The relation between prior knowledge and students' collaborative discovery learning processes

In this study we investigate how prior knowledge influences knowledge development during collaborative discovery learning. Fifteen dyads of students (pre-university education, 15-16 years old) worked on a discovery learning task in the physics field of kinematics. The (face-to-face) communication between students was recorded and the interaction with the environment was logged. Based on students' individual judgments of the truth-value and testability of a series of domain-specific propositions, a detailed description of the knowledge configuration for each dyad was created before they entered the learning environment. Qualitative analyses of two dialogues illustrated that prior knowledge influences the discovery learning processes, and knowledge development in a pair of students. Assessments of student and dyad definitional (domain-specific) knowledge, generic (mathematical and graph) knowledge, and generic (discovery) skills were related to the students' dialogue in different discovery learning processes. Results show that a high level of definitional prior knowledge is positively related to the proportion of communication regarding the interpretation of results. Heterogeneity with respect to generic prior knowledge was positively related to the number of utterances made in the discovery process categories hypotheses generation and experimentation. Results of the qualitative analyses indicated that collaboration between extremely heterogeneous dyads is difficult when the high achiever is not willing to scaffold information and work in the low achiever's zone of proximal development

Sustainable seabed mining: guidelines and a new concept for Atlantis II Deep

The feasibility of exploiting seabed resources is subject to the engineering solutions, and economic prospects. Due to rising metal prices, predicted mineral scarcities and unequal allocations of resources in the world, vast research programmes on the exploration and exploitation of seabed minerals are presented in 1970s. Very few studies have been published after the 1980s, when predictions were not fulfilled. The attention grew back in the last decade with marine mineral mining being in research and commercial focus again and the first seabed mining license for massive sulphides being granted in Papua New Guinea’s Exclusive Economic Zone.Research on seabed exploitation and seabed mining is a complex transdisciplinary field that demands for further attention and development. Since the field links engineering, economics, environmental, legal and supply chain research, it demands for research from a systems point of view. This implies the application of a holistic sustainability framework of to analyse the feasibility of engineering systems. The research at hand aims to close this gap by developing such a framework and providing a review of seabed resources. Based on this review it identifies a significant potential for massive sulphides in inactive hydrothermal vents and sediments to solve global resource scarcities. The research aims to provide background on seabed exploitation and to apply a holistic systems engineering approach to develop general guidelines for sustainable seabed mining of polymetallic sulphides and a new concept and solutions for the Atlantis II Deep deposit in the Red Sea.The research methodology will start with acquiring a broader academic and industrial view on sustainable seabed mining through an online survey and expert interviews on seabed mining. In addition, the Nautilus Minerals case is reviewed for lessons learned and identification of challenges. Thereafter, a new concept for Atlantis II Deep is developed that based on a site specific assessment.The research undertaken in this study provides a new perspective regarding sustainable seabed mining. The main contributions of this research are the development of extensive guidelines for key issues in sustainable seabed mining as well as a new concept for seabed mining involving engineering systems, environmental risk mitigation, economic feasibility, logistics and legal aspects

New approaches to rural policy : lessons from around the world : a conference summary

New approaches to rural policy are badly needed, as past reliance on subsidies and policies focused on a single sector are yielding diminishing results. Fortunately, a new frontier of policy experiments is emerging, and this frontier holds great promise in helping rural regions seize new economic potential. ; This was the consensus of more than 120 leading officials and rural policy experts from around the world who gathered near Washington, D.C., on March 25-26, 2004, to explore new approaches to rural policy. The conference was jointly sponsored by the Federal Reserve Bank of Kansas City, the Organization for Economic Cooperation and Development, the Rural Policy Research Institute, and The Countryside Agency (UK). ; Amid a flurry of new initiatives, participants agreed that new rural policies generally have two distinguishing features. First, they focus on exploiting each region’s distinct economic assets instead of trying to develop a sector that will “lift all boats,” as in most developed nations historically, where the sector of choice for rural regions has been agriculture. Second, public funds are aimed at constructing the public goods that will spur private sector investments. Indeed, investment is a strong theme of many new initiatives, with a deliberate attempt to scale back subsidies.Rural areas ; Rural development

