Curves that must be retraced

We exhibit a polynomial time computable plane curve Γ that has finite length, does not intersect itself, and is smooth except at one endpoint, but has the following property. For every computable parametrization f of Γ and every positive integer m, there is some positive-length subcurve of Γ that f retraces at least m times. In contrast, every computable curve of finite length that does not intersect itself has a constant-speed (hence non-retracing) parametrization that is computable relative to the halting problem.     

Cross-domain probabilistic inference in a clinical decision support system: examples for dermatology and rheumatology

Introduction

Maintaining a large diagnostic knowledge base (KB) is a demanding task for any person or organization. Future clinical decision support system (CDSS) may rely on multiple, smaller and more focused KBs developed and maintained at different locations that work together seamlessly. A cross-domain inference tool has great clinical import and utility.

Methods

We developed a modified multi-membership Bayes formulation to facilitate the cross-domain probabilistic inferencing among KBs with overlapping diseases. Two KBs developed for evaluation were non-infectious generalized blistering diseases (GBD) and autoimmune diseases (AID). After the KBs were finalized, they were evaluated separately for validity.

Result

Ten cases from medical journal case reports were used to evaluate this “cross-domain” inference across the two KBs. The resultant non-error rate (NER) was 90%, and the average of probabilities assigned to the correct diagnosis (AVP) was 64.8% for cross-domain consultations.

Conclusion

A novel formulation is now available to deal with problems occurring in a clinical diagnostic decision support system with multi-domain KBs. The utilization of this formulation will help in the development of more integrated KBs with greater focused knowledge domains.     

User perceptions of security,convenience and usability for ebanking authentication tokens

This research compared three different two-factor methods of eBanking authentication. Three devices employing incremental security layers in the generation of one time passcodes (OTPs) were compared in a repeated-measures, controlled experiment with 50 eBanking customers. Attitudes towards usability and usage logs were taken for each experience. Comparisons of the devices in terms of overall quality, security and convenience as perceived by participants were also recorded. There were significant differences between all three methods in terms of usability measures, perceived quality, convenience and security ratings – with the perceived security ratings following a reverse order to the other measures. Almost two thirds of the participant sample chose the device they perceived the least secure as their preference. Participants were asked to use their preferred method again and tended to find their chosen device more usable. This research illustrates the usability-security trade off, where convenience, quality and usability are sacrificed when increasing layers of security are required. In their preferences, customers were driven by their attitudes towards usability and convenience rather than their perceptions of security.     

High-Throughput Screening for High Affinity Antibodies

The UCB SLAM process described here has had a positive and dramatic effect on the way we select therapeutic candidate antibodies. An example of the number of cells that can be screened using UCB SLAM is shown in Table 2. UCB previously used the hybridoma method to generate antibodies for both research and for therapy.^{[5] and [6]} This method, we believed, was not particularly amenable to automation, due to the large amount of cell culture involved in both setting up the fusion and then maintaining the hybridoma cell lines, although this approach has been adopted by others.⁷ The in vitro culture of B cells, combined with the process automation has allowed many more antibodies to be screened, with hybridoma only those B cells that have fused with the myeloma are available for screening, this is only a small proportion of the total number of B cells. UCB SLAM B cell cultures can be screened a week after they are set up compared with 2–3 weeks for hybridoma. Advances in the molecular biology have allowed us to move away from the time-consuming dilution cloning of cells to select antibodies; the antibody genes can be isolated, sequenced, and recombinant antibody transiently expressed in 2 weeks. The method does not require a species specific, myeloma cell line as a fusion partner, which means there is no constraint on B cell source species. The lack of a B cell fusion event means that a highly efficient sampling of the B cell repertoire can be achieved. We have found the process to be applicable to generating research reagents, high quality antibodies to animal target antigens.⁸ These research reagents can be raised to different target antigen epitopes than used in both in vitro and in vivo mechanistic and disease models. The research reagents are a significant aid to investigate the complex biology of our targets. The lack of species-specific fusion partners makes this approach a challenge for hybridoma, particularly when there is a need to generate antibodies to mouse and rat antigens.     

