1,870 research outputs found

    Evidences of relationships between statistics of rainfall extremes and mean annual precipitation: an application for design-storm estimation in northern central Italy

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    International audienceSeveral hydrological analyses need to be founded on a reliable estimate of the design storm, which is the expected rainfall depth corresponding to a given duration and probability of occurrence, usually expressed in terms of return period. The annual series of precipitation maxima for storm duration ranging from 15 min to 1 day are observed at a dense network of raingauges sited in northern central Italy are statistically analyzed using an approach based on L-moments. The study investigates the statistical properties of rainfall extremes and identifies important relationships between these properties and the mean annual precipitation (MAP). On the basis of these relationships, we develop a regional model for estimating the rainfall depth for a given storm duration and recurrence interval in any location of the study region. The reliability of the regional model is assessed through Monte Carlo simulations. The results are relevant given that the proposed model is able to reproduce the statistical properties of rainfall extremes observed for the study region

    Relationships between statistics of rainfall extremes and mean annual precipitation: an application for design-storm estimation in northern central Italy

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    Several hydrological analyses need to be founded on a reliable estimate of the design storm, which is the expected rainfall depth corresponding to a given duration and probability of occurrence, usually expressed in terms of return period. The annual series of precipitation maxima for storm duration ranging from 15 min to 1 day, observed at a dense network of raingauges sited in northern central Italy, are analyzed using an approach based on L-moments. The analysis investigates the statistical properties of rainfall extremes and detects significant relationships between these properties and the mean annual precipitation (MAP). On the basis of these relationships, we developed a regional model for estimating the rainfall depth for a given storm duration and recurrence interval in any location of the study region. The applicability of the regional model was assessed through Monte Carlo simulations. The uncertainty of the model for ungauged sites was quantified through an extensive cross-validation

    Modelling mental rotation in cognitive robots

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    Mental rotation concerns the cognitive processes that allow an agent mentally to rotate the image of an object in order to solve a given task, for example to say if two objects with different orientations are the same or different. Here we present a system-level bio-constrained model, developed within a neurorobotics framework, that provides an embodied account of mental rotation processes relying on neural mechanisms involving motor affordance encoding, motor simulation and the anticipation of the sensory consequences of actions (both visual and proprioceptive). This model and methodology are in agreement with the most recent theoretical and empirical research on mental rotation. The model was validated through experiments with a simulated humanoid robot (iCub) engaged in solving a classical mental rotation test. The results of the test show that the robot is able to solve the task and, in agreement with data from psychology experiments, exhibits response times linearly dependent on the angular disparity between the objects. This model represents a novel detailed operational account of the embodied brain mechanisms that may underlie mental rotation. © The Author(s) 2013

    Optical Properties of (SrMnO3)n/(LaMnO3)2n superlattices: an insulator-to-metal transition observed in the absence of disorder

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    We measure the optical conductivity of (SrMnO3)n/(LaMnO3)2n superlattices (SL) for n=1,3,5, and 8 and 10 < T < 400 K. Data show a T-dependent insulator to metal transition (IMT) for n \leq 3, driven by the softening of a polaronic mid-infrared band. At n = 5 that softening is incomplete, while at the largest-period n=8 compound the MIR band is independent of T and the SL remains insulating. One can thus first observe the IMT in a manganite system in the absence of the disorder due to chemical doping. Unsuccessful reconstruction of the SL optical properties from those of the original bulk materials suggests that (SrMnO3)n/(LaMnO3)2n heterostructures give rise to a novel electronic state.Comment: Published Online in Nano Letters, November 8, 2010; http://pubs.acs.org/doi/abs/10.1021/nl1022628; 5 pages, 3 figure

    Biological cumulative learning through intrinsic motivations: a simulated robotic study on development of visually-guided reaching

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    This work aims to model the ability of biological organisms to achieve cumulative learning, i.e. to learn increasingly more complex skills on the basis of simpler ones. In particular, we studied how a simulated kinematic robotic system composed of an arm and an eye can learn the ability to reach for an object on the basis of the ability to systematically look at the object, which, in our set-up, represented a prerequisite for the reaching task. We designed the system by following several biological constraints and investigated which kind of sub-task reinforcements might facilitate the development of the final skill. We found that the performance in the reaching task was optimized when the reinforcement signal included not only the extrinsic reinforcement provided by touching the object but also an intrinsic reinforcement given by the error in the prediction of fovea activation. We discuss how these results might explain biological data regarding the neural basis of action discovery and reinforcement earning, in particular with respect to the neuromodulator dopamine