New approaches to rural policy : lessons from around the world

Rural areas ; Rural development

Reply to 'A Comment on '"The Far Future of Exoplanet Direct Characterization" - the Case for Interstellar Space Probes'

Reply to A Comment on The Far Future of Exoplanet Direct Characterization - the Case for Interstellar Space Probess by Ian Crawford. The paper The Far Future of Exoplanet Direct Characterization resulted from the collective work of TE-SAT, a team appointed by ESA in 2003 to assess a strategy to find and characterize Terrestrial Exoplanets. The interstellar flight aspect was not part of the TE-SAT work and was added afterward as side remarks in the chapter on {\guillemotleft} The Far Future of Exoplanet Direct Characterization {\guillemotright}. As an introductory general remark, the intention of the paper was not to discourage work on interstellar flight prospective. On the contrary, any advance in this field that makes interstellar travel closer to us is welcome. In the framework of this short reply, the discussion can only be qualitative; it would deserve a full future paper.Comment: Published in Astrobiology 10, 857 (2010). Arxiv.org: 0910.072

Comprehensibility and the basic structures of dialogue

The study of what makes utterances difficult or easy to understand is one of the central topics of research in comprehension. It is both theoretically attractive and useful in practice. The more we know about difficulties in understanding the more we know about understanding. And the better we grasp typical problems of understanding in certain types of discourse and for certain recipients the better we can overcome these problems and the better we can advise people whose job it is to overcome such problems. It is therefore not surprising that comprehensibility has been the object of much reflection as far back as the days of classical rhetoric and that it is a center of lively interest in several present-day scientific disciplines, ranging from artificial intelligence and educational psychology to linguistics

Quantum Modelling of Electro-Optic Modulators

Many components that are employed in quantum information and communication systems are well known photonic devices encountered in standard optical fiber communication systems, such as optical beamsplitters, waveguide couplers and junctions, electro-optic modulators and optical fiber links. The use of these photonic devices is becoming increasingly important especially in the context of their possible integration either in a specifically designed system or in an already deployed end-to-end fiber link. Whereas the behavior of these devices is well known under the classical regime, in some cases their operation under quantum conditions is less well understood. This paper reviews the salient features of the quantum scattering theory describing both the operation of the electro-optic phase and amplitude modulators in discrete and continuous-mode formalisms. This subject is timely and of importance in light of the increasing utilization of these devices in a variety of systems, including quantum key distribution and single-photon wavepacket measurement and conformation. In addition, the paper includes a tutorial development of the use of these models in selected but yet important applications, such as single and multi-tone modulation of photons, two-photon interference with phase-modulated light or the description of amplitude modulation as a quantum operation.Comment: 29 pages, 10 figures, Laser and Photonics Reviews (in press

How Hume and Mach Helped Einstein Find Special Relativity

In recounting his discovery of special relativity, Einstein recalled a debt to the philosophical writings of Hume and Mach. I review the path Einstein took to special relativity and urge that, at a critical juncture, he was aided decisively not by any specific doctrine of space and time, but by a general account of concepts that Einstein found in Hume and Mach’s writings. That account required that concepts, used to represent the physical, must be properly grounded in experience. In so far as they extended beyond that grounding, they were fictional and to be abjured (Mach) or at best tolerated (Hume). Einstein drew a different moral. These fictional concepts revealed an arbitrariness in our physical theorizing and may still be introduced through freely chosen definitions, as long as these definitions do not commit us to false presumptions. After years of failed efforts to conform electrodynamics to the principle of relativity and with his frustration mounting, Einstein applied this account to the concept of simultaneity. The resulting definition of simultaneity provided the reconceptualization that solved the problem in electrodynamics and led directly to the special theory of relativity

Investigation of some parameters affecting the stability of a hingeless helicopter blade in hover

Equations of motion are used to investigate the effects of the choice of the mode shape and built-in coning angle on the stability boundaries of hingeless blades in hover. The results obtained indicate that the stability boundaries are dependent upon the mode shape to a considerable degree. It was also found that positive built-in coning is usually destabilizing while a negative amount of built-in coning can be quite stabilizing