399 research outputs found

    Intersegmental Coordination in the Kinematics of Prehension Movements of Macaques

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    The most popular model to explain how prehensile movements are organized assumes that they comprise two "components", the reaching component encoding information regarding the object's spatial location and the grasping component encoding information on the object's intrinsic properties such as size and shape. Comparative kinematic studies on grasping behavior in the humans and in macaques have been carried out to investigate the similarities and differences existing across the two species. Although these studies seem to favor the hypothesis that macaques and humans share a number of kinematic features it remains unclear how the reaching and grasping components are coordinated during prehension movements in free-ranging macaque monkeys. Twelve hours of video footage was filmed of the monkeys as they snatched food items from one another (i.e., snatching) or collect them in the absence of competitors (i.e., unconstrained). The video samples were analyzed frame-by-frame using digitization techniques developed to perform two-dimensional post-hoc kinematic analyses of the two types of actions. The results indicate that only for the snatching condition when the reaching variability increased there was an increase in the amplitude of maximum grip aperture. Besides, the start of a break-point along the deceleration phase of the velocity profile correlated with the time at which maximum grip aperture occurred. These findings suggest that macaques can spatially and temporally couple the reaching and the grasping components when there is pressure to act quickly. They offer a substantial contribution to the debate about the nature of how prehensile actions are programmed

    Classification of uranium ore concentrates applying support vector machine to spectrophotometric and textural features

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    Uranium ore concentrates (UOCs) are produced in the early stages of the nuclear fuel cycle, prior to conversion to uranium hexafluoride. Because of their high uranium content and the large-scale production, UOCs diversion from civilian use and proliferation are potential risks. This implies the necessity to develop methods able to recognise characteristic parameters correlating each UOC powder to its history and origin. Here, a novel methodology is proposed: first the reflectance spectra of 79 commercial UOCs are acquired and clustered by means of Ward\u27s clustering analysis, then classified by Support Vector Machine (SVM). Second, SVM classification is applied to the image textural features extracted with the Grey Level Co-occurrence Matrix (GLCM) and the Angle Measure Technique (AMT) algorithms for powders in two different colour groups. The developed SVM models present good classification quality: a Matthews correlation coefficient (MCC) of 0.95 is obtained for the classification based on colours while macro-F1 is generally greater than 0.81 (MCC larger than 0.75) for the texture-based classification. These results reveal the potentiality of the present automated classification for the scopes of nuclear forensics in the identification of an unknown uranium ore concentrate sample

    Developmental profiles of young children with autism spectrum disorder and global developmental delay: A study with the Griffiths III scales

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    The purpose of this study was to identify developmental profiles associated with autism spectrum disorder (ASD) and global developmental delay (DD) in pre-school aged Italian children. Developmental profiles were evaluated by means of a standardized tool widely used for the assessment of psychomotor development in early childhood, the Griffiths III scales, recently adapted and standardized for the Italian population. Specifically, we compared the Griffiths III profiles of children with ASD and DD (ASD + DD) with those of children with DD alone. Moreover, we inspected the psychometric function of single items by comparing children with ASD + DD and children with DD with typically developing (TD) children from the Griffiths III normative sample. In this way, we aimed to isolate the effects of each diagnostic class on psychomotor abilities and on the psychometric function of single items. The ASD + DD and DD groups were found to share the presence of lower age equivalent scores relative to their chronological age in all the developmental domains considered: Foundations of Learning, Language and Communication, Eye and Hand Coordination, Personal–Social-Emotional and Gross Motor Skills. However, the DD group displayed a homogeneous profile with similar levels of delay in all developmental domains, while children with ASD + DD exhibited relative weaknesses in the Language and Communication and Personal–Social-Emotional scales. The analysis of the psychometric function drawn for each item has confirmed different profiles in social-communicative and non-verbal items between the two diagnostic groups and in relation to TD normative sample. The Griffiths III is a valid psychometric tool for identifying atypical developmental profiles and its use may be recommended during the diagnostic process of ASD and DD, to detect specific strengths and weaknesses and guide person-centered treatment

    Response of Silicon photo-multipliers to a constant light flux

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    The response of a Silicon Photomultiplier to a constant illumination has been interpreted in term of Geiger- Mueller avalanche frequency, actually correlated to the photon flux via the photon detection efficiency. The hypothesis has been verified in laboratory tests and applied throughout the development of a device for real-time dosimetry in mammography

    The SMILING project : prevention of falls by a mechatronic training device

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    Ageing is characterized by functional changes that can create gait and balance disturbances, which are the main risk factors of falling. Elderly people at risk of falling can be considered to be suffering from an involuntary motor behaviour that restricts their participation in society. One method to overcome such a situation is to activate a new learning process to train for real life tasks, which represents innovation. The SMILING system is intended to challenge the elderly to solve new problems in real time by inducing variable environments that need active response and problem solving. Variable environments induced by perturbations will weaken stiff motor behaviour(s), induce flexibility and thus enable effective training and improve mobility in real life environments. The SMILING solution provides a changeable yet safe environment that needs active response and problem solving by the user. It consists of a wearable non-invasive computer-controlled system that applies chaotic perturbations to the lower extremities during walking through small alterations of the height and slope of weight-bearing surfaces. The complete system consists of 3 modules: i) a complete walking analysis system; ii) a pair of motorised training shoes; iii) a user friendly portable control unit

