Teaching a lecture course in introductory human physiology with 40-183 students provided an opportunity to test the hypothesis that regular attendance is correlated with higher examination scores. Data on 556 students were recorded during five semesters, each consisting of three classes per week for 14 weeks. The students were in the second year of pharmacy, nursing, physical education, and dental hygiene programs. Attendance was recorded in each class. Regular attendance was encouraged but was not used to influence scores. The maximum possible score was 400 points, based on two 1-h examinations and a 2-h final examination. Examinations consisted of multiple-choice questions derived from reading assignments in a required textbook. Linear regression analysis indicated a small negative relation between total point scores and absences, amounting to an average decrease of 2 points for each absence, or a decrease of 0.5% per absence. Correlation coefficients averaged -0.33. The results suggest that regular attendance was helpful in a statistical sense but was not a decisive factor in learning human physiology as presented in current textbooks.
The asexual embryos of Volvox turn themselves inside out (invert) during development. Data presented indicate that inversion of the embryos is the result of several simple cellular shape changes, coordinated in space and time. Using whole embryos, cell groups and individual embryonic cells isolated by watchmaker's forceps and pressure on the coverslip, it was shown that the phialopore (opening) enlargement and concurrent stretching of the border cells is due to a constriction formed at the equator. However, if the posterior hemisphere is removed, this constriction no longer effects the expansion of the phialopore (which is in the anterior hemisphere) because the equatorial region is no longer anchored and has no base to support the outwardly directed force against the phialopore cells. If the posterior hemisphere is isolated several hours before inversion, the opening resulting from the incision acts as a “phialopore” and the direction of inversion is reversed. Individual cells and cells in groups undergo the same shape changes as corresponding cells in an intact embryo during inversion. This suggests that these cellular deformations are autonomous and inversion is a result of them.
The citation analysis literature of the last twenty years is selectively reviewed for papers dealing with citation accuracy, citer motivation and the relationship between citation frequency and library use of materials. Although this relationship is rather complex. the two activity measures are moderately correlated. Citation of an item should promote its use and vice versa. There are some factors, however, which inhibit a very high correlation. Faculty who cite use nonlibrary as well as library materials, and hey tend to use scholarly journals which often do not circulate (circulation k i n g one measure of library use). Citations are not simply countable data points; some are more important than others, or differ in purpose. Further, there is a subliterature detailing h e degree of inaccuracy among citations. Collectively, these variables tend to dilute the correlation between use of library materials and citation frequency. These limitations notwithstanding, citations represent an auditable trail of scholarship, and citation analysis remains a useful tool for evaluation of library collections and subject literatures.
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