381 research outputs found
The Inforum-IIASA International System of Input-Output Models
Today's economies depend heavily on one another through international trade. To model them properly, the models need to depend on one another. For the models to work together, they must observe similar conventions for input and output of data, and ways of specifying alternative futures must be similar. At the same time, economies are very different and the models describing them must have much freedom for diversity in internal structure.
These simple ideas are the foundation of a gradually evolving consortium of input-output models and their builders. By working together, much time can be saved by avoiding repetitious programming and very little freedom lost in model specification. What could never be done by one group may perhaps be accomplished together.
Models are presently available for Japan, the United States, Canada, Belgium, France, the Federal Republic of Germany, and Britain. Models of Hungary and the Netherlands are under construction. Groups in Austria, South Korea, Sweden, Finland, and the German Democratic Republic expect to begin work on members of the family in the near future.
This paper describes the steps in the construction of a national model in this family; it explains how scenarios may be specified and shows typical structures of the real and the price sides of these models. The plan for the international linking system is explained and progress towards its realization described
Linked Input-Output Models for France, Germany, and Belgium
This paper presents a provisional method for the linking of national input-output models. The national models of Belgium, France and the Federal Republic of Germany are linked through export equations in which domestic demands of the buying countries are used to derive the export projections by sector of each country.
Two national scenarios are presented for comparison with a "basic case" scenario to illustrate the process. Alternative growth rates of exports by sector for 1980-87 are compared. An iterative method of solutions is used: the models are solved in succession. Convergence was found to take place in two iterations; a third iteration resulted in virtually no change.
The method has the drawback that consistency between imports and exports is not strictly adhered to. It has the virtues that new countries can easily be added to the existing set. An expansion of a set of countries to include the U.S., Canada and the U.K. is now planned
Path Curves and Plant Buds: An Introduction to the Work of Lawrence Edwards
To discover in the world of nature the geometrical forms of our own thinking is one of Man's most exciting experiences. A child delights in the hexagonal symmetry of a snow flake, and Kepler and thousands after him have joyed In the beauty of the laws of planetary motion. These experiences stir us, for they reveal that behind material nature there is a creative world in which we can participate through our thinking.
Such experiences are even more moving when they come from the world of living forms. The work of Lawrence Edwards on plant buds offers the finest example known to me. In over four-fifths of the species he has examined, the bud profiles are fit extremely closely by a family of curves known as path curves, for they are the paths taken by points under repeated application of a projective transformation of three-dimensional space
Recommended from our members
Method and device for disinfecting a toilet bowl
This invention is comprised of a method and device for disinfecting a flush toilet. The device is an electrocell mounted in the tank of the toilet, with two wire mesh electrodes immersed in the water in the tank and a battery applying approximately one to two volts of electric potential to the electrodes so that they chemically reduce a portion of the water in the tank to hydrogen peroxide. Then, when the tank is flushed, the peroxide is carried into the bowl where it can kill bacteria
Recommended from our members
The Effects of Workshop Training and Coaching on the Acquisition and Generalization of Teaching Skills
The purpose of this study was threefold: (a) to examine the separate effects of increased accuracy on multiple-choice/rank-order written tests and coaching on the teaching performance of participants; (b) to compare generalization across tasks produced by the workshop and coaching; and (c) to assess maintenance of teaching performance. Following baseline, two adults received a lecture on discrete trial teaching procedures. A written test measured verbal performance on workshop material periodically throughout this phase. During the next phase, each adult then experienced further training via in-situ coaching. A multiple baseline design across tasks was used during the coaching phase. Results of the workshop training package revealed an inverse relationship between the strongest verbal performance and strongest teaching performance skill areas. In addition, only with the introduction of the in-situ coaching package did teacher performance improve significantly across all behaviors. Child responding remained relatively constant throughout the study, regardless of teacher performance. Some generalization of teacher behavior was observed across tasks, but was extremely variable across both workshop and coaching conditions. After the cessation of coaching, teacher performance remained stable across maintenance phases and at a 6-week follow-up
Shear strength of woods for joggles
Thesis (BS)--University of Illinois, 1889TypescriptBound with 5 other University of Illinois theses IU-
Importance of replication in analyzing time-series gene expression data: Corticosteroid dynamics and circadian patterns in rat liver
