502 research outputs found

    Heyting frames and Esakia duality

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    We introduce the category of Heyting frames and show that it is equivalent to the category of Heyting algebras and dually equivalent to the category of Esakia spaces. This provides a frame-theoretic perspective on Esakia duality for Heyting algebras. We also generalize these results to the setting of Brouwerian algebras and Brouwerian semilattices by introducing the corresponding categories of Brouwerian frames and extending the above equivalences and dual equivalences. This provides a frame-theoretic perspective on generalized Esakia duality for Brouwerian algebras and Brouwerian semilattices

    Coalgebras for the powerset functor and Thomason duality

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    We describe the endofunctor HH on the category CABACABA of complete and atomic boolean algebras and complete boolean homomorphisms such that the category Alg(H)Alg(H) of algebras for HH is dually equivalent to the category Coalg(P)Coalg(\mathcal{P}) of coalgebras for the powerset endofunctor P\mathcal{P} on SetSet. As a consequence, we derive Thomason duality from Tarski duality

    Hydrogen Desorption below 150 °c in MgH2-TiH2 Composite Nanoparticles: Equilibrium and Kinetic Properties

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    Reversible hydrogen sorption coupled with the MgH2 <-> Mg phase transformation was achieved in the remarkably low 340-425 K temperature range using MgH2-TiH2 composite nanoparticles obtained by reactive gas-phase condensation of Mg Ti vapors under He/H-2 atmosphere. The equilibrium pressures determined by in situ measurements at low temperature were slightly above those predicted using enthalpy Delta H and entropy Delta S of bulk magnesium. A single van't Hoff fit over a range extended up to 550 K yields the thermodynamic parameters Delta H = 68.1 0.9 kJ/molH(2) and Delta S = 119 2 J/(Kmo1H2) for hydride decomposition. A desorption rate of 0.18 wt % H-2/min was measured at T = 423 K and p(H-2) approximate to 1 mbar, i.e., close to equilibrium, without using a Pd catalysts. The nanoparticles displayed a small absorption desorption pressure hysteresis even at low temperatures. We critically discuss the influence exerted by nanostructural features such as interface free energy, elastic clamping, and phase mixing at the single nanopartide level on equilibrium and kinetic properties of hydrogen sorption

    Biological application of Compressed Sensing Tomography in the Scanning Electron Microscope

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    The three-dimensional tomographic reconstruction of a biological sample, namely collagen fibrils in human dermal tissue, was obtained from a set of projection-images acquired in the Scanning Electron Microscope. A tailored strategy for the transmission imaging mode was implemented in the microscope and proved effective in acquiring the projections needed for the tomographic reconstruction. Suitable projection alignment and Compressed Sensing formulation were used to overcome the limitations arising from the experimental acquisition strategy and to improve the reconstruction of the sample. The undetermined problem of structure reconstruction from a set of projections, limited in number and angular range, was indeed supported by exploiting the sparsity of the object projected in the electron microscopy images. In particular, the proposed system was able to preserve the reconstruction accuracy even in presence of a significant reduction of experimental projections

    SMART-M3 v.0.9: A semantic event processing engine supporting information level interoperability in ambient intelligence

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    This tutorial is addressed to all students in Electronic Engineering and Information Engineering at the Scuola di Ingegneria e Architettura of the University of Bologna attending the following courses: Laboratory of Interoperability of Embedded Systems, "Calcolatori Elettronici M" and "Attività Progettuale di Calcolatori Elettronici M". This tutorial includes the guidelines to build distributed applications where clients may interact with physical space. Inter-client interaction occurs through a semantic event processing engine. Information interoperability is based on a shared knowledge representation model named ontology. This tutorial is focused on client design and on the SPARQL primitives that provide the means for client-event processing engine interaction

    Nuovi formati commerciali e polarità interregionali: Lombardia, Piemonte, Emilia Romagna

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    En este artículo presentamos la investigación "Evaluación del impacto territorial de los polos comerciales: factoty outlets, multicines, centros comerciales. Una aproximación interregional", realizada entre 2005 y 2007 por los Departamentos de Architettura e Pianificazione del Politécnico de Milán, el Interateneo del Territorio del Politécnico de Turín y el Departamento de Economía de la Universidad de Parma. La investigación ha sido promovida por las Regiones de Lombardía, Piamonte y Emilia Romagna, con el fin de desarrollar un enfoque común tanto para el estudio de los fenómenos como para el desarrollo de directrices de gestión. A partir de la observación de la innovación en formatos comerciales y de las vías de su regulación por las Regiones, se ha prestado especial atención a la formación de "polos comerciales interregionales"

    Duality for powerset coalgebras

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    Let CABA be the category of complete and atomic boolean algebras and complete boolean homomorphisms, and let CSL be the category of complete meet-semilattices and complete meet-homomorphisms. We show that the forgetful functor from CABA to CSL has a left adjoint. This allows us to describe an endofunctor H on CABA such that the category Alg(H) of algebras for H is dually equivalent to the category Coalg(P) of coalgebras for the powerset endofunctor P on Set. As a consequence, we derive Thomason duality from Tarski duality, thus paralleling how J\'onsson-Tarski duality is derived from Stone duality

    Bone Anchored Hearing Aids for the Treatment of Asymmetric Hearing Loss

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    OBJECTIVES: Asymmetric hearing loss is generally defined as a moderate-to-profound hearing loss in the poorer ear and a mild-to-moderate hearing loss in the better ear. Application of a bone conduction hearing aid is one of the possible treatments for the poorer ear in asymmetric hearing loss. However, the device essentially stimulates the contralateral better ear, precluding true binaural hearing. The aim of this paper is to evaluate the application and utility of bone-anchored hearing aids in the treatment of asymmetric hearing loss. MATERIALS and METHODS: We retrospectively evaluated 215 implanted subjects in our clinic and extracted a series of 27 patients affected by asymmetric hearing loss and treated with bone-anchored hearing aids. All 27 subjects had a mixed hearing loss after middle ear surgery. The preoperative and postoperative audiological data of these patients were collected and analyzed. RESULTS: The audiological tests showed an improvement in the performance of hearing perception of sound and speech in quiet and noise.Moreover, the subjects have positively answered the questionnaires administered to evaluate subjective benefits. All subscales of the abbreviated profile of hearing aid benefit and speech, spatial, and qualities of hearing scale showed a significant improvement with the device. CONCLUSION: Bone-anchored hearing aids are a suitable treatment for asymmetric hearing loss. When other devices cannot be utilized or are not indicated, the bone conduction devices may allow good audiological results
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