Ballistic movements on data-entry keypads

Research to date on movement times on data-entry keypads has assumed that the movements are made under visual control [Drury, C.G., Hoffmann, E.R., 1992. A model for movement times on data-entry keyboards. Ergonomics 35, 129-147; Hoffmann, E.R., Tsang, K.T., Mu, A., 1995. Data-entry keyboard geometry and keying movement times. Ergonomics 38 (5), 940-950; Silfverberg, M., MacKenzie, I.S., Korhonen, P., 2000. Predicting text entry speed on mobile phones. In: Proceedings of the ACM Conference on Human Factors in Computing Systems - CHI 2000. ACM, New York, pp. 9-16]. This is often not the case; where the value of Fitts’ Index of Difficulty is low, it is likely that movements will be made ballistically. A survey of commonly used keypads on devices such as mobile phones and ATMs shows that there is a need to study movement times when these ID values are less than those for which movements are likely to be made under visual control [Gan, K.-C., Hoffmann, E.R., 1988a. Geometrical conditions for ballistic and visually-controlled movements. Ergonomics 31, 829-839]. A series of experiments on simulated and real keypads indicates that the ballistic form of movement is generally valid and may be modelled by a modification of the ballistic movement time model of Hoffmann [1981. An ergonomics approach to predetermined motion time systems. In: Australian Institute of Industrial Engineers, Proceedings, Ninth National Conference, pp. 33-47] and of Gan and Hoffmann [1988a. Geometrical conditions for ballistic and visually-controlled movements. Ergonomics 31, 829-839l; 1988b. Sequential ballistic movement. Ergonomics 31 (10), 1421-1436]. A model is developed for the time to complete sequences of number entries containing up to 5 numbers. In this model, the movement times are related to the square-root of the sum of the movement amplitudes.

Relevance to industry

Many industrial applications require the use of keypads for data entry. Movements may be made ballistically or visually controlled, depending on the geometry of the keypad. As the time for data entry is dependent on geometry, a model for time taken is necessary for predicting human performance.     

Ground Movement Predictions for Braced Excavations in Undrained Clay

The writers introduce a design approach for braced excavations based directly on the data of carefully chosen soil tests, conceived within the framework of plasticity theory, but allowing for strain hardening. Mobilized shear stresses beneath and around braced excavations are found by a stability calculation based on a proposed plastic deformation mechanism. Strains required to mobilize these stresses are deduced from a direct simple shear test on a representative sample taken from a selected location in the plastic zone of influence. These strains are entered into a simple plastic deformation mechanism to predict boundary displacements. Hence, the proposed Mobilizable Strength Design (MSD) method can satisfy both safety and serviceability in a single step of calculation, without the need for finite element analyses. In this method, design parameters can be chosen rationally with regard to the initial state of soil, the stiffness following the appropriate stress path, and the level of acceptable deformations under working conditions. Examples demonstrating the success of the MSD method are given for a variety wall and soil conditions. Comparisons are made both with previously published field studies and with comprehensive nonlinear finite element analyses.     

Subtyping for session types in the pi calculus

Extending the pi calculus with the session types proposed by Honda et al. allows high-level specifications of structured patterns of communication, such as client-server protocols, to be expressed as types and verified by static typechecking. We define a notion of subtyping for session types, which allows protocol specifications to be extended in order to describe richer behaviour; for example, an implemented server can be refined without invalidating type-correctness of an overall system. We formalize the syntax, operational semantics and typing rules of an extended pi calculus, prove that typability guarantees absence of run-time communication errors, and show that the typing rules can be transformed into a practical typechecking algorithm. Malcolm Hole died on 28th February 2004, a few weeks after the original submission of this paper.     

Split tolerance to a viral antigen expressed in thymic epithelium and keratinocytes

When expressed as a transgene from the keratin 14 (K14) promoter in an MHC class II-deficient mouse, I-Ab expressed in thymic cortical epithelium promotes positive but not negative selection of I-Ab-restricted CD4+ T cells (Laufer, T. M. et al., Nature 1996. 383:81-85). Transgenic mice expressing the E7 protein of human papilloma virus 16 from the K14 promoter were studied to determine the consequence of expression of a cytoplasmic/ nuclear protein from the K14 promoter. K14E7-transgenic mice express E7 in the thymus and skin without evidence for autoimmunity to E7. Repeated immunization of FVB(H-2q) or F1(C57BL/6JxFVB) mice with E7 elicited similar antibody responses to the defined B cell epitopes of E7 in K14E7-transgenic and non-transgenic animals. In contrast, for each genetic background, a single immunization with E7 elicited demonstrable T cell proliferative responses to the major promiscuous T helper epitope of E7 in the transgenic but not the non-transgenic animals. Further, E7-immunized non-transgenic F1 (FVBxC57BL/6J) animals developed strong E7-specific cytotoxic T lymphocyte (CTL) responses and were protected against challenge with E7+ tumors, whereas similarly immunized K14E7-transgenic animals had a markedly reduced CTL response to E7 and no E7-specific tumor protection was observed, although the antibody and CTL response to ovalbumin was normal. Expression of E7 protein as a transgene from the K14 promoter in the skin and thymus thus induces E7-specific tolerance in the cytotoxic T effector repertoire, together with expansion of the E7-specific T helper repertoire. These findings demonstrate that limited tissue distribution of an autoantigen may result in "split" tolerance to that autoantigen.     

