Enantioselective Synthesis of Stereogenic-At-Phosphorus(V) Compounds via Hydrogen-Bond-Donor Catalysis

Forbes, Katherine Carmen Harvard University ProQuest Dissertations & Theses 2023 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

In Chapter 1, we review organocatalytic approaches for the enantioselective synthesis of stereogenic-at-P(V) compounds. General organocatalytic activation modes used for constructing P(V) stereocenters are discussed, including covalent catalysis, hydrogen-bond-donor catalysis, and general base catalysis. Existing synthetic methods applying these modalities for the enantioselective synthesis of stereogenic-at-P(V) compounds are reviewed, and the proposed mechanisms for these reactions are discussed. In Chapter 2, we report the development of a hydrogen-bond-donor catalyzed desymmetrization of phosphonic dichlorides with amines to enantioselectively furnish chlorophosphonamidate building blocks using a commercially available catalyst. We demonstrate that chlorophosphonamidates possess two leaving groups which can be displaced sequentially and stereospecifically. Furthermore, we explore the use of chlorophosphonamidates as bifunctional stereogenic-at-P(V) building blocks which can serve as synthetic precursors to access a diverse array of stereogenic-at-P(V) targets. The synthetic utility of this methodology is established through its application to the synthesis of bioactive P-stereogenic targets. In Chapter 3, we detail the development of a hydrogen-bond-donor catalyzed desymmetrization of phosphinic acids via an enantioselective alkylation reaction with sulfonium reagents to generate chiral phosphinate esters. Evaluation of different sulfonium reagents revealed a significant effect of the sulfonium structure on enantioselectivity, with a thianthrene-derived sulfonium reagent yielding the phosphinate products with the highest levels of enantioenrichment. Moderate levels of enantioselectivity are observed with sterically hindered and unhindered phosphinic acids. .

Reinforcement learning for autonomous vehicles

Forbes, Jeffrey Roderick Norman University of California, Berkeley 2002 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Autonomous vehicle control presents a significant challenge for artificial intelligence and control theory. The act of driving is best modeled as a series of sequential decisions made with occasional feedback from the environment. Reinforcement learning is one method whereby the agent successively improves control policies through experience and feedback from the system. Reinforcement learning techniques have shown some promise in solving complex control problems. However, these methods sometimes fall short in environments requiring continual operation and with continuous state and action spaces, such as driving. This dissertation argues that reinforcement learning utilizing stored instances of past observations as value estimates is an effective and practical means of controlling dynamical systems such as autonomous vehicles. I present the results of the learning algorithm evaluated on canonical control domains as well as automobile control tasks.

Factors that influence effective staff development: A descriptive study of two Connecticut public high schools

Forbes, Lisa Renee Columbia University Teachers College 2003 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

The purpose of this descriptive study was to examine and compare the state of staff development in two Connecticut public high schools as well as investigate barriers to effective staff development in the selected high schools and teacher descriptions and rating of actual staff development experiences. An additional purpose was to investigate the influence of state-mandates on staff development. This study's research questions were developed based upon the current body of literature on staff development. A specific focus of this study was the extent of alignment of each district's staff development with <italic>NSDC's Standards for Staff Development</italic> (2001). Once the degree of alignment was established a comparison was conducted to test the hypothesis that socio-economic characteristics of the districts relates to the quality of district staff development. Furthermore, an investigation of high school teachers' perceptions was conducted of the current state of staff development in their district in relation to the <italic>NSDC's Standards for Staff Development</italic> (2001) and barriers of effective staff development. These results were also compared by district to reveal differences based on the socio-economic characteristics of the districts. Data were collected using surveys, analysis of content of teacher contract, calendar, daily schedule, and district budget and staff development content as reported by teachers and administrators and teacher responses to open-ended questions. Data analysis included mean response, standard deviation, frequency of response, and content analysis. There was evidence in both districts that staff development programs were <italic>partially aligned</italic> with the <italic>NSDC's Standards for Staff Development</italic> (2001). Partially aligned means that there were elements of the NSDC standards in the practices of the districts across context, process and content. A key finding of this study is that inferential statistics revealed that teacher perceptions of effective staff development in suburban district and urban district were similar. A second key finding of this study is that inferential statistics revealed a statistical significance in teachers' perceptions of barriers. The suburban teachers were more likely to express barriers than the urban teachers. Both districts staff development was influenced by state-mandates.

