On buoyant convection in binary solidification

We consider the problem of nonlinear steady buoyant convection in horizontal mushy layers during the solidification of binary alloys. We investigate both cases of zero vertical volume flux and constant pressure, referred to as impermeable and permeable conditions, respectively, at the upper mush???liquid interface. We analyze the effects of several parameters of the problem on the stationary modes of convection in the form of either hexagonal cells or non-hexagonal cells, such as rolls, rectangles and squares. [More ...]published or submitted for publicationis not peer reviewe

Power and temporal commitment preference: An investigation in Portugal, Turkey, and the United States

The current research explores the impact of power on temporal commitment preference (an individual?s preference for shorter or longer time durations for agreements in decision making situations) across three countries: Portugal, Turkey, and the United States. A pilot study (N = 356) established cultural differences in uncertainty avoidance, which was expected to impact choices and behaviors involving power and temporality. The main study (N = 433) investigated the relationship between power and temporal commitment preference. Across all countries, high power individuals preferred shorter temporal commitments than low power individuals. In addition, the U.S. participants preferred longer temporal commitments than either the Portuguese or Turkish participants. We argue that differences in uncertainty avoidance help explain some of the differences in individuals? temporal commitment preferences across diverse cultural settings. Implications for practice and future directions are also discussed.Power, Time, National culture, Uncertainty avoidance

Machinability of High Mn Steel Using Tool Life Criteria

High Mn steel alloys have shown to provide both high strength and ductility. However, current literature offers limited guidance on the machinability of these steel alloys. Therefore, this work provides turning recommendations for high Mn steel that is based on tool life data. Several indexable carbide inserts with various rake angles were used to machine cast billets of high Mn steel. Turning characteristics from various feed rates, cutting speeds, and depths of cut were analyzed. Through a design of experiments, it was determined that the feed rate was the most significant factor affecting tool life and that a tool with a negative rake angle had a longer tool life than one with a positive rake angle. The effect of coolant on tool life was seen to be dependent on the tool material. Optimal cutting conditions, which provided a long tool life while maintaining a decent material removal rate, were found for a cutting speed of 150 ft/min, a feed rate of 0.008 in/rev, and a depth of cut of 0.080 inches. In addition, microhardness analysis was used to determine the thickness of the work-hardened layer on machined surfaces. Microhardness was seen to increase between 0.028 and 0.040 inches from the machined surfaces for each cutting condition, explaining the difficulty experienced in machining high Mn steel alloys. The availability of these recommendations for machining high Mn steel encourages the application of this material in a more efficient and productive manner

Power and temporal commitment preference: an investigation in Portugal, Turkey, and the United States

The current research explores the impact of power on temporal commitment preference (an individual’s preference for shorter or longer time durations for agreements in decision making situations) across three countries: Portugal, Turkey, and the United States. A pilot study (N = 356) established cultural differences in uncertainty avoidance, which was expected to impact choices and behaviors involving power and temporality. The main study (N = 433) investigated the relationship between power and temporal commitment preference. Across all countries, high power individuals preferred shorter temporal commitments than low power individuals. In addition, the U.S. participants preferred longer temporal commitments than either the Portuguese or Turkish participants. We argue that differences in uncertainty avoidance help explain some of the differences in individuals’ temporal commitment preferences across diverse cultural settings. Implications for practice and future directions are also discussed

Particle size distribution instrument. Topical report 13

The development of an instrument to measure the concentration of particles in gas is described in this report. An in situ instrument was designed and constructed which sizes individual particles and counts the number of occurrences for several size classes. Although this instrument was designed to detect the size distribution of slag and seed particles generated at an experimental coal-fired magnetohydrodynamic power facility, it can be used as a nonintrusive diagnostic tool for other hostile industrial processes involving the formation and growth of particulates. Two of the techniques developed are extensions of the widely used crossed beam velocimeter, providing simultaneous measurement of the size distribution and velocity of articles

Conservation and global distribution of non-canonical antigens in enterotoxigenic Escherichia coli

