1. The aim of this study was to demonstrate that goal-directed pointing movements, executed at normal speed to a small visual target, but without vision of the movement, do not rely on preprogrammed commands (open-loop process); by contrast these responses are under the control of a feedback loop, which compares the ongoing response and the goal (or its internal representation). When the location of this goal is changed at the onset of the movement, an automatic correction of the path occurs. Modification of the goal was obtained by presenting a target in the peripheral visual field that the subject had to look at and point at as quickly and accurately as possible. When the orienting ocular saccade reached its peak velocity, statistically corresponding to the hand movement onset, the target was suddenly shifted 10 degrees in a random direction. This perturbation was undetected by the subject because of the absence of perception during the saccade. For the compensation to occur, the initial orientation of the movement and also its extent had to be modified. The results revealed 1) a nearly complete compensation of the movement path and a 66- to 80-ms duration lengthening; 2) relatively short reaction times to the perturbations (from 145 to 174 ms, with effective reaction times even 40 ms shorter); 3) nearly identical spatiotemporal movement characteristics to the perturbations, regardless of whether vision of the hand was allowed, suggesting that corrections were subserved by the same mechanisms. 2. The spatiotemporal characteristics of these unconscious corrections were similar to those observed in the classical double-step experiments investigating the intentional modifications of ongoing movements and suggest that they might share some common low-level mechanisms. That is, they could rely on visuokinesthetic feedback loops, which compare the updated information provided by the eye at the end of the saccade and the proprioceptive information of the end point effector (the fingertip here); they could also rely on feed-forward processes detecting the discrepancy between an efference copy of the movement and the new goal; or they could rely on a combination of those two main processes.

This paper presents an audio-visual emotion database that can be used as a reference database for testing and evaluating video, audio or joint audio-visual emotion recognition algorithms. Additional uses may include the evaluation of algorithms performing other multimodal signal processing tasks, such as multimodal person identification or audio-visual speech recognition. This paper presents the difficulties involved in the construction of such a multimodal emotion database and the different protocols that have been used to cope with these difficulties. It describes the experimental setup used for the experiments and includes a section related to the segmentation and selection of the video samples, in such a way that the database contains only video sequences carrying the desired affective information. This database is made publicly available for scientific research purposes.

Adaptive optics provides real time correction of wavefront disturbances on ground based telescopes. Optimizing control and performance is a key issue for ever more demanding instruments on ever larger telescopes affected not only by atmospheric turbulence, but also by vibrations, windshake and tracking errors. Linear Quadratic Gaussian control achieves optimal correction when provided with a temporal model of the disturbance. We present in this paper the first on-sky results of a Kalman filter based LQG control with vibration mitigation on the CANARY instrument at the Nasmyth platform of the 4.2-m William Herschel Telescope. The results demonstrate a clear improvement of performance for full LQG compared with standard integrator control, and assess the additional improvement brought by vibration filtering with a tip-tilt model identified from on-sky data, thus validating the strategy retained on the instrument SPHERE at the VLT.

Objective To improve patient safety and clinical outcomes by reducing the risk of prescribing errors, we tested the accuracy of a hybrid clinical decision support system in prioritizing prescription checks. Materials and Methods Data from electronic health records were collated over a period of 18 months. Inferred scores at a patient level (probability of a patient’s set of active orders to require a pharmacist review) were calculated using a hybrid approach (machine learning and a rule-based expert system). A clinical pharmacist analyzed randomly selected prescription orders over a 2-week period to corroborate our findings. Predicted scores were compared with the pharmacist’s review using the area under the receiving-operating characteristic curve and area under the precision-recall curve. These metrics were compared with existing tools: computerized alerts generated by a clinical decision support (CDS) system and a literature-based multicriteria query prioritization technique. Data from 10 716 individual patients (133 179 prescription orders) were used to train the algorithm on the basis of 25 features in a development dataset. Results While the pharmacist analyzed 412 individual patients (3364 prescription orders) in an independent validation dataset, the areas under the receiving-operating characteristic and precision-recall curves of our digital system were 0.81 and 0.75, respectively, thus demonstrating greater accuracy than the CDS system (0.65 and 0.56, respectively) and multicriteria query techniques (0.68 and 0.56, respectively). Discussion Our innovative digital tool was notably more accurate than existing techniques (CDS system and multicriteria query) at intercepting potential prescription errors. Conclusions By primarily targeting high-risk patients, this novel hybrid decision support system improved the accuracy and reliability of prescription checks in a hospital setting.

