The Born and Markov approximations for atom lasers

We discuss the use of the Born and Markov approximations in describing the dynamics of an atom laser. In particular, we investigate the applicability of the quantum optical Born-Markov master equation for describing output coupling. We derive conditions based on the atomic reservoir, and atom dispersion relations for when the Born-Markov approximations are valid and discuss parameter regimes where these approximations fail in our atom laser model. Differences between the standard optical laser model and the atom laser are due to a combination of factors, including the parameter regimes in which a typical atom laser would operate, the different reservoir state which is appropriate for atoms, and the different dispersion relations between atoms and photons. We present results based on an exact method in the regimes in which the Born-Markov approximation fails. The exact solutions in some experimentally relavent parameter regimes give non-exponential loss of atoms from a cavity.Comment: 10 pages, 3 figures. (2 new figues). Exact solutions have been included in section II. Sections IV and V have been expanded. A new section discussing the effects of gravity has been include

Some economic and social aspects of residential internet use in Australia

This study constructs a profile of the representative Australian residential Internet user from data obtained from a web-based survey. Survey data indicate the representative user is male, 20 to 40 years of age, highly educated, uses the Internet 8 hrs per week for e-mail and FTP, and has a monthly bill of AUD32. Anordered-logit model relates Internet use to price, sociodemographic and connection capacity variables. Model estimates show the probability of higher Internet use is greater for middle-income households, but declines with age of the user. Policy may be required to enhance access to lower-income groups, and to inform the elderly of the potential capabilities of the new technology. Further, model estimates suggest that Australian Internet subscribers prefer flat-rate pricing (or a combination of flat-rate and usagesensitive pricing) over usage-sensitive pricing schemes. This result is consistent with Australian consumer attitudes toward local telephone and mobile cellular pricing.Residential internet use in Australia, economic and social aspects

Telecommunications productivity, catch-up and innovation

This study examines telecommunications productivity, technological catch-up and innovation in 74 countries for the period 1991-1995. A summary of partial productivity indicators is presented, and total factor productivity (TFP) growth is calculated using the Malmquist productivity change index. Decomposition of the Malmquist index provides preliminary evidence that developing countries can enhance productivity through catch-up. An econometric model is estimated that relates innovation to market size and two measures of market structure, viz., market concentration and private ownership. Model estimates support the Schumpeterian hypothesis that market size is conducive to innovation. However, the hypothesis that concentration (the dominant carrier's share of international message telephone service (IMTS) traffic) is positively related to innovation is rejected. Finally, the model suggests that increased private ownership of the dominant local-exchange carrier can enhance innovation.Catch-up; innovation; market structure; productivity; telecommunications

Market structure, competition, and pricing in United States international telephone service markets

Abstract—Several national governments argue international telephone prices are high because of asymmetric competition and inefficiencies in the accounting arrangements that govern the telecommunications services trade. This paper develops a model of U.S. international telephone pricing that allows for the accounting rate system and contains market-structure variables for both the U.S. and foreign ends of bilateral markets. Model estimation is on 39 bilateral telephone markets from 1991 through 1994. Parameter estimates reveal that settlement rates, market concentration, competition at either end of the bilateral market, and ownership are significant determinants of prices. These findings support initiatives promoting accounting-rate reductions and increased competition.United States international telephone service markets

CEE telecommunications investment and economic growth

The antiquated state of the telecommunications network in the transitional economies of Central and Eastern Europe has been identified by the OECD (1993) and the ITU (1994) as a significant impediment to regional productivity, international competitiveness and trade performance. This situation suggests that the upgrading and extension of the telecommunications network should be a priority objective for policy-makers in order to facilitate growth. This paper empirically examines the relationship between gross fixed investment, telecommunications infrastructure investment and economic growth for a sample of transitional economies in Central and Eastern Europe. In particular, the paper focuses on empirically determining the direction of influence, and timing, between investment and growth.Economies in transition; Investment and growth; Telecommunications infrastructure

Subscriber churn in the Australian ISP market

Rapid growth in Internet use, combined with easy market entry by Internet service providers (ISPs), has resulted in a highly competitive supply of Internet services. Australian ISPs range in size from a few large national operators to niche ISPs focused on specialised service. With many ISPs currently not profitable, subscriber retention is an important aspect of survival. This study develops a model which relates the probability of subscriber churn to various service attributes and subscriber characteristics. Estimation results show that churn probability is positively associated with monthly ISP expenditure, but inversely related to household income. Pricing also matters with subscribers preferring ISPs which offer flat-rate pricing arrangements.

Trade imbalance in international message telephone services

An econometric model is estimated to identify determinants of trade imbalance in international message telephone services markets. Results indicate that asymmetric market structure is important in explaining bilateral market imbalances for high income country pairs. For low and high income country pairs, GDP per capita is the dominant cause of traffic imbalances. The findings suggest that telecommunications liberalization policies are effective in reducing distortions in international traffic flows and settlement payments. However, liberalization should be accompanied by developmental programmes that enhance income per capita and telecommunications network investment in developing countries. Such programmes may be effective in providing a more equitable distribution of the gains from telecommunications reform across countries.Trade imbalance; international message telephone services

Understanding European Union international message telephone services demand

This study provides a contemporary understanding of demand relations in European Union (EU) international message telephone service (IMTS) markets prior to full liberalization at January 1 1998. Point-to-point demand equations that relate IMTS demand to prices, income, population and distance are estimated on bilateral market data for ten EU countries from 1990 to 1995. Model estimates suggest price elasticities of outgoing and incoming demand between 20.175 and 20.456, and 20.215 and 20.674, respectively. These elasticity estimates provide an empirical base from which to calculate welfare gains from the full deregulation of EU IMTS markets after 1998.Elasticity; European Union; International telephone demand

Economies of scale and scope in Australian telecommunications

This paper employs a composite cost function to examine the cost structure of Australian telephone services. The composite cost model combines the log-quadratic input price structure of the translog model with a quadratic structure for multiple outputs. Quadratic output structures permit the measurement of economies of scale, economies of scope, and subadditivity without prejudging their presence. Model estimates, on Telstra system data from 1926 to 1991, show that the production of Australian telephone services exhibits economies of scope but no ray economies of scale.Telecommunications; production; scale; scope; Australia

Asia-Pacific telecommunications liberalisation and productivity performance

This study examines the growth in total factor productivity (TFP) of 12 Asia-Pacific telecommunications carriers for the period 1987 through 1990. Carriers are chosen to represent the stages of telecommunications liberalisation identified by the International Telecommunication Union (1995a). A model relating TFP growth to output growth, changes in output mix, technology change and market competition and private ownership is estimated on a unique data set obtained from telecommunications carrier annual reports. Empirical results show competition, private ownership, technology change and scale economies improve carrier TFP growth.Asia-Pacific telecommunications; liberalisation and productivity performance