Coarse Graining to Invesitigate Peptide-Lipid Interactions

Experimental characterization of molecular details is challenging, and although single molecule experiments have gained prominence, oligomer characterization remains largely unexplored. The ability to monitor the time evolution of individual molecules while they self assemble is essential in providing mechanistic insights about biological events. Molecular dynamics (MD) simulations can fill the gap in knowledge between single molecule experiments and ensemble studies like NMR, and are increasingly used to gain a better understanding of microscopic properties. Coarse-grained (CG) models aid in both exploring longer length and time scale molecular phenomena, and narrowing down the key interactions responsible for significant system characteristics. Over the past decade, CG techniques have made a significant impact in understanding physicochemical processes. However, the realm of peptide-lipid interfacial interactions, primarily binding, partitioning and folding of amphipathic peptides, remains largely unexplored compared to peptide folding in solution. The main drawback of existing CG models is the inability to capture environmentally sensitive changes in dipolar interactions, which are indigenous to protein folding, and lipid dynamics. We have used the Drude oscillator approach to incorporate structural polarization and dipolar interactions in CG beads to develop a minimalistic peptide model, WEPPROM (Water Explicit Polarizable PROtein Model), and a lipid model WEPMEM (Water Explicit Polarizable MEmbrane Model). The addition of backbone dipolar interactions in a CG model for peptides enabled us to achieve alpha-beta secondary structure content de novo, without any added bias. As a prelude to studying amphipathic peptide-lipid membrane interactions, the balance between hydrophobicity and backbone dipolar interactions in driving ordered peptide aggregation in water and at a hydrophobic-hydrophilic interface, was explored. We found that backbone dipole interactions play a crucial role in driving ordered peptide aggregation, both in water and at hydrophobic-hydrophilic interfaces; while hydrophobicity is more relevant for aggregation in water. A zwitterionic (POPC: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and an anionic lipid (POPS: 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine) are used as model lipids for WEPMEM. The addition of head group dipolar interactions in lipids significantly improved structural, dynamic and dielectric properties of the model bilayer. Using WEPMEM and WEPPROM, we studied membrane-induced peptide folding of a cationic antimicrobial peptide with anticancer activity, SVS-1. We found that membrane-induced peptide folding is driven by both (a) cooperativity in peptide self interaction and (b) cooperativity in membrane-peptide interactions. The dipolar interactions between the peptide and the lipid head-groups contribute to stabilizing folded conformations. The role of monovalent ion size and peptide concentration in driving lipid domain formation in anionic/zwitterionic lipid mixtures was also investigated. Our study suggest monovalent ion size to be a crucial determinant of interaction with lipid head groups, and hence domain formation in lipid mixtures. This study reinforces the role of dipole interactions in protein folding, lipid membrane properties, membrane induced peptide folding and lipid domain formation. Therefore, the models developed in this thesis can be used to explore a multitude of biomolecular processes, both at longer time-scales and larger system sizes.

A Stationless Bikeshare Proof of Concept for College Campuses

Bikeshares promote healthy lifestyles and sustainability among commuters, casual riders, and tourists. However, the central pillar of modern systems, the bike station, cannot be easily integrated into a compact college campus. Fixed stations lack the flexibility to meet the needs of college students who make quick, short-distance trips. Additionally, the necessary cost of implementing and maintaining each station prohibits increasing the number of stations for user convenience. Therefore, the team developed a stationless bikeshare based on a smartlock permanently attached to bicycles in the system. The smartlock system design incorporates several innovative approaches to provide usability, security, and reliability that overcome the limitations of a station centered design. A focus group discussion allowed the team to receive feedback on the early lock, system, and website designs, identify improvements and craft a pleasant user experience. The team designed a unique, two-step lock system that is intuitive to operate while mitigating user error. To ensure security, user access is limited through near field ii communications (NFC) technology connected to a mechatronic release system. The said system relied on a NFC module and a servo working through an Arduino microcontroller coded in the Arduino IDE. To track rentals and maintain the system, each bike is fitted with an XBee module to communicate with a scalable ZigBee mesh network. The network allows for bidirectional, real-time communication with a Meteor.js web application, which enables user and administrator functions through an intuitive user interface available on mobile and desktop. The development of an independent smartlock to replace bike stations is essential to meet the needs of the modern college student. With the goal of creating a bikeshare that better serves college students, Team BIKES has laid the framework for a system that is affordable, easily adaptable, and implementable on any university expressing an interest in bringing a bikeshare to its campus.

