Relating relative humidity fluctuations to damage in oak panel paintings by a simple experiment

ABSTRACT

Panel paintings are essentially wooden boards painted on one side. Due to the vapor resistance of the paint layer, changing ambient conditions lead to exchange of moisture on only one surface. Subsequently, a non-uniform moisture content profile is formed across the thickness of the board. As a result, differential expansion causes the board to bend in case of no mechanical restriction, or it leads to a build-up of stresses inside the material if restrained. Experiments with oak boards sealed on one side and exposed to a change in the ambient relative humidity (RH) were performed. By scaling, the response of any board with different thickness can be predicted. Since the bending of the board can be described as a linear system behavior, the frequency response can be predicted based on the step response. In combination with critical strains for wood and gesso from the literature, this gives insight into allowable RH fluctuations in terms of frequency and amplitude for different board thicknesses.     

Accuracy of students' self‐assessment and their beliefs about its utility

The purpose of the two studies presented here was to evaluate the accuracy of students' self‐assessment ability, to examine whether this ability improves over time and to investigate whether self‐assessment is more accurate if students believe that it contributes to improving learning. To that end, the accuracy of the self‐assessments of 3588 first‐year students enrolled in a post‐secondary institution was studied throughout a semester during which each student made approximately 80 self‐assessments about his or her own learning process. These self‐assessments were then compared with multiple judgements by peers and tutors. The overall correlations between the scores of self‐, peer and tutor assessments suggest weak to moderate accuracy of student self‐assessment ability. The findings also reveal an ability effect; students judged as more academically competent were able to self‐assess with higher accuracy than their less competent peers. Comparing the accuracy of student self‐assessment averaged over four consecutive periods indicates that the accuracy does not improve over time. In a second study, a questionnaire aimed at eliciting student's beliefs about the effects of self‐assessment on their learning was administered to 936 first‐year students. Based on their responses, sub‐groups of students were identified: those who either believed in the usefulness of self‐assessment or did not. Results suggest that there is no significant association between student beliefs about the utility of self‐assessment and the accuracy of their self‐assessments.     

Learning more by being taught less: a “time-for-self-study” theory explaining curricular effects on graduation rate and study duration

In this article, an alternative for Tinto’s integration theory of student persistence is proposed and tested. In the proposed theory, time available for individual study is considered a major determinant of both study duration and graduation rate of students in a particular curriculum. In this view, other activities in the curriculum, in particular lectures, constrain self-study time and therefore must have a negative impact on persistence. To test this theory, we collected study duration and graduation rate information of all—almost 14,000 students—enrolling in eight Dutch medical schools between 1989 and 1998. In addition, information was gathered regarding the timetables of each of these curricula in the particular period: lectures hours, hours spent in small-group tutorials, practicals, and time available for self-study. Structural equation modeling was used to study relations among these variables. In line with our predictions, time available for self-study was the only determinant of graduation rate and study duration. Lectures were negatively related to self-study time, negatively related to graduation rate, and positively related to study duration. The results suggest that extensive lecturing may be detrimental in higher education. However, in the curricula employing limited lecturing considerable energy was spent in supporting self-study activities of students and preventing postponement of learning. Given our findings, both activities will likely have large pay offs, in particular in curricula with low graduation rates.     

Library Catalog Analysis as a tool in studies of social sciences and humanities: An exploratory study of published book titles in Economics

This paper explores the use of Library Catalog Analysis (LCA), defined as the application of bibliometric or informetric techniques to a set of library online catalogs, to describe quantitatively a scientific-scholarly field on the basis of published book titles. It focuses on its value as a tool in studies of Social Sciences and Humanities, especially its cognitive structures, main book publishers and the research performance of its actors. The paper proposes an analogy model between traditional citation analysis of journal articles and Library Catalog Analysis of book titles. It presents the outcomes of an exploratory study of book titles in Economics included in 42 academic library catalogs from 7 countries. It describes the process of data collection and cleaning, and applies a series of indicators and thematic mapping techniques. It illustrates how LCA can be fruitfully used to assess book production and research performance at the level of an individual researcher, a research department, an entire country and a book publisher. It discusses a number of issues that should be addressed in follow-up studies and concludes that LCA of published book titles can be developed into a powerful and useful tool in studies of Social Sciences and Humanities.     

荷兰教育中以能力为基础的课程体系建设

在以能力为基础的教育(CBE)中,对于某个既定的职业,根据对职业的任务、功能和角色的详细分析,进行专业课程的设计.因此,以能力为基础的教育能够把教育与实际工作联系起来.本文论述了在职业教育中开发以能力为基础的教育体系的主要步骤和应该考虑的问题,强调了学习方法和教学方法的选择、恰当的评估手段和教师角色的转化的重要性.在阐述中,还列举了荷兰在过去20年里关于职业教育中以能力为基础的教育实践方面的例子.     

University of Utrecht 1636–1676: res ecclesia,res publica and … res pecunia

The early history of Utrecht University (founded 1636) reflects an emerging public sphere (Habermas’s ‘bürgerliche öffentlichkeit’) of a major town in the Netherlands. This public sphere was a contested field among the different groups establishing and administering the university: university professors, town magistrates and representatives of the newly established Reformed Church and the former dominant Catholic Church. The factionalised magistrates developed a public sphere, while also trying to limit the passionate but destabilising debate concerning the new philosophy of Descartes. They supported the Calvinistic anti-Descartes movement while permitting, and even advocating, the establishment of the new philosophy at the university. They ambivalently protected the academy from the consistory’s control while simultaneously trying to safeguard their own (financial) position. It is concluded that the Habermasian framework has to be fleshed out in local histories, such as this case study of Utrecht University, to demonstrate the ‘messy’ complexities in reality.     

Coverage and citation impact of oncological journals in the Web of Science and Scopus

This paper reviews a number of studies comparing Thomson Scientific’s Web of Science (WoS) and Elsevier’s Scopus. It collates their journal coverage in an important medical subfield: oncology. It is found that all WoS-covered oncological journals (n = 126) are indexed in Scopus, but that Scopus covers many more journals (an additional n = 106). However, the latter group tends to have much lower impact factors than WoS covered journals. Among the top 25% of sources with the highest impact factors in Scopus, 94% is indexed in the WoS, and for the bottom 25% only 6%. In short, in oncology the WoS is a genuine subset of Scopus, and tends to cover the best journals from it in terms of citation impact per paper. Although Scopus covers 90% more oncological journals compared to WoS, the average Scopus-based impact factor for journals indexed by both databases is only 2.6% higher than that based on WoS data. Results reflect fundamental differences in coverage policies: the WoS based on Eugene Garfield’s concepts of covering a selective set of most frequently used (cited) journals; Scopus with broad coverage, more similar to large disciplinary literature databases. The paper also found that ‘classical’, WoS-based impact factors strongly correlate with a new, Scopus-based metric, SCImago Journal Rank (SJR), one of a series of new indicators founded on earlier work by Pinski and Narin [Pinski, G., & Narin F. (1976). Citation influence for journal aggregates of scientific publications: Theory, with application to the literature of physics. Information Processing and Management, 12, 297–312] that weight citations according to the prestige of the citing journal (Spearman’s rho = 0.93). Four lines of future research are proposed.