the analysis of mixtapes, archival material, and interviews, this project works to create an emic view of Hip Hop as a culture that has always, and continues to create, re-imagine, and sustain knowledge and history through technological innovation, writing, and community building. This dissertation focuses on Houston because of DJ Screw and his development of a style (Screwed and Chopped) and mixtape series (Screw Tapes) that continues to impact and define a community’s identity. Through Screw Tapes, DJ Screw and the Houston Hip Hop community negotiation the relationship between Hip Hop and local styles in the production of diverse forms of communication.
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Title: Social influence on the Net : a mindset approach
Creator: Sah, Young June
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Social media afford a context within which users interact with other users. Recognizing variations in contexts afforded by social media, the current study classified social media into two types, i.e., relational media, which allow users to build individual social connections, and categorical media, which support group-based connections. Effects of relational and categorical media were examined, employing a mindset approach as a theoretical framework. The mindset approach manifests the...
Show moreSocial media afford a context within which users interact with other users. Recognizing variations in contexts afforded by social media, the current study classified social media into two types, i.e., relational media, which allow users to build individual social connections, and categorical media, which support group-based connections. Effects of relational and categorical media were examined, employing a mindset approach as a theoretical framework. The mindset approach manifests the situated nature of cognition, emphasizing individuals’ tendency to harness immediate contexts in meaning-making processing. Based on this postulation, the current study proposed that social media induced distinctive mindsets, entailing self-concept, goal-orientation, and concrete-abstract level in perceiving others.The current study also examined effects of social media on users’ group identification and belief change. Based on previous literature on social identity, it is proposed that distinctive mechanisms determine group identification in relational and categorical media. For relational media users, perception of individual relations to other users was expected to mediate the effect of relational media on group identification. In contrast, for categorical media users, perception of being a member of a group and perception of a homogeneous group were expected to mediate the effect of categorical media on group identification. Furthermore, based on the automatic social influence literature, the present study proposed that relational and categorical media, compared to non-social media, induce greater belief changes, and the belief changes are mediated by group identification. The predictions were tested using an online experiment (N = 705), in which participants used a mock-up social media, in which they formed social connections of either relational or categorical type, or used it without building social connection. Participants read others’ posts and comments revealing their opinions on health-related issues. Participants’ mindset, social perception, group identification, and belief changes were assessed. Results revealed that using social media influenced participants’ mindset: The relational group reported greater in-group self-concept and considered in-group goals more important, and used less concrete terms when describing their group members. Also, the categorical group considered in-group goals more important. Furthermore, using social media influenced group identification: The relational and categorical group reported greater group identification than the control group. Yet, the relative contributions of predictors of group identification differed across the conditions. For the relational media, relational perception was a dominant determinant of group identification and homogeneity perception was the least influential. For the categorical group, homogeneity perception was a predictor as significant as others. Lastly, effects of social media use on belief changes was not different across the social media type.The current study contributes to our understanding of how social media influence users by employing a novel theoretical framework, mindset approach, in examining subtle differences generated by social media. The mindset approach enables us to find nuanced effects: Different types of social media afford distinctive mindsets and psychological mechanisms for group identification.
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Title: Affective and cognitive responses to insects and other arthropods
Creator: Lorenz-Reaves, Amanda R.
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "Insects are the most abundant and diverse group of animals on Earth. Though as a group they do far more ecological good than harm, previous studies have shown that human attitudes toward insects are mainly negative. Attitudes have affective (emotions) and cognitive (beliefs, mental representations) components that interact to influence behavior. Negative attitudes toward insects are associated with negative affect such as disgust and fear, and can have negative consequences, such as a lack...
Show more"Insects are the most abundant and diverse group of animals on Earth. Though as a group they do far more ecological good than harm, previous studies have shown that human attitudes toward insects are mainly negative. Attitudes have affective (emotions) and cognitive (beliefs, mental representations) components that interact to influence behavior. Negative attitudes toward insects are associated with negative affect such as disgust and fear, and can have negative consequences, such as a lack of conservation funding. In addition, negative attitudes can cause people to avoid insects and/or feel distress when insects are present, prompting a disconnection between the public and the insect world. To explore affective responses to insects, Chapter Two focuses on the emotion of disgust. Disgust is associated with avoidance of objects that cause sickness (e.g. rotten meat) or undesirable social conduct (e.g. moral disgust). Disgust is partitioned into distinct domains - pathogen, moral, sexual, etc. To determine whether disgust stimulated by insects belongs in a unique domain, incoming freshmen at a large public university were surveyed (Chapter Two). Survey items pertained to moral, pathogen, and insect-specific disgust. Factor analyses indicate that insect disgust and pathogen disgust are part of the same construct, unique from moral disgust. This implies that insects are perceived with the same feelings of disgust felt for pathogens. To explore cognition associated with insects, Chapter Three and Appendix One focus on mental models of insects and other arthropods. Mental models are internal representations of external entities that are used to reason, make inferences, conduct thought experiments, and anticipate future events. Drawings reflect important qualities of mental models including knowledge categorization and organization. Drawings of insects were collected from participants with high and low expertise in entomology. Salient insect features were indexed and principal components analysis applied to detect underlying patterns. Two distinct components emerged - (1) a non-winged "crawling" insect, and (2) a legless winged "flying" insect, implying that flying and crawling insects are perceived as distinct from each other (Chapter Three). A similar analysis of children's drawings of insects also showed a distinction between crawling and flying insects (Appendix One). Finally, to explore the interaction between affective and cognitive responses to insects, drawings of "disgusting" and "not disgusting" insects from participants sampled in Chapter Three were compared. Participants were also surveyed to gain a quantitative measure of disgust associated with insects. Experts exhibited significantly lower disgust responses than novices. Additionally, the inclusion of legs on drawings of insects deemed not disgusting correlated negatively with disgust. In contrast, the inclusion of legs on drawings of disgusting insects correlated positively with disgust. This suggests that crawling insects may be regarded as being more disgusting than flying insects. A multiple linear regression was conducted on the not disgusting insect drawings to determine whether drawing a crawling insect as well as one's expertise level, could predict insect-associated disgust. Approximately 35% of the variation in disgust was attributable to subject group (expertise) and the degree to which drawings aligned with the crawling insect model. In addition, this study also demonstrates that examining drawings of insects can be a useful tool to shed light on affect and cognition associated with insects."--Pages ii-iii.
