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Young stars are surrounded by massive, rotating disks of dust and gas, which supply a reservoir of material that may be incorporated into planets or accreted onto the central star. In this dissertation, I use high angular resolution observations at a range of wavelengths to understand the structure, ubiquity, and evolutionary timescales of protoplanetary disks.First, I describe a study of Class I protostars, objects believed to be at an evolutionary stage between collapsing spherical clouds and fully-assembled young stars surrounded by protoplanetary disks. I use a Monte Carlo radiative transfer code to model new 0.9 micron scattered light images, 1.3 mm continuum images, and broadband spectral energy distributions. This modeling shows that Class I sources are probably surrounded by massive protoplanetary disks embedded in massive infalling envelopes. For the best-fitting models of the circumstellar dust distributions, I determine several important properties, including envelope and disk masses, mass infall rates, and system inclinations, and I use these results to constrain the evolutionary stage of these objects.Second, I discuss observations of the innermost regions of more evolved disks around T Tauri and Herbig Ae/Be stars, obtained with the Palomar Testbed and Keck Interferometers. I constrain the spatial and temperature structure of the circumstellar material at sub-AU radii, and demonstrate that lower-mass stars are surrounded by inclined disks with puffed-up inner edges 0.1-1 AU from the star. In contrast, the truncated inner disks around more massive stars may not puff-up, indicating that disk structure depends on stellar properties. I discuss the implications of these results for disk accretion, terrestrial planet formation and giant planet migration.Finally, I put these detailed studies of disk structure into a broader context by constraining the mass distribution and evolutionary timescales of circumstellar disks. Using the Owens Valley Millimeter Array, I mapped the millimeter continuum emission toward >300 low-mass stars in the NGC 2024 and Orion Nebula clusters. These observations demonstrate that the average disk mass in each cluster is comparable to the "minimum-mass protosolar nebula," and that there may be disk evolution on one million year timescales.

This dissertation proposes a computational technique for automated "invention" of conceptual schemes of thermal systems. The input provided to the automated problem solver is a description of the streams entering and leaving the system. The output is a network of elementary processes: compression, expansion, heating, cooling, and chemical processes. The problem solver seeks a network that is feasible, and offers an optimal (or at least favorable) combination of energy and capital costs. The synthesis process is modeled as a heuristic search conducted in a state-space of all possible design versions. The main ideas of the dissertation have been implemented in a computer program called TED, which invented a number of nontrivial schemes.TED starts with an initial state (or states), which may be either proposed by the user or generated automatically. TED evaluates each state using a special technique of exergy analysis applied to an infinitesimal temperature interval. This allows us to describe the thermal system by several integral characteristics which are functions of temperature. One particularly important integral characteristic - a measure of system's Second Law infeasibility - is introduced in this work; it allows a uniform treatment of both feasible and infeasible design states.TED then selects the most promising of the available designs. This selection is guided by a specialized search algorithm BP* which is shown to be probabilistically admissible. The results of the exergy analysis are used to perform a look-ahead evaluation of the design states. BP* also uses backpropagation of the state evaluation function to reduce the amount of backtracking.TED then improves the selected design by applying one of the transforming operators and thereby generating a new design. Each transformation involves addition of an incremental network of thermal processes to the original state and reduces either irreversibility (exergy loss) or infeasibility of the thermal system. The application of the transformations is controlled by a heuristic move generation function that selects the most promising transformations. The new design is added to the database of the available design states.The search continues with these evaluate-select-transform iterations until an (approximately) optimal design is found.

The purpose of this book was to describe the variables that contributed to the establishment of a charter school in an urban Arizona and rural California school district, noting the similarities and dissimilarities and disclosing the factors used to justify implementation of the Montessori theory of education. The secondary purpose of this book was to describe the guidelines for maintaining a charter school, the evaluation methods and factors used in the school's unique experience with staff development. The two schools experienced many similarities when the same variables were applied to both schools. As a result, the stakeholders of both schools used the principles of the organizational theory area of empowerment to implement choices in curriculum. This book provides an insight for parents, teachers, and community leaders to develop strategies by utilizing the same principles to meet the educational needs of children.

There has been a lot of interest among marketing practitioners and researchers in the concept of marketing communications as related to computer-mediated marketing environments as a result of the commercialization of the World Wide Web (WWW) as a marketing and communication medium. Despite growing interest, there is a dearth of research on the processual nature of communication between marketers and consumers. The overall aim of this study, therefore, is to expand our understanding of marketing communication within the computer-mediated marketing environments. This understanding is achieved in the thesis by incorporating ideas from traditional marketing communication models those based on a one-way, general outbound, linear model in which marketers deliver communication to customers and prospects and contemporary marketing communications theory within a contextualist framework, to examine the evolving marketing communication medium. Given the growing empowerment of customers through information technology that has created the interactive marketplace, the study aims to illuminate concretely that Internet exerts a mediating influence on the relationship between marketers and consumers. Following this articulation, the study considers computer-mediated marketing environments as a technological development that increases the options for marketing communications. Placing marketing communication and computer-mediated marketing environments within a historical context of technology as consistent with social constructivist framework rather than thinking about the medium as an isolated phenomenon, builds the base for understanding the opportunities and difficulties associated with marketing communications and the Internet in contrast to capabilities for marketing prior to the Internet. The current study indicates that marketing communication in the computer-mediated marketing environments possess some fundamental uniqueness, which are ancillary and augment the consumption processes. The study proposed a conceptual framework for understanding marketing communication trajectory in the evolving interactive marketplace. The framework proposed provides a new base for developing a wide range of marketing communication programmes for practitioners and academic researchers.

American, African, European, and Middle Eastern (N = 420) technical professional employees of a multinational organization were surveyed to explore the relationship between perceived values congruence (PVC) and organizational commitment (OC). PVC was looked at as a function of fit between: (a) person s and organization s actual values and (b) organization s espoused and actual values. Four dimensions of values (ethics, people, change, and bottom line) and three components of OC (affective, continuance, and normative) were considered. The key findings of the study were: (a) PVC was related to OC; (b) the relationship was different for each component of OC and socio-cultural group; and (c) the regression models that described these relationships showed that each socio-cultural group was most strongly associated with a different dimension of values: change for Americans, bottom line for Africans, people for Europeans, and ethics for Middle Easterners.

Modality is a grammatical, or semantic-grammatical, category. It is an important component of human languages. This is at least the case in most European languages. To what extent is it a near-universal? This thesis is to contribute to the question. It focuses on modal verbs in English and Chinese, two genetically and geographically unrelated languages, and analyzes what these two languages have in common and how they differ in their systems of modality. To achieve the aim, the thesis adopts the theoretical framework proposed by van der Auwera (1996, 1998 with Plungian, 2001) for the typological study of modality. Its language-specific descriptions involve the morphosyntactic features, notional functions, modal logic, and diachronic development. With these descriptions, it constructs a cross-linguistic database in a uniform, parallel structure. Then on the basis of this database, it deals with the cross-linguistic issues about modality in English and Chinese. Like many of the studies in this area, this research makes use of the well-sampled data in the relevant literature, thereby assuring the same degree of representativeness. When the data do not meet this need, it resorts to computer-based corpora. In the diachronic study of Chinese modality, quantitative analysis is adopted in proposing a development path for the senses of a modal. English translation is given particular attention in the description of Chinese modality and cross-linguistic analyses. One can only know one's own language only if one compares it with other languages. The present study is conducive to a better understanding of English and Chinese. It contributes not only to the investigation of language universals, but also to the study of human cognition and other linguistic or applied linguistic issues.