1,608 research outputs found
Corneal Biomechanics
No full textThe corne a is the first and mos t powe rful refrac tive surface of the optical syst em of 6 the eye. 7 The produc tion of an accur ate image in the ret inal rece ptors requires the cornea 8 to be transpa rent and have a suitabl e refractive po wer [ 1 ? 3 ]. 9 The struct ural integr ity o f the corne a can be altered in the CR modify ing its 10 refrac tive prope rties. These procedure s have been develop ed emp irically without 11 detailed kno wledge of corneal behavior . 12 Measuri ng the change in corneal shape has been available in the past d ecade 13 through com puterized analysis of the reflec tion of photo keratos copic ring surface of 14 the cornea (corneal topog rapher). 15 Little is know n about the behavio r of the internal structure of the corne a. 16 Altho ugh the ult rastructu re was analyzed by elect ron micro scopy, the rol e of each 17 one of the layers has not been examined in detail. We shall see below attempt s to 18 define such roles, which still need further anal ysis. 19 The tools to measur e and under stand these proce sses ari se from mechani cal 20 engineer ing and have been used in othe r medica l specialties , such as o rthopedics, 21 which evaluates quantitative ly the require ments of the prosthes is. Many of these 22 methods are not suitable for soft tissue such as the corne a, but the general princi ples 23 can be appl ied.Fil: Guarnieri, Fabio Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; Argentin
Efficient 3-D Domain Decomposition with Dual Basis Functions
No full textNovel basis functions are proposed for enforcing continuity constraints in 3-D elliptic problems discretized by non-conforming domain decomposition methods. The major advantage over standard coupling methods is that the projection matrix, mapping degrees of freedom from master to slave surface, can be constructed with minimum computing effort since the slave matrix is diagonal. The accuracy of matching conditions and convergence properties of the method are tested on a benchmark problem
Electricity in the Age of Enlightenment
No full textThe author gives a review of the historical development of electricity during the Age of Enlightenment (1600-1800), including work from William Gilbert to Benjamin Franklin
Politica in Italia. I fatti dell'anno e le interpretazioni. Edizione 2005
No full textIn attesa di una poco probabile conclusione della transizione politica italiana, il 2004 è stato un anno di mutamenti relativamente limitati, in cui varie riforme sono state annunciate ma non sono state realizzate, oppure hanno assunto un carattere compromissorio. E' emersa una situazione di stallo fra i due schieramenti di centro-destra e di centro-sinistra che si sono divisi in parti quasi eguali l'elettorato in occasione del voto europeo. Questa ventesima edizione di "Politica in Italia" esamina, in primo luogo, i risultati elettorali, sia europei sia locali, e l'evoluzione dei rapporti di forza all'interno dei due grandi schieramenti, dedicando specifica attenzione a Forza Italia, al funzionamento della coalizione di governo e al ruolo del ministero dell'Economia e delle Finanze. Vengono analizzati l'operato del governo nei confronti del processo di formazione della Costituzione europea, il progetto di riforma costituzionale, il nuovo ordinamento giudiziario e, infine, la riforma delle pensioni, l'unica riforma di rilievo effettivamente varata nel corso dell'anno. Neppure il crack della Parmalat è riuscito a sollecitare l'approvazione di una riforma delle istituzioni di tutela del risparmio. Infine, due contributi si soffermano su trasformazioni in corso nella società italiana: la svolta all'interno della Confindustria, con la presidenza di Luca Cordero di Montezemolo, e il crescente malessere del ceto medio. Se il 2004 ha confermato il relativo miglioramento dell'efficacia decisionale del sistema politico italiano, ha anche messo in luce che quest'ultimo continua a non essere all'altezza delle sfide, interne ed esterne, che gli si presentano. Il problema di fondo resta ancora l'eterogeneità delle coalizioni, fatto che si riflette negativamente sul governo e sull'opposizione e, in ultima analisi, sul funzionamento complessivo delle istituzioni politiche.