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Title: Physics-based crystal plasticity modeling of single crystal niobium
Creator: Maiti, Tias
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Crystal plasticity models based on thermally activated dislocationkinetics has been successful in predicting the deformation behavior ofcrystalline materials, particularly in face-centered cubic (fcc) metals.In body-centered cubic (bcc) metals success has been limited owing toill-defined slip planes. The flow stress of a bcc metal is stronglydependent on temperature and orientation due to the non-planar splittingof a/2<111> screw dislocations. As a consequence of this, bccmetals show two...
Show moreCrystal plasticity models based on thermally activated dislocationkinetics has been successful in predicting the deformation behavior ofcrystalline materials, particularly in face-centered cubic (fcc) metals.In body-centered cubic (bcc) metals success has been limited owing toill-defined slip planes. The flow stress of a bcc metal is stronglydependent on temperature and orientation due to the non-planar splittingof a/2<111> screw dislocations. As a consequence of this, bccmetals show two unique deformation characteristics: (a) thermally-activated glide of screw dislocations - the motion of screwcomponents with their non-planar core structure at the atomistic leveloccurs even at low stress through the nucleation (assisted by thermalactivation) and lateral propagation of dislocation kink pairs; (b)break-down of the Schmid Law, where dislocation slip is driven only bythe resolved shear stress.Since the split dislocation core has to constrict for a kink pairformation (and propagation), the non-planarity of bcc screw dislocationcores entails an influence of (shear) stress components acting on planesother than the primary glide plane on their mobility. Anotherconsequence of the asymmetric core splitting on the glide plane is adirection-sensitive slip resistance, which is termed twinning/atwinningsense of shear and should be taken into account when developingconstitutive models.Modeling thermally-activated flow including the above-mentionednon-Schmid effects in bcc metals has been the subject of much work,starting in the 1980s and gaining increased interest in recent times.The majority of these works focus on single crystal deformation ofcommonly used metals such as Iron (Fe), Molybdenum (Mo), and Tungsten(W), while very few published studies address deformation behavior inNiobium (Nb). Most of the work on Nb revolves around fitting parametersof phenomenological descriptions, which do not capture adequately themacroscopic multi-stage hardening behavior and evolution ofcrystallographic texture from a physical point of view. Therefore, weaim to develop a physics-based crystal plasticity model that can capturethese effects as a function of grain orientations, microstructureparameters, and temperature.To achieve this goal, first, a new dilatational constitutive model isdeveloped for simulating the deformation of non-compact geometries (foamsor geometries with free surfaces) using the spectral method. The modelhas been used to mimic the void-growth behavior of a biaxially loadedplate with a circular inclusion. The results show that the proposedformulation provides a much better description of void-like behaviorcompared to the pure elastic behavior of voids. Using the developeddilatational framework, periodic boundary conditions arising from thespectral solver has been relaxed to study the tensile deformationbehavior of dogbone-shaped Nb single crystals.Second, a dislocation density-based constitutive model with storage andrecovery laws derived from Discrete Dislocation Dynamics (DDD) isimplemented to model multi-stage strain hardening. The influence ofpre-deformed dislocation content, dislocation interaction strengths andmean free path on stage II hardening is then simulated and compared within-situ tensile experiments.
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Title: Mechanisms mediating life history traits in the spotted hyena (Crocuta crocuta
Creator: Lewin, Nora Shannon
Date: 2017
Collection: Electronic Theses & Dissertations
Description: My dissertation focuses on understanding the mechanisms underpinning growth, reproduction, and survival in the spotted hyena. Following a general introductory chapter, my dissertation is composed of four independent research chapters. I begin with Chapter 2 in which my colleagues and I document a positive linear relationship between social dominance rank and telomere length. We also report significant variability in telomere length of high-ranking females among different social groups,...
Show moreMy dissertation focuses on understanding the mechanisms underpinning growth, reproduction, and survival in the spotted hyena. Following a general introductory chapter, my dissertation is composed of four independent research chapters. I begin with Chapter 2 in which my colleagues and I document a positive linear relationship between social dominance rank and telomere length. We also report significant variability in telomere length of high-ranking females among different social groups, suggesting that both social dominance rank and group membership influence this important biomarker of aging. In Chapter 3, we describe the role of juvenile concentrations of the hormone, insulin-like growth-factor -1 (IGF-1), in predicting trade-offs between early-life growth and later-life reproduction and survival among female hyenas. In Chapter 4, I explore IGF-1 as a potential mechanism of female-biased sexual size dimorphism by documenting sex-biased concentrations, sensitivities, and adaptive values of IGF-1 during the early postnatal period. Finally, in Chapter 5, I describe that age-related improvement and senescence in reproductive performance varies with social dominance rank among female hyenas. Cumulatively, my dissertation is an exploration of how physiological mechanisms may be used to understand social, physiological, and evolutionary forces operating in a free-living social carnivore. My work offers a unique contribution to the field of life-history evolution and furthers our understanding of the mechanisms that give rise to it.
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Title: Expanding the survivor support net : a qualitative evaluation of a flexible funding program for intimate partner violence survivors
Creator: Bomsta, Heather
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "Intimate partner violence (IPV) affects nearly one in four US women in their lifetime. IPV survivors need access to material and community resources - whether they are leaving their abusers or choosing to stay in the relationship. Previous research has found that women who have experienced IPV are four times as likely to experience housing instability. The current IPV system focuses mainly on providing shelter, support groups, counseling, and legal advocacy, but has fewer financial resources...
Show more"Intimate partner violence (IPV) affects nearly one in four US women in their lifetime. IPV survivors need access to material and community resources - whether they are leaving their abusers or choosing to stay in the relationship. Previous research has found that women who have experienced IPV are four times as likely to experience housing instability. The current IPV system focuses mainly on providing shelter, support groups, counseling, and legal advocacy, but has fewer financial resources. This qualitative study focused on a pilot program in Washington D.C. that offered select survivors financial grants to address whatever the survivor defined as threatening their housing stability. Survivors were interviewed 30-days post-grant to assess their housing status and explore other grant impacts. All survivors in the sample were still housed 30- days post-grant. Survivors described the impact of the grants as extending beyond financial issues, resulting in stress relief, improved parenting, increased ability to focus on work and family and improvements in physical and mental health. The financial aspect of the grant was important, but the role of advocacy also appears crucial to these survivors."--Page ii.
