Minimum count sums for charcoalconcentration estimates in pollen slides: accuracy and potential errors

Charcoal particles in pollen slides are often abundant, and thus analysts are faced with the problem of setting the minimum counting sum as small as possible in order to save time. We analysed the reliability of charcoal-concentration estimates based on different counting sums, using simulated low-to high-count samples. Bootstrap simulations indicate that the variability of inferred charcoal concentrations increases progressively with decreasing sums. Below 200 items (i.e., the sum of charcoal particles and exotic marker grains), reconstructed fire incidence is either too high or too low. Statistical comparisons show that the means of bootstrap simulations stabilize after 200 counts. Moreover, a count of 200-300 items is sufficient to produce a charcoal-concentration estimate with less than+5% error if compared with high-count samples of 1000 items for charcoal/marker grain ratios 0.1-0.91. If, however, this ratio is extremely high or low (> 0.91 or < 0.1) and if such samples are frequent, we suggest that marker grains are reduced or added prior to new sample processing.

Use and abuse of audivisual media in the college classroom. Slides show and web pages

The multimedia development that has taken place within the university classrooms in recent years has caused a revolution at psychological level within the collectivity of students and teachers inside and outside the classrooms. The slide show applications have become a key supporting element for university professors, who, in many cases, rely blindly in the use of them for teaching. Additionally, ill-conceived slides, poorly structured and with a vast amount of multimedia content, can be the basis of a faulty communication between teacher and student, which is overwhelmed by the appearance and presentation, neglecting their content. The same applies to web pages. This paper focuses on the study and analysis of the impact caused in the process of teaching and learning by the slide show presentations and web pages, and its positive and negative influence on the student’s learning process, paying particular attention to the consequences on the level of attention within the classroom, and on the study outside the classroom. The study is performed by means of a qualitative analysis of student surveys conducted during the last 8 school Civil Engineering School at the Polytechnic University of Madrid. It presents some of the weaknesses of multimedia material, including the difficulties for students to study them, because of the many distractions they face and the need for incentives web pages offer, or the insignificant content and shallowness of the studies due to wrongly formulated presentations.

Molecular Techniques (2015-2016). Slides for the Genetics Laboratory practices introduction

Slides for the Genetics Laboratory practices introduction.

Material for lantern slides on wood preservation /

The plates are accompanied by a covering letter (6 l. at beginning) dated Oct. 11, 1919, from the compiler to Professor E.E. King of the University of Illinois, who had requested the material.

Slides and photographs. List.

Reprinted in part from the Annual reports of the State Department of Education.

Cataloging and classifying audio-visual materials; a guide to the preparation of films, filmstrips, slides, and records for use in the Materials Center of the School of Library Training and Service, Florida State University.

Mode of access: Internet.

Chicago public schools, catalogue of 16mm. sound and silent motion picture films and stereopticon slides ... 1942-1943

Mode of access: Internet.

Lantern slides: how to make and color them.

Copyrighted in 1894.

Health film catalog including filmstrips, slides, transcriptions /

Description based on: 1967.

Lantern slides and film strips of the United States Department of Agriculture /

"Issued March, 1930."