Markov analysis of qualitative dynamics1

Common sense sometimes predicts events to be likely or unlikely rather than merely possible. We extend methods of qualitative reasoning to predict the relative likelihoods of possible qualitative behaviors by viewing the dynamics of a system as a Markov chain over its transition graph. This involves adding qualitative or quantitative estimates of transition probabilities to each of the transitions and applying the standard theory of Markov chains to distinguish persistent states from transient states and to calculate recurrence times, settling times, and probabilities for ending up in each state. Much of the analysis depends solely on qualitative estimates of transition probabilities, which follow directly from theoretical considerations and which lead to qualitative predictions about entire classes of systems. Quantitative estimates for specific systems are derived empirically and lead to qualitative and quantitative conclusions, most of which are insensitive to small perturbations in the estimated transition probabilities. The algorithms are straightforward and efficient.     

Immiscibility and the System Lanthanum Oxide–Boric Oxide

The phase equilibrium diagram for the system La₂O₃-B₂O₃ has been determined experimentally. The compounds La₂O₃-3B₂O₃and La₂O₃-B₂O₃ melt congruently at 1141°± 5°C. and 1660°± 15°C, respectively. At 1488°± 5°C, La₂O₃-B₂O₃ inverts from the aragonite-type structure to a high-temperature form. Trilanthanum borate, 3La₂O₃ B₂O₃, melts incongruently at 1386°± 5°C. to give liquid and La₂O₃. No solid solutions exist in the system. A region of liquid immiscibility exists in the system and extends at 1136°± 5°C. from almost pure B₂O₃ to 21.5 mole % La₂O₃. The experimental value for the extent of immiscibility agrees with that calculated from theoretical considerations. A second method for estimating immiscibility in the system is demonstrated, which requires experimentally only the determination of the index of refraction of the modifier-rich liquid. Principles governing immiscibility are discussed.     

Quantification of Shrimp in Shrimp-Surimi Mixtures using Urea Gel Isoelectric Focusing

A method of quantitate the percent content by weight of shrimp in surimi-pink shrimp mixtures was developed by comparing peak areas of two Alaska pollock surimi-specific (pI 7.11 and 7.17) and two shrimp-specific (pI 5.46 and 5.52) protein bands on isoelectric focusing (IEF) gels. An equation describing the linear relationship between peak areas and protein from the standard samples of surimi, shrimp and surimi-pink shrimp mixtures was also developed. Using this method, unknown mixtures containing 10.0, 12.4 and 5.7% pink shrimp, respectively, were determined in blind studies to contain 8.3, 12.0 and 4.4% shrimp and 85.7, 86.8, and 92.7% surimi, respectively.     

Qualitative Methods Used in the Assessment of Engineering Education

This article clarifies key concepts that undergird qualitative research, which is being used increasingly as engineering educators improve classrooms, programs, and institutions. The paper compares quantitative and qualitative research, describes some qualitative data collection strategies used in engineering education, addresses methods for establishing trustworthiness, and discusses strategies for analyzing qualitative data. Also included are illustrative examples of recent engineering education research that features qualitative data analysis and mixed‐method (quantitative and qualitative) approaches.     

Local Connection Criteria and Single Homeless People's Geographical Mobility: Evidence from Brighton and Hove

In December 2001 Brighton and Hove City Council introduced a set of Local Connection Criteria aimed at stemming the flow of homeless people apparently making their way to the city in search of services. Under the new criteria, only those previously resident in Brighton and Hove can make use of the city's night shelters and hostels. Similar such criteria have recently been introduced elsewhere and represent an important change in local responses to the problems of single homelessness. The paper examines in detail the movements of 41 recently and long-term homeless men interviewed at a night shelter and hostel in Brighton and Hove prior to the introduction of the local connection rule. Finding the majority to have recently moved to the city having become homeless elsewhere, it is suggested that the introduction of such criteria is liable to have a considerable impact on the lives of some single homeless people. Examining the reasons why these men had moved, however, it is suggested that the future movement of single homeless people to the city, or other 'homeless places', is unlikely to be significantly affected by such policies.     

Measuring Netted Muskmelon Maturity by Delayed Light Emission

Netted muskmelon fruits of Hale's Best, Magnum 45 and Saticoy cultivars in 6 different maturity classes, from immature to mature were examined. Maturity class was based on days after anthesis. The melons were evaluated for differences in delayed light emission (DLE) measurements and physical and chemical properties that relate to maturity. DLE, firmness, and chlorophyll decreased with increasing maturity, whereas Hunter a and soluble solids increased. DLE correlated highly (r =?0.94) with a calculated maturity index, indicating that DLE could be used as a nondestructive technique for measuring the maturity of netted muskmelon.