Cognitive engineering practice: melting theory into reality

Given the growing scope of cognitive engineering, our intent in this paper is to help uncover some of the regularities of the discipline. Adopting a pragmatic view, we attempt to interpret what cognitive engineers really do in practice, and to partly systematize this reality. The paper stresses the need for: (i) an explicit consideration of the demand for intervention and the analyst's preconceptions during the framing of the world-to-study, (ii) the adoption of multiple views for a sufficient understanding of the analysed world, (iii) a continuous reframing of the system under consideration (i.e., topological boundaries as well as timeframes) as the understanding of reality unfolds, (iv) acceptance and exploitation of the dialectic process between analysis/understanding and design/prediction.     

Correction to: The effect of cognitive workload on decision authority assignment in human–robot collaboration

Cognition, Technology & Work -     

Economic considerations of breeding for polled dairy cows versus dehorning in the United States

This paper examines the costs and benefits of selecting for polled dairy heifers versus traditional dehorning practices. Stochastic budgets were developed to analyze the expected costs (EC) associated with polled dairy genetics. The economic assessment was expanded beyond on-farm cash costs by incorporating cost and benefit estimates to generate industry-wide discussion, and preliminary economic evaluations, surrounding the public acceptance and attitude toward polled genetics versus dehorning calves. Triangular distributions, commonly used to represent distributions with limited data, were used to represent labor costs for dehorning, the likelihood of treatment of calf, and the cost of veterinary treatment. In total, 10,000 iterations were run using @Risk v 6.0 (Palisade Corp., Newfield, NY). The EC of the 4 traditional dehorning methods evaluated in this study ranged from $6 to $25/head, with a mean EC around $12 to $13/head. The EC of incorporating polled genetics into a breeding program ranged from $0 to $26/head depending on the additional cost, or premium, associated with polled relative to horned genetics. Estimated breakeven premiums associated with polled genetics indicate that, on average, producers could spend up to $5.95/head and $11.90/head more for heterozygous and homozygous polled genetics, respectively, compared with conventional horned genetics (or $2.08 and $4.17/straw of semen at an assumed average conception rate of 35%). Given the parameters outlined, sensitivity to individual farm semen and dehorning costs are likely to swamp these differences. Beyond on-farm costs, industry-wide discussion may be warranted surrounding the public's acceptance and attitude toward polled genetics versus dehorning or disbudding of calves. The value of avoiding dehorning may be larger for the industry, and perhaps some individual farms, than initially suggested if additional value is put on calf comfort and possible worker aversion to dehorning. If public perception of dehorning influences market access, the EC of dehorning may be large but that cost is unknown at present.     

Computational fluid-dynamics modeling of the hydrodynamics of fluidization in the sand surrounding a lost-foam casting pattern

In many modern industries, complex shapes arise which require advanced metal casting processes to produce a component. The problem with these cast parts is the empiricism required to develop the casting process and the accompanying time and expense involved. There has been interest in using a fluidized bed to allow molding sand to better encapsulate the complicated surface geometries of lost-foam patterns. Fluidization, coupled with a single mixing jet of much greater magnitude than the minimum fluidization velocity, helps to homogenize the sand through stirring and may improve the integrity of the casting. At the bottom of the bed is an array of fluidizing jets distributed through a porous plate, which maintain the bed at minimum fluidization. Superimposed upon these smaller jets is a large mixing jet, which serves to mix and homogenize the sand. At issue is the hydrodynamics of the sand and air surrounding the foam pattern. The PHOENICS commercial software package was amended to simulate the flow around the precasting foam geometry. Employing a two-fluid approach, each phase was considered a fluid that interpenetrates the other phase. The modification required that the kinetic theory of granular flow for the sand phase be incorporated into the recompilable PHOENICS code. The results of this study consisted of time-averaged voidage patterns, with voidage being defined as the volume fraction of air in the mixture, around the foam pattern submerged in a two-dimensional fluidized bed. The model was benchmarked against fluidized-bed experiments performed by previous investigators. In order to elucidate the dependence of the voidage around the lost-foam pattern, selected physical parameters were varied, and the resultant void-fraction maps were predicted with the model. Physical parameters such as the aspect ratio of the width to length of the foam pattern, the placement of the mixing jet, and different mixing-jet velocities were varied to illustrate the dependence of the time-averaged void fraction on those variables. The simulations identified the presence of channeling around the lost-foam pattern, with the extent of the channeling and void formation reliant to a greater degree upon the placement of the mixing jet and, to a lesser degree, on the mixing-jet velocity and aspect ratio. The placement of the mixing jet halfway between the internal foam pattern and the right wall had the desirable benefit of granting the sand-churning benefits of a penetrating jet. With this optimal jet placement, more of the excess jet air was allowed to disperse through the molding sand and to homogenize the sand. The degree of channeling of the excess air input by the penetrating jet was minimized.     

Monolithic column HPLC separation of intact proteins analyzed by LC-MALDI using on-plate digestion: An approach to integrate protein separation and identification

A method is developed to integrate a protein separation by monolithic capillary reversed-phase high-performance liquid chromatography to on-probe tryptic digestion for subsequent analyses by MALDI-TOF MS and MALDI-TOF/TOF MS. The method provides a means of directly interfacing separations to MALDI-MS, reducing the amount of time required for traditional procedures involving in-solution enzymatic digestion and sample cleanup prior to MALDI-MS analysis. When used with pI-based fractionation as a first dimension, it provides a means of analyzing complex mixtures of proteins with minimal sample handling and cleanup. The use of monolithic capillary columns sufficiently resolved intact proteins so that peptide mass fingerprinting analysis by MALDI-TOF MS resulted in the identification of close to 40 unique proteins from 120 ng of sample obtained from a prefractionated MCF10 cell line at pH 6.34, where the identifications of several of these proteins were also confirmed by intact MW and tandem mass spectrometric analysis. The reproducibility of this method has been demonstrated to be sufficient for the purpose of protein identifications. Experimental values of protein intact MW are obtained and compared to that expected for each protein identified.     

Ion mobility-mass spectrometry (IM-MS) for top-down proteomics: increased dynamic range affords increased sequence coverage

A general approach that combines mass spectrometry (MS), collision-induced dissociation (CID), ion mobility (IM), and MS for top-down proteomics is described, denoted as MS-CID-IM-MS. Using this approach, CID product ions are dispersed in two dimensions, specifically size-to-charge (IM) and mass-to-charge (MS), and the resulting 2D data display greatly facilitates peptide/protein mass mapping, amino acid sequence analysis, and determination of site-specific protein modifications. Also, this approach alleviates some of the inherent limitations of top-down proteomics, viz. the limitations in dynamic range for fragment ion abundances owing to the number of fragmentation channels available to large ionic systems as well as the resulting spectral congestion. For large peptides such as melittin (2845 Da), CID of the [M + 3H](3+), [M + 4H](4+), and [M + 5H](5+) ions yields amino acid sequence coverage of 42.3%, 38.5%, and 7.7%, respectively, whereas the hybrid MS-CID-IM-MS approach yields amino acid sequence coverages of 84.6%, 65.4%, and 69.2%, respectively. For large biomolecules such as ubiquitin (8565 Da), the amino acid sequence coverage increases from 39% to 76%. The MS-CID-IM-MS top-down approach allows for greater depth of information by allowing the assignment and study of internal fragment ions. Lastly, analysis of the methyl esterification of ubiquitin and single point mutation of human iron sulfur cluster U (HISCU, 14.3 kDa) demonstrates the ability of MS-CID-IM-MS to rapidly identify the presence and sites of modifications.