1,433 research outputs found

    BANKRUPTCY GAMES AND THE IBN EZRA'S PROPOSAL

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    This paper follows the interpretation of the bankruptcy problems in terms of TU games given in O'Neill (1982). In this context we propose the analysis of the Transition Game associated to each bankruptcy problem. We explore an old solution described by Ibn Ezra in the XII century. Firstly, we study the extension of the Ibn Ezra's proposal by O'Neill (1982), the Minimal Overlap solution. We provide a characterization of this value and show that it can be understood as the composition of the Ibn Ezra solution and the Constrained Equal Loss rule. Secondly, we introduce a new way of extending the Ibn Ezra's proposal, the Generalized Ibn Ezra solution, by imposing that the general distribution principle in which is inspired remains fixed. The characterization of our proposal clarifies the analogies and differences between the two ways of generalizing the Ibn Ezra's proposal.Bankruptcy Problems, Cooperative Games, Ibn Ezra's proposal, Minimal Overlap solution.

    Adaptive saccade controller inspired by the primates' cerebellum

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    Saccades are fast eye movements that allow humans and robots to bring the visual target in the center of the visual field. Saccades are open loop with respect to the vision system, thus their execution require a precise knowledge of the internal model of the oculomotor system. In this work, we modeled the saccade control, taking inspiration from the recurrent loops between the cerebellum and the brainstem. In this model, the brainstem acts as a fixed-inverse model of the oculomotor system, while the cerebellum acts as an adaptive element that learns the internal model of the oculomotor system. The adaptive filter is implemented using a state-of-the-art neural network, called I-SSGPR. The proposed approach, namely recurrent architecture, was validated through experiments performed both in simulation and on an antropomorphic robotic head. Moreover, we compared the recurrent architecture with another model of the cerebellum, the feedback error learning. Achieved results show that the recurrent architecture outperforms the feedback error learning in terms of accuracy and insensitivity to the choice of the feedback controller

    Do Global Pandemics Matter for Stock Prices? Lessons from the 1918 Spanish Flu

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    We study the impact of the 1918 Spanish Flu on U.S. stock prices. We use the death rate to control for the impact of the global pandemic and war news reported in the New York Times to capture the positive effects of the end of World War I on stock prices. Using a new weekly hand collected NYSE stock price index, we show that there is a -.73 correlation between the aggregate stock market and the death rate. Furthermore, vector autoregressions demonstrate that the death rate can explain up to 24 percent of the forecast error variance in the aggregate stock index from September 1918 until the end of the pandemic in March 1920. We also find that the flu had a significant, but varied impact on nine NYSE sectors. The empirical analysis indicates that pandemics can matter big time for stock prices

    FROM THE ELABORATION PROCESS OF POINT CLOUD TO INFORMATION SYSTEMS BOTH FOR PLANNING AND DESIGN MANAGEMENT OF CULTURAL HERITAGE

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    Abstract. Nowadays we are able to produce geometric models of historical building at different scale of detail using photos and measurements. More and more we are facing with lack of preservation actions and maintenance activities, bad foreseen policies, unexpected natural events, that are forcing professionals and researchers to operate without usual data. In these cases, we need consistent repository to collect and distribute data to produce information. Furthermore, we need to "give intelligence" to these repositories in order to query them with respect geometrical instances, topological issues, historical features.We dispose of tons of xyz points: how can we pass from the point cloud to a building information model, then to a geographic information system, not necessarily in this order? A simple Scan-to-BIM-to-GIS and Scan-to-GIS-to-BIM process were tested in order to consequently evaluate, with purposes of preservation and of enhancing of resilience, some practices that could became the best, also in terms of time and cost saving.The work we propose is a part of an ongoing research focused on the application of H-BIM approach for the management of historical building heritage, focused on a district management (H-DIM, at an urban level). In particular, with regard to the resilience theme, both the acquisition phase and the archive research process are of great importance for protecting our undefended building heritage.Regarding the case study of the paper, UNESCO sites represent important areas for collective interests of humanity. This contribution proposes a possible solution applying a digital cultural heritage to the historical part of the Municipality of Serralunga d'Alba belonging to the UNESCO site called Vineyard Landscape of Langhe-Roero and Monferrato.</p

    Integration of Static and Self-motion-Based Depth Cues for Efficient Reaching and Locomotor Actions

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    The common approach to estimate the distance of an object in computer vision and robotics is to use stereo vision. Stereopsis, however, provides good estimates only within near space and thus is more suitable for reaching actions. In order to successfully plan and execute an action in far space, other depth cues must be taken into account. Self-body movements, such as head and eye movements or locomotion can provide rich information of depth. This paper proposes a model for integration of static and self-motion-based depth cues for a humanoid robot. Our results show that self-motion-based visual cues improve the accuracy of distance perception and combined with other depth cues provide the robot with a robust distance estimator suitable for both reaching and walking actions

    A new prospect of additivity in bankruptcy problems

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    As it is known, there is no rule satisfying Additivity on the complete domain of bankruptcy problems. This paper proposes a notion of partial Additivity in this context, to be called µ-Additivity. We find that µ-Additivity, together with two quite compelling axioms, Anonymity and Continuity, identify the Minimal Overlap rule, introduced by O'Neill (1982).bankruptcy problems, additivity, minimal overlap rule.

