A procedure for determining the chemical composition of binder and aggregate in ancient mortars: its application to mortars from some medieval buildings in Pisa     

Marco Franzini  Leonardo Leoni  Marco Lezzerini 《Journal of Cultural Heritage》2000,1(4):365

The use of a scanning electron microscope equipped with a microanalytical system is proposed for characterising ancient mortars. A calculation procedure is presented that allows a determination of the binder and aggregate compositions (including volatile components) from microprobe data collected on the binder, and chemical, mineralogical, petrographical and physical data collected on the mortar bulk sample. The proposed procedure is applied to 11 mortar samples from three historical monuments built in Pisa throughout the Middle Ages. The binder of the analysed samples consists of a carbonate crystalline fraction and an amorphous carbonate-free fraction that makes up from 20 to 60 % by weight of the binder. The aggregate composition, on average, is close to that of the Arno River sands.  相似文献   

Institutions of Higher Education and the Nationalist State     

Marco Adria 《British Journal of Sociology of Education》2000,21(4):575-590

Significant changes in state economic priorities are likely to have a formative and fateful effect on institutions of higher education. Yet economic accounts cannot themselves explain changes in the economic priorities of nationalist states, in part because of the ideological character of such states. The nationalist state's influence on institutions of higher education is often indirect, involving the interactions of social and political actors who are themselves influenced by prevailing social ideologies. Social ideologies contribute to shifts in state economic priorities, and these changes can indirectly but significantly influence the trajectory of institutions of higher education. A longitudinal case study of a Canadian distanceeducation university demonstrates the means by which nationalist sentiment encouraged a shift in state economic priorities, which in turn created a welcoming social climate for a new university's consumerist model of education.  相似文献   

The Representation of Virtual Reality in Education     

Alessandro Antonietti  Chiara Rasi  Ernesto Imperio  Marco Sacco 《Education and Information Technologies》2000,5(4):317-327

Students' opinions about the opportunities and the implications of VR in instruction were investigated by administering a questionnaire to humanities and engineering undergraduates. The questionnaire invited participants to rate a series of statements concerning motivation and emotion, skills, cognitive styles, benefits and learning outcomes associated with the use of VR in education. The representation which emerged was internally consistent and articulated into specific dimensions. It was not affected by gender, by the previous use of VR software, or by the knowledge of the main topics concerning the introduction of IT in instruction. Also the direct participation in a training session based on an immersive VR experience did not influence such a representation, which was partially modulated by the kind of course attended by students.  相似文献