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Title: A global modeling framework for plasma kinetics : development and applications
Creator: Parsey, Guy Morland
Date: 2017
Collection: Electronic Theses & Dissertations
Description: The modern study of plasmas, and applications thereof, has developed synchronously with com-puter capabilities since the mid-1950s. Complexities inherent to these charged-particle, many-body, systems have resulted in the development of multiple simulation methods (particle-in-cell,fluid, global modeling, etc.) in order to both explain observed phenomena and predict outcomesof plasma applications. Recognizing that different algorithms are chosen to best address specifictopics of interest, this...
Show moreThe modern study of plasmas, and applications thereof, has developed synchronously with com-puter capabilities since the mid-1950s. Complexities inherent to these charged-particle, many-body, systems have resulted in the development of multiple simulation methods (particle-in-cell,fluid, global modeling, etc.) in order to both explain observed phenomena and predict outcomesof plasma applications. Recognizing that different algorithms are chosen to best address specifictopics of interest, this thesis centers around the development of an open-source global model frame-work for the focused study of non-equilibrium plasma kinetics. After verification and validationof the framework, it was used to study two physical phenomena: plasma-assisted combustion andthe recently proposed optically-pumped rare gas metastable laser.Global models permeate chemistry and plasma science, relying on spatial averaging to focusattention on the dynamics of reaction networks. Defined by a set of species continuity and energyconservation equations, the required data and constructed systems are conceptually similar acrossmost applications, providing a light platform for exploratory and result-search parameter scan-ning. Unfortunately, it is common practice for custom code to be developed for each application-an enormous duplication of effort which negatively affects the quality of the software produced.Presented herein, the Python-based Kinetic Global Modeling framework (KGMf) was designed tosupport all modeling phases: collection and analysis of reaction data, construction of an exportablesystem of model ODEs, and a platform for interactive evaluation and post-processing analysis. Asymbolic ODE system is constructed for interactive manipulation and generation of a Jacobian,both of which are compiled as operation-optimized C-code.Plasma-assisted combustion and ignition (PAC/PAI) embody the modernization of burning fuelby opening up new avenues of control and optimization. With applications ranging from engineefficiency and pollution control to stabilized operation of scramjet technology in hypersonic flows,developing an understanding of the underlying plasma chemistry is of the utmost importance.While the use of equilibrium (thermal) plasmas in the combustion process extends back to the ad-vent of the spark-ignition engine, works from the last few decades have demonstrated fundamentaldifferences between PAC and classical combustion theory. The KGMf is applied to nanosecond-discharge systems in order to analyze the effects of electron energy distribution assumptions onreaction kinetics and highlight the usefulness of 0D modeling in systems defined by coupled andcomplex physics.With fundamentally different principles involved, the concept of optically-pumped rare gasmetastable lasing (RGL) presents a novel opportunity for scalable high-powered lasers by takingadvantage of similarities in the electronic structure of elements while traversing the periodic ta-ble. Building from the proven concept of diode-pumped alkali vapor lasers (DPAL), RGL systemsdemonstrate remarkably similar spectral characteristics without problems associated with heatedcaustic vapors. First introduced in 2012, numerical studies on the latent kinetics remain immature.This work couples an analytic model developed for DPAL with KGMf plasma chemistry to bet-ter understand the interaction of a non-equilibrium plasma with the induced laser processes anddetermine if optical pumping could be avoided through careful discharge selection.
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Title: Freshwater resources : an evaluation of Michigan residents' perception of wetland ecosystem services
Creator: Walkowiak, Toni Anne
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "Thus, this research serves two purposes: (1), to gather information about Michigan residents' overall knowledge of wetlands ecosystems; (2), to establish whether residents can accurately distinguish between wetland functions and values. Two activities: semi-structured focus group interviews and online digital card sorts were conducted within Chippewa, Huron, and Macomb Counties of Michigan, to evaluate individuals' environmental perceptions of wetland ecosystems." -- Abstract.

Title: Ultrafast transient states in nonequilibrium quantum systems
Creator: Hwang, Bin
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Photo-induced phase transitions (PIPT) in quantum systems are the epitome of challenging non-equilibrium many-body phenomena, that also have a wide range of potential applications. Recently interest in light-matter coupled states with an energy gap have yielded evidence for Floquet topological states. In this study we demonstrate nonequilibrium Floquet band formation under ultrafast optical excitation using a one-dimensional topological insulator. As an example, the effects are illustrated...
Show morePhoto-induced phase transitions (PIPT) in quantum systems are the epitome of challenging non-equilibrium many-body phenomena, that also have a wide range of potential applications. Recently interest in light-matter coupled states with an energy gap have yielded evidence for Floquet topological states. In this study we demonstrate nonequilibrium Floquet band formation under ultrafast optical excitation using a one-dimensional topological insulator. As an example, the effects are illustrated using a new Zig-Zag Su-Schrieffer-Heeger model of polyacetylene, which is a paradigmatic Hamiltonian exhibiting nontrivial edge states. Our results indicate short optical pulses feasible in experiments can induce novel topological states, local spectral selection and novel pseudospin textures in polyacetylene. Pump-probe photoemission spectroscopy is able to study these states by measuring Floquet band formation and sizeable energy gaps on femtosecond time scales. We find that optically activated nontrivial variations of sublattice mixing could lead to novel topological phenomenon.The rich variety of states induced by lasers have a wide range of potential applications so that control of these states has become a key objective. We present a computational approach to finding optimal ultrafast laser pulse shapes to induce target states and population inversion in pump-probe PIPT experiments. The Krotov approach for Quantum optimal control theory (QOCT) is combined with a Keldysh Green’s function calculation to describe experimental outcomes such as photoemission, transient single particle density of states and optical responses. Results for a simple model charge density wave (CDW) system are presented, including generation of almost complete population inversion and negative temperature states.
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Title: A practical approach for ultra high performance concrete construction
Creator: Chen, Yang (Graduate of Michigan State University in civil engineering)
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "Ultra-high-performance concrete (UHPC) with compressive strengths in excess of 150 MPa promise to enhance the structural efficiency and durability of concrete-based infrastructure systems. In order to transition UHPC materials into mainstream construction practices, there are needs to develop refined mix design procedures that enable production of UHPC using primarily locally available materials, resolves the problems with production of homogeneous UHPC mixtures using commonly available...
