Polymorphic bytecode instrumentation

Bytecode instrumentation is a widely used technique to implement aspect weaving and dynamic analyses in virtual machines such as the Java virtual machine. Aspect weavers and other instrumentations are usually developed independently and combining them often requires significant engineering effort, if at all possible. In this article, we present polymorphic bytecode instrumentation(PBI), a simple but effective technique that allows dynamic dispatch amongst several, possibly independent instrumentations. PBI enables complete bytecode coverage, that is, any method with a bytecode representation can be instrumented. We illustrate further benefits of PBI with three case studies. First, we describe how PBI can be used to implement a comprehensive profiler of inter‐procedural and intra‐procedural control flow. Second, we provide an implementation of execution levels for AspectJ, which avoids infinite regression and unwanted interference between aspects. Third, we present a framework for adaptive dynamic analysis, where the analysis to be performed can be changed at runtime by the user. We assess the overhead introduced by PBI and provide thorough performance evaluations of PBI in all three case studies. We show that pure Java profilers like JP2 can, thanks to PBI, produce accurate execution profiles by covering all code, including the core Java libraries. We then demonstrate that PBI‐based execution levels are much faster than control flow pointcuts to avoid interference between aspects and that their efficient integration in a practical aspect language is possible. Finally, we report that PBI enables adaptive dynamic analysis tools that are more reactive to user inputs than existing tools that rely on dynamic aspect‐oriented programming with runtime weaving. These experiments position PBI as a widely applicable and practical approach for combining bytecode instrumentations. © 2015 The Authors. Software: Practice and Experience Published by John Wiley & Sons Ltd.     

Development of a 3D HUD using a tunable bandpass filter for wavelength multiplexing

A 3D stereoscopic head‐up display using a tunable bandpass filter to perform left and right image spectral separation is presented. Using a single filter reduces the size and the cost of the head‐up display optical engine and enables each spectral band to be accurately tuned. Experiments performed on the first prototype demonstrate the ability to continuously tune the bandpass frequency on 30‐nm range while keeping a 20‐nm bandwidth. Such a system avoids the use of a bulky and costly rotating wheel and enables the use of holographic optical elements known to be wavelength selective.     

Road‐Centered Map‐Aided Localization for Driverless Cars Using Single‐Frequency GNSS Receivers

Accurate localization with high availability is a key requirement for autonomous vehicles. It remains a major challenge when using automotive sensors such as single‐frequency Global Navigation Satellite System (GNSS) receivers, a lane detection camera, and proprioceptive sensors. This paper describes a method that enables the estimation of stand‐alone single‐frequency GNSS errors by integrating the measurements from a forward‐looking camera matched with lane markings stored in a digital map. It includes a parameter identification method for a shaping model, which is evaluated using experimental data. An algebraic observability study is then conducted to prove that the proposed state vector is fully observable in a road‐oriented frame. This observability property is the basis to develop a road‐centered Extended Kalman filter (EKF) that can maintain the observability of every component of the state vector on any road, whatever its orientation. To accomplish this, the filter needs to handle road changes, which it does using bijective transformations. The filter was implemented and tested intensely on an experimental vehicle for driverless valet parking services. Field results have shown that the performance of the estimation process is better than solutions based on EKF implemented in a fixed working frame. The proposed filter guarantees that the drift along the road direction remains bounded. This is very important when the vehicle navigates autonomously. Furthermore, the road‐centered modeling improves the accuracy, consistency, and robustness of the localization solver.     

Binding of the tautomeric forms of isoniazid-NAD adducts to the active site of the Mycobacterium tuberculosis enoyl-ACP reductase (InhA): a theoretical approach

The front-line antituberculosis drug isoniazid (INH) inhibits InhA, the NADH-dependent fatty acid biosynthesis enoyl ACP-reductase from Mycobacterium tuberculosis, via formation of covalent adducts with NAD (INH-NAD adducts). While ring tautomers were found the main species formed in solution, only the 4S chain INH-NAD tautomer was evidenced in the crystallized InhA:INH-NAD complex. In this study we attempted to explore the modes of interaction and energy binding of the different isomers placed in the active site of InhA with the help of various molecular modelling techniques. Ligand and enzyme models were generated with the help of the Vega ZZ program package. Resulting ligands were then docked into the InhA active site individually using computational automated docking package AUTODOCK 3.0.5. The more relevant docked conformations were then used to compute the interaction energy between the ligands and the InhA cavity. The AM1 Hamiltonian and the QM/MM ONIOM methodologies were used and the results compared. The various tautomers were found docked in almost the same place where INH-NAD was present as predicted by earlier X-ray crystallographic studies. However, some changes of ligand conformation and of the interactions ligand-protein were evidenced. The lower binding energy was observed for the 4S chain adduct that probably represents the effective active form of the INH-NAD adducts, as compared to the 4R epimer. The two 4S,7R and 4R,7S ring tautomers show intermediate and similar binding energies contrasting with their different experimental inhibitory potency on InhA. As a possible explanation based on calculated conformations, we formulated the hypothesis of an initial binding of the two ring tautomers to InhA followed by opening of only the ring hemiamidal 4S,7R tautomer (possibly catalyzed by Tyr158 phenolate basic group) to give the 4S chain INH-NAD tight-binding inhibitor. The predictions of ligand-protein interactions at the molecular level can be of primary importance in elucidating the mechanisms of action of isoniazid and InhA-related resistances, in identifying the effective mycobactericidal entities and, in further step, in the design of a new generation of antitubercular drugs.     

