No interference of task complexity with circadian rhythmicity in a constant routine protocol

Time course in task performance has been studied extensively. In particular, the investigation of circadian rhythmicity in task performance that varied in complexity. However, these studies disclosed heterogeneous outcomes. This could be the result of confounding exogenous factors, the use of diverse tasks, as well as accumulating sleepiness interfering with the underlying circadian drive. The present study varied task demands systematically within a single task and a dual task, using a constant routine protocol to examine the unmasked influence of the endogenous circadian oscillator on the periodicity of performance. Moreover, the subjects were divided into an early-start and a late-start group to estimate the potential interaction of circadian rhythmicity with the duration of prior wakefulness. The results revealed a distinct congruence in the circadian rhythms of all performance measures, with which prior wakefulness (< 40 h) did not interact. Also, single-task as well as dual-task complexity did not interfere with circadian rhythmicity. In conclusion, when sufficiently controlled for masking exogenous factors, task complexity is removed from the underlying circadian rhythms.     

Customising agile methods to software practices at Intel Shannon

Tailoring of methods is commonplace in the vast majority of software development projects and organisations. However, there is not much known about the tailoring and engineering of agile methods, or about how these methods can be used to complement each other. This study investigated tailoring of the agile methods, eXtreme programming (XP) and Scrum, at Intel Shannon, and involved experienced software engineers who continuously monitored and reflected on these methods over a 3-year period. The study shows that agile methods may individually be incomplete in supporting the overall development process, but XP and Scrum complement each other well, with XP providing support for technical aspects and Scrum providing support for project planning and tracking. The principles of XP and Scrum were carefully selected (only six of the 12 XP key practices were implemented, for example) and tailored to suit the needs of the development environment at Intel Shannon. Thus, the study refutes the suggestion that agile methods are not divisible or individually selectable but achieve their benefits through the synergistic combination of individual agile practices; rather, this study shows that an a la carte selection and tailoring of practices can work very well. In the case of Scrum, some local tailoring has led to a very committed usage by developers, in contrast to many development methods whose usage is limited despite being decreed mandatory by management. The agile practices that were applied did lead to significant benefits, including reductions in code defect density by a factor of 7. Projects of 6-month and 1-year duration have been delivered ahead of schedule, which bodes well for future ability to accurately plan development projects.     

Cobra: a light-weight tool for static and dynamic program analysis

Static source code analysis tools have become indispensable for the development of reliable software applications. The best analyzers can reveal subtle flaws in a code base, but they can also be slow. In part this is due to the collection of detailed information about the possible data and control flow of an application to support the broadest possible range of analyses. For larger code bases it is not unusual that even the best of breed static analyzers can take an hour or more to complete an analysis. In this paper we describe a framework for a much faster, but more light-weight type of static analysis that can support interactive use for standard types of queries. The Cobra tool we designed for this purpose can scale to explore millions of lines of code interactively. The tool is mostly language agnostic, and can therefore easily be configured to resolve even dynamic program analysis queries.     

Provision and maintenance of presence and immersion in hand‐held virtual reality through motion based interaction

Hand‐held devices are also becoming computationally more powerful and being equipped with special sensors and non‐traditional displays for diverse applications aside from just making phone calls. As such, it raises the question of whether realizing virtual reality, providing a minimum level of immersion and presence, might be possible on a hand‐held device capable of only relatively “small” display. In this paper, we propose that motion based interaction can widen the perceived field of view (FOV) more than the actual physical FOV, and in turn, increase the sense of presence and immersion up to a level comparable to that of a desktop or projection display based VR systems. We have implemented a prototype hand‐held VR platform and conducted two experiments to verify our hypothesis. Our experimental study has revealed that when a motion based interaction was used, the FOV perceived by the user for the small hand held device was significantly greater than (around 50%) the actual. Other larger display platforms using the conventional button or mouse/keyboard interface did not exhibit such a phenomenon. In addition, the level of user felt presence in the hand‐held platform was higher than or comparable to those in VR platforms with larger displays. We hypothesize that this phenomenon is related to and analogous to the way the human vision system compensates for differences in acuity resolution in the eye/retina through the saccadic activity. The paper demonstrates the distinct possibility of realizing reasonable virtual reality even with devices with a small visual FOV and limited processing power. Copyright © 2010 John Wiley & Sons, Ltd.     