Show more"Ultra-high-performance concrete (UHPC) with compressive strengths in excess of 150 MPa promise to enhance the structural efficiency and durability of concrete-based infrastructure systems. In order to transition UHPC materials into mainstream construction practices, there are needs to develop refined mix design procedures that enable production of UHPC using primarily locally available materials, resolves the problems with production of homogeneous UHPC mixtures using commonly available concrete mixers, develop convenient fresh mix workability test methods that consider the peculiar rheology of fresh UHPC mixtures, and quantify some aspects of the UHPC material properties that have not been fully characterized. The UHPC materials were tested for fresh mix flow and hardened concrete compressive strength. The trends in the effects of packing density, water film thickness and excess paste film thickness on compressive strength and fresh mix flow were investigated. The results were used to identify viable ranges of these defining characteristics of UHPC mixtures. Response surface analysis of the fresh mix flow and the hardened concrete compressive strength test results led to identification of the optimum values of mix design parameters. The optimum mix was prepared, and was found to produce a highly desired balance of fresh mix flow and hardened concrete compressive strength, which occurred within the ranges predicted by response surface analysis of experimental results."--Page ii.
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Title: Managing carrot foliar diseases in commercial production fields in Michigan
Creator: Donne, Irene Mariel
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "Fungal foliar diseases caused by Alternaria dauci and Cercospora carotae occur annually on carrots. Our goal was to update the disease management tactics by: 1) Testing OMRI-approved and conventional fungicides and 2) Evaluating TOM-CAST. Trials were conducted in 2015 and 2016. Disease severity was visually assessed weekly using the Horsfall-Barratt scale and a petiole health scale; the area under the disease progress curve (AUDPC) was calculated for these parameters. Root yield was...
Show more"Fungal foliar diseases caused by Alternaria dauci and Cercospora carotae occur annually on carrots. Our goal was to update the disease management tactics by: 1) Testing OMRI-approved and conventional fungicides and 2) Evaluating TOM-CAST. Trials were conducted in 2015 and 2016. Disease severity was visually assessed weekly using the Horsfall-Barratt scale and a petiole health scale; the area under the disease progress curve (AUDPC) was calculated for these parameters. Root yield was determined at harvest. Based on AUDPC results obtained in 2015 and 2016, the copperbased fungicides (copper hydroxide and copper hydroxide + copper oxychloride) were the only OMRI-approved products that significantly and consistently limited foliar blight. On the final assessment dates in both years, all conventional fungicides limited foliar and petiole blighting compared to the control with one exception; the propiconazole treatment in 2016 was similar to the control for petiole health. Yields differed significantly among the conventional treatments in 2016 but not in 2015. All treatments yielded significantly higher than the control except for iprodione. Treatments of pyraclostrobin + boscalid, fluxapyroxad + pyraclostrobin, and boscalid had statistically higher yields than penthiopyrad, iprodione, and propiconazole. TOM-CAST 15 and 25 DSV fungicide application schedules effectively reduced foliar blighting in 2015 under relatively light disease pressure. However, the TOM-CAST 25 DSV schedule did not adequately limit disease in 2016 when disease pressure was increased. Recently registered fungicides such as penthiopyrad and fluxapyroxad + pyraclostrobin and using TOM-CAST at the more conservative spray threshold of 15 DSV can help growers limit fungal foliar blight in years with higher disease pressure."--Page ii.
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Title: Social-ecological systems, values, and the science of "people management"
Creator: Piso, Zachary Amedeo
Date: 2017
Collection: Electronic Theses & Dissertations
Description: This dissertation interrogates a shift in environmental science, policy, and management toward conceptualizing the environment as a social-ecological system. Social-ecological systems science reflects an interdisciplinary effort to understand how individuals and communities achieve their environmental goals through the institutions that they maintain. Though the paradigmatic institutions concern economic behavior (e.g. property rights institutions), the field embraces the social sciences...
Show moreThis dissertation interrogates a shift in environmental science, policy, and management toward conceptualizing the environment as a social-ecological system. Social-ecological systems science reflects an interdisciplinary effort to understand how individuals and communities achieve their environmental goals through the institutions that they maintain. Though the paradigmatic institutions concern economic behavior (e.g. property rights institutions), the field embraces the social sciences broadly, with contributions from sociology, anthropology, geography, political science, and so on. That said, social science is fairly narrowly conceived; leaders in the field stress that they are studying social mechanisms in order to predict and manage social behavior. In a popular textbook on the subject, Fikret Berkes and Carl Folke stress that "resource management is people management" and call for a social science of this management.Social-ecological systems scientists have generally neglected the ethics of people management-for the most part they subscribe to a fairly typical fact/value dichotomy according to which scientists describe social-ecological systems while managers and policymakers prescribe actions in light of these descriptions. Following several philosophical traditions (in particular pragmatist philosophy of science), I call attention to the ways that social-ecological systems science is value-laden. I take environmental pragmatism to provide a roadmap for conducting social-ecological systems science ethically. Environmental pragmatists stress that science is always embedded in practical problem-solving activities that presuppose particular goals for, and side constraints to, inquiry. Many traditions in the philosophy of environmental science embrace social science for the specific role of facilitating this deliberation, but these traditions do not seem to anticipate the explanatory ambitions of social sciences. This leaves unaddressed several pertinent questions about how social explanations work (i.e. how functional distinction structure inquiry), which have very practical implications for which social science disciplines should be included in a collaboration and how social and ecological knowledge should be integrated. For example, most social situations are characterized by property rights institutions, cultural traditions, political alliances, and other social institutions within the purview of particular social science disciplines, but researchers are not reflexive about whether to explain environmental change according to one set of practices or another.The dissertation traverses the following terrain: the first chapter more carefully motivates the questions above regarding the need for ethics and the promise, but present inadequacy, of environmental pragmatism to meet this need. Chapter two attends to Dewey's theory of inquiry, in particular the dialogical dimension of inquiry that authorizes warranted assertions. Through reflection on Daniel Bromley's volitional pragmatism and a debate between Richard Rorty and hermeneutic social scientists, chapter three attends to the way that social science structures inquiry in order to intervene in the normative practices of a community. Chapter four analyzes social-ecological explanations in order to locate normative and evaluative assumptions that should be accountable to democratic deliberation. Finally, chapter five redescribes interdisciplinary integration as an ethical project where decisions about the centering and decentering of different sciences is as much ethical as epistemological.
