963 research outputs found

    Vision-Based Hazard Detection with Artificial Neural Networks for Autonomous Planetary Landing

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    In this paper a hazard detection and landing site selection algorithm, based on a single, visible light, camera acquisition, processed by Artificial Neural Networks (ANNs), is presented. The system is sufficiently light to run onboard a spacecraft during the landing phase of a planetary exploration mission. Unsafe terrain items are detected and arranged in a hazard map, exploited to select the best place to land, in terms of safety, guidance constraints and scientific interest. A set of statistical indexes is extracted from the raw frame, progressively at different scales in order to characterize features of different size and depth. Then, a set of feed-forward ANNs interprets these parameters to produce a hazard map, exploited to select a new target landing site. Validation is carried out by the application of the algorithm to images not considered during the training phase. Landing sites maps are compared to ground-truth solution, and performances are assessed in terms of false positives ratio, false negatives ratio and final selected target safety. Results for different scenarios are shown and discussed, in order to highlight the effectiveness of the proposed system

    Surgical Training in Libya: The Way Forward

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    The General Surgical Training Programmes worldwide are designed to ensure that the advanced surgical trainee in surgery achieves competency in knowledge, skill and attitude, both operative and non-operative in a wide range of common surgical conditions, enabling the trainee to practice competently as a surgeon. Therefore, the goal of the surgical training is to train broad-based, highly qualified surgical specialists who can provide excellence in the care of patients with a wide range of surgical diseases. To this end we have to strive to a training programme that emphasizes education over service, training in all major surgical subspecialties, and strong academic affiliations

    The neural correlates of orienting to walking direction in 6-month-old infants: an ERP study

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    The ability to detect social signals represents a first step to enter our social world. Behavioral evidence has demonstrated that 6‐month‐old infants are able to orient their attention toward the position indicated by walking direction, showing faster orienting responses toward stimuli cued by the direction of motion than toward uncued stimuli. The present study investigated the neural mechanisms underpinning this attentional priming effect by using a spatial cueing paradigm and recording EEG (Geodesic System 128 channels) from 6‐month‐old infants. Infants were presented with a central point‐light walker followed by a single peripheral target. The target appeared randomly at a position either congruent or incongruent with the walking direction of the cue. We examined infants' target‐locked event‐related potential (ERP) responses and we used cortical source analysis to explore which brain regions gave rise to the ERP responses. The P1 component and saccade latencies toward the peripheral target were modulated by the congruency between the walking direction of the cue and the position of the target. Infants' saccade latencies were faster in response to targets appearing at congruent spatial locations. The P1 component was larger in response to congruent than to incongruent targets and a similar congruency effect was found with cortical source analysis in the parahippocampal gyrus and the anterior fusiform gyrus. Overall, these findings suggest that a type of biological motion like the one of a vertebrate walking on the legs can trigger covert orienting of attention in 6‐month‐old infants, enabling enhancement of neural activity related to visual processing of potentially relevant information as well as a facilitation of oculomotor responses to stimuli appearing at the attended location

    Long-term effects of monocular deprivation revealed with binocular rivalry gratings modulated in luminance and in color

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    During development, within a specific temporal window called the critical period, the mammalian visual cortex is highly plastic and literally shaped by visual experience; to what extent this extraordinary plasticity is retained in the adult brain is still a debated issue. We tested the residual plastic potential of the adult visual cortex for both achromatic and chromatic vision by measuring binocular rivalry in adult humans following 150 minutes of monocular patching. Paradoxically, monocular deprivation resulted in lengthening of the mean phase duration of both luminance-modulated and equiluminant stimuli for the deprived eye and complementary shortening of nondeprived phase durations, suggesting an initial homeostatic compensation for the lack of information following monocular deprivation. When equiluminant gratings were tested, the effect was measurable for at least 180 minutes after reexposure to binocular vision, compared with 90 minutes for achromatic gratings. Our results suggest that chromatic vision shows a high degree of plasticity, retaining the effect for a duration (180 minutes) longer than that of the deprivation period (150 minutes) and twice as long as that found with achromatic gratings. The results are in line with evidence showing a higher vulnerability of the P pathway to the effects of visual deprivation during development and a slower development of chromatic vision in humans. Introductio

