Herbivores limit the population size of big-leaf mahogany trees in an Amazonian forest

The Janzen–Connell hypothesis proposes that specialized herbivores maintain high numbers of tree species in tropical forests by restricting adult recruitment so that host populations remain at low densities. We tested this prediction for the large timber tree species, Swietenia macrophylla, whose seeds and seedlings are preyed upon by small mammals and a host-specific moth caterpillar Steniscadia poliophaea, respectively. At a primary forest site, experimental seed additions to gaps – canopy-disturbed areas that enhance seedling growth into saplings – over three years revealed lower survival and seedling recruitment closer to conspecific trees and in higher basal area neighborhoods, as well as reduced subsequent seedling survival and height growth. When we included these Janzen–Connell effects in a spatially explicit individual-based population model, the caterpillar's impact was critical to limiting Swietenia's adult tree density, with a > 10-fold reduction estimated at 300 years. Our research demonstrates the crucial but oft-ignored linkage between Janzen–Connell effects on offspring and population-level consequences for a long-lived, potentially dominant tree species.

The Big Five in Context: Personality, Diversity and Attitudes toward Equal Opportunities for Immigrants in Switzerland

The paper analyzes the link between personality traits and attitudes of Swiss citizens toward equal opportunities for immigrants. In particular, we examine the extent to which this relationship is moderated by the socio-structural context. We test the assumption that the direct links between personality traits and attitudes toward equal opportunities are strengthened by perceived ethnic diversity. Based on our empirical analyses, we are able to replicate central findings of the research on personality traits and attitudes toward immigrants for the Swiss context. While openness toward experience and agreeableness are positively related to a preference for equal opportunities, conscientiousness is negatively linked to these attitudes. Furthermore, our results reveal that the link between conscientiousness and attitudes toward equal opportunities is significantly moderated by the perceived share of foreigners in the neighborhood. This finding is especially relevant for future research on the effects of personality traits.

A big data platform for large scale event processing

To date, big data applications have focused on the store-and-process paradigm. In this paper we describe an initiative to deal with big data applications for continuous streams of events. In many emerging applications, the volume of data being streamed is so large that the traditional ‘store-then-process’ paradigm is either not suitable or too inefficient. Moreover, soft-real time requirements might severely limit the engineering solutions. Many scenarios fit this description. In network security for cloud data centres, for instance, very high volumes of IP packets and events from sensors at firewalls, network switches and routers and servers need to be analyzed and should detect attacks in minimal time, in order to limit the effect of the malicious activity over the IT infrastructure. Similarly, in the fraud department of a credit card company, payment requests should be processed online and need to be processed as quickly as possible in order to provide meaningful results in real-time. An ideal system would detect fraud during the authorization process that lasts hundreds of milliseconds and deny the payment authorization, minimizing the damage to the user and the credit card company.