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As a developing discipline, research results in the field of human computer interaction (HCI) tends to be "soft". Many workers in the field have argued that the advancement of HCI lies in "hardening" the field with quantitative and robust models. In reality, few theoretical, quantitative tools are available in user interface research and development. A rare exception to this is Fitts' law. Extending information theory to human perceptual-motor system, Paul Fitts (1954) found a logarithmic relationship that models speed accuracy tradeoffs in aimed movements. A great number of studies have verified and / or applied Fitts' law to HCI problems, such as pointing performance on a screen, making Fitts' law one of the most intensively studied topic in the HCI literature.

Article Free Access Share on Beyond Fitts' law: models for trajectory-based HCI tasks Authors: Johnny Accot Centre d'Études de la, Navigation Aérienne, 7 avenue Edouard Belin, 31055 Toulouse cedex, France and Input Research Group, CSRI, University of Toronto, Toronto, ON M5S 1A4, Canada Centre d'Études de la, Navigation Aérienne, 7 avenue Edouard Belin, 31055 Toulouse cedex, France and Input Research Group, CSRI, University of Toronto, Toronto, ON M5S 1A4, CanadaView Profile , Shumin Zhai Input Research Group, CSRI, University of Toronto, Toronto, ON M5S 1A4, Canada and IBM Almaden, Research Center, 650 Harry Road, San Jose, CA Input Research Group, CSRI, University of Toronto, Toronto, ON M5S 1A4, Canada and IBM Almaden, Research Center, 650 Harry Road, San Jose, CAView Profile Authors Info & Claims CHI '97: Proceedings of the ACM SIGCHI Conference on Human factors in computing systemsMarch 1997 Pages 295–302https://doi.org/10.1145/258549.258760Published:27 March 1997Publication History 328citation6,971DownloadsMetricsTotal Citations328Total Downloads6,971Last 12 Months602Last 6 weeks96 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

Chronic inflammatory diseases are associated with increases in cardiovascular diseases (CVD) and subclinical atherosclerosis as well as early-stage endothelial dysfunction screening using the FMD method (Flow Mediated Dilation). This phenomenon, referred to as accelerated pathological remodeling of arterial wall, could be attributed to traditional risk factors associated with atherosclerosis. Several new non-invasive techniques have been used to study arterial wall's structural and functional alterations. These techniques (based of Radio Frequency, RF) allow for an assessment of artery age through calculations of intima-media thickness (RF- QIMT), pulse wave rate (RF- QAS) and endothelial dysfunction degree (FMD). The inflammatory and autoimmune diseases should now be considered as new cardiovascular risk factors, result of the major consequences of oxidative stress and RAS (Renin Angiotensin System) imbalance associated with the deleterious effect of known risk factors that lead to the alteration of the arterial wall. Inflammation plays a key role in all stages of the formation of vascular lesions maintained and exacerbated by the risk factors. The consequence of chronic inflammation is endothelial dysfunction that sets in and we can define it as an integrated marker of the damage to arterial walls by classic risk factors. The atherosclerosis, which develops among these patients, is the main cause for cardiovascular morbi-mortality and uncontrolled chronic biological inflammation, which quickly favors endothelial dysfunction. These inflammatory and autoimmune diseases should now be considered as new cardiovascular risk factors.

Human-computer interaction is multidisciplinary, drawing paradi~ar$ techniques from both the natural sciences and the design disciplines. HCI cannot be considered a pure natural science because it studies the interaction betweett people and artificiaUy-created artifacts, rather than naturallyoccurring phenomena, which violates several basic assumptions of naturat seienee. Similarly,HCI cannot be eortsidered a pure design discipline because it strives to independently verify design decisions and processes, and borrows many value-s from scientists.

Interaction tasks on a computer screen can technically be scaled to a much larger or much smaller sized input control area by adjusting the input device's control gain or the control-display (C-D) ratio. However, human performance as a function of movement scale is not a well concluded topic. This study introduces a new task paradigm to study the scale effect in the framework of the steering law. The results confirmed a U-shaped performance-scale function and rejected straight-line or no-effect hypotheses in the literature. We found a significant scale effect in path steering performance, although its impact was less than that of the steering law's index of difficulty. We analyzed the scale effects in two plausible causes: movement joints shift and motor precision limitation. The theoretical implications of the scale effects to the validity of the steering law, and the practical implications of input device size and zooming functions are discussed in the paper.