    Performance of the EUDET-type beam telescopes

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    Test beam measurements at the test beam facilities of DESY have been conducted to characterise the performance of the EUDET-type beam telescopes originally developed within the EUDET project. The beam telescopes are equipped with six sensor planes using MIMOSA26 monolithic active pixel devices. A programmable Trigger Logic Unit provides trigger logic and time stamp information on particle passage. Both data acquisition framework and offline reconstruction software packages are available. User devices are easily integrable into the data acquisition framework via predefined interfaces. The biased residual distribution is studied as a function of the beam energy, plane spacing and sensor threshold. Its standard deviation at the two centre pixel planes using all six planes for tracking in a 6\,GeV electron/positron-beam is measured to be (2.88\,\pm\,0.08)\,\upmu\meter.Iterative track fits using the formalism of General Broken Lines are performed to estimate the intrinsic resolution of the individual pixel planes. The mean intrinsic resolution over the six sensors used is found to be (3.24\,\pm\,0.09)\,\upmu\meter.With a 5\,GeV electron/positron beam, the track resolution halfway between the two inner pixel planes using an equidistant plane spacing of 20\,mm is estimated to (1.83\,\pm\,0.03)\,\upmu\meter assuming the measured intrinsic resolution. Towards lower beam energies the track resolution deteriorates due to increasing multiple scattering. Threshold studies show an optimal working point of the MIMOSA26 sensors at a sensor threshold of between five and six times their RMS noise. Measurements at different plane spacings are used to calibrate the amount of multiple scattering in the material traversed and allow for corrections to the predicted angular scattering for electron beams

    Endoscopic resection of sinonasal inverted papilloma: a multivariate retrospective analysis of factors affecting recurrence and persistence

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    Sinonasal inverted papilloma (IP) is the most common benign epithelial tumor in the nasal cavity and paranasal sinuses, with a worldwide incidence between 0.6 and 1.5/100 000 persons per year. However, only a few studies have investigated patient-dependent factors related to IP recurrence and persistence. According to available evidence, these factors are still debated, and results are contradictory. In this multicenter retrospective study, we analyzed the clinical records of 130 patients who were surgically treated for sinonasal IP to evaluate the factors affecting recurrence and persistence of IP and compared the curative rates of different surgical approaches. Our analysis showed that IP recurrence is strongly related to specific risk factors including incomplete surgical removal, stage of disease, site of the lesion, surgical technique, and malignancy rate. In conclusion, the recurrence of IP may be affected by several risk factors; these factors must be carefully considered during clinical evaluation and especially during the follow-up of patients with IP

    Recent progress of the ATLAS Planar Pixel Sensor R&D Project

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    The foreseen luminosity upgrade for the LHC (a factor of 5-10 more in peak luminosity by 2021) poses serious constraints on the technology for the ATLAS tracker in this High Luminosity era (HL-LHC). In fact, such luminosity increase leads to increased occupancy and radiation damage of the tracking detectors. To investigate the suitability of pixel sensors using the proven planar technology for the upgraded tracker, the ATLAS Planar Pixel Sensor R&D Project was established comprising 17 institutes and more than 80 scientists. Main areas of research are the performance of planar pixel sensors at highest fluences, the exploration of possibilities for cost reduction to enable the instrumentation of large areas, the achievement of slim or active edge designs to provide low geometric inefficiencies without the need for shingling of modules and the investigation of the operation of highly irradiated sensors at low thresholds to increase the efficiency. In the following I will present results from the group, concerning mainly irradiated-devices performance, together with studies for new sensors, including detailed simulations.Comment: 9 pages,12 figure

    Flexible control of movement in plants

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    Although plants are essentially sessile in nature, these organisms are very much in tune with their environment and are capable of a variety of movements. This may come as a surprise to many non-botanists, but not to Charles Darwin, who reported that plants do produce movements. Following Darwin\u2019s specific interest on climbing plants, this paper will focus on the attachment mechanisms by the tendrils. We draw attention to an unsolved problem in available literature: whether during the approach phase the tendrils of climbing plants consider the structure of the support they intend to grasp and plan the movement accordingly ahead of time. Here we report the first empirical evidence that this might be the case. The three-dimensional (3D) kinematic analysis of a climbing plant (Pisum sativum L.) demonstrates that the plant not only perceives the support, but it scales the kinematics of tendrils\u2019 aperture according to its thickness. When the same support is represented in two-dimensions (2D), and thus unclimbable, there is no evidence for such scaling. In these circumstances the tendrils\u2019 kinematics resemble those observed for the condition in which no support was offered. We discuss these data in light of the evidence suggesting that plants are equipped with sensory mechanisms able to provide the necessary information to plan and control a movement
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