    Implications of CP violating 2HDM in B physics

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    The charged fermion mass matrices are invariant under U(1)3U(1)^3 symmetry linked to the fermion number transformation. Under the condition that the definition of this symmetry in arbitrary weak basis does not depend upon Higgs parameters such as ratio of vacuum expectation values, a class of two Higgs doublet models (2HDM) can be identified in which tree level flavor changing neutral currents normally present in 2HDM are absent. However unlike the type I or type II Higgs doublet models, the charged Higgs couplings in these models contain additional flavor dependent CP violating phases. These phases can account for the recent hints of the beyond standard model CP violation in the BdB_d and BsB_s mixing. In particular, there is a range of parameters in which new phases do not contribute to the KK meson CP violation but give identical new physics phases in the BdB_d and BsB_s meson mixing.Comment: 7 pages, 1 figure, Talk given by Bhavik P. Kodrani at 16th International Symposium on Particles, Strings and Cosmology, July 19th - 23rd, 2010, Valencia, Spai

    Broadband integrated beam splitter using spatial adiabatic passage

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    Light routing and manipulation are important aspects of integrated optics. They essentially rely on beam splitters which are at the heart of interferometric setups and active routing. The most common implementations of beam splitters suffer either from strong dispersive response (directional couplers) or tight fabrication tolerances (multimode interference couplers). In this paper we fabricate a robust and simple broadband integrated beam splitter based on lithium niobate with a splitting ratio achromatic over more than 130 nm. Our architecture is based on spatial adiabatic passage, a technique originally used to transfer entirely an optical beam from a waveguide to another one that has been shown to be remarkably robust against fabrication imperfections and wavelength dispersion. Our device shows a splitting ratio of 0.52±\pm 0.03 and 0.48±\pm 0.03 from 1500\,nm up to 1630\,nm. Furthermore, we show that suitable design enables the splitting in output beams with relative phase 0 or π\pi. Thanks to their independence to material dispersion, these devices represent simple, elementary components to create achromatic and versatile photonic circuits

    Regorafenib also can cause osteonecrosis of the jaw

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    Economic evaluations of interventions to optimize medication use in older adults with polypharmacy and multimorbidity: A systematic review

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    Purpose: To conduct a systematic review of the economic impact of interventions intended at optimizing medication use in older adults with multimorbidity and polypharmacy. Methods: We searched Ovid-Medline, Embase, CINAHL, Ageline, Cochrane, and Web of Science, for articles published between 2004 and 2020 that studied older adults with multi-morbidity and polypharmacy. The intervention studied had to be aimed at optimizing medication use and present results on costs. Results: Out of 3,871 studies identified by the search strategy, eleven studies were included. The interventions involved different provider types, with a majority described as a multidisciplinary team involving a pharmacist and a general practitioner, in the decision-making process. Interventions were generally associated with a reduction in medication expenditure. The benefits of the intervention in terms of clinical outcomes remain limited. Five studies were cost-benefit analyses, which had a net benefit that was either null or positive. Cost-utility and cost-effectiveness analyses resulted in incremental cost-effectiveness ratios that were generally within the willingness-to-pay thresholds of the countries in which the studies were conducted. However, the quality of the studies was generally low. Omission of key cost elements of economic evaluations, including intervention cost and payer perspective, limited interpretability. Conclusion: Interventions to optimize medication use may provide benefits that outweigh their implementation costs, but the evidence remains limited. There is a need to identify and address barriers to the scaling-up of such interventions, starting with the current incentive structures for pharmacists, physicians, and patients
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