Tectonic setting and evolution of late Archaean greenstone belts of Superior Province, Canada

Late Archean (3.0-2.5 Ga) greenstone belts are a major component of the Superior Province of the Canadian Shield where alternating, metavolcanic - rich and metasedimentary - rich subprovinces form a prominent central striped region bordered in part by high-grade gneiss subprovinces, the Pikiwitonei and Minto in the north, and the Minnesota River Valley in the south. The high-grade gneiss subprovinces are characterized by granulite facies gneiss of plutonic and supracrustal origin, and by abundant plutonic rocks. Minnesota River Valley has rocks older than 3.5 Ga; absolute ages of Pikiwitonei and Minto rocks are unknown but Minto does have north-south structural trends distinctive from the dominant east-west structures of Superior Province. A discussion follows

Do Financial Incentives Encourage Welfare Recipients to Work? Evidence from a Randomized Evaluation of the Self-Sufficiency Project

This paper reports on a randomized evaluation of an earnings subsidy offered to long-term welfare recipients in Canada. The program -- known as the Self-Sufficiency Project (SSP) -- provides a supplement equal to one-half of the difference between a target earnings level and a participant's actual earnings. The SSP supplement is similar to a negative income tax with two important differences: (1) eligibility is limited to long-term welfare recipients who find a full-time job; and (2) the payment depends on individual earnings rather than family income. Our evaluation is based on a classical randomized design: one half of a group of single parents who had been on welfare for over a year were eligible to receive the SSP supplement, while the other half were assigned to a control group. Results for an early cohort of SSP participants and controls suggest that the financial incentives of the Self-Sufficiency Program increase labor market attachment and reduce welfare participation.

Greenstone belts: Their boundaries, surrounding rock terrains and interrelationships

Greenstone belts are an important part of the fragmented record of crustal evolution, representing samples of the magmatic activity that formed much of the Earth's crust. Most belts developed rapidly, in less than 100 Ma, leaving large gaps in the geological record. Surrounding terrains provide information on the context of greenstone belts. The effects of tectonic setting, structural geometry and evolution, associated plutonic activity and sedimentation are discussed

Workshop on a Cross Section of Archean Crust

Various topics relevant to crustal genesis, especially the relationship between Archean low - and high-grade terrains, were discussed. The central Superior Province of the Canadian Shield was studied. Here a 120 km-wide transition from subgreenschist facies rocks of the Michipicoten greenstone belt to granulite facies rocks of the Kapuskasing structural zone represents an oblique cross section through some 20 km of crust, uplifted along a northwest-dipping thrust fault

Thermal buckling analysis for stiffened orthotropic cylindrical shells

Structural analysis of thermal buckling of orthotropic, multilayered, stiffened cylindrical shell using finite differences and determinant plotting or modal iteratio

The Limits to Wage Growth: Measuring the Growth Rate of Wages For Recent Welfare Leavers

We study the rate of wage growth among welfare leavers in the Self Sufficiency Program (SSP), an experimental earnings subsidy offered to long-term welfare recipients in Canada. Single parents who started working in response to the SSP incentive are younger, less educated, and have more young children than those who would have been working regardless of the program. They also earn relatively low wages in their first few months of work: typically within $1 of the minimum wage. Despite these differences, their rate of wage growth is similar to other welfare leavers. We estimate that people who were induced to work by SSP experienced real wage growth of about 2.5 - 3 percent per year - a rate consistent with conventional measures of the return to experience for similar workers.

The Measurement of Medicaid Coverage in the SIPP: Evidence from California, 1990-1996

This paper studies the accuracy of reported Medicaid coverage in the Survey of Income and Program Participation (SIPP) using a unique data set formed by matching SIPP survey responses to administrative records from the State of California. Overall, we estimate that the SIPP underestimates Medicaid coverage in the California population by about 10 percent. Among SIPP respondents who can be matched to administrative records, we estimate that the probability someone reports Medicaid coverage in a month when they are actually covered is around 85 percent. The corresponding probability for low-income children is even higher - at least 90 percent. These estimates suggest that the SIPP provides reasonably accurate coverage reports for those who are actually in the Medicaid system. On the other hand, our estimate of the false positive rate (the rate of reported coverage for those who are not covered in the administrative records) is relatively high: 2.5 percent for the sample as a whole, and up to 20 percent for poor children. Some of this is due to errors in the recording of Social Security numbers in the administrative system, rather than to problems in the SIPP.

The Archean crust in the Wawa-Chapleau-Timmins region. A field guidebook prepared for the 1983 Archean Geochemistry-Early Crustal Genesis Field Conference

This guidebook describes the characteristics and interrelationships of Archean greenstone-granite and high-grade gneiss terrains of the Superior Province. A 300-km long west to east transect between Wawa and Timmins, Ontario will be used to illustrate regional-scale relationships. The major geological features of the Superior Province are described

Intuitive visualization technique to support eye tracking data analysis: A user-study

While fixation distribution is conventionally visualized using heat maps, there is still a lack of a commonly accepted technique to visualize saccade distributions. Inspired by wind maps and the Oriented Line Integral Convolution (OLIC) technique, we visualize saccades by drawing ink droplets which follow the direction indicated by a flow direction map. This direction map is computed using a kernel density estimation technique over the tangent directions to each saccade gaze point. The image is further blended with the corresponding heat map. It results in an animation or a static image showing main directions of the transitions between different areas of interest. We also present results from a web-based user study where naive non-expert users where asked to identify the direction of the flow and simple patterns. The results showed that these visualizations can successfully be used to support visual analysis of the eye-tracking data. It also showed that the use of animation allows to ease the task and to improve the performance

Financial Incentives for Increasing Work and Income Among Low-Income Families

This paper investigates the impact of financial incentive programs, which have become an increasingly common component of welfare programs. We review experimental evidence from several such programs. Financial incentive programs appear to increase work and raise income (lower poverty), but cost somewhat more than alternative welfare programs. In particular, windfall beneficiaries -- those who would have been working anyway -- can raise costs by participating in the program. Several existing programs limit this effect by targeting long-term welfare recipients or by limiting benefits to full-time workers. At the same time, because financial incentive programs transfer support to working low-income families, the increase in costs due to windfall beneficiaries makes these programs more effective at alleviating poverty and raising incomes. Evidence also indicates that combining financial incentive programs with job search and job support services can increase both employment and income gains. Non-experimental evidence from the Earned Income Tax Credit (EITC) and from state Temporary Assistance to Needy Families (TANF) programs with enhanced earnings disregards also suggests that these programs increase employment, and this evidence is consistent with the experimental evidence on the impact of financial incentive programs.