Optimizations of the naïve-Bayes classifier for the prognosis of B-Chronic Lymphocytic Leukemia incorporating flow cytometry data

Prognosis of B-Chronic Lymphocytic Leukemia (B-CLL) remains a challenging problem in medical research and practice. While the parameters obtained by flow cytometry analysis form the basis of the diagnosis of the disease, the question whether these parameters offer additional prognostic information still remains open. In this work, we attempt to provide computer-assisted support to the clinical experts of the field, by deploying a classification system for B-CLL multiparametric prognosis that combines various heterogeneous (clinical, laboratory and flow cytometry) parameters associated with the disease. For this purpose, we employ the na?ve-Bayes classifier and propose an algorithm that improves its performance. The algorithm discretizes the continuous classification attributes (candidate prognostic parameters) and selects the most useful subset of them to optimize the classification accuracy. Thus, in addition to the high classification accuracy achieved, the proposed approach also suggests the most informative parameters for the prognosis. The experimental results demonstrate that the inclusion of flow cytometry parameters in our system improves prognosis.     

Least eccentric ellipses for geometric Hermite interpolation

We present a rational Bézier solution to the geometric Hermite interpolation problem. Given two points and respective unit tangent vectors, we provide an interpolant that can reproduce a circle if possible. When the tangents permit an ellipse, we produce one that deviates least from a circle. We cast the problem as a theorem and provide its proof, and a method for determining the weights of the control points of a rational curve. Our approach targets ellipses, but we also present a cubic interpolant that can find curves with inflection points and space curves when an ellipse cannot satisfy the tangent constraints.     

Layered Working-Set Trees

The working-set bound [Sleator and Tarjan in J. ACM 32(3), 652–686, 1985] roughly states that searching for an element is fast if the element was accessed recently. Binary search trees, such as splay trees, can achieve this property in the amortized sense, while data structures that are not binary search trees are known to have this property in the worst case. We close this gap and present a binary search tree called a layered working-set tree that guarantees the working-set property in the worst case. The unified bound [B?doiu et al. in Theor. Comput. Sci. 382(2), 86–96, 2007] roughly states that searching for an element is fast if it is near (in terms of rank distance) to a recently accessed element. We show how layered working-set trees can be used to achieve the unified bound to within a small additive term in the amortized sense while maintaining in the worst case an access time that is both logarithmic and within a small multiplicative factor of the working-set bound.     

Behavioral adaptation of information systems through goal models

Customizing software to perfectly fit individual needs is becoming increasingly important in information systems engineering. Users want to be able to customize software behavior through reference to terms familiar to their diverse needs and experience. We present a requirements-driven approach to behavioral customization of software systems. Goal models are constructed to represent alternative behaviors that users can exhibit to achieve their goals. Customization information is then added to restrict the space of possibilities to those that fit specific users, contexts, or situations. Meanwhile, elements of the goal models are mapped to units of source code. This way, customization preferences posed at the requirements level are directly translated into system customizations. Our approach, which we apply to an on-line shopping cart system and an automated teller machine simulator, does not assume adoption of a particular development methodology, platform, or variability implementation technique and keeps the reasoning computation overhead from interfering with the execution of the configured application.     

Non-parametric estimate of the system function of a time-varying system

The task of identifying an unknown dynamic system is made easier with prior knowledge on its behaviour. Using a frequency domain approach, the non-parametric maximum likelihood estimator of the system function, associated with the time-dependent impulse response of a time-varying system, is constructed. This is accomplished by the use of a simple linear least squares fitting algorithm, applied to the spectral response of the system to a multisine excitation. The noise variance on the system function is estimated simultaneously, and modelling errors can be detected, as illustrated on a simulation example.     

Implementation of physical coordination training and cognitive behavioural training interventions at cleaning workplaces--secondary analyses of a randomised controlled trial

This study evaluates the implementation of physical coordination training (PCT) and cognitive behavioural training (CBTr) interventions in a randomised controlled trial at nine cleaners' workplaces. Female cleaners (n = 294) were randomised into a PCT, a CBTr or a reference (REF) group. Both 12-week interventions were performed in groups guided by an instructor. Records were kept on intervention dose (adherence) unanticipated events at the work place (context) and quality of intervention delivery (fidelity). Participant adherence was 37% in the PCT and 49% in the CBTr interventions. Optimal implementation was reached by only 6% in PCT and 42% in the CBTr. Analysis of the barriers to successful implementation indicated that the intervention process is sensitive to unanticipated events. In order to succeed in improving the health of high-risk populations such as cleaners and to correctly interpret intervention effects, more research on implementation is needed. Trial registration: ISRCTN96241850. PRACTITIONER SUMMARY: Both physical coordination training and cognitive behavioural training are potential effective workplace interventions among low educated job groups with high physical work demands. However, thorough consideration should be given to feasibility in the design of interventions. The optimal intervention should be tailored to closely match the implementation context and be robust and flexible to minimise susceptibility to changes in work organisation.     

