The Impact of Agricultural Research in Tropical Africa: A Study of the Collaboration between the International and National Research Systems

CGIAR Study Paper on the problems and opportunities of international agricultural research in Sub Saharan Africa, and the impact of CGIAR Centers on African national agricultural research systems and on agricultural production and food security in Africa. Written by Hans E. Jahnke, Dieter Kirschke, and Johannes Lagermann and published as CGIAR Study Paper No. 21, part of the series comprising the CGIAR Impact Study of the 1980s

The Peregrine Falcon's Dive: On the Pull-Out Maneuver and Flight Control Through Wing-Morphing

During the pull-out maneuver, Peregrine falcons were observed to adopt a succession of specific flight configurations which are thought to offer an aerodynamic advantage over aerial prey. Analysis of the flight trajectory of a falcon in a controlled environment shows it experiencing load factors up to 3 and further predictions suggest this could be increased up to almost 10g during high-speed pull-out. This can be attributed to the high maneuverability promoted by lift-generating vortical structures over the wing. Wind-tunnel experiments on life-sized models in the different configurations together with high fidelity CFD Simulations(LES) show that deploying the hand-wing in a pull-out creates extra vortex-lift, similar to that of combat aircraft with delta wings. The aerodynamic forces and the position of aerodynamic center were calculated from the Simulations of the flow around the different configurations. This allowed for an analysis of the longitudinal static stability in the early pull-out phase, confirming that the falcon is flying unstably in pitch with a positive slope in the pitching moment and a trim angle of attack of about 5◦, possibly to maximize responsiveness. The hand-wings/primaries were seen to contribute to the augmented stability acting as ‘elevons’ would on a tailless blended-wing-body aircraft

Bridging the gap between educational research and educational practice: The need for critical distance

The contributions to this special issue explore a range of different aspects of the relationship between research and practice in education. All start from the assumption that there is a gap between research and practice. Some authors take a descriptive approach in that they try to outline the nature of and reasons for the alleged gap between research and practice. Educational research is, after all, never simply research on education but always in some sense also research for education. This, in sum, reveals that it is as important to try to bridge gaps between research and practice as it is to keep a critical distance between the two, both from the side of educational research and from the side of educational practice

Involuntary Monitoring of Sound Signals in Noise Is Reflected in the Human Auditory Evoked N1m Response

Constant sound sequencing as operationalized by repeated stimulation with tones of the same frequency has multiple effects. On the one hand, it activates mechanisms of habituation and refractoriness, which are reflected in the decrease of response amplitude of evoked responses. On the other hand, the constant sequencing acts as spectral cueing, resulting in tones being detected faster and more accurately. With the present study, by means of magnetoencephalography, we investigated the impact of repeated tone stimulation on the N1m auditory evoked fields, while listeners were distracted from the test sounds. We stimulated subjects with trains of either four tones of the same frequency, or with trains of randomly assigned frequencies. The trains were presented either in a silent or in a noisy background. In silence, the patterns of source strength decline originating from repeated stimulation suggested both, refractoriness as well as habituation as underlying mechanisms. In noise, in contrast, there was no indication of source strength decline. Furthermore, we found facilitating effects of constant sequencing regarding the detection of the single tones as indexed by a shortening of N1m latency. We interpret our findings as a correlate of a bottom-up mechanism that is constantly monitoring the incoming auditory information, even when voluntary attention is directed to a different modality

Learning from multimedia and hypermedia

Computer-based multimedia and hypermedia resources (e.g., the world wide web) have become one of the primary sources of academic information for a majority of pupils and students. In line with this expansion in the field of education, the scientific study of learning from multimedia and hypermedia has become a very active field of research. In this chapter we provide a short overview with regard to research on learning with multimedia and hypermedia. In two review sections, we describe the educational benefits of multiple representations and of learner control, as these are the two defining characteristics of hypermedia. In a third review section we describe recent scientific trends in the field of multimedia/hypermedia learning. In all three review sections we will point to relevant European work on multimedia/hypermedia carried out within the last 5 years, and often carried out within the Kaleidoscope Network of Excellence. According to the interdisciplinary nature of the field this work might come not only from psychology, but also from technology or pedagogy. Comparing the different research activities on multimedia and hypermedia that have dominated the international scientific discourse in the last decade reveals some important differences. Most important, a gap seems to exist between researchers mainly interested in a “serious” educational use of multimedia/ hypermedia and researchers mainly interested in “serious” experimental research on learning with multimedia/hypermedia. Recent discussions about the pros and cons of “design-based research” or “use-inspired basic research” can be seen as a direct consequence of an increasing awareness of the tensions within these two different cultures of research on education