Single stage to orbit/SDIO

This paper included a discussion of the United States' need for a launch system that demonstrates both high capacity and low cost. Current systems, which typically require two years' lead time to provide on-orbit service to space platforms, are too inflexible for many missions. A system is needed that is able to operate in much the same way as existing commercial aircraft. The SSTO program is focused on satisfying aircraft-like operations and logistics support requirements such as engine-out intact abort capability and seven-day, 350-man-day vehicle turnaround times

Were Japanese Stock Prices Too High?

The difference between reported price-earnings ratios in the United States and Japan is not as puzzling as it appears at first glance. Nearly half the disparity is caused by differences in accounting practices with respect to consolidation of earnings from subsidiaries and depreciation of fixed assets. If Japanese firms used U.S. accounting rules, we estimate that the P/E ratio for the Tokyo Stock Exchange would have been 32.1, not the reported 54.3, at the end of 1988. Accounting differences are unable, however, to explain the sharp rise in the Japanese stock market during the mid-1980s. Changes in required returns on equities, or in investor expectations of future growth for Japanese firms, must be invoked to explain this phenomenon. Real interest rates declined during the period of rapid price increase, but there is little evidence that growth expectations became more optimistic. The real interest rate changes do not, however, appear large enough to fully account for the change in stock prices.

Jet pump-drive system for heat removal

The invention does away with the necessity of moving parts such as a check valve in a nuclear reactor cooling system. Instead, a jet pump, in combination with a TEMP, is employed to assure safe cooling of a nuclear reactor after shutdown. A main flow exists for a reactor coolant. A point of withdrawal is provided for a secondary flow. A TEMP, responsive to the heat from said coolant in the secondary flow path, automatically pumps said withdrawn coolant to a higher pressure and thus higher velocity compared to the main flow. The high velocity coolant is applied as a driver flow for the jet pump which has a main flow chamber located in the main flow circulation pump. Upon nuclear shutdown and loss of power for the main reactor pumping system, the TEMP/jet pump combination continues to boost the coolant flow in the direction it is already circulating. During the decay time for the nuclear reactor, the jet pump keeps running until the coolant temperature drops to a lower and safe temperature where the heat is no longer a problem. At this lower temperature, the TEMP/jet pump combination ceases its circulation boosting operation. When the nuclear reactor is restarted and the coolant again exceeds the lower temperature setting, the TEMP/jet pump automatically resumes operation. The TEMP/jet pump combination is thus automatic, self-regulating and provides an emergency pumping system free of moving parts

Investor Diversification and International Equity Markets

The benefits of international diversification have been recognized for decades. In spite of this, most investors hold nearly all of their wealth in domestic assets. In this paper, we construct new estimates of the international equity portfolio holdings of investors in the U.S., Japan, and Britain. More than 98% of the equity portfolio of Japanese investors is held domestically; the analogous percentages are 94% for the U.S., and 82% for Britain. We use a simple model of investor preferences and behavior to show that current portfolio patterns imply that investors in each nation expect returns in their domestic equity market to be several hundred basis points higher than returns in other markets. This lack of diversification appears to be the result of investor choices, rather than institutional constraints.

CRYOGENIC UPPER STAGE SYSTEM SAFETY

NASA s Exploration Initiative will require development of many new systems or systems of systems. One specific example is that safe, affordable, and reliable upper stage systems to place cargo and crew in stable low earth orbit are urgently required. In this paper, we examine the failure history of previous upper stages with liquid oxygen (LOX)/liquid hydrogen (LH2) propulsion systems. Launch data from 1964 until midyear 2005 are analyzed and presented. This data analysis covers upper stage systems from the Ariane, Centaur, H-IIA, Saturn, and Atlas in addition to other vehicles. Upper stage propulsion system elements have the highest impact on reliability. This paper discusses failure occurrence in all aspects of the operational phases (Le., initial burn, coast, restarts, and trends in failure rates over time). In an effort to understand the likelihood of future failures in flight, we present timelines of engine system failures relevant to initial flight histories. Some evidence suggests that propulsion system failures as a result of design problems occur shortly after initial development of the propulsion system; whereas failures because of manufacturing or assembly processing errors may occur during any phase of the system builds process, This paper also explores the detectability of historical failures. Observations from this review are used to ascertain the potential for increased upper stage reliability given investments in integrated system health management. Based on a clear understanding of the failure and success history of previous efforts by multiple space hardware development groups, the paper will investigate potential improvements that can be realized through application of system safety principles

