Parallel Evaluation of Multi-join Queries

A number of execution strategies for parallel evaluation of multi-join queries have been proposed in the literature. In this paper we give a comparative performance evaluation of four execution strategies by implementing all of them on the same parallel database system, PRISMA/DB. Experiments have been done up to 80 processors. These strategies, coming from the literature, are named: Sequential Parallel, Synchronous Execution, Segmented Right-Deep, and Full Parallel. Based on the experiments clear guidelines are given when to use which strategy. This is an extended abstract; the full paper appeared in Proc. ACM SIGMOD'94, Minneapolis, Minnesota, May 24–27, 199

Forest management after the economic transition

Germany and Scandinavia represent two paradigmatic forest management traditions, based on management for volume and management for profit, respectively. This study examines the prevailing silvicultural regimes and resulting economic outcomes in Germany and Sweden as benchmarks, and then corresponding analyses are performed for post-transition EU countries, represented by Poland, Lithuania and Latvia. The analyses reveal a regional gradient where Poland stands closest to the German tradition, Latvia goes through a “scandinavisation”, and Lithuania takes an intermediate position. Poland adheres to longer rotations and follows the principle of self-sufficiency, while economic efficiency has gained increased importance in Latvia. The observed gradient is likely to be sustained in the coming decades as the survey of key forest sector stakeholders reveals ideological patterns that correlate with the pace of reform of State forestry in Poland, Lithuania and Latvia

Who Pays to Protect Native Vegetation? Costs to Farmers in Moree Plains Shire, New South Wales

The Native Vegetation Conservation Act was introduced on January 1st 1998 to limit the clearing of native grassland and woodland in NSW. The Act has limited clearing and development to crops, has protected biodiversity, and may have enhanced soil and water conservation. But this analysis of the prices paid for land in Moree Plains Shire shows that the Act has reduced land values by some 21 per cent and has already reduced annual incomes by 10 per cent across the whole Shire. This reduction in annual incomes may well reach 18 per cent by 2005. This decrease in income means that farm households in the Shire currently must give up 15.6 per cent of their household income because they must protect native vegetation on their farms. In contrast, urban households in Australia must give up only 0.55 per cent of one per cent of their income through taxes for the same purpose. The Act has imposed these costs on farmers who are already struggling financially, has made the distribution of income in the community less equal, and has made farm families bear far higher costs than urban families. Do these outcomes enhance an objective of equity, or fairness within the community?native vegetation, opportunity costs, land values, Environmental Economics and Policy, Farm Management, Land Economics/Use,

Do private sustainability standards contribute to income growth and poverty alleviation? : a comparison of different coffee certification schemes in Ethiopia

Private sustainability standards are increasingly important in food trade with developing countries, but the implications for smallholder farmers are still poorly understood. We analyze the implications of different coffee certification schemes in Ethiopia using cross-sectional survey data, and regression and propensity-score-matching techniques. We find that: Rainforest Alliance (RA) and double Fairtrade-Organic (FT-Org) certifications are associated with higher incomes and reduced poverty, mainly because of higher prices; Fairtrade (FT) certification hardly affects welfare; and Organic (Org) certification reduces incomes, chiefly due to lower yields. Cooperative heterogeneity importantly shapes these results. Results imply that private standards may not always deliver what they promise to consumers

Emerging East-West collaborative networks: An appraisal

Although an extensive amount of literature reviews emerging patterns of east-west co-operation, it is not easy to grasp the state of the art. Too many of the books, articles and papers tend to mark the trees rather than to map the forest. The paper analyses recent trends from the point of view of modern economics which emphasizes the growing use of a wide variety of new types of co-operative mechanisms between firms in organizing international business. It takes an appraising look at the outcome of a recent research project of a group of scholars from east and west. The paper comes to the conclusion that east-west integration is proceeding at a considerable rate. But it is dominated by shallow modes - by arm's length transactions and contract work. To a certain extent, this might reflect new patterns of inter-firm co-operation. But this might also be an indication that co-operation with partners in CECTs is still in a flat state. Eastern firms find it hard to obtain an adequate position in international networks. Their lack of competence, reliability and reputation is often an insurmountable barrier. Accordingly, they must improve upon their technological and organizational standards to be considered by western firms as competent, reliable and trustworthy and, hence, equal partners in collaborational networks.

Balancing Hydraulic Fracturing’s Environmental and Economic Impacts: The Need for a Comprehensive Federal Baseline and the Provision of Local Rights

Reliable evaluation methods is needed to ensure that investments in energy conservation measures (ECMs) and the construction of new energy efficient buildings lives up to the promised and expected performance. This thesis presents and evaluates a regression method for estimation of influential building parameters: transmission losses above ground (including air leakage), ground heat loss, and overall heat loss coefficient. The analysis is conducted with separately metered electricity, heating and weather data using linear regression models based on the simplified steady-state power balance for a whole building. The evaluation consists of analyzing the robustness of the extracted parameters, their suitability to be used as input values to building energy simulations (BES) tools. In addition, differences between uncalibrated and calibrated BES models are analyzed when they are used to calculate energy savings. Finally the suitability of using a buildings overall heat loss coefficient as a performance verification tool is studied. The presented regression method exhibits high robustness and good agreement with theory. Knowledge of these parameters also proved beneficial in BES calibration procedures as well as in performance verifications. Thus, the presented method shows promising features for reliable energy performance assessments of buildings