Light-induced cracking and abrasion of inkjet prints: Damage and mitigation

This study is part of a larger research project at the Image Permanence Institute dedicated to digital print preservation issues – the Digital Print Preservation Portal (DP3). Previous DP3 studies determined that certain digital print types are prone to cracking and/or abrasion, and that factors such as low relative humidity, pollutants, and light increase the brittleness of the ink-receiving layer of some inkjet papers. The purpose of this investigation was to explore if light also increases the propensity of inkjet prints to abrade, and to examine the potential of framing glazings to mitigate light-induced physical damage (cracking and abrasion) by attenuating some portion of the UV spectrum. Inkjet papers and prints were subjected to xenon lighting (to simulate daylight through window glass) without glazing, or in sealed framing packages with plain framing glass (soda-lime) or UV filtering glass. Before and after light exposure, brittleness, and abrasion resistance were evaluated independently using two tests: ISO 18907 (Imaging materials – Photographic films and papers – Wedge test for brittleness) and a rub test utilizing a Sutherland® Rub Tester. In this study, exposure to light increased the cracking and/or abrasion tendency of some specimens. The use of UV filtering glass reduced this light-induced propensity in all cases. Plain glass protected all samples from at least one of these two types of surface damage, but was less effective than UV glass. Light-induced brittleness and sensitivity to abrasion were mostly, though not exclusively, caused by UV radiation. It was also seen that some prints may become brittle and/or prone to abrasion in the absence of image fade. Budgeting the amount of light these objects can be exposed to, protecting them from UV radiation, and handling prints with caution especially after exhibition, is essential in order to limit physical damage.     

Teaching imaginary children: University students’ narratives about their Latino practicum children

This study investigates the dialogic processes involved in how teachers talk about their students and what consequences their ways of talking (i.e., “narratives”) may have for their guidance. We take a sociocultural perspective on learning as transformation of students’ subjectivity. Teaching, as a process of guiding and facilitating learning, cannot be effective if the teacher does not actively seek how the student perceives and understands reality. We borrow and adapt from Bakhtin (1999) four narrative ways of talking about others: objectivizing, subjectivizing, problematizing and finalizing. The presence of these narratives in web discussion postings of our pre-service teachers about the Latino children they worked with in a community center are analyzed. We then compare their ways of talking about children with print- and web-based discussions about children made by in-service teachers, model teachers and our pre-service teachers in a school-based practicum. Using mixed quantitative and qualitative methodologies, we found an overwhelming predominance of objectivizing and finalizing in our pre-service teachers’ narratives about the children with whom they work that seems to define a certain pedagogical regime that we call here “teaching imaginary children/students.” This “way of talking” about children seems to be characterized by unchecked speculations guiding instruction that are not tested by finding out from the children themselves how they understand the instruction and the world. These speculations, in turn, can lead to a dogmatic approach towards children.     

Teacher motivation to implement an educational innovation: factors differentiating users and non-users of cooperative learning

This study applied expectancy theory to integrate the numerous and disparate explanations that researchers and educators have proposed to account for teacher resistance to implementing cooperative learning as an educational innovation. The cooperative learning implementation questionnaire (CLIQ) contained 48 items grouped under three broad motivational categories: perceived value of the innovation, expectancy of success, and perceived cost. These items accounted for 42.3% of the total variance in self-reported use of cooperative learning among 933 teachers. Expectancy of success issues were most important in differentiating users and non-users, suggesting that increased emphasis on professional development should be used to enhance teachers' beliefs that they can succeed in implementing an innovation in their own context. This may require both follow-up support and adaptation of the innovation.     

A review of the literature on Attention-Deficit Hyperactivity Disorder children: Peer interactions and collaborative learning

ADHD children may have social skill deficits in at least three main areas: social communication, poor emotional regulation, and social-cognitive biases. They also have cognitive difficulties which have implications for their learning. Based on a review of the literature, it is argued that maladaptive classroom peer interactions for ADHD children may disadvantage their learning on collaborative tasks. Although the literature is sparse in the area of peer interactions and collaborative learning for ADHD children, some suggestions for practice and future research are suggested. © 1996 John Wiley & Sons, Inc.     

Emission of electrons from cold metal surfaces

The results of Del Rosario on cold emission are shown to result from the fact that, through the attainment of specially good vacuum conditions and freedom from contamination, the cold electron current from the wire was suppressed up to field strengths greater than those at which measurable current was obtained in the work of previous observers. It was in fact suppressed beyond the point at which discharge started from points on the welding of the support. The results of Del Rosario are thus probably characteristic of conditions other than those pertaining to the wire, a conclusion which accounts for his current voltage curves. The formula of Fowler and Nordheim is found to apply in the measurable regions in form directly and in magnitude only if irregularities of the surface are such as to raise the field at the surface to a sufficiently high value. Breakdowns after intense heat treatment are studied and found to be caused by immeasurably small currents of electrons knocking ions from the anode. The erratic original curves obtained by previous investigators are found to be caused by successive breakdowns similar to those found after intense heating.