Communicating simulation outputs of mesoscale coastal evolution to specialist and non-specialist audiences

Coastal geomorphologists and engineers worldwide are increasingly facing the non-trivial challenge of visualising and communicating mesoscale modelling assumptions, uncertainties and outcomes to both coastal specialists and decision-makers. Visualisation of simulation outcomes is a non-trivial problem because the more abstract scientific visualisation techniques favoured by specialists for data exploration and hypothesis-testing are not always as successful at engaging decision-makers and planners. In this paper, we show how the risk of simulation model outcomes becoming disconnected from more realistic visualisations of model outcomes can be minimised by using the Coastal Modelling Environment (CoastalME). CoastalME is a modelling framework for coastal mesoscale morphological modelling that can achieve close linkages between the scientific model abstractions, in the form of lines, areas and volumes, and the 3D representation of topographic and bathymetric surfaces and shallow sub-surface sediment composition. We propose and illustrate through the study case of Happisburgh (eastern England, UK), a transparent methodology to merge the required variety of data types and formats into a 3D-thickness model that is used to initialise a simulation. We conclude by highlighting some of the barriers to the adoption of the methodology proposed

Trichomonas vaginalis: Diagnosis and Clinical Characteristics in Pregnancy

Objective: The objectives of this study were to 1) determine the prevalance and characterize the symptomatology of Trichomonas vaginalis (TV) infection in pregnant women on entry into prenatal care in an inner-city population; 2) compare conventional microscopic methods vs. culture techniques in diagnosing TV in both symptomatic and asymptomatic pregnant patients; and 3) correlate wet mount microscopic and microbiologic characteristics of varying manifestations of trichomoniasis

The Second Conference on Lunar Bases and Space Activities of the 21st Century, volume 1

These papers comprise a peer-review selection of presentations by authors from NASA, LPI industry, and academia at the Second Conference (April 1988) on Lunar Bases and Space Activities of the 21st Century, sponsored by the NASA Office of Exploration and the Lunar Planetary Institute. These papers go into more technical depth than did those published from the first NASA-sponsored symposium on the topic, held in 1984. Session topics covered by this volume include (1) design and operation of transportation systems to, in orbit around, and on the Moon, (2) lunar base site selection, (3) design, architecture, construction, and operation of lunar bases and human habitats, and (4) lunar-based scientific research and experimentation in astronomy, exobiology, and lunar geology

The Second Conference on Lunar Bases and Space Activities of the 21st Century, volume 2

These 92 papers comprise a peer-reviewed selection of presentations by authors from NASA, the Lunar and Planetary Institute (LPI), industry, and academia at the Second Conference on Lunar Bases and Space Activities of the 21st Century. These papers go into more technical depth than did those published from the first NASA-sponsored symposium on the topic, held in 1984. Session topics included the following: (1) design and operation of transportation systems to, in orbit around, and on the Moon; (2) lunar base site selection; (3) design, architecture, construction, and operation of lunar bases and human habitats; (4) lunar-based scientific research and experimentation in astronomy, exobiology, and lunar geology; (5) recovery and use of lunar resources; (6) environmental and human factors of and life support technology for human presence on the Moon; and (7) program management of human exploration of the Moon and space

Trichomonas vaginalis Weakens Human Amniochorion in an In Vitro Model of Premature Membrane Rupture

Objective: Trichomonas vaginalis (TV) infection is associated with preterm rupture of membranes (PROM) and preterm birth. We evaluated the effects of TV growth and metabolism on preparations of human amniochorion to understand and characterize how TV may impair fetal-membrane integrity and predispose to PROM and preterm birth