A Graph Rewriting Visual Language for Database Programming

Textual database programming languages are computationally complete, but have the disadvantage of giving the user a non-intuitive view of the database information that is being manipulated. Visual languages developed in recent years have allowed naive users access to a direct representation of data, often in a graph form, but have concentrated on user interface rather than complex programming tasks. There is a need for a system which combines the advantages of both these programming methods. We describe an implementation of Spider, an experimental visual database programming language aimed at programmers. It uses a graph rewriting paradigm as a basis for a fully visual, computationally complete language. The graphs it rewrites represent the schema and instances of a database. The unique graph rewriting method used by Spider has syntactic and semantic simplicity. Its form of algorithmic expression allows complex computation to be easily represented in short programs. Furthermore, Spider has greater power than normally provided in textual systems, and we show that queries on the schema and associative queries can be performed easily and without requiring any additions to the language

Social Costs of Mass Privatization

According to leading economic theorists, creating capitalism out of communism requires rapid privatization. In this article we empirically test the welfare implications of privatization policies in Post-Soviet countries by using cross-national panel mortality data as an indicator of social costs. We find that rapid privatization ñ whether measured by a novel measure of mass privatization program implementation or Enterprise Bank for Reconstruction and Development privatization outcome scores ñ is a critical determinant of life expectancy losses, and that when privatization policies are reversed, life expectancy improves. Using selection models, we show that endogeneity understates the social costs of rapid privatization.http://deepblue.lib.umich.edu/bitstream/2027.42/64393/1/wp890.pd

Modelling Reactive Multimedia: Design and Authoring

Multimedia document authoring is a multifaceted activity, and authoring tools tend to concentrate on a restricted set of the activities involved in the creation of a multimedia artifact. In particular, a distinction may be drawn between the design and the implementation of a multimedia artifact. This paper presents a comparison of three different authoring paradigms, based on the common case study of a simple interactive animation. We present details of its implementation using the three different authoring tools, MCF, Fran and SMIL 2.0, and we discuss the conclusions that may be drawn from our comparison of the three approaches

Homological algebra of twisted quiver bundles

Several important cases of vector bundles with extra structure (such as Higgs bundles and triples) may be regarded as examples of twisted representations of a finite quiver in the category of sheaves of modules on a variety/manifold/ringed space. We show that the category of such representations is an abelian category with enough injectives by constructing an explicit injective resolution. Using this explicit resolution, we find a long exact sequence that computes the Ext groups in this new category in terms of the Ext groups in the old category. The quiver formulation is directly reflected in the form of the long exact sequence. We also show that under suitable circumstances, the Ext groups are isomorphic to certain hypercohomology groups.Comment: 20 pages; v2: substantially revised version; v3: minor clarifications and correction

Schooling in Developing Countries: The Roles of Supply, Demand and Government Policy

In developing countries, rising incomes, increased demand for more skilled labor, and government investments of considerable resources on building and equipping schools and paying teachers have contributed to global convergence in enrollment rates and completed years of schooling. Nevertheless, in many countries substantial education gaps persist between rich and poor, between rural and urban households and between males and females. To address these gaps, some governments have introduced school vouchers or cash transfers programs that are targeted to disadvantaged children. Others have initiated programs to attract or retain students by expanding school access or by setting higher teacher eligibility requirements or increasing the number of textbooks per student. While enrollments have increased, there has not been a commensurate improvement in knowledge and skills of students. Establishing the impact of these policies and programs requires an understanding of the incentives and constraints faced by all parties involved, the school providers, the parents and the children. The chapter reviews the economic literature on the determinants of schooling outcomes and schooling gaps with a focus on static and dynamic household responses to specific policy initiatives, perceived economic returns and other incentives. It discusses measurement and estimation issues involved with empirically testing these models and reviews findings. Governments have increasingly adopted the practice of experimentation and evaluation before taking steps to expand new policies. Often pilot programs are initiated in settings that are atypically appropriate for the program, so that the results overstate the likely impact of expanding the program to other settings. Program expansion can also result in general equilibrium feedback effects that do not apply to isolated pilots. These behavioral models provide a useful context within which to frame the likely outcomes of such expansion.

Post Claims Underwriting and Rescission Practices

Based on case studies in four states, examines the effectiveness of regulation of the individual health insurance market and consumer protections against insurers canceling, rescinding, or limiting coverage after claims are submitted. Recommends reforms

High-extinction-ratio resonant cavity polarizer for quantum-optics measurements

The use of a high-finesse Fabry-Perot ring cavity with an odd number of reflections as a high-extinction-ratio resonant polarizer is shown. Experimental results from quantum-noise measurements using resonant cavities as spatial and spectral filters and precision polarizers are presented

Welfare and Work in the 1990s: Experiences in Six Cities

Our study examines the dynamic structure of welfare participation and the labor market involvement of recipients starting in the early 1990s and extending through 1999 in the core counties containing six major urban areas: Atlanta, Baltimore, Chicago, Fort Lauderdale, Houston, and Kansas City. By focusing on six major cities, we can examine the extent to which differences in state and local policy, administrative directives, and local labor market conditions contribute to observed trends.Welfare Reform