BACKGROUND: Enterotoxigenic Escherichia coli (ETEC) cause significant diarrheal morbidity and mortality in children of resource-limited regions, warranting development of effective vaccine strategies. Genetic diversity of the ETEC pathovar has impeded development of broadly protective vaccines centered on the classical canonical antigens, the colonization factors and heat-labile toxin. Two non-canonical ETEC antigens, the EtpA adhesin, and the EatA mucinase are immunogenic in humans and protective in animal models. To foster rational vaccine design that complements existing strategies, we examined the distribution and molecular conservation of these antigens in a diverse population of ETEC isolates. METHODS: Geographically diverse ETEC isolates (n = 1159) were interrogated by PCR, immunoblotting, and/or whole genome sequencing (n = 46) to examine antigen conservation. The most divergent proteins were purified and their core functions assessed in vitro. RESULTS: EatA and EtpA or their coding sequences were present in 57.0% and 51.5% of the ETEC isolates overall, respectively; and were globally dispersed without significant regional differences in antigen distribution. These antigens also exhibited \u3e93% amino acid sequence identity with even the most divergent proteins retaining the core adhesin and mucinase activity assigned to the prototype molecules. CONCLUSIONS: EtpA and EatA are well-conserved molecules in the ETEC pathovar, suggesting that they serve important roles in virulence and that they could be exploited for rational vaccine design

Cryptosporidium hominis Infection of the Human Respiratory Tract

Cryptosporidium oocysts, observed in a natural sputum sample of a patient with HIV, were further studied by using DNA markers to determine the species of the parasite. C. hominis was identified as the species infecting the patient’s respiratory tract, a finding that strengthens evidence regarding this pathogen’s role in human disease

The Elderly and Waterborne Cryptosporidium Infection: Gastroenteritis Hospitalizations before and during the 1993 Milwaukee Outbreak

We used the Temporal Exposure Response Surfaces modeling technique to examine the association between gastroenteritis-related emergency room visits and hospitalizations in the elderly and drinking water turbidity before and during the 1993 Milwaukee waterborne Cryptosporidium outbreak. Before the outbreak, the rate of such events increased with age in the elderly (p<0.002), suggesting that the elderly are at an increased risk. During the outbreak, strong associations between turbidity and gastroenteritis-related emergency room visits and hospitalizations occurred at temporal lags of 5–6 days (consistent with the Cryptosporidium incubation period). A pronounced second wave of these illnesses in the elderly peaked at 13 days. This wave represented approximately 40% of all excess cases in the elderly. Our findings suggest that the elderly had an increased risk of severe disease due to Cryptosporidium infection, with a shorter incubation period than has been previously reported in all adults and with a high risk for secondary person-to-person transmission

Understanding collaborative working in a facilitated interdisciplinary environment

Purpose: This paper reports on the trial of a new form of project insurance in UK construction designed to improve collaborative working among project participants by enhancing their joint responsibility for project outcomes. Its purpose is to examine the interprofessional collaborative endeavour under these new insurance arrangements, drawing on a structuration model of interdisciplinary collaboration developed in the field of healthcare studies. Design/Methodology/Approach: The research involved a longitudinal, action research approach with participant observation over the period of the trial project. A novel element included a project facilitator as part of the action research team. In addition, qualitative and quantitative data were collected using semi-structured interviews with project participants and close scrutiny of the documented project record. Findings: The study findings are in line with other social practice-based studies of collaboration in construction in which collaborators socialise the collaborative endeavour, developing their interpretation of what collaboration means and their own modus operandi. However, project structure emerges as a more important element in the collaboration process than is typically recognised in practice-based studies. More significantly, the analysis reveals that it is the interplay of structure, the socialising processes of the participants, and facilitation that helps develop interdependence among project participants and provides a basis for understanding collaboration on the trial project. Research limitations/implications: The case study project provides a unique context for the examination of collaboration under the new project insurance arrangements. But the results have implications for the study of collaboration in highlighting the important relationship between project structure, collaboration and facilitation. Practical implications: Understanding the importance of how interdependency is developed through structure, the socialising processes of collaborators, and facilitation has important implications for those concerned with designing project arrangements and managing collaborative processes. Originality/value: The trial project is the first full trial of the new project insurance arrangements in the UK, and provides a unique context for the study of collaboration. By highlighting the significance of project structure, and the interplay between structure, the collaborators’ emerging practices and facilitation, the paper departs from other work in this area to suggest fruitful avenues for further enquiry, and for practice

Human Challenge Pilot Study with Cyclospora cayetanensis

We describe a pilot study that attempted to infect human volunteers with Cyclospora cayetanensis. Seven healthy volunteers ingested an inoculum of Cyclospora oocysts (approximately 200–49,000 oocysts). The volunteers did not experience symptoms of gastroenteritis, and no oocysts were detected in any stool samples during the 16 weeks volunteers were monitored