New routes to early memories

Stimulation of one side of the olfactory system during training with odor-milk pairings in neonatal rats results in their ability to recall an odor memory by using the trained but not the untrained side of the brain. In 12-day-old rats, olfactory learning can be recalled by stimulation of either the trained or untrained side. The development of bilateral recall reflects the maturation of olfactory commissural pathways that provide access to the olfactory memory stored on the contralateral side. Furthermore, the commissural pathways need not be present at the time of memory formation but can establish new and specific access to already existing olfactory memories.     

Use of Internet-based resources to support an introductory animal and poultry science course.

This article describes the development and implementation of a World Wide Web page to support a team-taught introductory animal and poultry science course. The objectives were to examine the capabilities of this type of instructional resource, determine students' willingness to use this type of resource, create opportunities for interactive learning, and improve students' enthusiasm for the subject area. A variety of course materials were made available through the Internet, including the class syllabus, lecture notes, and practice questions to support and augment class lectures. Additional on-line resources included a bulletin board for instructor announcements, a list-serve for student discussions concerning administrative and educational issues arising during the semester, a class E-mail list, and a page with links to other sites of agricultural interest. Materials were accessible from a variety of computer resources, including campus computing laboratories, dial-up access, and access via other Internet service providers. Use of the materials was evaluated by analysis of log files from the server. Effectiveness of the resources was determined from surveys of students conducted before and after implementation of the on-line resource. Students indicated that the most useful components of the Web page were the class notes and practice/review questions. Effectiveness of the site was related to the amount of material available through the site, the level of interaction, whether the task was required, and the ease of access to computers and the Web site. Student evaluations indicated that this form of instructional supplement is a viable method for enhancing the learning experience in the introductory animal sciences.     

Use of force-deformation curves to estimate Young's modulus and its applications to soil aggregate breakdown

Soil aggregates from a clay and a sandy loam were subjected to uniaxial compression and their force-deformation relationships determined. From these relationships the elastic deformation was identified, and estimates were made of Young's modulus, elastic strain energy and work of fracture. Also estimated were the increases in surface area produced on breakdown and hence surface energies. The results were interpreted in terms of Griffith's crack theory, and apparent crack lengths were calculated. The calculated values were high, but the variability of the data prevented a full assessment of this approach to the study of brittle failure of aggregates.     

Recording of the reticular motility in cattle with experimental and spontaneous traumatic reticuloperitonitis

Using the method described in a previous publication for recording the reticulum action in normal cows the authors have investigated three cows with experimentally produced reticuloperitonitis as well as a group of cows with spontaneous peritonitis under treatment at the stationary clinic. The experimental animals were provided with permanent rumen fistulas.In the three cows with experimentally produced peritonitis the pointed object worked loose spontaneously during the first 24 hrs. The symptoms were mild after the first perforation and became aggravated after further perforations.An abnormally prolonged reticulum interval was recorded immediately after the perforation and continued to be clearly distinguishable for two to three days. In the cows with spontaneous peritonitis, this change was observed only in the acute stage.Prolongation of the second phase of the reticulum was the most pronounced finding from the recordings of the reticular movements, both in the cows with experimental peritonitis and in those in the spontaneous group. The change was at its height after two to seven days, and then subsided gradually in the experimental animals in which repeated recordings had been made.The pressure elevation in reticulum during the contractions was lower both in the animals with experimental peritonitis and in the spontaneous group than in the healthy animals.The cows with reticuloperitonitis also displayed impaired ability to pass the recording catheter from the atrium ruminis to the reticulum.     

Estimating butterfly numbers

While various experimental methods may show the number of butterflies in a given area, this, of itself, is no pointer either to general scarcity or to the reverse. Even less can it be taken as being the result of a particular set of outside influences. However, low levels in certain (otherwise plentiful) species may be taken as indicating unsuitable management trends.