The FRIENDS system developed at LAAS-CNRS is a metalevel architecture providing libraries of metaobjects for fault tolerance, secure communication, and group-based distributed applications. The use of metaobjects provides a nice separation of concerns between mechanisms and applications. Metaobjects can be used transparently by applications and can be composed according to the needs of a given application, a given architecture, and its underlying properties. In FRIENDS, metaobjects are used recursively to add new properties to applications. They are designed using an object oriented design method and implemented on top of basic system services. This paper describes the FRIENDS software-based architecture, the object-oriented development of metaobjects, the experiments that we have done, and summarizes the advantages and drawbacks of a metaobject approach for building fault-tolerant systems.

Energy transfers between modes obtained from the proper orthogonal decomposition (POD) of a turbulent flow past a backward-facing step are analysed with the aim of providing guidelines for modelling unresolved modes in truncated POD–Galerkin models. It is observed that energy transfers are local in the POD basis, and that the Fourier-decomposition-based concepts of forward and backward energy cascades are also valid in the POD basis, the net effect being a forward energy cascade. General features of the eddy-viscosity representation of kinetic energy transfers are investigated through a priori tests. It is observed that the ideal eddy-viscosity model should exhibit a cusp behaviour near the cutoff mode.

presents the coding and part six give several numerical applications.

In this article, we present mathematical modeling for en route conflict resolution, discuss the mathematical complexity of this problem, and show that classical mathematical optimization techniques are not suited to solve it. Instead, a stochastic optimization algorithm based on genetic techniques is presented. This algorithm can find many different nearly optimal solutions in real time, even in very complex situations involving many aircraft. Different examples of resolution with highly loaded traffic are presented and the results of the solver on an air traffic controller simulation prototype with real flight plans are evaluated. Limitations of the system and possible improvements are discussed. © 1996 John Wiley & Sons, Inc.

Field observations and focused interviews of Air Traffic Controllers have been used to generate a list of key complexity factors in Air Traffic Control. The underlying structure of the airspace was identified as relevant in many of the factors. A preliminary investigation has revealed that the structure appears to form the basis for abstractions that reduce the difficulty of maintaining Situational Awareness, particularly the projection of future traffic situations. Three examples of such abstractions were identified: standard flows, groupings, and critical points. Preliminary approaches to developing metrics including these structural considerations are discussed.

Episodic memory impairment is a hallmark for early diagnosis of Alzheimer's disease. Most actual tests used to diagnose Alzheimer's disease do not assess the spatiotemporal properties of episodic memory and lead to false-positive or -negative diagnosis. We used a newly developed, nonverbal navigation test for Human, based on the objective experimental testing of a spatiotemporal experience, to differentially Alzheimer's disease at the mild stage (N = 16 patients) from frontotemporal lobar degeneration (N = 11 patients) and normal aging (N = 24 subjects). Comparing navigation parameters and standard neuropsychological tests, temporal order memory appeared to have the highest predictive power for mild Alzheimer's disease diagnosis versus frontotemporal lobar degeneration and normal aging. This test was also nonredundant with classical neuropsychological tests. As a conclusion, our results suggest that temporal order memory tested in a spatial navigation task may provide a selective behavioral marker of Alzheimer's disease.

Abstract A new zonal multi‐domain Reynolds averaged numerical simulation/large‐Eddy simulation (RANS/LES) method is presented and assessed. The main occurring problem is the coupling at the domain interfaces between a 1D or 2D, ensemble averaged solution computed with the RANS approach with the 3D, filtered, unsteady solution obtained using the LES approach. Both low‐ and high‐normal velocity interface cases are considered, resulting in a fully general approach. A coupling procedure well suited for cell‐centred finite volume numerical method is proposed. Numerical tests are carried out for the plane channel and the plane plate with a blunt trailing‐edge configurations. Copyright © 2002 John Wiley & Sons, Ltd.

The visual responses of neurons in the primary visual cortex (V1) are influenced by the animal's position in the environment [1-5]. V1 responses encode positions that co-fluctuate with those encoded by place cells in hippocampal area CA1 [2, 5]. This correlation might reflect a common influence of non-visual spatial signals on both areas. Place cells in CA1, indeed, do not rely only on vision; their place preference depends on the physical distance traveled [6-11] and on the phase of the 6-9 Hz theta oscillation [12, 13]. Are V1 responses similarly influenced by these non-visual factors? We recorded V1 and CA1 neurons simultaneously while mice performed a spatial task in a virtual corridor by running on a wheel and licking at a reward location. By changing the gain that couples the wheel movement to the virtual environment, we found that ∼20% of V1 neurons were influenced by the physical distance traveled, as were ∼40% of CA1 place cells. Moreover, the firing rate of ∼24% of V1 neurons was modulated by the phase of theta oscillations recorded in CA1 and the response profiles of ∼7% of V1 neurons shifted spatially across the theta cycle, analogous to the phase precession observed in ∼37% of CA1 place cells. The influence of theta oscillations on V1 responses was more prominent in putative layer 6. These results reveal that, in a familiar environment, sensory processing in V1 is modulated by the key non-visual signals that influence spatial coding in the hippocampus.