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Title: The meaning of teaching mathematics : teacher positionings as embedded in algebra teachers' guides
Creator: Suh, Heejoo
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Teacher educators have been examining the professional status of teaching, including defining central practices of teaching, comparing teaching to other professions, and understanding teachers’ own perspective via interviews, surveys, and observations. The present study intends to contribute to the discussion by examining the meaning of teaching as reflected in teachers’ guides. I chose to examine teachers’ guides because they are known to have impact on teachers. Being a resource that is...
Show moreTeacher educators have been examining the professional status of teaching, including defining central practices of teaching, comparing teaching to other professions, and understanding teachers’ own perspective via interviews, surveys, and observations. The present study intends to contribute to the discussion by examining the meaning of teaching as reflected in teachers’ guides. I chose to examine teachers’ guides because they are known to have impact on teachers. Being a resource that is close to teachers’ everyday practices, curriculum materials inspire teachers with what they could do in their classroom. Educators intending large-scale educational reform pay attention to curriculum materials. Careful use of linguistic features therein could enhance thus further support teachers’ guides in effective communication with teachers.I investigated four 8 th grade Algebra teachers’ guides - TG, selectively chosen to represent variety. Drawing on positioning theory, I observed positionings regularly appearing in each of those four. Then I turned to idiosyncratically-observable positionings. Two research questions sought understanding of what teaching mathematics entails as presented in the TGs, hence how each guide constructs teaching mathematics. Last, I examined the guides’ linguistic features. This was for understanding the degree of teacher professional judgment acknowledged by the guides.My results indicated that, as constructed by each guide, teaching mathematics does not differ much across the guides. Those guides presented various types of knowledge as entailed in teaching mathematics. Compared to aspects on teacher professionalism in the literature, the guides occasionally addressed teacher research, interaction with colleagues, utilizing knowledge, and acknowledging uncertainty. In addressing these aspects, the guides in most cases did so with insufficient support. Examining idiosyncratic positionings, I found two types: i) positionings occurred idiosyncratic only, and ii) positionings occurred idiosyncratically in addition to their regular appearance. The latter can be classified into two types: a) one that succeeds the context of the communication actions associated with the general positioning, and b) one dissociated from the context. My linguistic examination of the guides suggested that they varied in their use of voice. Some are more directive, others are more suggestive, indicating different levels of acknowledgement of teachers’ professional judgment. In this dissertation’s last chapter, I present ways in which this study contributes to understanding of curriculum materials and of teacher professionalism. I end this dissertation with implications for curriculum authors, teachers, teacher educators, and researchers.
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Title: Exploring the possibilities of Teachtown MKE : using local cultural institutions to support novice teachers' access to community resources
Creator: Shattuck, Tamara M.
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Cultural institutions have the capacity to provide teachers with material resources for curriculum use in the classroom, professional support through connection to professional learning communities, promotion of self-confidence in teaching, and gains in subject content knowledge. There is building evidence that these types of support systems help novice teachers (i.e., teachers in their first three year of teaching), however many teachers do not have access to such support. And while access...
Show moreCultural institutions have the capacity to provide teachers with material resources for curriculum use in the classroom, professional support through connection to professional learning communities, promotion of self-confidence in teaching, and gains in subject content knowledge. There is building evidence that these types of support systems help novice teachers (i.e., teachers in their first three year of teaching), however many teachers do not have access to such support. And while access to resources is important for novice teachers, there is also evidence that access does not guarantee the use of resources. This descriptive study explores the inclusion of cultural institutions as partners in novice teacher support programs though the investigation of Milwaukee, Wisconsin's Key to the City Pass (KCP), which provides new teachers access to over 22 local cultural institutions. I also investigate how novice teachers develop and use the skill of relational agency -the ability to "work fluidly across professional boundaries" (Edwards, 2005a p. 177) and understand the utility of materials for problem solving. I hypothesize building the skill of relational agency helps novice teachers' better access KCP resources for professional use. Thus, four research questions drive this study; 1) How do teachers use KCP benefits? 2) Do teachers who participate in the KCP program incorporate community/cultural institution resources in their teaching practices, and if so how? 3) What barriers exist, and how can the KCP program be made more accessible for teachers? 4) Do participant teachers display the skill of relational agency, does this skill apply to KCP use? I used both quantitative and qualitative methods to analyze data and document teachers' use of the KCP through: (1) a teacher survey, (2) semi-structured focus group interviews, and (3) case study teacher interviews and artifact analysis. The quantitative survey data was analyzed first to gather general patterns of KCP use across participant teachers. I analyzed survey data using descriptive and inferential statistics. The qualitative data was analyzed in a second phase to gather information about how teachers use KCP resources. For the qualitative data analysis, I used deductive coding. Findings indicate that participants were mostly using the KCP program for personal reasons (e.g., trips with friends and family), and that they were able to connect with the local community through these trips. Through personal trips, teachers were also able to assess whether taking field trips to certain cultural institutions was appropriate for their students. Few teachers used the skill of relational agency in connection to the KCP and noted they were more likely to use cultural institution resources if they were clearly connected with state and district standards. Teachers were also more likely to use cultural institution resources if they had the opportunity to collaborate with cultural institution staff. This study enabled me to observe barriers to KCP use before generalizing how such a program might be created in other cities. Which in turn allowed me to understand the steps other cities should take in order to build stronger partnerships. Based on my findings of the barriers to KCP use I suggest cities who wish to form partnership programs: 1) gather input from all constituents, 2) create a strong mission statement, 3) connect to district wide initiatives, and 4) ensure a pathway for clear and continual communication between partners and participants.
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Title: Solid-state nuclear magnetic resonance studies of the structures, membrane locations, cholesterol contact, and membrane motions of membrane-associated HIV Fusion Peptide (HFP
Creator: Jia, Lihui (Scientist)
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Membrane fusion is the key step during HIV viral entry to cells, and the process is catalyzed by HIV membrane fusion protein gp41. HFP is the ~25-residue N-terminal domain of gp41 and is required for membrane fusion with significant decreases in fusion activity with point mutations. Both viral and host cell membrane contain ~30mol % cholesterol (CHOL), and HFP induced fusion is faster in membrane with CHOL. However, how HFP interacts with membrane lipids and CHOL is unknown. In this thesis,...
