Surface phenomena in plasma environments

Plasma interactions and their effects on materials depend on a number of factors, including the pre-existing environment, the properties of surface materials and the characteristics of the system. An additional dimension is the question of mission: some payloads may be much more sensitive to plasma interactions than others. As an example, a payload whose objective is to measure the ambient environment will be more sensitive to any effects than will a power system. Material specific effects include charging and its associated effects, which can result in short- and long-term damage. Selection of materials for a particular application requires consideration of all factors and assessment of effects due to all causes. Proper selection and suitability determination requires analysis to identify the actual environment combined with testing under exposure to single and combined environment factors

Wages, the Terms of Trade, and the Exchange Rate Regime

This paper analyzes a two-commodity short-run macroeconomic model under fixed and flexible exchange rates. Goods are disaggregated into imports and exports. Both are consumed domestically, but only the latter is produced at home. While imports are available in international markets at a fixed price, relative size matters in that the country’s specialized export good faces a less than infinitely elastic foreign demand. The seemingly natural disaggregation used here yields a model that is better suited than traditional models for the analysis of such problems as imported inflation and for flexible exchange rates. Also, the terms of trade is explicit and hence easily distinguished from the exchange rate, and the model can be used to illustrate the relationship between the elasticities, absorption and monetary approaches. A common theme in the contemporary literature on flexible exchange rates is that the exchange rate is determined by financial portfolio decisions; a key assumption implicit in such models is that changes in the exchange rate have no real effects, even in the short run. The present approach imposes more structure on the problem by introducing possible short-run real effects of the exchange rate due to less than infinitely elastic export demand and explicitly specified domestic supply. The stability and comparative static properties of the model are shown to depend crucially on the specification of aggregate supply and the behavior of wages, in addition to relative size, and it is surprising that so little attention has been paid in the literature to this issue

Interaction of large, high power systems with operational orbit charged particle environments

A potentially hazardous spacecraft environment interaction is discussed. The interaction of large high voltage systems with low energy (less than 50 eV) plasmas which can result in loss of power and/or arching was examined. The impact of this class of interactions where the ambient operation is most severe at low orbits where the ambient plasmas are densest. Results of experimental work and predictions of simple analytical models were presented and their implications for design of space systems were reviewed

Technology, Trade and Factor Mobility

The well-known factor price equalization theorem is often invoked to provide trade theorists with justification for the conventional assumption of complete international immobility of factors of production. If conditions of the theorem are satisfied, and free trade does in fact give rise to the equalization of factor returns, then it is inconsequential in which country production takes place. Mundell's original analysis then brings us full circle to the "commodity price equalization theorem". If the conditions of the factor price equalization theorem are met, but a tariff on trade is imposed, then factor mobility can replace trade in establishing productive efficiency. Recent work by Jones and Kemp have analysed further the implications of introducing factor mobility and in particular capital mobility into the analysis of international trade. However, these have concentrated on generating optimum tariff and tax( on capital services) formulae for the individual country trying to maximize its own welfare. The present paper is more in the tradition of the Mundell analysis in that we are more concerned with world efficiency in production--that is, in maximizing potential world welfare.

More on Growth and the Balance of Payments: The Adjustment Process

The effect of an economy's growth on its balance of payments has been a subject which has received a good deal of attention in the recent literature in international economics. Much of this attention derives from general dissatisfaction with the theoretical and empirical aspects of the standard Keynesian analysis which argues that, via the existence of a positive marginal propensity to import, growth in a country's income will lead to an increase in imports. Hence, the argument proceeds, for given exports, growth leads to a deterioration in the balance of payments. As a result, we have developed the "monetary approach" to growth and the balance of payments emphasizing the role of asset market equilibrium. Further we have demonstrated this approach to be capable of yielding insights into the short-run or transitional effects on the balance of payments of various exogenous disturbances. It is hoped that the examples provided in the following article will highlight the importance of considering impact effects and adjustment processes when looking at balance of payments or any other macroeconomic phenomena, and that future research will reflect such considerations.

Use of telemetric tracking to examine environmental influences on catch/effort indices. A case study of Atlantic Salmon (Salmo salar L.)in the R. Tywi, S. Wales

A case study of Atlantic Salmon runs into the R. Tyvi (S. Wales) is presented. Radio tracking of over 200 salmon in 1988 and 1989 has demonstrated that flow is an important factor in modifying both run timing and migratory success. Entry of salmon into the river is typically in response to flow events, and periods of low falling flows delay entry and may directly result in reduced runs into the river. Delayed entry may also increase the proportion of the run migrating after the end of both rod and net fishing seasons. The implications of these results for net and rod catch and catch/effort data are discussed, using both statutory reported catch data and data from specific catch/effort studies. Flow is demonstrated to be a dominant factor in determining the within-season distribution of rod catch and catch/effort during low-flow years. Estuarial seine net catch and catch/effort tend to be controlled more by time of return than by flow although low flows may delay runs. Annual reported rod catch is correlated with flow, which controls in season availability, catchability and consequently the amount of fishing effort. Use of catch or catch/effort data should take account of inter-year variations in flow and other environmental factors. Although catch and catch/effort are valuable indicators of fishery performance, they are inadequate to represent changing stock levels