Documents in Place: Demarcating Places for Collaboration in Healthcare Settings

The notion of place often connotes our understood reality populated with people, practices, meanings, and artifacts. This paper suggests that documents, whether electronic, paper-based, or set in stone, offer important insights into how people establish and maintain places for communication and coordination. Data from an ethnographic study in a large hospital system illustrates how doctors carefully craft their medical histories in various electronic record systems to demarcate specific places for their communication and coordination with specific collaborators. Such documents serve as portable places, allowing the doctors to navigate a constantly changing landscape of relevant patients, participants, times, and spaces. The documents demarcate such places by pointing out the interdependencies among particular participants, places, and times. Doctors care deeply about these documents and they play a central part not only in securing efficient communication and coordination but also in the socialization of newcomers. A study of the complex interrelationships between documents and place, therefore, offers important insights into organizational environments characterized by distributed and mobile work practices.     

Strengthening mechanisms in solid solution aluminum alloys

A number of commercial and high-purity non-heat-treatable aluminum alloys are investigated in this work. It is found that both magnesium and manganese in solid solution give a nearly linear concentration dependence of the strength at a given strain for commercial alloys. This deviates from high-purity AlMg binary alloys, where a parabolic concentration dependence is found. Mn in solid solution is found to give a considerably higher strengthening effect per atom than Mg, both in terms of yield stress and initial work hardening rate. This strengthening effect is stronger comparing commercial grades to high-purity alloys. This enhanced strengthening is believed to be a synergy or clustering effect caused by interaction between Mn atoms and trace elements, probably silicon, in solid solution.     

Large strain work hardening of aluminum alloys and the effect of mg in solid solution

The work-hardening behavior of a range of aluminum-magnesium alloys, from 0.5 to 4.55 wt pct Mg, is followed up to large strains using compression testing and cold rolling. At large strains, stage IV, an unexpectedly low work-hardening rate of high-Mg alloys is observed, and the work-hardening rate in stage IV is almost unaffected by the Mg content. A model for work hardening is applied and discussed in relation to the experimental observations. Based on microstructural observations of the cold-rolled materials, the low work-hardening rate of high-Mg alloys is ascribed to a different storage pattern of dislocations caused by an increased amount of shear bands and a higher dislocation density inside subgrains.     

Computer aided part manufacturing

The decisions made by manufacturing engineers have to be flavoured by the value system of the times. The rapid change in value systems caused by the human/environmental revolution, will bring about the beginning of a new epoch in manufacturing. This will make old ways of doing things obsolete, but also create new possibilities. Therefore, manufacturing industry may change to a new pattern better adapted to the new environments.In order to meet this challenge in the Norweigan society, an industrial concept, a cell concept, has been developed by the Production Engineering Laboratory NTH-SINTEF. Vital parts of the cell concept have been tested in a full scale pilot plant, in which a variety of diesel engine parts are machined.Part programming, machine loading and scheduling in the cell together with the cell control functions, are performed computer aided, using a three level computer hierarchy.     

Solid helium. I. Ground-state energy and compressibility

The ground-state energy and the compressibility of solid helium is calculated by means of a modified Brueckner theory. The Bethe-Goldstone equation is solved to give the reaction matrix or the effective interaction in coordinate space, and the ground-state energy for the two helium isotopes³He and⁴He is calculated. Also, the compressibility is estimated from the dependence of the ground-state energy on density or molar volume. Both bcc and hcp structures are considered. The calculations are done for two different two-body potentials, an Yntema-Schneider potential given by Brueckner and Gammel, and a Frost-Musulin potential given by Bruch and McGee. Theoretical results for the ground-state energy per particle are 0.2 to 2.6 K for solid³He at a molar volume of 24 cm³/mole, and –2.4 to –5.9 K for solid⁴He at a molar volume of 20 cm³/mole. The corresponding experimental results are –1.0 and –5.6 K, respectively. Theoretical results for the compressibility are 0.0031–0.0042 atm^–1 for solid³He at a molar volume of 22 cm³/mole, and 0.0014–0.0022 atm^–1 for solid⁴He at a molar volume of 18 cm³/mole. The corresponding experimental results are 0.0032 and 0.0014 atm^–1, respectively. The agreement with experimental results is reasonably good since higher order cluster terms are not included in this first approximation.     