    Far infrared properties of the rare-earth scandate DyScO3

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    We present reflectance measurements in the infrared region on a single crystal the rare earth scandate DyScO3. Measurements performed between room temperature and 10 K allow to determine the frequency of the infrared-active phonons, never investigated experimentally, and to get information on their temperature dependence. A comparison with the phonon peak frequency resulting from ab-initio computations is also provided. We finally report detailed data on the frequency dependence of the complex refractive index of DyScO3 in the terahertz region, which is important in the analysis of terahertz measurements on thin films deposited on DyScO3

    A bio-inspired learning signal for the cumulative learning of different skills

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    Building artificial agents able to autonomously learn new skills and to easily adapt in different and complex environments is an important goal for robotics and machine learning. We propose that providing artificial agents with a learning signal that resembles the characteristic of the phasic activations of dopaminergic neurons would be an advancement in the development of more autonomous and versatile systems. In particular, we suggest that the particular composition of such a signal, determined both by intrinsic and extrinsic reinforcements, would be suitable to improve the implementation of cumulative learning. To validate our hypothesis we performed some experiments with a simulated robotic system that has to learn different skills to obtain rewards. We compared different versions of the system varying the composition of the learning signal and we show that only the system that implements our hypothesis is able to reach high performance in the task

    Exploring the role of fallopian ciliated cells in the pathogenesis of high-grade serous ovarian cancer

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    High-grade serous epithelial ovarian cancer (HGSOC) is the fifth leading cause of cancer death in women and the first among gynecological malignancies. Despite an initial response to standard chemotherapy, most HGSOC patients relapse. To improve treatment options, we must continue investigating tumor biology. Tumor characteristics (e.g., risk factors and epidemiology) are valuable clues to accomplish this task. The two most frequent risk factors for HGSOC are the lifetime number of ovulations, which is associated with increased oxidative stress in the pelvic area caused by ovulation fluid, and a positive family history due to genetic factors. In the attempt to identify novel genetic factors (i.e., genes) associated with HGSOC, we observed that several genes in linkage with HGSOC are expressed in the ciliated cells of the fallopian tube. This finding made us hypothesize that ciliated cells, despite not being the cell of origin for HGSOC, may take part in HGSOC tumor initiation. Specifically, malfunction of the ciliary beat impairs the laminar fluid flow above the fallopian tube epithelia, thus likely reducing the clearance of oxidative stress caused by follicular fluid. Herein, we review the up-to-date findings dealing with HGSOC predisposition with the hypothesis that fallopian ciliated cells take part in HGSOC onset. Finally, we review the up-to-date literature concerning genes that are located in genomic loci associated with epithelial ovarian cancer (EOC) predisposition that are expressed by the fallopian ciliated cells

    From the kilns to the fair: producing building materials at Faragola and Canusium (northern Apulia, Italy)

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    Faragola and Canusium potters used Ca-rich clays—widely available nearby—for the production of build- ing materials. The clayey materials were used as received, before being fired in the local kilns at temperatures between 600 and ~1000 ° C. No technological distinctions were made in relation to the type of object to be produced (tile, brick, etc). The investigated productions are compositionally distinguish- able from both coarse wares for cooking and fine table ware produced in the same archaeological sites. A fine clayey ma- terial, very similar to that used for table ware, was supplied for the production of these building materials, which are chemi- cally, mineralogically and petrographically very similar among themselves. Hence, the Faragola and Canusium bricks and tiles cannot be easily discriminated but the presence/ absence of volcanites and volcanic glass represents an effec- tive discriminating factor, able to indicate areas of different supplies within two main deposits: the Pleistocene marine and alluvial terraced deposits, typical of northern Apulia

    Multiple hazards and risk perceptions over time: the availability heuristic in Italy and Sweden under COVID-19

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    The severe impact of global crises, such as COVID-19 and climate change, is plausibly reshaping the way in which people perceive risks. In this paper, we examine and compare how global crises and local disasters influence public perceptions of multiple hazards in Italy and Sweden. To this end, we integrate information about the occurrence of hazardous events with the results of two nationwide surveys. These included more than 4000 participants and were conducted in two different phases of the COVID-19 pandemic corresponding to low (August 2020) and high (November 2020) levels of infection rates. We found that, in both countries, people are more worried about risks related to experienced events. This is in line with the cognitive process known as the availability heuristic: individuals assess the risk associated with a given hazard based on how easily it comes to their mind. Epidemics, for example, are perceived as less likely and more impactful in Italy compared to Sweden. This outcome can be explained by cross-country differences in the impact of, as well as governmental responses to, COVID-19. Notwithstanding the ongoing pandemic, people in both Italy and Sweden are highly concerned about climate change, and they rank it as the most likely threat
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