WTFM, software for well test analysis in fractured media combining fractional flow with double porosity and leakance approaches

The identification of the hydraulic characteristics and transport properties of fractured reservoirs requires the development of specific models that account for (i) the medium heterogeneity, e.g. the presence of major conductive fractures that delimit capacitive matrix blocks, with weakly open, dead end or isolated fractures, and (ii) for the geometrical arrangement of the major conductive fractures network, which dominates the flow at the scale of the well tests.Well Tests in Fractured Media (WTFM) software takes into account these two main features by combining radial flow generalized to fractional dimension, with the theory of double-porosity, including diffusivity in the second porosity, transient inter-porosity flow and inter-porosity skin effect, and with leakance. The implementation of this nD model, with n fractional, extends usefully the domain of application of the usual 1D/2D/3D double-porosity/leakance models for a large range of connection levels of fracture networks. Although the fractures geometry and properties are not considered one by one, or by directional families, they are taken into account by averaged properties and by the impact that the whole network has on the hydrodynamic behaviour. The accuracy of the coupled transient behaviours analysis is augmented by taking into account wellbore storage and skin effects. All together, the use of these different options allows matching a wide range of pumping test curves, characteristics of distinctive behaviours, with a limited number of parameters. Distinctive well test experiments, in both sedimentary and crystalline rocks, are presented for enlightening how the pertinent use of the model options improves predictions.     

Using DAG Transformations to Verify Euler/Venn Homogeneous and Euler/Venn FOL Heterogeneous Rules of Inference

In this paper we will present a graph-transformation based method for the verification of heterogeneous first order logic (FOL) and Euler/Venn proofs. It has been shown that a special collection of directed acyclic graphs (DAGs) can be used interchangeably with Euler/Venn diagrams in reasoning processes [4]. Thus, proofs which include Euler/Venn diagrams can be thought of as proofs with DAGs where steps involving only Euler/Venn diagrams can be treated as particular DAG transformations. In the work reported here, we will show how the characterization of these manipulations can be used to verify Euler/Venn proofs. Also, a method for verifying the use of heterogeneous Euler/Venn and FOL reasoning rules will be presented that is also based upon DAG transformations.     

A Review of the Effectiveness of CPS Training: A Focus on Workplace Issues

A major focus within the field of creativity has been on the development of methodologies aimed at deliberately nurturing creative thinking. These methodologies have attempted to mirror the creative process in ways that allow individuals and groups to explicitly call on and employ their creative faculties. In an attempt to uplift employees’ creative capabilities many of these methodologies have been introduced into organizations through training programs, as well as through application to business challenges. Do these methods work? What is the empirical evidence that these deliberate creative process methods enhance employees’ creativity? Though there are a handful of creative process methods, few have married the concern for application with an interest in demonstrating the benefits of these applied efforts through systematic research. Creative Problem Solving (CPS), one of the more popular creative process models, has been one of the rare exceptions. The purpose of this paper is to synthesize the research literature that reports on the impact of CPS training carried out within organizational contexts, that is training programs that involved professionals or students working on real business challenges. Additionally, the positive benefits of CPS are further examined through reports that cite the outcomes of applying CPS to business challenges. In a field replete with methods that have been commercialized, it is imperative to strike a balance between research and practice as an imbalance towards practice may foster a field dominated by individuals who offer untested products and services.     

Bullwhip reduction for ARMA demand: The proportional order-up-to policy versus the full-state-feedback policy

A ‘proportional’ order-up-to policy reacting to ARMA demand is analyzed using stochastic optimal control theory. This policy is compared with a full-state-feedback order-up-to policy. Necessary conditions for an optimum of a weighted sum of the inventory and the ordering variances for both policies are formulated. Based on this a relatively simple expression for the ‘full-state’ policy is derived. The comparison between the two policies demonstrates that the ‘intuitively’ designed proportional policy does not fulfill the objective of controlling both the inventory and ordering variance for all parameter values of the demand model as well as the full-state-feedback policy. The full-state-feedback policy outperforms the proportional policy in several aspects.