No abstract

The first on-sky results obtained by CANARY, the multi-object adaptive optics (MOAO) demonstrator, are analysed. The data were recorded at the William Herschel Telescope, at the end of September 2010. We describe the command and calibrations algorithms used during the run and present the observing conditions. The processed data are MOAO-loop engaged or disengaged slopes buffers, comprising the synchronised measurements of the four natural guide stars (NGS) wavefront sensors running in parallel, and near infrared (IR) images. We describe the method we use to establish the error budget of CANARY. We are able to evaluate the tomographic and the open loop errors, having median values around 216 nm and 110 nm respectively. In addition, we identify an unexpected residual quasi-static field aberration term of mean value 110 nm. We present the detailed error budget analysed for three sets of data for three different asterisms. We compare the experimental budgets with the numerically simulated ones and demonstrate a good agreement. We find also a good agreement between the computed error budget from the slope buffers and the measured Strehl ratio on the IR images, ranging between 10% and 20% at 1530 nm. These results make us confident in our ability to establish the error budget of future MOAO instruments.

We examined the interaction between the control of posture and an aiming movement. Balance control was varied by having subjects aim at a target from a seated or a standing position. The aiming difficulty was varied using a Fitts'-like paradigm (movement amplitude=30 cm; target widths=0.5, 1.0, 2.5 and 5 cm). For both postural conditions, all targets were within the reaching space in front of the subjects and kept at a fixed relative position with respect to the subjects' body. Hence, for a given target size, the aiming was differentiated only by the postural context (seated vs. upright standing). For both postural conditions, movement time (MT) followed the well-known Fitts' law, that is, it increased with a decreasing target size. For the smallest target width, however, the increased MT was greater when subjects were standing than when they were seated suggesting that the difficulty of the aiming task could not be determined solely by the target size. When standing, a coordination between the trunk and the arm was observed. Also, as the target size decreased, the center of pressure (CP) displacement increased without any increase in CP speed suggesting that the subjects were regulating their CP to provide a controlled referential to assist the hand movement. When seated, the CP kinematics was scaled with the hand movement kinematics. Increasing the index of difficulty led to a strong correlation between the hand speed and CP displacement and speed. The complex organization between posture and movement was revealed only by examining the specific interactions between speed-accuracy and postural constraints.

The capability of reprogramming movement responses following changes in the visual goal has been studied through the double-step paradigm. These studies have shown that: (a) continuous internal feedback-loops correct unconsciously the dynamic errors throughout the movement; (b) proprioceptive information and/or the efference copy have a privileged status among central processes, insuring on-line regulation of the initial motor commands; and (c) generation of the motor program starts after target presentation, and is continuously updated in the direction of the current internal representation of the target, at least until the onset of hand movement. This main corrective process of the initial program appears to be basically independent of visual reafference from the moving hand. However, the agreement with the possibility of a visuomotor loop, based on the comparison of the new updated representation of the target position and on the information from the moving hand, has not determined whether the correcting process is proprioceptive feedback dependent, or whether internal feedback-loops (efferent copies) are responsible for quick corrections of unfolding motor responses. To answer this question, the present experiment investigated the pointing behavior of a deafferented subject, using a double-step paradigm under various conditions of visual feedback and movement initiation. Overall, the present study (a) clearly showed the capacity of the motor system to modify and correct erroneous trajectories on the mere basis of internal feedback-loops and (b) emphasized the crucial role played by the target jump/arm triggering delay and the importance of the eye efferent copy for providing information about the spatial goal of the movement.