Movement and population dynamics of two ladybeetle (Coleoptera: Coccinellidae) species in agricultural crops

Forbes, Katherine Janet The University of Wisconsin - Madison 2008 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Scientists have debated the relative advantages of specialist and generalist biological control agents. The two species of ladybeetle that I study, Coccinella septempunctata L. and Harmonia axyridis Pallas, potentially show attributes of both---they are specialists on specific prey when that prey is common, but have the capacity to act as generalists when their focal prey is rare. Demonstrating that individual insects shift between prey species (e.g., act as generalists) requires one to develop a means of inferring insect movement. Chapter 1 of this thesis develops one such technique, utilizing stable carbon isotopes, and examines its overall utility. Chapter 2 uses this technique to examine how H. axyridis and C. septempunctata use different crops, and finds evidence that H. axyridis moves between crops, consistent with the patterns of adult abundance I observed in the field (e.g., there is evidence that H. axyridis acts as a generalist). Chapter 3 examines the associations between each ladybeetle species and a different aphid species (e.g., how each species acts as a specialist). As a whole, the thesis finds evidence of each ladybeetle species acting as a specialist on a different species of aphid, but also finds evidence of one ladybeetle, H. axyridis, acting as a generalist when densities of its focal prey, soybean aphids, are low. While there is circumstantial evidence (presented elsewhere) that suggests that C. septempunctata may also have the potential to behave as a generalist, the thesis as a whole suggests that there are differences between C. septempunctata and H. axyridis in this regard, notably in the likelihood of each species to consume aphids from C4-photosynthetic crops.

Discourse semantics of S-modifying adverbials

Forbes, Katherine Margaret University of Pennsylvania 2003 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

In this thesis, we address the question of why certain S-modifying adverbials are only interpretable with respect to the discourse or spatio-temporal context, and not just their own matrix clause. It is not possible to list these adverbials because the set of adverbials is compositional and therefore infinite. Instead, we investigate the mechanisms underlying their interpretation. We present a corpus-based analysis of the predicate argument structure and interpretation of over 13,000 S-modifying adverbials. We use prior research on discourse deixis and clause-level predicates to study the semantics of the arguments of S-modifying adverbials and the syntactic constituents from which they can be derived. We show that many S-modifying adverbials contain semantic arguments that may not be syntactically overt, but whose interpretation nevertheless context. Prior work has investigated only a small subset of these <italic> discourse connectives</italic>; at the clause-level their semantics has been largely ignored and at the discourse level they are usually treated as “signals” light on the space of relations imparted by a much wider variety of adverbials. We further show how their predicate argument structure and interpretation can be formalized and incorporated into a rich intermediate model of discourse that alone among other models views discourse connectives as predicates whose syntax and semantics must be specified and recoverable to interpret discourse. It is not only due to their argument structure and interpretation that adverbials have been treated as discourse connectives, however. Our corpus contains adverbials whose semantics alone does not cause them to be interpreted with respect to We explore other explanations for why these adverbials evoke discourse context for their interpretation; in particular, we show how the interaction of prosody with the interpretation of S-modifying adverbials can contribute to discourse coherence, and we also show how S-modifying adverbials can be used to convey implicatures.

