Ethnic Diversity and Organizational Performance: Assessing Diversity Effects at the Managerial and Street Levels

As the public sector workforce becomes more ethnically diverse and as government agencies make attempts to "manage" that diversity, the importance of understanding how diversity affects workplace interactions and work-related outcomes increases. Little public sector research has examined the impact of diversity on performance outcomes. This paper seeks to fill this gap by studying the effects of the ethnic diversity of managers and street level bureaucrats on work-related outcomes. We use basic in-group/out-group theories from psychology to form hypotheses relating diversity to performance. The results of diversity research using social identification and categorization theory and similarity/attraction theory led us to form the hypothesis that greater levels of ethnic diversity among public managers and street-level bureaucrats will lead to lower organizational performance, when the task requires significant coordination and collaboration. Diversity research that uses the information and decision-making theory, while scant, led us to form a second hypothesis that greater levels of ethnic diversity among public managers and street-level bureaucrats will lead to higher organizational performance, when the task does not require significant coordination and collaboration. Our results were mixed. We found support for the first hypothesis with respect to street-level bureaucrats but not for managers. The results did not support our second hypothesis -- we actually found an opposite relationship for street-level bureaucrats from what we expected. Overall, the results support previous research that suggests that increased levels of ethnic diversity can lead to process-oriented difficulties in the workplace and negatively affect workrelated outcomes. Working Paper 06-3

What do Women Want? Men, Women, and Job Satisfaction in the Public Service

Research in organizational behavior and public administration has long considered differences between men and women at work. Research indicates that men and women often communicate differently, prefer different approaches to organizational structure and design, and view rewards through different lenses. As women become better represented in public organizations, and at higher levels, it becomes even more important to explore sex-based differences. This paper seeks to uncover differences between men and women when it comes to determinants of job satisfaction. We use the existing literature to develop a series of hypotheses about the different factors that predict job satisfaction for the sexes. We test these hypotheses using data from a survey of health and human services managers, finding that there are more commonalities than differences when it comes to what satisfies men and women at work. Working Paper 06-3

Are tsetse fly populations close to equilibrium ?

Glossina or tsetse flies, the vector of sleeping sickness, form a unique group of insect with remarkable characteristics. They are viviparous with a slow rhythm of reproduction (one larva approximately every 10 days) determined by the regular ovulation of alternate ovaries. This unusual physiology enables the age of the females to be estimated by examining the ovaries. The resulting ovarian age structure of tsetse fly populations has been used to develop research into the demography of tsetse flies. Several authors have proposed methods of estimating populations growth rates from ovarian age distribution data. However, such methods are applicable only when the growth rate (lambda) is equal to 1 (i.e. the intrinsic rate of increase r is equal to 0). In fact in this type of estimation, the adult survival rate a (or equivalently the mortality rate) cannot be dissociated from the growth rate. Other independently determined demographic parameters must be used to remove this lack of identifiability. We have built a matrix model of the dynamics of tsetse fly populations which enables the growth rate to be calculated from the pupal survival rate, the pupal period and the adult survival rate. Assuming that the age-groups of the population studied have reached a stable distribution, it is possible to calculate the probabilities for the observed sample of belonging to each of the age-groups, to construct a likewood function and thus to obtain an estimate of the "apparent survival rate" bêta = a/lambda. If the pupal survival rate and the pupal period are known, a and lambda can then be calculated from bêta. The application of this method to data collected for other two annual cycles in a savannah habitat (Burkina-Faso) showed a high overall stability in the populations of #Glossina palpalis gambiensis$... (D'après résumé d'auteur

Two-Phase Modeling of Hot Tearing in Aluminum Alloys: Applications of a Semicoupled Method

Hot tearing formation in both a classical tensile test and during direct chill (DC) casting of aluminum alloys has been modeled using a semicoupled, two-phase approach. Following a thermal calculation, the deformation of the mushy solid is computed using a compressive rheological model that neglects the pressure of the intergranular liquid. The nonzero expansion/compression of the solid and the solidification shrinkage are then introduced as source terms for the calculation of the pressure drop and pore formation in the liquid phase. A comparison between the simulation results and experimental data permits a detailed understanding of the specific conditions under which hot tears form under given conditions. It is shown that the failure modes can be quite different for these two experiments and that, as a consequence, the appropriate hot tearing criterion may differ. It is foreseen that a fully predictive theoretical tool could be obtained by coupling such a model with a granular approach. These two techniques do, indeed, permit coverage of the range of the length scales and the physical phenomena involved in hot tearin

Observation de la réponse de surfaces agricoles aux pluies par télédétection en hyperfréquence active aéroportée

La télédétection active en hyperfréquence à partir d'un radar aéroporté a été employée pour suivre le comportement hydrique de parcelles agricoles au cours des périodes d'humectation et de ressuyage. On montre l'effet du travail du sol sur le signal rétrodiffusé et la capacité du radar à mesurer l'humidité de surface du sol. L'utilisation de cette technique permet d'appréhender la variabilité spatiale de l'humidité des sols et la variabilité de comportement hydrique des surfaces agricoles en fonction du type de couvert végétal et des travaux culturaux antécédents. A l'échelle du bassin versant, on obtient une indication concernant l'évolution de l'état hydrique moyen du sol, pouvant être reliée aux données de pluies et de débits mesurés par ailleurs. On discute de l'intérêt de cette méthode en hydrologie, à partir des données des futurs satellites équipés de radar. (Résumé d'auteur

Bt maize: a tool for improving food safety of grains at harvest

A new EU (European Union) regulation came into force in 2007 with Regulation (EC) No. 1126/2007 which established maximum levels for fumonisins B1 and B2 (4000 ppb), deoxynivalenol (1750 ppb) and zearalenone (350 ppb) in maize and maize products. In order to evaluate French maize food safety, studies were carried out by the national Biological Risk Monitoring (BRM) Network. In this study, field trials involving 84 plots were conducted with Bt maize (MON 810) and its isogenic non-Bt counterpart in 2005 and 2006 in South-western France. Mycotoxin levels were determined in grain at harvest. Fumonisins B1 and B2, deoxynivalenol, and zearalenone were analyzed by LC-MS-MS and the results treated statistically using non parametric tests for mycotoxins and analysis of variance test for weather variables. As the climate was homogenous inside the experimental area, the transgenic event introduced into the maize was the only key parameter which differed between Bt and non-Bt maize plots. Our results showed that all mycotoxin families were not impacted in the same way. The efficacy of Bt maize reduced mycotoxins more than 90% for fumonisins and more than 50% for zearalenone although deoxynivalenol was lightly increased. Therefore a competition between the different Fusarium spp. which produced fumonisins or trichothecenes is hypothesized. According to Regulation (EC) No. 1126/2007, 93% of the maize of Bt maize plots were able to be commercialized compared to only 45% for non-Bt maize plots. The results of this work showed that Bt maize improved food safety and constituted an useful tool to reduce significantly mycotoxin levels in harvested and stored grains. Keywords: Bt (MON810) maize, Fumonisins B1 and B2, Deoxynivalenol (DON), Zearalenone, EC regulation 1126/2007 threshold