Exploring the links between skills and productivity

An assessment of the direct and indirect link between skills and productivity in the context of the Treasury's '5 drivers' of growth. Based on a literature review covering the debate around the extent and nature of the contribution of skills to economic performance, tested through an analysis of labour market data for the East Midlands region

Effects of D-instantons

Scattering of fundamental states of type IIB supergravity and superstring theory is discussed at low orders in perturbation theory in the background of a D-instanton. The integration over fermionic zero modes in both the low energy supergravity and in the string theory leads to explicit nonperturbative terms in the effective action. These include a single instanton correction to the known tree-level and one-loop $R^4$ interactions. The `spectrum' of multiply-charged D-instantons is deduced by T-duality in nine dimensions from multiply-wound world-lines of marginally-bound D-particles. This, and other clues, lead to a conjectured SL(2,Z) completion of the $R^4$ terms which suggests that they are not renormalized by perturbative corrections in the zero-instanton sector beyond one loop. The string theory unit-charged D-instanton gives rise to point-like effects in fixed-angle scattering, raising unresolved issues concerning distance scales in superstring theory.Comment: 31 pages, 6 figures, Latex, Reference added, corrected coefficients in expansion of generalized Eisenstein series in equation 66 now agree with hep-th/970414

Concept-based Analysis of Surface and Structural Misfits (CASSM) Tutorial notes

Concept-based Analysis of Surface and Structural Misfits (CASSM) in a novel approach to usability analysis that focuses attention on misfits between user and system concepts. We believe that as an approach it has several desirable qualities: o It focuses on concepts rather than tasks or procedures. Consequently, it complements the majority of existing approaches to usability evaluation. In particular, it analyses conceptual misfits between user and system. o By intentionally supporting ‘sketchy’ analysis, CASSM avoids the ‘death by detail’ that plagues many evaluation techniques. CASSM analyses do not have to be complete or consistent to be useful – though of course a thorough analysis is likely to have these properties. Also, CASSM analyses are often quite succinct, compared to (for example) a Cognitive Walkthrough (Wharton et al, 1994), Heuristic Evaluation (Nielsen, 1994) or GOMS analysis (John & Kieras, 1996). o As a notation, it provides a ‘bridge’ between the core ideas underpinning work on mental models and design issues, and may thus make prior work on mental models more readily accessible to design practice. [This should be regarded as a hypothesis that has not yet been tested.] o The CASSM notation provides a relatively formal definition of many of Green’s Cognitive Dimensions (see, for example, Green, 1989; Green & Petre, 1996; Blackwell & Green 2003). In this way, it further supports assessment of a system in terms of CDs. This is discussed in detail towards the end of this document. Although the name (CASSM: Concept-based Analysis of Surface and Structural Misfits) emphasises the importance of misfits, you should be aware that there are other kinds of user–system misfits that are outside the scope of CASSM; for example, inconsistencies in procedures for similar tasks would be picked up by other techniques but are not directly addressed within CASSM. CASSM focuses on conceptual structures

Fillet Weld Stress Using Finite Element Methods

Average elastic Von Mises equivalent stresses were calculated along the throat of a single lap fillet weld. The average elastic stresses were compared to initial yield and to plastic instability conditions to modify conventional design formulas is presented. The factor is a linear function of the thicknesses of the parent plates attached by the fillet weld

A charging model for three-axis stabilized spacecraft

A charging model was developed for geosynchronous, three-axis stabilized spacecraft when under the influence of a geomagnetic substorm. The differential charging potentials between the thermally coated or blanketed outer surfaces and metallic structure of a spacecraft were determined when the spacecraft was immersed in a dense plasma cloud of energetic particles. The spacecraft-to-environment interaction was determined by representing the charged particle environment by equivalent current source forcing functions and by representing the spacecraft by its electrically equivalent circuit with respect to the plasma charging phenomenon. The charging model included a sun/earth/spacecraft orbit model that simulated the sum illumination conditions of the spacecraft outer surfaces throughout the orbital flight on a diurnal as well as a seasonal basis. Transient and steady-state numerical results for a three-axis stabilized spacecraft are presented