Overlapping melodic alarms are almost indiscriminable

OBJECTIVE: We explore how accurately and quickly nurses can identify melodic medical equipment alarms when no mnemonics are used, when alarms may overlap, and when concurrent tasks are performed. BACKGROUND: The international standard IEC 60601-1-8 (International Electrotechnical Commission, 2005) has proposed simple melodies to distinguish seven alarm sources. Previous studies with nonmedical participants reveal poor learning of melodic alarms and persistent confusions between some of them. The effects of domain expertise, concurrent tasks, and alarm overlaps are unknown. METHOD: Fourteen intensive care and general medical unit nurses learned the melodic alarms without mnemonics in two sessions on separate days. In the second half of Day 2 the nurses identified single alarms or pairs of alarms played in sequential, partially overlapping, or nearly completely overlapping configurations. For half the experimental blocks nurses performed a concurrent mental arithmetic task. RESULTS: Nurses' learning was poor and was no better than the learning of nonnurses in a previous study. Nurses showed the previously noted confusions between alarms. Overlapping alarms were exceptionally difficult to identify. The concurrent task affected response time but not accuracy. CONCLUSION: Because of a failure of auditory stream segregation, the melodic alarms cannot be discriminated when they overlap. Directives to sequence the sounding of alarms in medical electrical equipment must be strictly adhered to, or the alarms must redesigned to support better auditory streaming. APPLICATION: Actual or potential uses of this research include the implementation of IEC 60601-1-8 alarms in medical electrical equipment.     

Dynamic Control of Walking Cycle with Initiation Process for Humanoid Robot

This paper focuses on numerical method to solve the dynamic equilibrium of a humanoid robot during the walking cycle with the gait initiation process. It is based on a multi-chain strategy and a dynamic control/command architecture previously developed by Gorce. The strategy is based on correction of the trunk center of mass acceleration and force distribution of the forces exerced by the limbs on the trunk. This latter is performed by mean of a Linear Programming (LP) method. We study the gait initiation process when a subject, initially in quiet erect stance posture, performs a walking cycle. In this paper, we propose to adjust the method for the multiphases (from double support to single support) and multicriteria features of the studied movement. This is done by adapting some specific constraints and criteria in order to ensure the global stability of the humanoid robot along the task execution. For that, we use a Real-Time Criteria and Constraints Adaptation method. Simulation results are presented to demonstrate criteria and constraints influences on the dynamic stability.     

Dialogue in context, towards a referential approach in collective learning

In this article, we present research in the making of a collective work environment within the framework of a distance education course. We base our theoretical and methodological standpoints on examples of dialogical discourses recorded within the framework of this CSCL system called Symba. In fact, the results of previous research lead us to rethink our vision of the study of collaborative moments between participants in a computer-supported human learning environment that proposes several communication tools. Redefining the methodological process aiming at finding and understanding these rich learning moments is also necessary. We intend to describe “socio-technical” instances during which these collaboration phases appear. More generally speaking, our aim is to draw up both new theoretical and methodological perspectives that would be reusable in CSCL environments; in view of the nature of these two perspectives, and the diversity of the domain knowledge (sociology, cognitivism, linguistics, philosophy, statistics, etc.) brought to bear in the study of the environment in question, our approach constitutes a trans-disciplinary reassessment of the uses of the communication tools—and the study thereof—proposed.

Misfit versus latency

In this paper we present a framework that combines some ideas of the behavioral modeling approach and the prediction error modeling approach. It is shown that the proposed model selection procedure can be rephrased as an optimization problem that only depends on the model parameters. Experiments illustrate the potential of the so-called misfit versus latency framework.     

Phylogeny of trichomonads based on partial sequences of large subunit rRNA and on cladistic analysis of morphological data

Several domains of large subunit rRNA from nine trichomonad species have been sequenced. Molecular phylogenies obtained with parsimony and distance methods demonstrate the trichomonads are a monophyletic group which branches very early in the eukaryotic tree. The topology of the trees is in general agreement with traditional views on evolutionary and systematic relationships of trichomonads. A clear dichotomy is noted between the subfamily Trichomonadinae and the subfamily Tritrichomonadinae. In the latter subfamily, a second division separates the "Tritrichomonas muris-type" species from the "Tritrichomonas augusta-type" ones. Previous evolutionary schemes in which the Monocercomonadidae were regarded as the most "primitive" and the Trichomonadidae as more "evolved" are not in agreement with our molecular data. The emergence of Monocercomonas and Hypotrichomonas at the base of the Tritrichomonas lineage suggests a secondary loss of some cytoskeletal structures, the costa and undulating membrane in these genera. This is corroborated by the early branching position of Trichomitus, which possesses a costa and an undulating membrane and has usually been placed among the Trichomonadidae on the basis of cytological characters. A cladistic analysis was applied to the available morphological characters in order to produce a hierarchical grouping of the taxa reflecting their morphological diversity.