Effectiveness of connectors in geofoam block construction

This paper reports the results of shear resistance tests conducted on geofoam blocks with no connection, blocks connected with barbed connector plates, and blocks connected with polyurethane adhesive. In the first phase, tests were completed in a large direct shear box (430 mm L × 280 mm W) under normal pressures of 14.8 kPa, 29.6 kPa, and 74.1 kPa. In phase II, tests were conducted on 1200 mm L × 600 mm W specimens using a computer controlled actuator under normal pressures of 9.3 kPa, 18.1 kPa and 26.9 kPa. The measured values of the coefficient of friction between blocks were found to be consistent with the values reported in the literature and conservative in terms of commonly used design values. The test results show that the presence of barbed connector plates did not provide additional interface shear resistance; however polyurethane adhesive was successful in bonding the blocks together thus virtually eliminating horizontal sliding between the blocks. Blocks connected with barbed connector plates subject to repeated loading showed signs of decreased shear resistance during reloading, but did reach the peak shear resistance measured during initial loading.     

Sequential dynamical systems

We present our work on the special class of dynamical systems referred to as discrete sequential dynamical systems (SDS). The definition of these systems is motivated by the generic structure of computer simulations. In computer simulations, we typically find agents or entities with certain properties or states. The entities can retrieve information from other entities, but usually only from the ones in their own vicinity. Based on these states, they may update their own state. A schedule will take care of the update order of the entities. One possible interpretation of this is to have each entity as a vertex in a (dependency) graph where two vertices are connected if the corresponding two entities can communicate. Without loss of generality, we can associate a binary state to each vertex or entity. Finally, we fix some ordering of the vertices that represents the update ordering of the entities. The above construction will be put in a strict mathematical context, and leads to the concept of a sequential dynamical system (SDS). This work was presented in part at the Sixth International Symposium on Artificial Life and Robotics, Tokyo, January 15–17, 2001     

Insertion element IS3-based PCR method for subtyping Escherichia coli O157:H7

An Escherichia coli O157:H7 subtyping method based on PCR amplification of variable DNA sequences between the repetitive element IS3 was developed. Template DNA was prepared by boiling cells in Chelex. Two separate IS3 PCR amplifications were performed for each isolate: one with a single primer (primer IS3A) and one with two primers (primers IS3A and IS3B). The IS3 PCR subtyping method was applied to 35 epidemiologically related and unrelated E. coli O157:H7 isolates that had been previously characterized by pulsed-field gel electrophoresis (PFGE). PFGE identified 25 different subtypes (difference of one or more bands). PCR with single primer IS3A and primer pair IS3A-IS3B identified 6 and 14 different subtypes, respectively. By combining the results of the two PCR amplifications, 15 different IS3 PCR subtypes were identified. While not as sensitive as PFGE, IS3 PCR subtyping grouped all outbreak-related isolates. IS3 PCR banding patterns were reproducible between amplifications and between subcultures. IS3 PCR could serve as a simple, rapid screening method for the identification of unrelated E. coli O157:H7 isolates.     

Variations in personal space as a function of authoritarianism, self-esteem, and racial characteristics of a stimulus situation.

Investigated "personal space," the portable, flexible area surrounding an individual which has been viewed as a buffer zone between him and his environment. It was hypothesized that when 20 high and 20 low self-esteem and authoritarian white male undergraduates were approached by white and black male stimuli, (a) the largest areas of personal space would be used by high authoritarian, and low self-esteem ss; and (b) these ss would also use larger areas of personal space in response to the approach of the black stimulus than the white. The hypotheses are supported. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Calorimetric method for the determination of rates of emulsion polymerisation applied to methyl methacrylate

A small-scale calorimetric method developed for following the rate of polymerisation of monomers in solution and in bulk has now been adapted by construction of a stirred reaction vessel for the study of rates of emulsion polymerisation recipes. Results obtained for the emulsion polymerisation of methyl methacrylate are compared with those for polymerisation under bulk conditions.