Why Women Rarely Rise to the Top: A Social Identity Model of Leader Prototypes.

Purpose We propose a social identity model of leader prototypes to address why the maleness of leader prototypes is more pronounced among men than among women (e.g., Schein, 2001). Specifically, we argue that individuals project their ingroup prototype (e.g., a male prototype) onto a valued other category (e.g., leaders) (e.g., Wenzel, Mummendey, Weber, & Waldzus, 2003) in order to maintain a positive ingroup (e.g., gender) identity. We hypothesized that both women and men engage in ingroup projection of their gender prototype on their leader prototype, and we expected this effect to be stronger for men than women. We also investigated intelligence as a moderator of ingroup projection. Methodology Participants (276 students, University of Lausanne) assessed to what extent attributes on a list of gender traits were characteristic of a successful leader. We computed relative ingroup similarity scores (e.g., Waldzus & Mummendey, 2004) representing the difference between how characteristic ingroup traits are for a successful leader, and how characteristic outgroup traits are for a successful leader. Results Results showed that men engaged in ingroup projection while women engaged in outgroup projection, and that men engaged in ingroup projection to a greater extent. We also found a small, but positive effect of intelligence on ingroup projection among men. Limitations The use of a student sample might limit the external validity of our findings. Implications Our findings contribute to research on the under-representation of women in managerial roles, and introduce intelligence as a predictor of ingroup projection. Value Our study allows for a more fine-grained understanding of the cognitive representations of leaders of men and women.

The Making of Experimental Economics: Witness Seminar on the Emergence of a Field

This book is the transcript of a witness seminar on the history of experimental economics, in which eleven high-profile experimental economists participated, including Nobel Laureates Vernon Smith, Reinhard Selten and Alvin Roth. The witness seminar was constructed along four different topics: skills, community, laboratory, and funding. The transcript is preceded by an introduction explaining the method of the witness seminar and its specific set-up and resuming its results. The participants' contribution and their lively discussion provide a wealth of insights into the emergence of experimental economics as a field of research.

Waddlia chondrophila induces systemic infection, organ pathology, and elicits Th1-associated humoral immunity in a murine model of genital infection.

Waddlia chondrophila is a known bovine abortigenic Chlamydia-related bacterium that has been associated with adverse pregnancy outcomes in human. However, there is a lack of knowledge regarding how W. chondrophila infection spreads, its ability to elicit an immune response and induce pathology. A murine model of genital infection was developed to investigate the pathogenicity and immune response associated with a W. chondrophila infection. Genital inoculation of the bacterial agent resulted in a dose-dependent infection that spread to lumbar lymph nodes and successively to spleen and liver. Bacterial-induced pathology peaked on day 14, characterized by leukocyte infiltration (uterine horn, liver, and spleen), necrosis (liver) and extramedullary hematopoiesis (spleen). Immunohistochemistry demonstrated the presence of a large number of W. chondrophila in the spleen on day 14. Robust IgG titers were detected by day 14 and remained high until day 52. IgG isotypes consisted of high IgG2a, moderate IgG3 and no detectable IgG1, indicating a Th1-associated immune response. This study provides the first evidence that W. chondrophila genital infection is capable of inducing a systemic infection that spreads to major organs, induces uterus, spleen, and liver pathology and elicits a Th1-skewed humoral response. This new animal model will help our understanding of the mechanisms related to intracellular bacteria-induced miscarriages, the most frequent complication of pregnancy that affects one in four women.

Antifungal activity against planktonic and biofilm Candida albicans in an experimental model of foreign-body infection.

OBJECTIVES: The treatment of Candida implant-associated infections remains challenging. We investigated the antifungal activity against planktonic and biofilm Candida albicans in a foreign-body infection model. METHODS: Teflon cages were subcutaneously implanted in guinea pigs, infected with C. albicans (ATCC 90028). Animals were treated intraperitoneally 12 h after infection for 4 days once daily with saline, fluconazole (16 mg/kg), amphotericin B (2.5 mg/kg), caspofungin (2.5 mg/kg) or anidulafungin (20 mg/kg). Planktonic Candida was quantified, the clearance rate and cure rate determined. RESULTS: In untreated animals, planktonic Candida was cleared from cage fluid in 25% (infected with 4.5 × 10(3) CFU/cage), 8% (infected with 4.8 × 10(4) CFU/cage) and 0% (infected with 6.2 × 10(5) CFU/cage). Candida biofilm persisted on all explanted cages. Compared to untreated controls, caspofungin reduced the number of planktonic C. albicans to 0.22 and 0.0 CFU/ml, respectively, and anidulafungin to 0.11 and 0.13 CFU/ml, respectively. Fluconazole cured 2/12 cages (17%), amphotericin B and anidulafungin 1/12 cages (8%) and caspofungin 3/12 cages (25%). CONCLUSION: Echinocandins showed superior activity against planktonic C. albicans. Caspofungin showed the highest cure rate of C. albicans biofilm. However, no antifungal exceeded 25% cure rate, demonstrating the difficulty of eradicating Candida biofilms from implants.

Mouse Model of Respiratory Tract Infection Induced by Waddlia chondrophila.

Waddlia chondrophila, an obligate intracellular bacterium belonging to the Chlamydiales order, is considered as an emerging pathogen. Some clinical studies highlighted a possible role of W. chondrophila in bronchiolitis, pneumonia and miscarriage. This pathogenic potential is further supported by the ability of W. chondrophila to infect and replicate within human pneumocytes, macrophages and endometrial cells. Considering that W. chondrophila might be a causative agent of respiratory tract infection, we developed a mouse model of respiratory tract infection to get insight into the pathogenesis of W. chondrophila. Following intranasal inoculation of 2 x 108 W. chondrophila, mice lost up to 40% of their body weight, and succumbed rapidly from infection with a death rate reaching 50% at day 4 post-inoculation. Bacterial loads, estimated by qPCR, increased from day 0 to day 3 post-infection and decreased thereafter in surviving mice. Bacterial growth was confirmed by detecting dividing bacteria using electron microscopy, and living bacteria were isolated from lungs 14 days post-infection. Immunohistochemistry and histopathology of infected lungs revealed the presence of bacteria associated with pneumonia characterized by an important multifocal inflammation. The high inflammatory score in the lungs was associated with the presence of pro-inflammatory cytokines in both serum and lungs at day 3 post-infection. This animal model supports the role of W. chondrophila as an agent of respiratory tract infection, and will help understanding the pathogenesis of this strict intracellular bacterium.

A cognitive hierarchy model of behavior in the action commitment game

We apply the cognitive hierarchy model of Camerer et al. (Q J Econ 119(3):861-898, 2004)-where players have different levels of reasoning-to Huck et al. (Games Econ Behav 38:240-264, 2002) discrete version of Hamilton and Slutsky (Games Econ Behav 2:29-46, 1990) action commitment game-a duopoly with endogenous timing of entry. We show that, for an empirically reasonable average number of thinking steps, the model rules out Stackelberg equilibria, generates Cournot outcomes including delay, and outcomes where the first mover commits to a quantity higher than Cournot but lower than Stackelberg leader. We show that a cognitive hierarchy model with quantal responses can explain the most important features of the experimental data on the action commitment game in (2002). In order to gauge the success of the model in fitting the data, we compare it to a noisy Nash model. We find that the cognitive hierarchy model with quantal responses fits the data better than the noisy Nash model.