Show moreMembrane fusion is the key step during HIV viral entry to cells, and the process is catalyzed by HIV membrane fusion protein gp41. HFP is the ~25-residue N-terminal domain of gp41 and is required for membrane fusion with significant decreases in fusion activity with point mutations. Both viral and host cell membrane contain ~30mol % cholesterol (CHOL), and HFP induced fusion is faster in membrane with CHOL. However, how HFP interacts with membrane lipids and CHOL is unknown. In this thesis, we used the newly developed 13C-2H Rotational Echo Double Resonance (REDOR) solid-state NMR method to study the membrane location of HFP in chemically-native membrane environment. HFP is 13CO labeled at specific residue, and the membrane is deuterated at specific regions of the membrane using selective regions deuterated phosphatidylcholine (PC) and CHOL. We study HFP wild type, HFP_V2E and L9R mutants because these two mutants eliminate and decrease fusion respectively. HFP is predominantly β sheet structure in bilayer membrane for both HFP wild type and HFP_V2E mutant, HFP_L9R has a different structure and is likely helical. Both HFP and HFP_V2E mutant have major deeply-inserted membrane location contacting membrane center and minor shallowly-inserted membrane location contacting half way of one membrane leaflet. The HFP_V2E mutant has bigger fraction of molecules with shallower membrane location, which is consistent with the strong correlation between membrane location insertion depth and the peptide fusogenicity. HFP_L9R mutant has majorly deeply inserted into membrane.By comparing the HFP- PC and HFP- CHOL contact, there is preferential contact between HFP and CHOL vs PC at several residues including G5, G10 and G16. The free energy difference for contacting PC vs CHOL is ~ 0.57(5) kcal.mol-1 for T= 300K. HFP- CHOL contact geometry is successfully modeled by Swiss Dock and YASARA energy minimization with two strands antiparallel HFP (1→16/16→1 registry). There are two energetically favorable binding models between HFP and CHOL, from docking, energy minimization and consistency with REDOR results. The contact models reveal tilted and curved-up tail orientation of Chol_d7. Fusion may be catalyzed by matching the curvature of lipids contacting HFPs with the membrane curvature during the fusion intermediates like the stalk. Membrane motion perturbation by HFP is studied by static deuterium NMR from deuterium powder pattern spectrum, order parameter profile and T2 relaxation time. The DMPC-d54 spectrum becomes ~10% narrower in membrane without CHOL with 4% HFP and in membrane with 33% CHOL with 1% HFP. Accordingly, the order parameter of lipid acyl chain becomes ~ 1-10% disordered by HFP. However, the spectrum becomes 20% broader in membrane with 33% CHOL with 4% HFP, and the order parameter of lipid acyl chain becomes ~ 20- 30% ordered by HFP. With HFP at 37 °C, DMPC-d54 T2 decreases ~ 70 %, and the CHOL T2 decreases ~ 30%. T2 reduction is probably associated with increased membrane curvature induced by HFP. With greater membrane curvature, the C-D bond will experience more orientation diversity relative to the external magnetic field. Thus, the quadrupolar field will have greater change, leading to faster relaxation and shorter T2. Gp41_V2E mutant eliminates cell-cell fusion. Our CD spectroscopy studies show that the FPHM_V2E mutant is helical and the melting temperature is above 90 °C in 10mM Tris buffer + 0.2 % SDS at pH 7.4. Protein is trimer and induces no lipid mixing in PC: CHOL= 2:1 vesicles.
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Title: The carbon sequestration and soil respiration after land use conversion in biofuel cropping ecosystems
Creator: Su, Yahn-Jauh
Date: 2017
Collection: Electronic Theses & Dissertations
Description: Global climate change alters Earth's carbon, hydrological and energy cycles from local to global scales, changing our climate patterns and impacting our lifestyles and prosperity. The development of bioenergy may partially mitigate the release of carbon dioxide during the combustion of fossil fuel. However, the carbon emissions from the bioenergy-induced land use change have long been debated and it is not certain whether they really represent a reduction of carbon emission. In this study, I...
Show moreGlobal climate change alters Earth's carbon, hydrological and energy cycles from local to global scales, changing our climate patterns and impacting our lifestyles and prosperity. The development of bioenergy may partially mitigate the release of carbon dioxide during the combustion of fossil fuel. However, the carbon emissions from the bioenergy-induced land use change have long been debated and it is not certain whether they really represent a reduction of carbon emission. In this study, I monitored the components of the net ecosystem exchange (NEE) of CO2, including gross primary production (GPP), ecosystem respiration (Reco), total soil respiration (Rs), autotrophic soil respiration (Ra) and heterotrophic soil respiration (Rh), to understand their responses to climate variability and in particular a severe drought event. I studied three major bioenergy crops (continuous corn, switchgrass and restored multicultural prairie) on fields with two different land use histories (conventional corn-soybean rotation and Conservation Reserve Program brome grass fields). I found that the amplitude, the duration and the seasonality of microclimatic variables (temperature and precipitation) were important for the carbon dynamics in the bioenergy cropping systems. The soil water content affected the annual NEE, GPP and Reco although it did not have strong correlations with these components of carbon fluxes at short-term scale. The short-term (1-2 week) normal summer water deficit may affect annual NEE while long-term (spring-summer) drought may change the community structure and affect the carbon cycling processes in the following years. The temperature sensitivities of soil respiration were shifted within and between years. In addition, crop types and land use histories affect the responses of ecosystem to climate events. The different phenology between annual and perennial crops and the establishment of dense root systems in perennial crops can change the ratio of the components of NEE and change the direction and the amounts of net ecosystem carbon flux. Annual and perennial crops have different strategies responding to different climate scenarios and their combinations. The monitoring of climate patterns at intra-annual scale is required to understand how the ecosystem respond to climate change.
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Title: Dynamic network analysis with applications to functional neural connectivity
Creator: Golibagh Mahyari, Arash
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "Contemporary neuroimaging techniques provide neural activity recordings with increasing spatial and temporal resolution yielding rich multichannel datasets that can be exploited for detailed description of anatomical and functional connectivity patterns in the brain. Studies indicate that the changes in functional connectivity patterns across spatial and temporal scales play an important role in a wide range of cognitive and executive processes such as memory and attention as well as in the...