How do we translate self-motion into goal-directed actions? Here we investigate the cognitive architecture underlying self-motion processing during exploration and goal-directed behaviour. The task, performed in an environment with limited and ambiguous external landmarks, constrained mice to use self-motion based information for sequence-based navigation. The post-behavioural analysis combined brain network characterization based on c-Fos imaging and graph theory analysis as well as computational modelling of the learning process. The study revealed a widespread network centred around the cerebral cortex and basal ganglia during the exploration phase, while a network dominated by hippocampal and cerebellar activity appeared to sustain sequence-based navigation. The learning process could be modelled by an algorithm combining memory of past actions and model-free reinforcement learning, which parameters pointed toward a central role of hippocampal and cerebellar structures for learning to translate self-motion into a sequence of goal-directed actions.

Array processing is a powerful tool to extract the noise source characteristics from the acoustic signals measured during wind-tunnels tests. For many years, this measurement technology is commonly being used to study airframe noise. Conventional beam forming methods have proven their efficiency in source localization, but it is well known that they are limited in the estimation of the power levels of extended sources. An approach based on a spectral estimation method (SEM) is proposed in order to determine the actual sound-pressure levels of the acoustic sources found by the localization method. The SEM is based on the array cross-spectral matrix, which contains an indirect measurement of the source power levels of interest and on a modeling of this matrix. Optimal estimates of the actual source power levels can be obtained by minimizing the mean square error between the measurement and model matrices. However, the direct minimization suffers from the sensitivity to noise inherent in the ill-posed nature of the problem. To obtain meaningful results, the problem is regularized by using a priori information. Numerical simulations involving multiple source areas are provided to illustrate the effectiveness of the estimation procedure. The method is successfully applied to compute the power levels of the main sources on a 1/11th-scaled model of the Airbus A320/A321 tested in CEPRA 19 wind tunnel. Nomenclature C mes,n (τ) = cross correlation between p mes (t) and p mes (t) C mod,n (τ) = cross correlation between p mod (t) and p mod (t) c

We present in this survey new technologies proposed for the evolution of the aeronautical communication infrastructure. Motivated by studies that estimate the growth of air traffic flow, it was decided to develop a future communication infrastructure (FCI) adapted to the future aeronautical scenario. The FCI development involves researchers, industrials, and aeronautical authorities from many countries around the world, and started in 2004. The L-band Digital Aeronautical Communication System (L-DACS) is the part of the FCI that will be in charge of continental communication. The L-DACS is being developed in Europe since 2007 and two candidates were preselected: L-DACS1 and L-DACS2. In this paper, we first describe the motivations of the FCI. We then give an overview of its development activities from 2004 to 2009. After that, we provide some insights about both preselected L-DACS candidates, at their physical and medium access layers. Finally, we address the challenges on the development of the FCI/L-DACS.

This paper aims at clarifying the articulation between the task models and system models encountered in CHI design practices. We demonstrate how the use of a formal task model may enhance the design of interactive systems, by providing quantitative results on which designers may base their decisions. We also demonstrate that it is possible to describe both task and system models within the same formal framework. This enables us firstly to formally prove that task and system models comply with each other, and secondly to perform quantitative analysis on the combination of task and system models. The approach is illustrated by a toy example which, despite its small size, allows us to develop both task and device models, and to perform several iterations of the design process. The device and tasks are modelled using the Interactive Cooperative Objects (ICO) formalism, which is based on Petri nets and on the object-oriented approach. The formality of Petri nets allows for axiomatic validation of isolated and interacting subsystems.

Abstract A new multi‐domain/multi‐resolution method is presented in the framework of the large‐eddy simulation (LES). The proposed treatment at the interfaces is conceived to deal with the problem of discontinuities on the characteristic length scales met in the case of two domains having different resolutions. It gives rise to an original approach taking into account not only the discontinuous aspect on the flow fields values but also, consequently, the non‐conservative aspect of transfer of fluxes through the interfaces. This new treatment at the interfaces has been assessed successfully in the case of a subsonic compressible channel flow. Copyright © 2001 John Wiley & Sons, Ltd.

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In this paper, we develop bounds on the distribution function of the empirical mean for general ergodic Markov processes having a spectral gap. Our approach is based on the perturbation theory for linear operators, following the technique introduced by Gillman.