Gradual structuring: Evolving the spreadsheet paradigm for expressiveness and learnability

© 2016 IEEE. Spreadsheets are arguably the most used form of programming and are frequently used in higher education to teach fundamental concepts about computation. Their success has shown that they are simple enough for a huge number of end users to learn and use. This is in contrast to traditional programming languages and the high dropout rate from introductory programming and computer science. However in comparison to traditional programming languages and structured modelling, spreadsheets are not expressive, placing a limit on the levels of computational thinking that can be taught using the spreadsheet paradigm. This limitation is imposed by the lack of programming language features and abstractions in the paradigm. Furthermore, more advanced spreadsheet features (e.g. array formulae, lookup formulae, R1C1 syntax) can be difficult to learn and use. This paper discusses the idea of adding language features to spreadsheets, enabling the gradual structuring of free-form spreadsheets to more structured models. We propose that this concept is termed Gradual Structuring, and is analogous to the programming language concept of gradual typing. In this analogy, spreadsheets take the place of dynamic programming and structured modelling of static programming. In programming languages, gradual typing allows dynamic programming to be mixed with static programming. It is our contention that dynamic programming is more learnable while static programming is more expressive and abstract. Gradual typing could be used to mitigate the issues in the teaching of traditional programming. Likewise Gradual Structuring can mitigate the conceptual limits that can be taught using current spreadsheets. The key language feature required to enable Gradual Structuring is the ability to logically group cells together so that a single formula can be applied to the grouped cells. This concept, termed cell grouping diminishes and can even eliminate the need for the ubiquitous and error-prone use of copy-pasted in spreadsheets. Moreover, it makes the structure present in spreadsheet models explicit. Cell grouping requires a cascade of other new languages features. Namely a more expressive referencing style, which in turned requires enabling labels to be moved to the row and column headers, and the hierarchical structuring of these headers. Respectively these language features are termed enhanced referencing and semantic axes. The ongoing research focusses on the usability and learnability of these language features. Spreadsheet applications exist that contain aspects of the features mentioned. However these applications do not enable Gradual Structuring and have taken a mainly technical, not human behavioural, approach to evolving the spreadsheet

Dialogical self strategies of self-organization: psychotherapy and restructuring of internal management

A identidade tem sido um conceito central na literatura em psicologia e na forma como as diferentes abordagens terapêuticas têm concebido os processos de mudança. Entre as inúmeras perspectivas desenvolvidas sobre essa dimensão do ser humano, destacamos o paradigma dialógico que tem vindo a influenciar de forma crescente a teoria e prática em psicoterapia. Segundo esta perspectiva, a funcionalidade psicológica está relacionada com o modo como os indivíduos conseguem articular e colocar em diálogo produtivo as suas várias vozes ou posições de identidade. Neste artigo apresentamos uma revisão da literatura sobre as estratégias que subjazem a essa capacidade auto-organizadora do sistema identitário e sobre as diretrizes que poderão orientar uma intervenção terapêutica dialógica quando essa capacidade se torna disfuncional.Self-concept has been playing a crucial role in psychological literature and in the way the different therapeutic approaches conceive the processes of change. From the diverse perspectives developed about this human dimension, we emphasise the dialogical paradigm that has been increasingly influential in the psychotherapeutic theory and practice. According to the dialogical perspective the psychological well-being is dependent on the way individuals articulate and maintain productive dialogues between the different voices of the self or “I-Positions”. In this paper we present a review of the literature on the strategies that underlie this self-regulatory ability of the self-system and the guidelines of the dialogical therapeutic intervention that could be used when these self-regulatory strategies become dysfunctional.(undefined

Fan blade protection system

In one type of aircraft propulsion system, propeller blades are mounted on a ring which surrounds a turbine. An annular space exists between the turbine and the ring. If a propeller blade should break free, the unbalanced centrifugal load tends to deform the ring. The invention reduces the deformation, as by locating spacers between the turbine and the ring

Learning robot in-hand manipulation with tactile features

Dexterous manipulation enables repositioning of objects and tools within a robot’s hand. When applying dexterous manipulation to unknown objects, exact object models are not available. Instead of relying on models, compliance and tactile feedback can be exploited to adapt to unknown objects. However, compliant hands and tactile sensors add complexity and are themselves difficult to model. Hence, we propose acquiring in-hand manipulation skills through reinforcement learning, which does not require analytic dynamics or kinematics models. In this paper, we show that this approach successfully acquires a tactile manipulation skill using a passively compliant hand. Additionally, we show that the learned tactile skill generalizes to novel objects

The mass miniature chest radiography programme in Cape Town, South Africa, 1948 - 1994: The impact of active tuberculosis case finding

Background. Tuberculosis (TB) control programmes rely mainly on passive detection of symptomatic individuals. The resurgence of TB has rekindled interest in active case finding. Cape Town (South Africa) had a mass miniature radiography (MMR) screening programme from 1948 to 1994.Objective. To evaluate screening coverage, yield and secular trends in TB notifications during the MMR programme.Methods. We performed an ecological analysis of the MMR programme and TB notification data from the City of Cape Town Medical Officer of Health reports for 1948 - 1994.Results. Between 1948 and 1962, MMR screening increased to 12% of the population per annum with yields of 14 cases per 1 000 X-rays performed, accounting for >20% of total annual TB notifications. Concurrent with increasing coverage (1948 - 1965), TB case notification decreased in the most heavily TB-burdened non-European population from 844/100 000 population to 415/100 000. After 1966, coverage declined and TB notifications that initially remained stable (1967 - 1978) subsequently increased to 525/100 000. MMR yields remained low in the European population but declined rapidly in the non-European population after 1966, coincidental with forced removals from District 6. An inverse relationship between screening coverage and TB notification rates was observed in the non-European adult population. Similar secular trends occurred in infants and young children who were not part of the MMR screening programme.Conclusion. MMR of a high-burdened population may have significantly contributed to TB control and was temporally associated with decreased transmission to infants and children. These historical findings emphasise the importance of re-exploring targeted active case finding strategies as part of population TB control

Enhancement of bulk second-harmonic generation from silicon nitride films by material composition

We present a comprehensive tensorial characterization of second-harmonic generation from silicon nitride films with varying composition. The samples were fabricated using plasma-enhanced chemical vapor deposition, and the material composition was varied by the reactive gas mixture in the process. We found a six-fold enhancement between the lowest and highest second-order susceptibility, with the highest value of approximately 5 pm/V from the most silicon-rich sample. Moreover, the optical losses were found to be sufficiently small (below 6 dB/cm) for applications. The tensorial results show that all samples retain in-plane isotropy independent of silicon content, highlighting the controllability of the fabrication process.Comment: 4 pages, 3 figures, 2 tables; Re-submitted to Optics Letter

Limit behaviour of upper and lower expected time averages in discrete-time imprecise Markov chains

We study the limit behaviour of upper and lower bounds on expected time averages in imprecise Markov chains; a generalised type of Markov chain where the local dynamics, traditionally characterised by transition probabilities, are now represented by sets of ‘plausible’ transition probabilities. Our main result is a necessary and sufficient condition under which these upper and lower bounds, called upper and lower expected time averages, will converge as time progresses towards infinity to limit values that do not depend on the process’ initial state. Remarkably, our condition is considerably weaker than those needed to establish similar results for so-called limit—or steady state—upper and lower expectations, which are often used to provide approximate information about the limit behaviour of time averages as well. We show that such an approximation is sub-optimal and that it can be significantly improved by directly using upper and lower expected time averages