Sincerity's failures: Patterns of self-consciousness in British Romantic and modern American poetry

Forbes, Deborah Ann Harvard University 2002 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

Is it possible to speak the truth about oneself? If self-knowledge is possible, what purpose does it serve? Does self-consciousness promise redemptive self-recuperation, or does it threaten endless self-deferral? The subject of this study is the intersection of these questions with the ways in which lyric poetry has been theorized and written in England and America over the past two hundred years. As an experiment in theorizing literary continuity, and following the Romantic intuition that the destinies of the questions “What is poetry?” and “What does it mean to be a self?” are linked, I argue that Romantic and post-Romantic poetry can be understood as an interlocking set of especially concentrated and flexible modes of self-consciousness. This study identifies three major modes of Romantic and post-Romantic self-consciousness: sincere, staged, and “impersonal.” I argue that the sincere mode of self-consciousness, represented by Wordsworth and Rich, fails to recuperate a personally accountable self, instead undergoing a pressure towards impersonality. Also, a sincerity that would cast off outmoded poetic forms (represented by Wordsworth, Rich, Lowell, and Plath) reproduces in new forms the artificiality it supposedly leaves behind. In the staged confession mode of self-consciousness, the separation between the poet and his or her dramatized speaker (found in poems by Browning, Eliot, Berryman, and Plath), tends to collapse. I identify poetry that expresses a specific personality (exemplified by Byron and Sexton) as “charismatic” poetry that carries the vestigial traces of a dramatic monologue that has broken down. Finally, I show that poets who write about the comparatively impersonal experience of writing poetry (for example, Keats and Stevens) find themselves defining “poetry” as impossible to embody in a poem. Poets who focus on the seemingly impersonal work of interpreting the external world (represented by Bishop and Merrill) cannot separate impersonal from more personal forms of reading, as the intractable surfaces of that world both resist them and uncontrollably give way. Romantic and post-Romantic poetry comes to appear as a set of unexpected, often seemingly unintended effects resulting from acts of self-consciousness directed elsewhere, a map of productive and frequently beautiful failures of self-expression.

Magnetizable implants for targeted drug delivery

Forbes, Zachary Graham Drexel University 2005 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

The capability to deliver high effective dosages to specific sites in the human body has become the holy grail of drug delivery research. Drugs with proven effectiveness under in vitro investigation often reach a major roadblock under in vivo testing due to a lack of an effective delivery strategy. In addition, many clinical scenarios require delivery of agents that are therapeutic at the desired delivery point, but otherwise systemically toxic. This project proposes a method for targeted drug delivery by applying high magnetic field gradients within the body to an injected superparamagnetic colloidal fluid carrying a drug, with the aid of modest uniform magnetic field. The design involves patterning of endovascular implants, such as coronary stents, with soft magnetic coatings capable of applying high local magnetic field gradients within the body. Examination of the feasibility of the design has been focused around the treatment of coronary restenosis following angioplasty. Drug-eluting stents, which have debuted in hospitals over the past two years, have thus far reduced restenosis rates to below 10%. Our local drug delivery system is a viable alternative or enhancement to drug-eluting stents, offering increased clinician control of dose size, the ability to treat a site repeatedly, and a wide array of applications for treatment of other pathologies. The theoretical models, parallel plate and pipe flow analysis, and cell culture models presented give insight into the use of micron and sub-micron scale magnetic particles for site-specific delivery of pharmaceuticals and magnetically labeled cells.

Broadening the playing field: Modernizing twentieth-century American telecommunications access policy to include the public interest

Forbes, Scott Cameron The Pennsylvania State University 2000 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

This dissertation answers a two-part formal research question via the development and subsequent explanation of a new telecommunications access theory named the Network Access Theory (NAT). The two parts answered over the five chapters of the dissertation are: (1) How has the concept of access to telecommunications networks changed as it relates to the public interest when compared during the Early Radio Era from 1912 to 1934 and the Internet Era from 1990 to 2000? (2) How could a modern telecommunications access theory be structured to explicitly incorporate the public interest?. The NAT is a normative theory grounded in Liberalism that includes a description of the existing telecommunications policy creation process and mandates a change in said process. It advocates telecommunications access policy to incorporate the public interest which it defines as the promotion of Public participation in the social, economic, and political realms of society. The goals of the NAT are to increase telecommunications access in the United States via comprehensive polices the involvement of government, industry involvement, and the Public. It argues that if current telecommunications access policies are continued, fewer members of the Public will be privy to increased telecommunications access than if its own policies are followed. Consequences of the NAT include a better educated group of telecommunications policy makers and greater Public access to the nation's telecommunications networks.