    A hierarchical system for a distributed representation of the peripersonal space of a humanoid robot

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    Reaching a target object in an unknown and unstructured environment is easily performed by human beings. However, designing a humanoid robot that executes the same task requires the implementation of complex abilities, such as identifying the target in the visual field, estimating its spatial location, and precisely driving the motors of the arm to reach it. While research usually tackles the development of such abilities singularly, in this work we integrate a number of computational models into a unified framework, and demonstrate in a humanoid torso the feasibility of an integrated working representation of its peripersonal space. To achieve this goal, we propose a cognitive architecture that connects several models inspired by neural circuits of the visual, frontal and posterior parietal cortices of the brain. The outcome of the integration process is a system that allows the robot to create its internal model and its representation of the surrounding space by interacting with the environment directly, through a mutual adaptation of perception and action. The robot is eventually capable of executing a set of tasks, such as recognizing, gazing and reaching target objects, which can work separately or cooperate for supporting more structured and effective behaviors

    Hydrogeochemical characteristics of a volcanic-sedimentary aquifer with special emphasis on Fe and Mn content: A case study in Mexico

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    Previous studies performed on the volcanic-sedimentary aquifer of the Tenancingo Valley (Mexico) reports high concentrations of Fe, Mn, and NO3 −, and water from several wells receives purification treatments due to presence of Fe and Mn. These studies have not achieved conclusive results regarding the origin of Fe and Mn, nor have hydrogeochemical evaluations of the aquifer been performed. The present study aimed to evaluate the physicochemical characteristics of the water and identify the geochemical processes that determine presence of Fe and Mn in groundwater. This characterization was based on physicochemical data from well and spring samples (16 samples) during dry and rainy seasons (June and November 2012, respectively). The EC, temperature and pH ranged from 125 to 793 μS cm−1 , 14.5 to 24.9 °C and 6.5 to 8.5 pH units, respectively. The Eh values ranged from −219 to 327 mV, indicating the existence of both reducing and oxidizing zones. Presence of Fe and Mn was detected in both springs and wells; concentrations were higher in well, exceeding 4 mg Fe L−1 and 0.5 mg Mn L−1 . Content of Si ranged from 12 to 47 mg L−1 . A model of the hydrogeochemical behavior of the aquifer was created to highlight the following: i) processes involved in water-rock interactions, including fluctuations in silicate levels that determine anionic and cationic content of water, and ii) redox reactions as the major control processes of Fe and Mn. Water quality for human use is restricted by Fe and Mn content and pH. For irrigation use, significant limitations were not presente

    Atresia anal en el perro y el gato

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    Ponencia en el XXXI CONGRESO NACIONAL DE LA ASOCIACIÓN MEXICANA DE MÉDICOS VETERINARIOS ESPECIALISTAS EN PEQUEÑAS ESPECIES, A.C.La atresia anal es una patología poco frecuente con una prevalencia del 0.13% y del 1.6% para el caso de los perros y de los gatos menores de un año de edad respectivamente, atendidos en nuestro centro hospitalario. En el presente documento se expone la experiencia en el diagnóstico y manejo de tres pacientes con atresia anal, realizamos una revisión de las teorías de los mecanismos fisiopatológicos involucrados en el desarrollo embrionario, y con base en esos criterios, sugerimos la mejor clasificación del tipo de atresia anal partiendo del análisis de las propuestas existentes y su relación con los conceptos actuales de la anatomía embriológica

    Disruption of cortical cell type composition and function underlies diabetes-associated cognitive decline

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    Cognitive decline; Cortex; MetabolismDeclivi cognitiu; Còrtex; MetabolismeDeterioro cognitivo; Corteza; MetabolismoAims/hypothesis Type 2 diabetes is associated with increased risk of cognitive decline although the pathogenic basis for this remains obscure. Deciphering diabetes-linked molecular mechanisms in cells of the cerebral cortex could uncover novel therapeutic targets. Methods Single-cell transcriptomic sequencing (scRNA-seq) was conducted on the cerebral cortex in a mouse model of type 2 diabetes (db/db mice) and in non-diabetic control mice in order to identify gene expression changes in distinct cell subpopulations and alterations in cell type composition. Immunohistochemistry and metabolic assessment were used to validate the findings from scRNA-seq and to investigate whether these cell-specific dysfunctions impact the neurovascular unit (NVU). Furthermore, the behavioural and cognitive alterations related to these dysfunctions in db/db mice were assessed via Morris water maze and novel object discrimination tests. Finally, results were validated in post-mortem sections and protein isolates from individuals with type 2 diabetes. Results Compared with non-diabetic control mice, the db/db mice demonstrated disrupted brain function as revealed by losses in episodic and spatial memory and this occurred concomitantly with dysfunctional NVU, neuronal circuitry and cerebral atrophy. scRNA-seq of db/db mouse cerebral cortex revealed cell population changes in neurons, glia and microglia linked to functional regulatory disruption including neuronal maturation and altered metabolism. These changes were validated through immunohistochemistry and protein expression analysis not just in the db/db mouse cerebral cortex but also in post-mortem sections and protein isolates from individuals with type 2 diabetes (74.3 ± 5.5 years) compared with non-diabetic control individuals (87.0 ± 8.5 years). Furthermore, metabolic and synaptic gene disruptions were evident in cortical NVU cell populations and associated with a decrease in vascular density. Conclusions/interpretation Taken together, our data reveal disruption in the cellular and molecular architecture of the cerebral cortex induced by diabetes, which can explain, at least in part, the basis for progressive cognitive decline in individuals with type 2 diabetes
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