<p>Abstract</p> <p>Background</p> <p>Microarray technology is a powerful and widely accepted experimental technique in molecular biology that allows studying genome wide transcriptional responses. However, experimental data usually contain potential sources of uncertainty and thus many experiments are now designed with repeated measurements to better assess such inherent variability. Many computational methods have been proposed to account for the variability in replicates. As yet, there is no model to output expression profiles accounting for replicate information so that a variety of computational models that take the expression profiles as the input data can explore this information without any modification.</p> <p>Results</p> <p>We propose a methodology which integrates replicate variability into expression profiles, to generate so-called 'true' expression profiles. The study addresses two issues: (i) develop a statistical model that can estimate 'true' expression profiles which are more robust than the average profile, and (ii) extend our previous micro-clustering which was designed specifically for clustering time-series expression data. The model utilizes a previously proposed error model and the concept of 'relative difference'. The clustering effectiveness is demonstrated through synthetic data where several methods are compared. We subsequently analyze <it>in vivo </it>rat data to elucidate circadian transcriptional dynamics as well as liver-specific corticosteroid induced changes in gene expression.</p> <p>Conclusions</p> <p>We have proposed a model which integrates the error information from repeated measurements into the expression profiles. Through numerous synthetic and real time-series data, we demonstrated the ability of the approach to improve the clustering performance and assist in the identification and selection of informative expression motifs.</p
Comparative analysis of acute and chronic corticosteroid pharmacogenomic effects in rat liver: Transcriptional dynamics and regulatory structures
<p>Abstract</p> <p>Background</p> <p>Comprehensively understanding corticosteroid pharmacogenomic effects is an essential step towards an insight into the underlying molecular mechanisms for both beneficial and detrimental clinical effects. Nevertheless, even in a single tissue different methods of corticosteroid administration can induce different patterns of expression and regulatory control structures. Therefore, rich <it>in vivo </it>datasets of pharmacological time-series with two dosing regimens sampled from rat liver are examined for temporal patterns of changes in gene expression and their regulatory commonalities.</p> <p>Results</p> <p>The study addresses two issues, including (1) identifying significant transcriptional modules coupled with dynamic expression patterns and (2) predicting relevant common transcriptional controls to better understand the underlying mechanisms of corticosteroid adverse effects. Following the orientation of meta-analysis, an extended computational approach that explores the concept of agreement matrix from consensus clustering has been proposed with the aims of identifying gene clusters that share common expression patterns across multiple dosing regimens as well as handling challenges in the analysis of microarray data from heterogeneous sources, e.g. different platforms and time-grids in this study. Six significant transcriptional modules coupled with typical patterns of expression have been identified. Functional analysis reveals that virtually all enriched functions (gene ontologies, pathways) in these modules are shown to be related to metabolic processes, implying the importance of these modules in adverse effects under the administration of corticosteroids. Relevant putative transcriptional regulators (e.g. RXRF, FKHD, SP1F) are also predicted to provide another source of information towards better understanding the complexities of expression patterns and the underlying regulatory mechanisms of those modules.</p> <p>Conclusions</p> <p>We have proposed a framework to identify significant coexpressed clusters of genes across multiple conditions experimented from different microarray platforms, time-grids, and also tissues if applicable. Analysis on rich <it>in vivo </it>datasets of corticosteroid time-series yielded significant insights into the pharmacogenomic effects of corticosteroids, especially the relevance to metabolic side-effects. This has been illustrated through enriched metabolic functions in those transcriptional modules and the presence of GRE binding motifs in those enriched pathways, providing significant modules for further analysis on pharmacogenomic corticosteroid effects.</p
Circadian signatures in rat liver: from gene expression to pathways
<p>Abstract</p> <p>Background</p> <p>Circadian rhythms are 24 hour oscillations in many behavioural, physiological, cellular and molecular processes that are controlled by an endogenous clock which is entrained to environmental factors including light, food and stress. Transcriptional analyses of circadian patterns demonstrate that genes showing circadian rhythms are part of a wide variety of biological pathways.</p> <p>Pathway activity method can identify the significant pattern of the gene expression levels within a pathway. In this method, the overall gene expression levels are translated to a reduced form, pathway activity levels, via singular value decomposition (SVD). A given pathway represented by pathway activity levels can then be as analyzed using the same approaches used for analyzing gene expression levels. We propose to use pathway activity method across time to identify underlying circadian pattern of pathways.</p> <p>Results</p> <p>We used synthetic data to demonstrate that pathway activity analysis can evaluate the underlying circadian pattern within a pathway even when circadian patterns cannot be captured by the individual gene expression levels. In addition, we illustrated that pathway activity formulation should be coupled with a significance analysis to distinguish biologically significant information from random deviations. Next, we performed pathway activity level analysis on a rich time series of transcriptional profiling in rat liver. The over-represented five specific patterns of pathway activity levels, which cannot be explained by random event, exhibited circadian rhythms. The identification of the circadian signatures at the pathway level identified 78 pathways related to energy metabolism, amino acid metabolism, lipid metabolism and DNA replication and protein synthesis, which are biologically relevant in rat liver. Further, we observed tight coordination between cholesterol biosynthesis and bile acid biosynthesis as well as between folate biosynthesis, one carbon pool by folate and purine-pyrimidine metabolism. These coupled pathways are parts of a sequential reaction series where the product of one pathway is the substrate of another pathway.</p> <p>Conclusions</p> <p>Rather than assessing the importance of a single gene beforehand and map these genes onto pathways, we instead examined the orchestrated change within a pathway. Pathway activity level analysis could reveal the underlying circadian dynamics in the microarray data with an unsupervised approach and biologically relevant results were obtained.</p
- …