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Monopole-vortex complex in a theta vacuum
No full textWe discuss aspects of the monopole-vortex complex soliton arising in a
hierarchically broken gauge system, G to H to 1, in a theta vacuum of the
underlying G theory. Here we focus our attention mainly on the simplest such
system with G=SU(2) and H=U(1). A consistent picture of the effect of the theta
parameter is found both in a macroscopic, dual picture and in a microscopic
description of the monopole-vortex complex soliton
Multi-iterative techniques of Multigrid type for solving large linear systems with structure of graph
No full textWe consider multi-iterative techniques of multigrid type for the numerical solution of large linear systems with (weighted) structure of graph. We combine proper coarser-grid operators with auxiliary techniques. We show that the most effective smoothers have to be of Krylov type with spanning tree preconditioners, while the projectors have to be designed for maintaining as much as possible the structure of graph matrix at the inner levels. Some necessary and sufficient conditions are proved; in this framework it is possible to explain why the classical projectors inherited from differential equations are good in the differential context and why they behave unsatisfactorily for unstructured graphs. Several numerical experiments have been conducted showing that our approach is effective even in very difficult cases where the known approaches are rather slow
Information processing at work: On a theory for experimental algorithm complexity
No full textIt is common experience to upgrade firmware of mobile devices and obtain longer battery life, living proof of how software affects power consumption of a device. Despite this empirical observation, there is a lack for models and methodologies correlating computations with power consumption [3-5]. In this paper we propose an experimental approach to computational complexity and a methodology for conducting measures which result independent of the underlying system running the algorithm/software to be tested. Early experimental results are presented and discussed, showing that our methodology is robust and can be used in many settings. We also introduce the foundations of a theory for experimental algorithm complexity, which mimics what is predicted by the classic theory of computational complexity (big-O or Theta notations), except for some notable exceptions that we highlight and comment. This theory is validated in many scenarios, by considering several architectures and algorithms. Because of the relation between time complexity and energy consumption, we may suggest that our work measures the “information work”: namely, the energy required for performing information processing.<p /
A purely probabilistic candle auction
No full textCandle auctions have been used in the past as a variant of the English auction with a random termination time associated either to the going out of a candle or to the falling of a needle inserted in a random position in a burning candle.In this case such auctions are used by the auctioneer A for the allocation of a good to one of the n bidders bi of the set B.Our basic motivation for the use of this type of auctions is the following.We are planning to use such auctions for the allocation of a chore at one bi from the set B whose members have been selected by A using a set of private criteria that do not depend on the willingness to attend of the single bidders.The to be selected bidder has to be chosen from the set B given that the available information about these bidders are imprecise or fuzzy. These features prevent the profitable and direct selection of a suitable bidder with the guarantee of choosing the best one.For this reason we plan to adopt an auction mechanism where the bidders pay for not getting the chore but one of them has to get it though he also receives a compensation for being the wining bidder.The compensation to the winning bidder derives him form the other bidders, the so called losing bidders, and is accumulated during the various steps or rounds on which the auction is based.<p /
Single-Producer/Single-Consumer Queues on Shared Cache Multi-Core Systems
No full textUsing efficient point-to-point communication channels is critical for implementing fine grained parallel program on modern shared cache multi-core architectures.This report discusses in detail several implementations of wait-free Single-Producer/Single-Consumer queue (SPSC), and presents a novel and efficient algorithm for the implementation of an unbounded wait-free SPSC queue (uSPSC). The correctness proof of the new algorithm, and several performance measurements based on simple synthetic benchmark and microbenchmark, are also discussed
Quali-quantitative analysis of flavonoids of Cornus mas L. (Cornaceae) fruits
No full textSUMMARY The methanol extract obtained from the ripe fruits of Cornus mas L. (Cornaceae) have been phytochemically studied. On the basis of HPLC–PDA–MS/MSn analysis eight compounds have been identified as quercetin, kaempferol, and aromadendrin glycosilated derivatives. Three major compounds have been also isolated by Sephadex LH-20 column chromatography followed by HPLC and characterised by NMR spectroscopy. Moreover, LC–PDA–MS analysis of the red pigment revealed the presence of three anthocyanins. The quantitative analysis of all compounds was reported
Light-time computations for the BepiColombo Radio Science Experiment
No full textSUMMARY The Radio Science Experiment is one of the on board experiments of the Mercury ESA mission BepiColombo that will be launched in 2014. The goals of the experiment are to determine the gravity field of Mercury and its rotation state, to determine the orbit of Mercury, to constrain the possible theories of gravitation (for example by determining the post-Newtonian (PN) parameters), to provide the spacecraft position for geodesy experiments and to contribute to planetary ephemerides improvement. This is possible thanks to a new technology which allows to reach great accuracies in the observables range and range rate; it is well known that a similar level of accuracy requires studying a suitable model taking into account numerous relativistic effects. In this paper we deal with the modelling of the space-time coordinate transformations needed for the light-time computations and the numerical methods adopted to avoid rounding-off errors in such computations
Il fiorentino Palazzo Pretorio di Anghiari (AR). Storia e restauri del XX secolo.
Get PDFAfter being deemed a National Monument in 1901, the medieval Palazzo Pretorio (Anghiari, Arezzo) the seat of the city's Florentine vicar, was subjected to a series of mostly structural and conservation restorations, almost contrary to expections without a restoration of style
Experimental Analysis of Selective Laser Sintering of Polyamide Powders: an Energy Perspective
No full textThe diffusion of innovative working process, including rapid prototyping techniques, is needed to achieve sustainable production technology. Selective Laser Sintering (SLS) has a potential as an environmental benign alternative to traditional processes but only few authors deal with the process optimisation including energy aspects. In the present paper an analysis of the energetic aspect of SLS is proposed. In addition, with respect to the classical technological parameters (resolution, productivity) attention is paid to energetic elements (energetic productivity, laser parameters) showing how the perspective of a sensible development of such a kind of technology could be beneficial not only from a technological point of view, but also for energy saving in a lot of manufacturing fields. A polyamide powder is the material tested to acquire some characteristics data of the process. It is shown that the energy intensity of the process in optimal condition could be of the order of 0.2 J for each mm3 of material agglomerated
Gli anni di Manlio Resta all'Universita di Pisa
No full textRIASSUNTO La nota si propone di fornire un’analisi documentaria sugli anni trascorsi dall’economista Manlio Resta all’Università di Pisa. Dopo aver ricostruito la vicenda dei suoi insegnamenti presso l’Ateneo pisano, il saggio si sofferma sugli scritti di Resta e in particolare sui materiali didattici da lui prodotti (manuale, dispense, raccolte di saggi). L’analisi del passaggio di Manlio Resta dall’Università di Pisa fornisce una vivida testimonianza del clima di rinnovamento e di intenso dibattito che nei primi anni cinquanta si verificò grazie alla tardiva affermazione delle idee di Keynes in Italia.
SUMMARY
This note aims to provide a documentary analysis of the years spent by Manlio Resta at the University of Pisa. After reconstructing Resta’s teaching activities at Pisa University, the paper examines his writings, particularly those of an educational kind (textbook, course notes, collections of papers). The study of Manlio Resta’s passage at the University of Pisa offers a lively testimony of the climate of renewal of economic theory and of intense debate that occurred in the early fifties thanks to the late success of Keynes’ ideas in Italy