Deciding between public and private providers of high technology commercial-like activities: The case of weapon system depot maintenance

Forbes, James A The George Washington University 2002 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

This research addressed four questions: what factors are important to the choice between public and private providers of U.S. Department of Defense depot maintenance, the relative importance of those factors, where there is consensus and where there is not, and to what extent the factors are consistent with available theory. The choice of depot maintenance providers is an instance of a broader issue—the choice between public and private providers of high-technology commercial-like activities generally. Thus results here may have broader implications. The author drew from the fields of neoclassical economic theory; transaction cost economics; principal-agent theory; public choice theory; public administration; technology and strategic management; relational, social exchange, and resource dependency theories; logistics and supply chain management; and theories having to do with organizational rationality and structure. From these fields, the author identified 14 theoretical constructs and, from them, 60 hypotheses which were tested using both indirect elicitation and survey methods. Generally speaking, factors from public choice, transaction cost economics, resource/competency, and relational/social exchange fields were the most important. It is with these fields, therefore, that the present research is most consistent. Within these fields, public choice and transaction cost economics factors dominated. This research identified two issues that went beyond the research questions. First, cognitive and motivational biases play a significant role, one that appears to have not been previously addressed. Second, there appear to be two sets of processes at work. One, principally centered in neoclassical economic considerations such as competition and scale economy, is explicit but of limited importance. The other, grounded in a combination of public choice theory, resource/competency theory, and relational/social exchange theory—but under the influence of cognitive and motivational biases—is tacit and considerably more important. This tacit process is deserving of more attention in both research and policy.

Course Choice Opportunity and Technical-Non-Technical Balance in Undergraduate Engineering Education

Forbes, Marissa Hagan University of Colorado at Boulder 2015 해외박사(DDOD)

소속기관이 구독 중이 아닌 경우 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

If we are to address the enrollment challenges that we face in engineering education, we must consciously adapt to better serve students in concert with their innate psychological needs and properly educate them for increasingly diverse career paths via more flexible degree programs. A conscious cultivation of program environments to meet students' need for autonomy coupled with a purposeful allocation of technical and non-technical degree program content that responsibly educates the engineers of our future are fundamental renovations suggested for undergraduate engineering education. This thesis lays foundational work for the advancement of engineering education by exploring the course choice opportunities and technical---non-technical coursework balance allocated to undergraduate engineering students in hundreds of diverse engineering degree programs across the United States. Course choice opportunities are defined as occasions over the duration of a degree program when a student is given the freedom to choose his or her courses, such as free electives, engineering electives, or humanities electives. Findings suggest that while comparatively minimal course choice opportunity is prevalent in engineering degree programs, this program model is unnecessary from an accreditation standpoint and incongruent with the psychological needs of students. Exceptional accredited, prestigious, and specialized undergraduate engineering degree programs exist that are far more autonomy-supportive in terms of providing substantial course choice opportunities to students, demonstrating exciting possibilities for reworking the design of undergraduate engineering degree programs to better support students' psychological needs. Results also indicate that a wide range of technical---non-technical balance exists across the nation's undergraduate engineering degree programs, which may cause students to find themselves enrolled in engineering programs that do not reflect the curricular experience they expected, nor are well-matched for their career aspirations. Today's engineering graduates go on to diverse career paths, in both what are traditionally categorized as "technical" and "non-technical" fields, requiring a blend of both skillsets in differing proportions. The community of engineering educators should become more informed, intentional, and forward-thinking about these differing curricular allocation opportunities, so that this wide range of technical---non-technical balance can become a conscious asset of differentiated education to better serve society and students.