Negotiated learning contracts in team projects

The successful evolution of a negotiated learning practice in software engineering team projects is described. The background to negotiated learning practices is reviewed and it is noted that a concern for process issues might be related to software quality management concerns. Negotiated learning was used to develop learning autonomy and to encourage process improvement. The integration of learning contracts and existing software engineering quality management techniques has produced an approach which has enabled teams of students to effectively define and reflect on systems development and learning processes. Individual assessment was enhanced by including processes for the visibility and traceability of contributions in the negotiation process. The gradual evolution of the practice is described with some detail of the current context provided. Evaluations have indicated that teams can become more actively engaged in learning and develop reflective skills in a structured manner by exploiting mechanisms for negotiation.     

Lattice coordination number in polystyrene solutions

Intrinsic viscosities of five polystyrene samples of molar masses ca. 10⁵–10⁶ have been measured at 34.5°C in cyclohexane (θ-solvent), 1,2,3,4-tetrahydronaphthalene (good solvent) and in binary mixtures of these two liquids. Experimental values of ⁵−³ (where is the expansion factor) were compared with values calculated on the basis of two theories which assume the lattice coordination number Z to be infinite and finite respectively. Z=∞ greatly overestimates ⁵−³, whilst good accord is obtained if Z=3 or 4 according to molar mass and solvent power.     

A Landsat-based study of black rock coatings proximal to base metal smelters,Sudbury, Ontario,Canada

Past emission of metal-bearing particulate matter, sulphur dioxide (SO₂), and sulphuric acid by base metal smelters in the Sudbury region led to widespread loss of vegetation, contamination of soils, and formation of black coatings on rock surfaces. These black coatings formed through the incorporation of smelter-borne particulate matter into the partly dissolved uppermost layers of siliceous minerals on exposed rock, and are characterized by high heavy-metal content. This study involved assessment of the reflectance properties of black coatings in the Sudbury region, and determination of the geographic distribution of coatings through supervised classification of reflectance data derived from a Landsat Enhanced Thematic Mapper Plus (ETM+) image. Classifications involved the use of the Spectral Angle Mapper (SAM), Maximum Likelihood, and Feedforward Backpropagation Neural Network algorithms. The reflectance spectra of black coatings in the Sudbury region are relatively flat and featureless, and are characterized by reflectance values less than ~13% across the visible, near-infrared, and short-wave infrared. Spectral properties are similar to those of magnetite, a spinel-group mineral known to be present in Sudbury coatings. The presence of carbon-rich soot particles may be an important influence on the reflectance properties of coatings. SAM classification results are characterized by the widespread mislabelling of uncoated urban and open-pit sites as mantled by black coatings, and neural network results problematically mislabel some uncoated wetland sites as coated. Results generated by the Maximum Likelihood algorithm most usefully depict the distribution of exposed black coatings in the Sudbury region. The mapping of black coatings using remote-sensing methods can provide useful information on the spatial character of environmental degradation in the vicinity of smelters, and should be helpful in the monitoring of environmental recovery where emissions have been reduced or eliminated.     

A Study of the Synergy of new Technology,Business Tools and Information to Optimize Mine Production Control

New technologies, sources of information, and business paradigms developed and perfected in other industries should enable mine optimization opportunities that were previously unfeasible. Surface mining opportunities include optimization of fragmentation, blending for comminution, and short term production planning. The key to the success of these opportunities is not the use of a single technology, business tool or bit of information, but the synergy from integrating all three. Data manipulation and analysis tools, and management mechanisms provide the ‘glue’ that is needed to gain the synergy from these technologies and information. These opportunities should enable mines to be more profitable and flexible with the ability to concentrate more on setting and achieving their strategic goals.     

Stability of physical assessment of older drivers over 1 year

Older adults represent the fastest-growing population of drivers with a valid driver's licence. Also common in this age group are multiple chronic medical conditions that may have an effect on physical function and driving ability. Determining the reliability of physical measures used to assess older drivers’ functional ability is important to identifying those who are safe to continue driving. Most previous reliability studies of clinical physical measures of health used test–retest intervals shorter than those between patient visits with a clinician. In the present study we examined a more clinically representative interval of 1 year to determine the stability of commonly used physical measures collected during the Candrive II prospective cohort study of older drivers. Reliability statistics indicate that the sequential finger–thumb opposition, rapid pace walk and the Pelli–Robson contrast sensitivity tests have adequate stability over 1 year. Poor stability was observed for the one-legged stance and Snellen visual acuity test. Several assessments with nominal data (Marottoli method [functional neck range of motion], whispered voice test, range of motion and strength testing) lacked sufficient variability to conduct reliability analyses; however, a lack of variability between test days suggests consistency over a 1-year time frame. Our results provide evidence that specific physical measures are stable in monitoring functional ability over the course of a year.