Show more"Contemporary neuroimaging techniques provide neural activity recordings with increasing spatial and temporal resolution yielding rich multichannel datasets that can be exploited for detailed description of anatomical and functional connectivity patterns in the brain. Studies indicate that the changes in functional connectivity patterns across spatial and temporal scales play an important role in a wide range of cognitive and executive processes such as memory and attention as well as in the understanding the causes of many neural diseases and psychopathologies such as epilepsy, Alzheimers, Parkinsons and schizophrenia. Early work in the area was limited to the analysis of static brain networks obtained through averaging long-term functional connectivity, thus neglecting possible time-varying connections. There is growing evidence that functional networks dynamically reorganize and coordinate on millisecond scale for the execution of mental processes. Functional networks consist of distinct network states, where each state is defined as a period of time during which the network topology is quasi-stationary. For this reason, there has been an interest in characterizing the dynamics of functional networks using high temporal resolution electroencephalogram recordings. In this thesis, dynamic functional connectivity networks are represented by multiway arrays, tensors, which are able to capture the complete topological structure of the networks. This thesis proposes new methods for both tracking the changes in these dynamic networks and characterizing or summarizing the network states. In order to achieve this goal, a Tucker decomposition based approach is introduced for detecting the change points for task-based electroencephalogram (EEG) functional connectivity networks through calculating the subspace distance between consecutive time steps. This is followed by a tensor-matrix projection based approach for summarizing multiple networks within a time interval. Tensor based summarization approaches do not necessarily result in sparse network and succinct states. Moreover, subspace based summarizations tend to capture the background brain activity more than the low energy sparse activations. For this reason, we propose utilizing the sparse common component and innovations (SCCI) model which simultaneously finds the sparse common component of multiple signals. However, as the number of signals in the model increases, this becomes computationally prohibitive. In this thesis, a hierarchical algorithm to recover the common component in the SCCI model is proposed for large number of signals. The hierarchical recovery of SCCI model solves the time and memory limitations at the expense of a slight decrease in the accuracy. This hierarchical model is used to separate the common and innovation components of functional connectivity networks across time. The innovation components are tracked over time to detect the change points, and the common component of the detected network states are used to obtain the network summarization. SCCI recovery algorithm finds the sparse representation of the common and innovation components of signals with respect to pre-determined dictionaries. However, input signals are not always well-represented by pre-determined dictionaries. In this thesis, a structured dictionary learning algorithm for SCCI model is developed. The proposed method is applied to EEG data collected during a study of error monitoring where two different types of brain responses are elicited in response to the stimulus. The learned dictionaries can discriminate between the response types and extract the error-related potentials (ERP) corresponding to the two responses."--Pages ii-iii.
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Title: Dual role of PU.1 in enhancer priming in macrophages
Creator: Tagore, Mohita Malay
Date: 2017
Collection: Electronic Theses & Dissertations
Description: All multicellular organisms arise from a single-celled zygote by the precise execution of a gene expression program which ensures appropriate cell identity. This process is particularly challenging in eukaryotic cells since eukaryotic DNA is packaged by architectural proteins called histones into chromatin, which might act as a barrier to the transcriptional machinery. Macrophages are cells of the immune system which undergo rapid, large scale changes in gene expression in response to...
Show moreAll multicellular organisms arise from a single-celled zygote by the precise execution of a gene expression program which ensures appropriate cell identity. This process is particularly challenging in eukaryotic cells since eukaryotic DNA is packaged by architectural proteins called histones into chromatin, which might act as a barrier to the transcriptional machinery. Macrophages are cells of the immune system which undergo rapid, large scale changes in gene expression in response to bacterial or viral challenge. This makes macrophages an excellent model for studying cell-type specific as well as inducible gene expression. Studies at the genome-wide level have shown that distal regulatory elements like enhancers play an essential role in determining the macrophage inducible response to microbial challenge. Further, lineage-specific transcription factors like PU.1 and C/EBPβ are known to bind inducible enhancers prior to gene induction in resting macrophages. Earlier studies using genome-wide approaches indicate that PU.1 is able to interact with chromatin, thus functioning as a 'pioneer factor' in macrophages. However, not much is known about the mechanism by which PU.1 keeps enhancers accessible prior to gene induction in resting macrophages. Using bone-marrow derived primary mouse macrophage cells as well as PU.1 deficient cell lines, my work highlights the changes in chromatin associated with PU.1 binding during macrophage differentiation as well as in response to bacterial infection. Using a quantitative nucleosome occupancy assay, we reported that PU.1 binding correlates with low nucleosome occupancy at an inducible enhancer in resting macrophages. Further upon induction with an appropriate stimulus, nucleosomes are stably evicted from the distal enhancer and the corresponding gene can be induced. More importantly, my results suggest that lack of PU.1 binding renders regulatory regions (enhancers and promoters) of inducible genes susceptible to heterochromatin formation and silencing by Polycomb repressive complex 2 (PRC2) in differentiated macrophages. PRC2-mediated silencing is also associated with an increase in nucleosome occupancy at the target regions and the corresponding genes cannot be induced. Results obtained from this research will provide important insights into the role of lineage-specific transcription factors at regulatory elements both during normal development and disease.
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Title: Inside practice-based teacher education : a study of one teacher educator's practice
Creator: Muirhead, Faith
Date: 2018
Collection: Electronic Theses & Dissertations
Description: "This dissertation builds on research about practice-based teacher preparation (e.g., Ball & Cohen, 1999; Ball, Sleep, Boerst, & Bass, 2009; Graziani, 2005; Heibert, Morris, Berk, & Jansen, 2007; Lampert, 2010), formative feedback (e.g., Black & Wiliam, 1998; Carless, Salter, Yang, & Lam, 2011; Evans, 2013; Hattie & Timperley, 2007; Kluger & DeNisi, 1996), teacher noticing, (e.g., van Es, 2011; van Es & Sherin, 2008; Sherin, Jacobs, & Philipp, 2011), and positioning theory (e.g., Esmonde,...
