331 research outputs found

    Numana and its ancient territory: new data and research perspectives

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    Numana is one of the most important centers for the Picenian civilization and prospered in the Marche and Abruzzo regions during the Iron Age. Almost all of the archaeological evidence found until now refers to the necropoleis spread over a broad territory, while data concerning inhabited areas are quite scarce. Although findings are plenty, the study of Ancient Numana is quite incomplete. As a matter of fact, all the published materials are related to single burials or finds and there are no overall studies on its territory. A recent research project involving a wider sector of the largest Numana necropolis (Quagliotti-Davanzali), has not been published yet but offers a detailed description since the excavation documentation is available. The project sets out to consider burials as organized systems, offering information on cultural transformations and on the social organization of the ancient community. The systematic analysis of the data from the burial and the single funerary sets - to be organized in a specific GIS - will be accompanied by an investigation of the ancient landscape in its many components - necropolis and inhabited area - in its diachronic development, thanks to the results of other recent analyses carried out in the Numana territory (geomorphology, GIS of the archaeological map, new surveys of the territory). The scope of the project is therefore to analyze times, ways of arrangements, shapes of the Ancient Numana, in its definition of a territorial, inhabited, rural space, by using methods and techniques to record and read new data, to build knowledge in a scenario which can be integrated with results coming from future research

    New methodologies to analyze and study the Hellenistic-Roman quarter in Agrigento

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    The Agrigento: insula III Project began in 2016 thanks to an agreement between the Parco Archeologico e Paesaggistico Valle dei Templi di Agrigento and DiSCi - Bologna University; it aims to document an entire sector of the Hellenistic-Roman quarter, in a three-year period. The main goal is to start a systematic study of private housing from the Archaic period to Late Antiquity and, at the same time, provide a critical understanding of the town planning scheme in this part of the town, which still lacks a modern archaeological and topographical documentation. The interpretation of the previous documentation is the starting point, along with new mapping with laser scanning and a systematic campaign of geophysical investigations to obtain a BIM. As the Bologna University tradition teaches, modern technologies can answer precise historical and archaeological questions: what are the primary phases of the town map? Which one is the starting module of each lot and what are the changes in different ages? Is it possible to reconstruct the original architecture of Hellenistic houses? What is the relationship between this quarter and the rest of the town? The integration of traditional investigational techniques with more recent ones is the methodological assumption of the project, in order to solve the analysis of the complex stratigraphy of the setting, which was inhabited for at least a millennium, from the Archaic to the Middle Ages

    Painful constipation: a neglected entity?

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    Functional chronic constipation is a common symptom in daily clinical practice. Although the definition of constipation may be variable, there is usually agreement that (at least for research purposes) the definition given by the Rome Committee are useful. However, some blind spots or hidden angles remain, even in the more thorough classifications; among these, there is painful constipation, a poorly defined yet clinically encountered entity. The present article reviews the current knowledge about painful constipation, trying to put together the scarce data available, and to frame it in the more general context of chronic constipation

    PBFT vs proof-of-authority: Applying the CAP theorem to permissioned blockchain

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    Permissioned blockchains are arising as a solution to federate companies prompting accountable interactions. A variety of consensus algorithms for such blockchains have been proposed, each of which has different benefits and drawbacks. Proof-of-Authority (PoA) is a new family of Byzantine fault-tolerant (BFT) consensus algorithms largely used in practice to ensure better performance than traditional Practical Byzantine Fault Tolerance (PBFT). However, the lack of adequate analysis of PoA hinders any cautious evaluation of their effectiveness in real-world permissioned blockchains deployed over the Internet, hence on an eventually synchronous network experimenting Byzantine nodes. In this paper, we analyse two of the main PoA algorithms, named Aura and Clique, both in terms of provided guarantees and performances. First, we derive their functioning including how messages are exchanged, then we weight, by relying on the CAP theorem, consistency, availability and partition tolerance guarantees. We also report a qualitative latency analysis based on message rounds. The analysis advocates that PoA for permissioned blockchains, deployed over the Internet with Byzantine nodes, do not provide adequate consistency guarantees for scenarios where data integrity is essential. We claim that PBFT can fit better such scenarios, despite a limited loss in terms of performance

    On fundamental domains and volumes of hyperbolic Coxeter-Weyl groups

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    We present a simple method for determining the shape of fundamental domains of generalized modular groups related to Weyl groups of hyperbolic Kac-Moody algebras. These domains are given as subsets of certain generalized upper half planes, on which the Weyl groups act via generalized modular transformations. Our construction only requires the Cartan matrix of the underlying finite-dimensional Lie algebra and the associated Coxeter labels as input information. We present a simple formula for determining the volume of these fundamental domains. This allows us to re-produce in a simple manner the known values for these volumes previously obtained by other methods.Comment: v2: to be published in Lett Math Phys (reference added, typo corrected

    Clar Sextet Analysis of Triangular, Rectangular and Honeycomb Graphene Antidot Lattices

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    Pristine graphene is a semimetal and thus does not have a band gap. By making a nanometer scale periodic array of holes in the graphene sheet a band gap may form; the size of the gap is controllable by adjusting the parameters of the lattice. The hole diameter, hole geometry, lattice geometry and the separation of the holes are parameters that all play an important role in determining the size of the band gap, which, for technological applications, should be at least of the order of tenths of an eV. We investigate four different hole configurations: the rectangular, the triangular, the rotated triangular and the honeycomb lattice. It is found that the lattice geometry plays a crucial role for size of the band gap: the triangular arrangement displays always a sizable gap, while for the other types only particular hole separations lead to a large gap. This observation is explained using Clar sextet theory, and we find that a sufficient condition for a large gap is that the number of sextets exceeds one third of the total number of hexagons in the unit cell. Furthermore, we investigate non-isosceles triangular structures to probe the sensitivity of the gap in triangular lattices to small changes in geometry

    Adsorption of Hexacontane on Hexagonal Boron Nitride

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    © 2018 American Chemical Society. We have investigated the adsorption of hexacontane (C60H122) on hexagonal boron nitride (hBN) using atomic force microscopy (AFM). The molecules can be deposited either by sublimation or from solution and form lamellar rows with dimensions of the order of 0.1-1 μm in three different rotational domains. High-resolution AFM images reveal that, similar to alkanes on graphite, the molecules are adsorbed parallel to the lattice vectors of hBN and we show using molecular mechanics that this corresponds to the lowest energy configuration. Lamellar rows with the same periodicity are observed even when several layers of hexacontane are deposited, although there is some orientational disorder in these multilayers. We also observe heat-induced modification of hexacontane, including recrystallization. We compare our results with recent X-ray studies of alkane adsorption on hBN and discuss the possible role of alkanes on steering molecular self-assembly on hBN

    The inverse moment problem for convex polytopes

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    The goal of this paper is to present a general and novel approach for the reconstruction of any convex d-dimensional polytope P, from knowledge of its moments. In particular, we show that the vertices of an N-vertex polytope in R^d can be reconstructed from the knowledge of O(DN) axial moments (w.r.t. to an unknown polynomial measure od degree D) in d+1 distinct generic directions. Our approach is based on the collection of moment formulas due to Brion, Lawrence, Khovanskii-Pukhikov, and Barvinok that arise in the discrete geometry of polytopes, and what variously known as Prony's method, or Vandermonde factorization of finite rank Hankel matrices.Comment: LaTeX2e, 24 pages including 1 appendi
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