A Material-Framework-Object Model for Learning Material Management
Following problems have been found in traditional learning material management model based on courseware: common redundancy, the overlapped and desultory construction of the learning materials, and hardly adaptive to the diversity of the learning objectives and teaching methodologies. In the paper, a material-framework-objective model was proposed to improve the efficiency and quality of learning material management in the distance education by separating and recombining the basic materials, courseware, knowledge-points and learning goals. The model can also achieve the unification of the reuse, mobility and pertinence of the learning materials. A prototyping based on this model has been developed and taken into practice in Dongbei University of Financial and Economics.
Making flexible learning more flexible
As a response to the changing environment in which the educational sector operates today and, in particular, the increasingly diverse student population, many universities opt for flexible delivery of their courses. However, there is a tendency to focus too much on technology per se and not on the learning process. At the same time educational technology itself which still is lingering behind current developments in the information technology (IT) industry. We argue that educational technologies are still task-oriented rather than process-oriented and as such not capable of effectively supporting an integrated study process. We present a concept of Flex-eL-a flexible, fully integrated, workflow enabled, learning environment. We argue that flexible learning should be even more flexible and based on that premise, we critically evaluate the existing technologies for flexible delivery. Furthermore, we describe the main features of Flex-eL and discuss some important issues that we have come across during its pilot implementation.
Pyrite multiple-sulfur isotope evidence for rapid expansion and contraction of the early Paleoproterozoic seawater sulfate reservoir
Abstract Earthʼs oxygenation is often described in terms of two unidirectional steps at the beginning and end of the Proterozoic Eon, separated by a long-lived intermediate redox state. Recent work defines a more complicated path to oxygenation, exemplified by an apparent drop in oxidation state following the early Paleoproterozoic Lomagundi carbon isotope excursion. The timing of this proposed drop in oxidation state is not well constrained, and it is not clear how it relates to redox conditions during the remainder of the Proterozoic. Here we present a study of pyrite multiple-sulfur isotopes, supported by Fe speciation and organic carbon isotopes, from early Paleoproterozoic black shales. We find evidence for the rapid expansion of the seawater sulfate reservoir during the Great Oxidation Event at ca. 2.3 Ga followed by a subsequent contraction in the size of the seawater sulfate reservoir at ca. 2.05 Ga. This scenario is consistent with the emerging view of a rise and fall in surface oxidation state during the early Paleoproterozoic. Comparison of our new data to other records of the seawater sulfate reservoir suggests that the elevated sulfate concentrations that characterize the early Paleoproterozoic did not return until the late Neoproterozoic.