Show more"This dissertation builds on research about practice-based teacher preparation (e.g., Ball & Cohen, 1999; Ball, Sleep, Boerst, & Bass, 2009; Graziani, 2005; Heibert, Morris, Berk, & Jansen, 2007; Lampert, 2010), formative feedback (e.g., Black & Wiliam, 1998; Carless, Salter, Yang, & Lam, 2011; Evans, 2013; Hattie & Timperley, 2007; Kluger & DeNisi, 1996), teacher noticing, (e.g., van Es, 2011; van Es & Sherin, 2008; Sherin, Jacobs, & Philipp, 2011), and positioning theory (e.g., Esmonde, 2009; Gresalfi & Cobb, 2006; Harré & van Langenhove, 1991; Herbel-Eisenmann & Wagner, 2010; Herbel-Eisenmann, Wagner, & Cortes, 2010; Wagner & Herbel-Eisenmann, 2009). In particular, I focus on how prospective elementary mathematics teachers are prepared, through a study of one teacher educator's practice. This dissertation is a self-study during a practice-based mathematics methods course for prospective elementary school teachers. Study participants consist of prospective elementary teachers (PTs) who were seniors enrolled in a mathematics methods course at a large Midwestern university. The data for this dissertation includes my lesson plans, videos of each class meeting, prospective teachers' assignments including videotaped lessons, the feedback I provided prospective teachers on assignments and teaching, and my own reflections on teaching. This dissertation contains an introductory chapter, concluding chapter, and three standalone manuscripts. Each manuscript examined a different aspect of my practice as a teacher educator. Each manuscript included a review of relevant literature, data collection, analysis, results, and discussion. Research on practice-based teaching viewed through the lens of examining my own practice provides the thread that sews the manuscripts in this dissertation together. The first manuscript details a lesson-planning tool co-edited with study participants. The tool helped PTs focus attention on student ideas and learning, the mathematical point of the lesson, and the facilitation of mathematically rich discussions. The tool draws liberally on research about lesson planning, orchestrating discussions, and attending to student thinking. The PT collaboration on this tool helped me to see the power of including the PTs' voices in their learning. The second manuscript is an empirical study examining the characteristics of effective feedback in teacher education. I argue that teacher education is a hybrid space where feedback practices bridge both K-12 and higher education contexts. I analyze the feedback I provided to prospective teachers, the characteristics of feedback that participants took up and used to further their learning, and the characteristics of feedback that closed down opportunities for further learning. The third manuscript is an empirical study that draws on the Learning to Notice Framework (van Es, 2011), which I combine with positioning theory (e.g. Harré & van Langenhove, 1991). These theories guide my analysis of student interviews collected in my methods course. Positioning theory points out the links between the ways PTs position students in their written analysis of the interviews and through their instructional decisions. I identify and define both explicit and implicit positioning and argue that static explicit positioning influences PTs' instructional choices and limits the opportunities PTs' students have to learn. I propose a framework for learning to notice positioning in teacher preparation--both for teacher educators and PTs."--Pages ii-iii.
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Title: Protease-containing membranes for rapid, controlled antibody digestion prior to mass spectrometry analysis
Creator: Pang, Yongle
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "Monoclonal antibodies are the fastest growing class of therapeutic drugs because of their high specificities to targeQt cells. Facile analysis of therapeutic mAbs and their post-translational modifications (PTMs) is essential for quality control, and mass spectrometry (MS) is the most powerful tool for antibody characterization. Conventional antibody characterization workflows contain an in-solution digestion step, which is labor-intensive and time-consuming. Protease-containing membranes...
Show more"Monoclonal antibodies are the fastest growing class of therapeutic drugs because of their high specificities to targeQt cells. Facile analysis of therapeutic mAbs and their post-translational modifications (PTMs) is essential for quality control, and mass spectrometry (MS) is the most powerful tool for antibody characterization. Conventional antibody characterization workflows contain an in-solution digestion step, which is labor-intensive and time-consuming. Protease-containing membranes are an attractive alternative platform for protein digestion because of their high local enzyme concentrations, short radial diffusion distances, rapid convection in pores, simple fabrication and low cost. Additionally, variation of protein residence time in the membrane gives control over the size of proteolytic peptides. This research focuses on developing workflows for monoclonal antibody characterization using functionalized porous membranes. Sequential adsorption of poly (styrene sulfonate) and pepsin in a porous nylon membrane forms a pepsin membrane reactor. Pepsin is inexpensive and catalyzes proteolysis in acidic solutions, which avoids the need to alkylate cysteine residues and limits antibody deamidation. Variation of the residence times (3 ms to 3 s) of antibody solutions in pepsin-containing membranes yields "bottom-up" (1-2 kDa) to 'middle-down' (5-15 kDa) peptides in less than 10 min. These peptic peptides cover the entire sequences of Herceptin and a WatersTM antibody. Compared with the performance of bottom-up (in-solution tryptic digestion) and top-down (intact protein fragmentation) analysis of an antibody light chain, middle-down (in-membrane peptic digestion) analysis gives the highest bond cleavage (99%). In-membrane digestion also facilitates detection of PTMs such as oxidation, deamidation, N-terminal pyroglutamic acid formation and glycosylation. Recently developed protease-containing spin membranes provide an excellent platform for rapid, membrane-based protein digestion prior to ultrahigh-resolution Orbitrap MS analysis. Centrifugation of 100-200 æL of pretreated protein solutions through the pepsin- or trypsin-containing membranes takes less than 1 min and gives nearly 100% coverage of the protein sequences in subsequent direct infusion MS analysis of digests of apomyoglobin and four commercial monoclonal antibodies (Herceptin, Avastin, Rituxan and Vectibix). MS analysis of peptic and tryptic peptides also reveals mAb PTMs such as N-terminal pyroglutamate formation, C-terminal Lysine clipping and glycosylation. Liquid chromatography coupled to tandem mass spectrometry analysis of tryptic spin digests and subsequent MaxQuant data searching show 100% sequence coverage of all four antibody light chains, and 75.1%-98.4% coverage of the heavy chains. Compared to in-solution tryptic digestion of mAbs, spin digestion yields higher sequence coverage and a larger number of unique peptides. In-membrane digestion also facilitates protein sequence comparison. Rapid peptic in-membrane digestion of two antibodies with direct infusion MS analysis accurately reveals the antibody modification site in less than 1 h. Overall, membrane-based protein digestion uses minimal sample preparation time and yields high peptide and sequence coverages for identification of protein PTMs."--Page ii-iii.
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