Online Cooperative Learning in Physical Chemistry

The use of cooperative learning in an online setting is examined using the online segment of a recently offered physical chemistry course as an example. The nature and function of classical, face-to-face cooperative learning are outlined. The online course segment is outlined and is analyzed with regard to the criteria for classical cooperative learning. Though this specific course segment functioned poorly when taught as online cooperative learning, it is possible to structure online courses to take advantage of the strengths of cooperative learning. The possible structure and function of an online cooperative learning community are explored, concluding with a specific model for online cooperative learning.     

A BIOECONOMIC APPROACH TO THE FAUSTMANN–HARTMAN MODEL: ECOLOGICAL INTERACTIONS IN MANAGED FOREST

Abstract This paper develops a bioeconomic forestry model that makes it possible to take ecosystem services that are independent of the age structure of trees into account. We derive the Faustmann–Hartman optimal harvesting strategy as a special case. The bioeconomic model is then extended to account for the fact that forest harvesting decisions impact on other ecological resources, which provide benefits for the wider community. The paper focuses on impacts associated with disturbance caused by logging operations and habitat destruction due to tree removal. This enables us to explore the interactions between forest management and the dynamics of ecological resources. The optimal rotation rule is obtained as a variation on the traditional Faustmann–Hartman equation, where an additional term captures the potential benefits derived from the growth of the ecological resource valued at its shadow price. The steady‐state solutions to the problem and sensitivity to model parameter are identified using numerical analysis.     

MOUSE SKIN PHOTOSENSITIZATION WITH BENZOPORPHYRIN DERIVATIVES AND PHOTOFRIN®: MACROSCOPIC AND MICROSCOPIC EVALUATION

A comparative study, at both the macroscopic and microscopic level, of skin photosensitivity caused by four isomeric forms of benzoporphyrin derivative (BPD) has been carried out, and compared to effects of Photofrin. Animals injected intravenously with BPD analogues and exposed to light 3 h later showed extensive photosensitivity. Animals receiving the monoacid derivatives of BPD (BPD-MA and BPD-MB) showed markedly more photosensitivity than those receiving the diacid derivatives (BPD-DA and BPD-DB). Animals receiving BPD analogues which were exposed to light 24 h or more later showed only minimal reactivity. Histological examination of biopsies taken after photosensitizer injection and light exposure showed extensive changes in epidermis and dermis, including epidermal erosion, degranulation of the stratum granulosum, spongiosis, depletion in cellularity and mast cell degranulation. These changes were noted to be similar to changes caused by Photofrin.