A distributional model of semantic context effects in lexical processinga

One of the most robust findings of experimental psycholinguistics is that the context in which a word is presented influences the effort involved in processing that word. We present a novel model of contextual facilitation based on word co-occurrence prob ability distributions, and empirically validate the model through simulation of three representative types of context manipulation: single word priming, multiple-priming and contextual constraint. In our simulations the effects of semantic context are mod eled using general-purpose techniques and representations from multivariate statistics, augmented with simple assumptions reflecting the inherently incremental nature of speech understanding. The contribution of our study is to show that special-purpose m echanisms are not necessary in order to capture the general pattern of the experimental results, and that a range of semantic context effects can be subsumed under the same principled account.›

Augmenting the GTAP Database with Data on Inter-Regional Transactions

This paper reports the results of an exercise to augment the GTAP database with information from the income and current transfers components of the current account of the balance of payments. The exercise demonstrates that the process of augmenting the GTAP database is relatively straightforward. A simple simulation exercise using the augmented and non-augmented versions of the database demonstrates that the results from a trade liberalisation scenario are sufficiently large to provide a justification for the augmentation of the GTAP database over and above the case that could be argued based on national accounting conventions.Social Accounting Matrix, Trade Analysis, Computable General Equilibrium

A Computable General Equilibrium (CGE) Analysis of the Impact of an Oil Price Increase in South Africa

Following recent international oil price increases, there has been considerable interest in how this external factor can affect the South African economy. This paper reports results from a computable general equilibrium (CGE) analysis of an increase (up to 30 per cent) in international oil prices. Background information is provided, which puts the magnitude of the price variations in historical context. We describe the procedure used to adjust the social accounting matrix (SAM), which is used to calibrate the model, to account explicitly for crude oil. Then, the effects of the crude oil price increase are traced through the economy, from markets, industries through to factors, households and the government. Predictably, the shock hurts the economy: a 20 per cent increase results in a drop in GDP of 1 per cent. It is found that the major impact is to be found in the petroleum industry itself, whereas the effects on liquid fuel dependent industries such as transport is not as large as may be supposed. In agriculture, it is found that the depreciating currency has a positive effect, offsetting most of the negative effects of higher petroleum prices, particularly in export-oriented areas. In a long-term scenario, capital and skilled labour becomes mobile, and the results suggest that such reallocation may not be to the overall advantage of the economy.Resource /Energy Economics and Policy,

The Role of the 1994-95 Coffee Boom in Uganda's Recovery

This paper reports a CGE analysis that explores the consequences of the 1994-95 rise in the international price of coffee for Uganda´s economy. Evidence is found for a small effect on medium-term growth and poverty reduction. Aid dependence is among the reasons why this effect is not found to be larger. Major beneficiary groups are not only the farmers to which the windfall initially accrued but also urban wage earners and the urban self-employed.Computable General Equilibrium, Coffee; Uganda; Dutch Disease

The Welfare Impacts of National and International Agricultural Efficiency Gains - A South African Case Study

Ongoing agricultural and food commodity price declines associated with efficiency gains in agricultural production, both domestically and internationally, can have important welfare effects for a country. The fact that consumers can buy cheaper imported and/or domestically produced foodstuffs has various spin-off effects in the economy. However, as with any economic shock there are winners and losers, and hence it is important to gain an understanding of the economywide effects, specifically in terms of the employment effects and the income- and substitution effects associated with relative price changes in the economy. In this paper the impact of domestic and international efficiency changes in the agricultural sector is modelled using a South African Computable General Equilibrium model with highly disaggregated food and agricultural sectors. The results indicate that while consumers gain from both domestic and international efficiency gains, domestic agricultural producers face a contraction in output when world trade prices decline as a result of international efficiency gains. Efficiency gains have different welfare impacts upon different types of household, with rural households not gaining as much as urban households due to job losses in the agricultural sector that offset welfare gains associated lower prices.Productivity Analysis,

Space Station Freedom altitude strategy

The Space Station Freedom (SSF) altitude strategy provides guidelines and assumptions to determine an altitude profile for Freedom. The process for determining an altitude profile incorporates several factors such as where the Space Shuttle will rendezvous with the SSF, when reboosts must occur, and what atmospheric conditions exist causing decay. The altitude strategy has an influence on all areas of SSF development and mission planning. The altitude strategy directly affects the micro-gravity environment for experiments, propulsion and control system sizing, and Space Shuttle delivery manifests. Indirectly the altitude strategy influences almost every system and operation within the Space Station Program. Evolution of the SSF altitude strategy has been a very dynamic process over the past few years. Each altitude strategy in turn has emphasized a different consideration. Examples include a constant Space Shuttle rendezvous altitude for mission planning simplicity, or constant micro-gravity levels with its inherent emphasis on payloads, or lifetime altitudes to provide a safety buffer to loss of control conditions. Currently a new altitude strategy is in development. This altitude strategy will emphasize Space Shuttle delivery optimization. Since propellant is counted against Space Shuttle payload-to-orbit capacity, lowering the rendezvous altitude will not always increase the net payload-to-orbit, since more propellant would be required for reboost. This altitude strategy will also consider altitude biases to account for Space Shuttle launch slips and an unexpected worsening of atmospheric conditions. Safety concerns will define a lower operational altitude limit, while radiation levels will define upper altitude constraints. The evolution of past and current SSF altitude strategies and the development of a new altitude strategy which focuses on operational issues as opposed to design are discussed

Globe: A SAM Based Global CGE Model using GTAP Data

This paper provides a technical description of a global computable general equilibrium (CGE) model that is calibrated from a Social Accounting Matrix (SAM) representation of the Global Trade Analysis Project (GTAP) database. An important feature of the model is the treatment of nominal and real exchange rates and hence the specification of multiple numéraire. Another distinctive feature of the model is the use of a ‘dummy’ region, known as globe, that allows for the recording of inter regional transactions where either the source or destination are not identified.

SeeResults: A Spreadsheet Application for the Analysis of CGE Model Results

CGE models tend to produce large amounts of result data, and it can be difficult and timeconsuming to view, import, process and keep track of these. SeeResults is an Excel-based spreadsheet application that has been developed within the PROVIDE project to facilitate viewing results and producing presentation output, such as charts. It effectively functions as a GDX (a binary format used for output from GAMS) file viewer, and has been designed to be flexible, user-friendly and immediately usable with minimal configuration. This paper describes the rationale for the application, its main features, a number of screen captures and implementation notes.Research and Development/Tech Change/Emerging Technologies,