Analysing quadratic effects of formative constructs by means of variance-based structural equation modelling

Together with the development of information systems research, there has also been increased interest in non-linear relationships between focal constructs. This article presents six Partial Least Squares-based approaches for estimating formative constructs’ quadratic effects. In addition, these approaches’ performance is tested by means of a complex Monte Carlo experiment. The experiment reveals significant and substantial differences between the approaches. In general, the performance of the hybrid approach as suggested by Wold (1982) is most convincing in terms of point estimate accuracy, statistical power, and prediction accuracy. The two-stage approach suggested by Chin et al (1996) showed almost the same performance; differences between it and the hybrid approach – although statistically significant – were unsubstantial. Based on these results, the article provides guidelines for the analysis of non-linear effects by means of variance-based structural equation modelling.     

Temporal Bayesian Knowledge Bases – Reasoning about uncertainty with temporal constraints

Time is ubiquitous. Accounting for time and its interaction with change is crucial to modeling the dynamic world, especially in domains whose study of data is sensitive to time such as in medical diagnosis, financial investment, and natural language processing, to name a few. We present a framework that incorporates both uncertainty and time in its reasoning scheme. It is based on an existing knowledge representation called Bayesian Knowledge Bases. It provides a graphical representation of knowledge, time and uncertainty, and enables probabilistic and temporal inferencing. The reasoning scheme is probabilistically sound and the fusion of temporal fragments is well defined. We will discuss some properties of this framework and introduce algorithms to ensure groundedness during the construction of the model. The framework has been applied to both artificial and real world scenarios.     

Influence of load biaxiality on the fracture load of center cracked sheets

Analysis of the problem of a plane infinite elastic body with a centrally located crack subject to uniform biaxial load along the remote outer boundaries, indicates that loads applied parallel to the crack influence the value of the critical (fracture) tensile load applied perpendicular to it, with the Poisson ratio of the material determining the characteristics of this influence. Experimental information from specially designed biaxial test programs, obtained by the authors and also from the published data of other investigators, shows that, while tensile loads parallel to the crack raise the critical value of perpendicular load for an aluminum alloy, they have a reverse effect on the critical load for plexiglass (polymethylmethacrylate or PMMA), in qualitative agreement with the predictions of the analysis.

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Résumé On analyse le problème d'un corps élastique plan infini comportant une fissure centrale soumise à une contrainte biaxiale le long de ses bords éloignés. L'analyse montre que les charges appliquées parallèlement à la fissure influencent la valeur de la contrainte critique de rupture en traction appliquée perpendiculairement à elle, les caractéristiques de cette influence étant régies par le rapport de Poisson du matériau. Des informations expérimentales venant de programme d'essais en condition biaxiale spécialement conçu et recueillies par les auteurs et par la littérature publiée par d'autres chercheurs montrent que tandis que les contraintes de traction parallèles à la fissure accroissent la valeur critique de la charge perpendiculaire dans le cas d'un alliage aluminium, elles ont un effet inverse sur la charge critique dans le cas du plexiglas (polyméthyleméthacrylate ou PMMA), ceci étant en accord qualitatif avec les prédictions de l'analyse.

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No menclature 2 crack length - (x, y), (r, ), (, ) rectangular, polar, elliptic coordinates, respectively - z x +iy, complex variable - t _jk ,e _jk components of the stress and strain tensors, respectively - T _k ,u _k ,b _k components of the surface traction, displacement and body force vectors, respectively - t _xx ,t _xy ,t _yy rectangular stress components - t ,t ,t elliptic stress components - u _x ,u _y ;u ,u rectangular and elliptic displacement components, respectively - U elastic strain energy per unit thickness - W work of forces applied to the body per unit thickness - P, V potential energies per unit thickness - surface energy per unit thickness - R bound region of thex-y plane - C ₁,C ₂ closed boundary curves ofR - , , , sectionally holomorphic functions of the complex variablez - E Young's modulus - k applied load biaxiality ratio,t _xx ()/t _yy () - stress applied to the outer boundary surface - µ elastic shear modulus - Poisson's ratio - surface energy density per unit area - (3-)/(1+) for plane stress, (3-4) for plane strain