QueRIE: Collaborative Database Exploration

Interactive database exploration is a key task in information mining. However, users who lack SQL expertise or familiarity with the database schema face great difficulties in performing this task. To aid these users, we developed the QueRIE system for personalized query recommendations. QueRIE continuously monitors the user’s querying behavior and finds matching patterns in the system’s query log, in an attempt to identify previous users with similar information needs. Subsequently, QueRIE uses these “similar” users and their queries to recommend queries that the current user may find interesting. In this work we describe an instantiation of the QueRIE framework, where the active user’s session is represented by a set of query fragments. The recorded fragments are used to identify similar query fragments in the previously recorded sessions, which are in turn assembled in potentially interesting queries for the active user. We show through experimentation that the proposed method generates meaningful recommendations on real-life traces from the SkyServer database and propose a scalable design that enables the incremental update of similarities, making real-time computations on large amounts of data feasible. Finally, we compare this fragment-based instantiation with our previously proposed tuple-based instantiation discussing the advantages and disadvantages of each approach

Correlating Fermi gamma-ray sources with ultra-high energy cosmic rays

The origin of ultra-high energy cosmic rays (UHECRs) is one of the enduring mysteries of high-energy astrophysics. To investigate this, we cross-correlate the recently released Fermi Large Area Telescope First Source Catalog (1FGL) with the public sample of UHECRs made available by the Pierre Auger collaboration. Of the 27 UHECRs in the sample, we find 12 events that arrived within 3.1 degrees of Fermi sources. However, we find similar or larger number of matches in 63 out of 100 artificial UHECR samples constructed using positions randomly drawn from the BATSE 4B catalog of gamma-ray bursts (GRBs) collected from 1991 until 1996. Based on our analysis, we find no evidence that UHECRs are associated with Fermi sources. We conclude with some remarks about the astrophysical origin of cosmic rays.Comment: Revised version that considers a smaller deflection angle for UHECRs (3.1 degrees) and a declination range for the artificial samples that extends to decl.= +24.8 in response to the referee comments. 4 pages, 2 figures, submitted to MNRA

Does Employment Protection Inhibit Labor Market Flexibility? Lessons from Germany, France and Belgium

Laws in most West European countries give workers strong job rights, including the right to advance notice of layoff and the right to severance pay or other compensation if laid off. Many of these same countries also encourage hours adjustment in lieu of layoffs by providing prorated unemployment compensation to workers on reduced hours. This paper compares the adjustment of manufacturing employment and hours in West Germany, France and Belgium, three countries with strong job security regulations and well-established short-time compensation systems, with that in the United States. Although the adjustment of employment to changes in output is much slower in the German, French and Belgian manufacturing sectors than in U.S. manufacturing, the adjustment of total hours worked is much more similar. The short-time system makes a significant contribution to observed adjustment in all three European countries. In addition, we find little evidence that the weakening of job security regulations that occurred in Germany, France and Belgium during the 1980s affected employers' adjustment to changes in output. These findings suggest that, given appropriate supporting institutions, strong job security need not inhibit employer adjustment to changing conditions.labor, market, flexibility, Europe, France, Belgium, Germany, Abraham, Houseman

Job Security and Work Force Adjustment: How Different are U.S. and Japanese Practices?

This paper compares employment and hours adjustment in Japanese and U.S. manufacturing. In contrast to some previous work, we find that adjustment of total labor input to demand changes is significantly greater in the United States than in Japan; adjustment of employment is significantly greater in the United States, while that of average hours is about the same in the two countries. Although workers in Japan enjoy greater employment stability than do U.S. workers, we find considerable variability in the adjustment patterns across groups within each country. In the United States, most of the adjustment is borne by production workers. In Japan, female workers, in particular, bear a disproportionate share of adjustment.

Work and Retirement Plans among Older Americans

We compare older workers' plans for work and retirement with their subsequent work and retirement outcomes using panel data from the Health and Retirement Study. Among those with retirement plans, about half indicate they would like to cut back on their work hours or otherwise change the type of work they do prior to, or instead of, fully retiring. Yet, the fraction that follows through on these alternative plans is dramatically lower than the fraction that realizes plans to stop working. Our analysis shows that individuals who likely would need to change jobs in order to reduce their work hours are much less likely to have plans to reduce hours and, conditional on having such plans, are much less likely to follow through on them. Instead, a large fraction of these individuals stop working entirely. Our findings suggest that older workers may face substantial barriers to job change, and we conclude with a discussion of potential policy implications.retirement, social security, older, workers, Houseman, Abraham

Labor Adjustment Under Different Institutional Structures: A Case Study of Germany and the United States

Like most Western European countries, Germany stringently regulates dismissals and layoffs. Critics contend that this regulation raises the costs of employment adjustment and hence impedes employers' ability to respond to fluctuations in demand. Other German labor policies, however, most especially the availability of unemployment insurance benefits for those on short time, facilitate the adjustment of average hours per worker in lieu of layoffs. Building on earlier work, we compare the adjustment of employment, hours and inventories to demand shocks in the German and U.S. manufacturing sectors. We find that, in the short run, whereas U.S. employers rely principally on the adjustment of employment levels to respond to demand shocks, German employers rely principally on the adjustment of average hours per worker. The adjustment of overall labor input is generally similar in the two countries. Short-time work makes a very important contribution to short-run hours adjustment in Germany. We find little evidence that inventories help to buffer demand fluctuations in either country. Our findings suggest that, given appropriate supporting institutions, strong worker job security can be compatible with employers' need for flexibility in staffing levels.labor, adjustment, layoffs, Germany, work, hours

Earnings Inequality in Germany

Recent studies have documented the growth of earnings inequality in the United States during the 1980s. In contrast to these studies' findings, our analysis of micro data for the former West Germany yields virtually no evidence of growth in earnings inequality over the same period. Between 1978 and 1988, a reduction in the dispersion of earnings among workers in the bottom half of the earnings distribution led to a narrowing of the overall dispersion of earnings in Germany. Earnings differentials across education and age groups remained roughly stable, and there was no general widening of earnings differentials within either education or age groups. German wage setting institutions tend to limit earnings differentials across groups of workers, but differences in wage setting institutions cannot fully explain the differences between trends in earnings inequality in Germany and those in the United States. Both the high quality of the training received by non-college-bound German youth and the fact that the growth of the highly-educated work force did not decelerate in Germany as it did in the United States seem likely to have contributed to these differences.wages, earnings, inequality, Germany, Abraham, Houseman

Labor Adjustment Under Different Institutional Structures: A Case Study of Germany and The United States

Like most Western European countries, Germany stringently regulates dismissals and layoffs. Critics contend that this regulation raises the costs of employment adjustment and hence impedes employers' ability to respond to fluctuations in demand. Other German labor policies, however, most especially the availability of unemployment insurance benefits for those on short time, facilitate the adjustment of average hours per worker in lieu of layoffs. Building on earlier work, we compare the adjustment of employment, hours and inventories to demand shocks in the German and U.S. manufacturing sectors. We find that, in the short run, whereas U.S. employers rely principally on the adjustment of employment levels to respond to demand shocks, German employers rely principally on the adjustment of average hours per worker. The adjustment of overall labor input is generally similar in the two countries. Short-time work makes a very important contribution to short-run hours adjustment in Germany. We find little evidence that inventories help to buffer demand fluctuations in either country. Our findings suggest that, given appropriate supporting institutions, strong worker job security can be compatible with employers' need for flexibility in staffing levels.