The Component Structure of a Self-Adapting Numerical Software System

Self-Adapting Numerical Software (SANS) systems aim to automate some of the laborious human decision making involved in adapting numerical algorithms to problem data, network conditions, and computational platform. In this paper we describe the structure of a SANS system that tackles automatic algorithm choice, based on dynamic inspection of the problem data. We describe the various components of such a system, and their interfaces.     

Conceptual and detailed design of an automotive engine cradle by using topology,shape, and size optimization

An automotive engine cradle supports many crucial components and systems, such as an engine, transmission, and suspension. Important performance measures for the design of an engine cradle include stiffness, natural frequency, and durability, while minimizing weight is of primary concern. This paper presents an effective and efficient methodology for engine cradle design from conceptual design to detailed design using design optimization. First, topology optimization was applied on a solid model which only contains the possible engine cradle design space, and an optimum conceptual design was determined which minimizes weight while satisfying all stiffness constraints. Based on topology optimization results, a design review was conducted, and a revised model was created which addresses all structural and manufacturability concerns. Shape and size optimization was then performed in the detailed design stage to further minimize the mass while meeting the stiffness and natural frequency targets. Lastly, the final design was validated for durability. The initial design domain had the mass of 82.6 kg; topology optimization in conceptual design reduced the mass to 26.7 kg; and the detailed design task involving shape and size optimization further reduced the mass to 21.4 kg.     

Latent features in similarity judgments: a nonparametric bayesian approach

One of the central problems in cognitive science is determining the mental representations that underlie human inferences. Solutions to this problem often rely on the analysis of subjective similarity judgments, on the assumption that recognizing likenesses between people, objects, and events is crucial to everyday inference. One such solution is provided by the additive clustering model, which is widely used to infer the features of a set of stimuli from their similarities, on the assumption that similarity is a weighted linear function of common features. Existing approaches for implementing additive clustering often lack a complete framework for statistical inference, particularly with respect to choosing the number of features. To address these problems, this article develops a fully Bayesian formulation of the additive clustering model, using methods from nonparametric Bayesian statistics to allow the number of features to vary. We use this to explore several approaches to parameter estimation, showing that the nonparametric Bayesian approach provides a straightforward way to obtain estimates of both the number of features and their importance.     

Office workers' computer use patterns are associated with workplace stressors

This field study examined associations between workplace stressors and office workers' computer use patterns. We collected keyboard and mouse activities of 93 office workers (68F, 25M) for approximately two work weeks. Linear regression analyses examined the associations between self-reported effort, reward, overcommitment, and perceived stress and software-recorded computer use duration, number of short and long computer breaks, and pace of input device usage. Daily duration of computer use was, on average, 30 min longer for workers with high compared to low levels of overcommitment and perceived stress. The number of short computer breaks (30 s–5 min long) was approximately 20% lower for those with high compared to low effort and for those with low compared to high reward. These outcomes support the hypothesis that office workers' computer use patterns vary across individuals with different levels of workplace stressors.     

Different computer tasks affect the exposure of the upper extremity to biomechanical risk factors

In order to determine differences in biomechanical risk factors across computer tasks, a repeated measures laboratory experiment was completed with 30 touch-typing adults (15 females and 15 males). The participants completed five different computer tasks: typing text, completing an html-based form with text fields, editing text within a document, sorting and resizing objects in a graphics task and browsing and navigating a series of intranet web pages. Electrogoniometers and inclinometers measured wrist and upper arm postures, surface electromyography measured muscle activity of four forearm muscles and three shoulder muscles and a force platform under the keyboard and force-sensing computer mouse measured applied forces. Keyboard-intensive tasks were associated with less neutral wrist postures, larger wrist velocities and accelerations and larger dynamic forearm muscle activity. Mouse-intensive tasks (graphics and intranet web page browsing) were associated with less neutral shoulder postures and less variability in forearm muscle activity. Tasks containing a mixture of mouse and keyboard use (form completion and text editing) were associated with higher shoulder muscle activity, larger range of motion and larger velocities and accelerations of the upper arm. Comparing different types of computer work demonstrates that mouse use is prevalent in most computer tasks and is associated with more constrained and non-neutral postures of the wrist and shoulder compared to keyboarding.