An analysis of the effect of aeroassist maneuvers on orbital transfer vehicle performance

This paper summarizes a Langley Research Summer Scholars (LARSS) research project (Summer 1986) dealing with the topic of the effectiveness of aeroassist maneuvers to accomplish a change in the orbital inclination of an Orbital Transfer Vehicle (OTV). This task was subject to OTV design constraints, chief of which were the axial acceleration and the aerodynamic heating rate limits of the OTV. The use of vehicle thrust to replace lost kinetic energy and, thereby, to increase the maximum possible change in orbital inclination was investigated. A relation between time in the hover orbit and payload to LEO was established. The amount of plane change possible during this type of maneuver was checked for several runs and a possible thrusting procedure to increase the plane change and still get to LEO was suggested. Finally, the sensitivity of various target parameters to controllable independent variables was established, trades between the amount of control allowed, and payload to LEO suggested

Propensity to Trust, Purchase Experience, and Trusting Beliefs of Unfamiliar E-Commerce Ventures

Trust has become a major issue among online shoppers. This underresearched subject will predictably determine the success or failure of e-commerce vendors. The lack of face-to-face interaction, the inability to inspect goods and services prior to purchase, and the asynchronous exchange of goods and money all contribute to the perceived risk of purchasing online and the resulting need for trust. Trust is particularly critical for small and new Internet ventures confronted by the liability of newness (Stinchcombe 1965). Lacking, among other things, a name that is readily recognized in the marketplace, entrepreneurial Internet ventures require trust if they are to succeed. The research presented in this article addresses this issue by building on the work of McKnight and colleagues and considering the effects of propensity to trust on trusting beliefs. Specifically, the author predicts that propensity to trust will significantly affect perceived ability, benevolence, and integrity but only for those individuals with limited direct experience. Based on a sample of web survey participants, the author found that propensity to trust significantly impacted perceived ability and benevolence for individuals with limited direct experience only. No statistically significant results were found for the effects of propensity to trust on perceived integrity

New and Small E-Commerce Ventures: The Importance of Legitimacy and Trust

This article reviews literatures on legitimacy, trust, and e-commerce and integrates them to propose a model of strategies designed to enhance the perceived legitimacy and trustworthiness of ventures

The Impact of Screening Criteria on Entrepreneurship Research

Entrepreneurship researchers use various types of screening criteria to select samples for study. In that selecting these criteria is, in effect, choosing a definition or model of entrepreneurship, the consequences are immense and have had a direct impact on the generalizability of research and theory development in our field. The purpose of this study is to help entrepreneurship researchers better understand these consequences and, thereby, improve our understanding of entrepreneurial phenomenon. Four of the most commonly used screening criteria are included in this study: firm age, firm size, firm growth, and innovation. Based on a sample of 368 manufacturing firms, the results indicate that few firms fit all or even most of the considered screening criteria and independent-dependent variable relationships vary considerably by screening criteria selection

Corporate Parents, Initial Legitimacy, and Resource Acquisition in Small and Medium Firms: An Empirical Examination

Small and medium enterprises (SMEs) commonly struggle to acquire needed financial, human, and technological resources. The above being stated, recent scholarly research argues that SMEs that are able to successfully navigate the legitimacy threshold are better able to gather the resources they need to survive and grow. This article provides an empirical test of that claim by examining whether the presence of a corporate parent positively influences SME resource acquisition. Results of the study show that SMEs with corporate parents, when compared to like-sized independent SMEs, have higher credit scores, have more complete management teams, use more computers, and are more likely to be on the Internet. These differences are most pronounced for very small firms and diminish in significance as firm size increases. Study implications include the notion that presence of a corporate parent likely represents a successful navigation of the legitimacy threshold, positively increasing SME resource acquisition

Primordial nucleosynthesis as a probe of fundamental physics parameters

We analyze the effect of variation of fundamental couplings and mass scales on primordial nucleosynthesis in a systematic way. The first step establishes the response of primordial element abundances to the variation of a large number of nuclear physics parameters, including nuclear binding energies. We find a strong influence of the n-p mass difference (for the 4He abundance), of the nucleon mass (for deuterium) and of A=3,4,7 binding energies (for 3He, 6Li and 7Li). A second step relates the nuclear parameters to the parameters of the Standard Model of particle physics. The deuterium, and, above all, 7Li abundances depend strongly on the average light quark mass hat{m} \equiv (m_u+m_d)/2. We calculate the behaviour of abundances when variations of fundamental parameters obey relations arising from grand unification. We also discuss the possibility of a substantial shift in the lithium abundance while the deuterium and 4He abundances are only weakly affected.Comment: v2: 34 pages, 2 figures, typo in last GUT scenario corrected, added discussion and graph of nonlinear behaviour in GUT scenarios, added short section discussing binding of dineutron and 8Be, refs added, conclusions unaltered. Accepted for publication, Phys. Rev.

The Range and Accessibility of Maternity Models of Care and Allied Health Service Delivery across Public Hospitals within Victoria, Australia

Australian Government maternity reform documents promote collaborative multidisciplinary models of care and strive to improve service provision and access for all childbearing women. In order to provide a quality and equitable maternity service, effective monitoring and mapping of service provision needs to be undertaken. This paper explored maternity models of care and key allied health services across Victorian public hospitals as per the Victorian Government Health Information Website (VGHIW)). Altogether, this study found discrepancies in information provided to consumers using the VGHIW, a scarcity of models offering continuity of care/r and an overall reduction in equity and access throughout rural maternity health service provisio