391 research outputs found
Numana and its ancient territory: new data and research perspectives
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
Horn conditions for quiver subrepresentations and the moment map
We give inductive conditions that characterize the Schubert positions of subrepresentations of a general quiver representation. Our results generalize Belkale’s criterion for the intersection of Schubert varieties in Grassmannians and refine Schofield’s characterization of the dimension vectors of general subrepresentations. This implies Horn type inequalities for the moment cone associated to the linear representation of the group G = ΠxGL(nx) associated to a quiver and a dimension vector n = (nx)
INTERMEDIATE SUMS ON POLYHEDRA: COMPUTATION AND REAL EHRHART THEORY
We study intermediate sums, interpolating between integrals and discrete sums, which were introduced by A. Barvi-nok [Computing the Ehrhart quasi-polynomial of a rational simplex, Math. Comp. 75 (2006), 1449–1466]. For a given semi-rational polytope p and a rational subspace L, we integrate a given polyno-mial function h over all lattice slices of the polytope p parallel to the subspace L and sum up the integrals. We first develop an al-gorithmic theory of parametric intermediate generating functions. Then we study the Ehrhart theory of these intermediate sums, that is, the dependence of the result as a function of a dilation of the polytope. We provide an algorithm to compute the resulting Ehrhart quasi-polynomials in the form of explicit step polynomi-als. These formulas are naturally valid for real (not just integer) dilations and thus provide a direct approach to real Ehrhart theory
New methodologies to analyze and study the Hellenistic-Roman quarter in Agrigento
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?
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
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
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
Caracterização do óleo e da torta de castanha-do-brasil
A castanha-do-brasil é reconhecida por sua elevada constituição lipídica com teores médios predominantes de ácidos graxos insaturados. Além disso, é fonte considerável de ômegas 6 e 9 e apresenta taxas importantes de ômega 3, confirmando a riqueza desta oleaginosa amazônica. A porção lipídica da castanha-do-brasil tem sido foco de grande interesse industrial, como matéria prima para cosméticos ou para uso culinário. Com este trabalho, objetivou-se caracterizar o óleo bruto e a torta de castanhas-do-brasil extraídos por prensa mecânica. As castanhas-do-brasil foram adquiridas com casca em um comércio de Sinop/MT. Após o descascamento, as amêndoas foram submetidas à prensagem mecânica e, visando extrair o máximo de óleo, a torta foi prensada quatro vezes. Em seguida, o óleo bruto extraído e a torta foram caracterizados. O óleo foi centrifugado e analisado, em triplicata, quanto à acidez, densidade a 25 °C e índices de peróxido, iodo e saponificação. A torta foi caracterizada, em triplicata, quanto ao teor de água, extrato etéreo, fibra bruta, solubilidade, capacidade de absorção de água e de óleo, atividade de água, formação de espuma e teor de cinzas. A prensagem das amêndoas gerou 37,32% de óleo e 62,68% de torta. A acidez média do óleo foi de 0,883 mg KOH g-1 de óleo. A densidade a 25 °C foi de 0,94 g mL-1. O índice de peróxido encontrado foi 8,12 mEq kg-1 de óleo, o índice de iodo de 106,38 g I2/100 g de amostra e índice de saponificação de 195,29 mg KOH g-1 de amostra. A torta de castanha-do-brasil apresentou 2,67% de teor de água, 56,61% de extrato etéreo, 6,6% de fibra bruta e 4,84% de cinzas. Além disso, pode ser caracterizada por 33,58% de solubilidade em água, 290,11% de capacidade de absorção de água, 174,29% de capacidade de absorção de óleo, atividade de água de 0,53 e não apresentou capacidade de formação de espuma. O óleo e a torta obtidos de castanha-do-brasil apresentam boa qualidade, uma vez que segundo padrões estabelecidos pela ANVISA, o valor máximo aceitável para acidez de óleo é 4,0 mg KOH g-1 de amostra e 15 mEq kg-1 de amostra para índice de peróxido. O índice de acidez revela a qualidade e o estado de conservação do óleo, sendo que valores elevados indicam que há quebras na cadeia do óleo liberando seus principais constituintes, os ácidos graxos, o que não é interessante. Quanto ao índice de saponificação, na literatura podem ser encontrados valores entre 181,53 e 198,50 mg KOH g-1, próximos ao obtido neste trabalho. Na torta, a fração lipídica encontrada foi considerada elevada quando comparada a produtos de outras espécies, indicando que o método de extração do óleo não foi eficiente
Clar Sextet Analysis of Triangular, Rectangular and Honeycomb Graphene Antidot Lattices
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
Exploiting Polyhedral Symmetries in Social Choice
A large amount of literature in social choice theory deals with quantifying
the probability of certain election outcomes. One way of computing the
probability of a specific voting situation under the Impartial Anonymous
Culture assumption is via counting integral points in polyhedra. Here, Ehrhart
theory can help, but unfortunately the dimension and complexity of the involved
polyhedra grows rapidly with the number of candidates. However, if we exploit
available polyhedral symmetries, some computations become possible that
previously were infeasible. We show this in three well known examples:
Condorcet's paradox, Condorcet efficiency of plurality voting and in Plurality
voting vs Plurality Runoff.Comment: 14 pages; with minor improvements; to be published in Social Choice
and Welfar
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