Liquid4He. II. Three-body correlations and their contribution to the binding energy and the depletion

The three-body contribution to the binding energy of liquid⁴He is calculated. The methods applied are those developed mainly by Bethe and collaborators for nuclearmatter calculations, and later modified by the author for liquid³He. Various two-body wave functions and reaction-matrix elements are calculated, as is the effective interaction or representation of the reaction matrix in coordinate space. Three-body wave functions and three-body energy contributions are then calculated or estimated. The calculations are repeated for several values of the density and for several values of the intermediate-state relative momentum between the two interacting particles. The three-body contribution to the binding energy is found to be approximately –1.3 to –1.6 K per particle. This is, however, a rather uncertain value because the results are very sensitive to the values chosen for the average relative momentum in the calculations of the effective interaction off the energy shell. Also, in parts of the calculations only theS wave is included, and it is taken to represent the effect of the total wave function. The total binding energy of liquid⁴He is estimated by adding together the contribution from separate calculations of the two-body and the three-body interaction. A self-consistent solution is obtained through the depletion of the zero-momentum state, which is also estimated. The calculations are done for two different two-body potentials, an Yntema-Schneider potential given by Brueckner and Gammel, and a Frost-Musulin potential given by Bruch and McGee. The theoretical results are –4.0 to –5.0 K for the binding energy and 44–50% for the depletion. The corresponding experimental results are –7 K and 83%, respectively, i.e., the difference is generally within a factor of 1.5–2. The agreement with experimental results is probably reasonably good (or bad) since four-body and higher order cluster terms are not included.     

The use of a pharmacophore model for identification of novel ligands for the benzodiazepine binding site of the GABAA receptor

A Catalyst pharmacophore model has been developed for the benzodiazepine site within the GABA(A) receptor complex. The model is based on a pharmacophore model originally proposed by Cook and co-workers (Drug Des. Discovery 1995, 12, 193-248) and further developed by Kahnberg et al. (J. Med. Chem. 2002, 45, 4188-4201). The Catalyst pharmacophore model has been validated by using a series of flavonoids with varying affinities for the benzodiazepine receptor and has then been used as a search query in database searching with the aim of finding novel structures which have the possibility to be modified into novel lead compounds. Five of the hits from the database searching were purchased and their affinities for the benzodiazepine site of the GABA(A) receptor were determined. Two of the compounds displayed K(i) values below 10 microM. The substance showing highest potency in-vitro displayed an affinity of 121 nM making it an interesting compound for optimization. The false positive compounds (K(i) values >10 microM affinities) have been analysed in terms of conformational energy penalties and possibilities for hydrogen bond interactions. The analysis clearly demonstrates the need for post processing of Catalyst hits.     

A Controlled Experiment Comparing the Maintainability of Programs Designed with and without Design Patterns—A Replication in a Real Programming Environment

Software design patterns seek to package proven solutions to design problems in a form that makes it possible to find, adapt and reuse them. To support the industrial use of design patterns, this research investigates when, and how, using patterns is beneficial, and whether some patterns are more difficult to use than others. This paper describes a replication of an earlier controlled experiment on design patterns in maintenance, with major extensions. Experimental realism was increased by using a real programming environment instead of pen and paper, and paid professionals from multiple major consultancy companies as subjects. Measurements of elapsed time and correctness were analyzed using regression models and an estimation method that took into account the correlations present in the raw data. Together with on-line logging of the subjects work, this made possible a better qualitative understanding of the results. The results indicate quite strongly that some patterns are much easier to understand and use than others. In particular, the Visitor pattern caused much confusion. Conversely, the patterns Observer and, to a certain extent, Decorator were grasped and used intuitively, even by subjects with little or no knowledge of patterns. The implication is that design patterns are not universally good or bad, but must be used in a way that matches the problem and the people. When approaching a program with documented design patterns, even basic training can improve both the speed and quality of maintenance activities.     

Melt penetration and chemical reactions in 16 industrial aluminum carbon cathodes

The study shows examples of the distribution of melt components in spent carbon cathodes from 16 industrial aluminum electrolysis cells shut down after 10 to 2534 days. The concentration of the phases was determined by quantitative X-ray diffraction (XRD), and the distribution was found by analyzing series of samples from several vertical cores from each cathode. The results show that the analysis is useful for characterizing phases in spent potlining, and the detailed distribution graphs are suitable for comparing different parts of a cathode, or different cathodes. The composition of the melt in the 16 cathodes changed systematically over time, and the stages in the evolution, the effect of the cathode material type, and the effect of the melt on the lining are discussed.