OVERCOMING INTERCULTURAL CHALLENGES IN INTERPRETING: A CASE STUDY ON CHINESE-ENGLISH CONFERENCE INTERPRETING

This exploratory case study examines the role of culture in Chinese-English conference interpreting. Given that there has been a lack of empirical research in understanding the role of culture in conference interpreting through the lens of intercultural communication frameworks, we know relatively little about conference interpreters’ experiences with intercultural communication challenges. This project helps address this research gap by investigating the types of intercultural communication challenges that Chinese-English conference interpreters experience and their strategies in managing those challenges. This study hears the voices of both professionals and postgraduate interpreting students. A total number of 27 participants were recruited for this research. Twenty professional conference interpreter were interviewed and seven interpreting students were organized for a focus group discussion. Grounded theory was used to analyze the participants’ observations and strategies in managing intercultural communication challenges when doing Chinese-English conference interpreting. The data analysis process led to the emergence of two procedural guidelines and one process – Interpreters’ Intercultural Mediation Process. The two procedural guidelines offer guidance for the interpreters to provide the most appropriate and effective service: meet with the clients beforehand and be prepared to offer intercultural insights when consulted. Interpreters are found to follow the Interpreters’ Intercultural Mediation Process to decide when and how to mediate intercultural communication challenges at work. This Process includes four criteria, seven intercultural challenges, and seven coping strategies. This study offers theoretical and applied contributions to our understanding of the role of culture in interpreting. By jointly applying frameworks from intercultural communication and interpreting studies to examine the conference interpreting process, this case study makes great efforts to connect the field of intercultural communication with the field of interpreting studies. This study identifies the types of intercultural differences that would lead to challenges in Chinese-English conference interpreting. It also contributes to the call for a cultural turn in interpreting studies. By learning the two procedural guidelines, conference interpreters can be better prepared for their work. By following the Interpreters’ Intercultural Mediation Process, conference interpreters can better anticipate and manage the intercultural challenges at work. This study also offers guidance on tailoring intercultural communication courses for postgraduate interpreting training programs.

Identifying the Supports and Challenges of High School Latino English Language Learners

Two out of three English Language Learners (ELLs) graduate from secondary schools nationwide. Of the nearly five million ELLs in public schools, more than 70% of these students’ first language is Spanish. In order to understand and resolve this phenomena and in an effort to increase the number of graduates, this research examined what high school Latino ELLs identified as the major external and internal factors that support or challenge them on the graduation pathway. The study utilized a 32 quantitative and qualitative question student survey, as well as student focus groups. Both the survey and the focus groups were conducted in English and Spanish. The questions considered the following factors: 1) value of education; 2) expectations in achieving their long-term goals; 3) current education levels; 4) expectations before coming to the United States; 5) family obligations; and 6) future aspirations. The survey was administered to 159 Latino ELLs enrolled in grades 9-12. Research took place at three high schools that provide English for Speakers of Other Languages (ESOL) classes in a large school system in the Mid-Atlantic region. The three schools involved in the study have more than 1,500 ELLs. Two of the schools had large ESOL instructional programs, and one school had a comparatively smaller ESOL program. The majority of students surveyed were from El Salvador (72%) and Guatemala (12.6%). Using Qualtrics, an independent facilitator and a bilingual translator administered the online survey tool to the students during their ESOL classes. Two weeks later, the researcher hosted three follow-up focus groups, totaling 37 students from those students who took the survey. Each focus group was conducted at the three schools by the lead researcher and the translator. The purpose of the focus group was to obtain deeper insight on how secondary age Latino ELLs defined success in school, what they identified to be their support factors, and how previous and present experiences helped or hindered their goals. From the research findings, ten recommendations range from suggested policy updates to cross-cultural/equity training for students and staff; they were developed, stemming from the findings and what the students identified.

Teaching Sight-Reading to Undergraduate Choral Ensemble Singers: Lessons from Successful Learners

This study was designed to investigate professional choral singers’ training, perceptions on the importance of sight-reading skill in their work, and thoughts on effective pedagogy for teaching sight-reading to undergraduate choral ensemble singers. Participants in this study (N=48) included self-selected professional singers and choral conductors from the Summer 2015 Oregon Bach Festival’s Berwick Chorus and conducting Master Class. Data were gathered from questionnaire responses and audio recorded focus group sessions. Focus group data showed that the majority of participants developed proficiency in their sight-reading skills from instrumental study, aural skills classes, and through on-the-job training at a church job or other professional choral singing employment. While participants brought up a number of important job skills, sightreading was listed as perhaps the single most important skill that a professional choral singer could develop. When reading music during the rehearsal process, the data revealed two main strategies that professional singers used to interpret the pitches in their musical line: an intervallic approach and a harmonic approach. Participants marked their scores systematically to identify problem spots and leave reminders to aid with future readings, such as marking intervals, solfege syllables, or rhythmic counts. Participants reported using a variety of skills other than score marking to try to accurately find their pitches, such as looking at other vocal or instrumental lines, looking ahead, and using knowledge about a musical style or time period to make more intuitive “guesses” when sight-reading. Participants described using additional approaches when sight-reading in an audition situation, including scanning for anchors or anomalies and positive self-talk. Singers learned these sight-reading techniques from a variety of sources. Participants had many different ideas about how best to teach sight-reading in the undergraduate choral ensemble rehearsal. The top response was that sight-reading needed to be practiced consistently in order for students to improve. Other responses included developing personal accountability, empowering students, combining different teaching methods, and discussing real-life applications of becoming strong sight-readers. There was discussion about the ultimate purpose of choir at the university level and whether it is to teach musicianship skills or produce excellent performances.