Indice: Gli avvenimenti del 2004. - Introduzione. 2004: un anno di attesa?, di C. Guarnieri e J.L. Newell. - 1. Gli equilibri politici dopo le elezioni di giugno, di M. Donovan. - 2. Il voto nelle città: ancora una sconfitta per il centro-destra, di G. Legnante. - 3. Forza Italia a dieci anni dalla fondazione, di J. Hopkin. - 4. Suonare lo spartito sbagliato? L'Italia e l'Unione europea nel 2004, di M. Gilbert. - 5. Le riforme costituzionali del centro-destra, di S. Vassallo. - 6. Il ruolo del ministero dell'Economia e delle Finanze, di D. Hine. - 7. La riforma dell'ordinamento giudiziario, di P. Pederzoli. - 8. La riforma previdenziale del governo Berlusconi e l'emergere di un "doppio cleavage" nelle politiche distributive, di D. Natali e M. Rhodes. - 9. Il crack della Parmalat, di M. Onado. - 10. La questione del ceto medio, di A. Bagnasco. - 11. La Confindustria di Montezemolo, di G. Berta. - Appendice documentaria, a cura di D. Mantovani
When cars went electric - part 1
No full textIn recent years, increasing attention to environmental pollution and concern about the depletion of oil reserves have boosted an interest in electric and hybrid cars as viable alternatives to gasoline-powered automobiles. R&D programs copiously supported in many countries are notably aimed at developing advanced management systems and high-efficiency motors and innovative batteries with high energy densities, both of the rechargeable and fuel-cell types. When we think of electric vehicles in this framework, they appear to us as future technologies in comparison with conventional internal combustion engines (ICEs). However, we may be surprised to learn that, a century ago, electric cars were far in advance of gasoline cars
Towards Automatic Registration of 3-D Views
No full textRecent advances in the field of laser scanning technology along with the availability of more powerful computing resources have favoured the increasing interest of surveyors, architects, archaeologists towards laser scanners technology as a very promising alternative for cultural heritage surveying. Thousands of points can be acquired in short time with an accuracy that is adequate to build 3D models for single objects so as for whole environments. At the present, resulting 3D digital models offer an invaluable mean for documentation, archiving, structural analysis and restoration of the large amount of objects spanning from Civil Engineering to Cultural Heritage assets. Usually, the end products of the whole workflow (survey and modeling) are VR representations (Vrml, Flash), movies (AVI, DVx, Mpeg), Dense Digital Surface Models (DDSM) and orthophotos as well. The creation of a 3D model requires a lot of data about the object surface or volume, which have then to be somehow aggregated, regardless the data structure and the acquisition device used. In most cases, the data registration step is based on ICP, that iterativelly finds the mutual orientation between two range maps, starting from an initial estimate provided by an operator. This approach is often time-consuming, increases the final cost of the 3D model and represents one of the major limits to the wide spreading of real object models.
In this paper an overview of an automatic range data registration system is presented, whose theoretical basis rely on the previous works of A. E. Johnson and L. Lucchese. The former proposed an innovative solution for the recognition of similarities between 3D surfaces, introducing the spin-image concept, while the latter developed an alternative procedure (Frequency Domain technique) for 3-D motion estimation of free-form surfaces, based on the Fourier transform of the 3-D intensity function, implicitly described by the registered time-sequences of range data
Characterizzation of dynamical properties of non-Markovian open quantum systems
No full textIn the present Thesis we study the behavior of multi-time correlation functions and of thermodynamical quantities such as heat in open quantum systems undergoing an evolution generally affected by the presence of memory effects, i.e. non-Markovian. In the last decade, a large part of the scientific community in this field has dedicated its efforts to the understanding, precise definition and quantification of non-Markovianity in the quantum realm and now we have at our disposal several benchmark results and a plethora of different estimators that allow to determine the degree of non-Markovianity of a given dynamics. It comes therefore natural to investigate how other different dynamical quantities relate to such estimators also in order to understand the physical implications of memory effects on the statistics of observable quantities.
In the first part of this work, a quantitative test of the violation of the so-called quantum regression theorem in presence of a non-Markovian dynamical regime is investigated. The quantum regression theorem represents a procedure that, whenever valid, allows to reconstruct two-time correlation functions of system's operators from the sole knowledge of the dynamics of mean values. It is worth stressing that two-time correlation functions are necessary in order to fully characterize the statistical properties of a quantum system, since they are able to catch aspects of the dynamics, such as fluorescence spectrum, in general not accessible looking at mean values. Despite their relevance however, obtaining two-time correlation functions often represents a formidable task, since the knowledge of the full "system+environment" dynamics is required, a generally too demanding request in the context of open quantum systems theory. The quantum regression theorem represents in this regard the easiest route to determine two-time correlation functions, this highlighting its importance. In this work we show that, in a pure-dephasing spin-boson model, the quantum regression theorem represents a stronger condition than non-Markovianity, in the sense that any presence of memory effects in the reduced dynamics inevitably results in violations to the former. These results have been published in [G.Guarnieri, A. Smirne, B. Vacchini, Phys. Rev. A 90, 022110 (2014)].
The second part of the Thesis is devoted to the characterization of heat ow at the microscopic level in open quantum systems, both finite and infinite dimensional. In particular we begin by studying the time behavior of its mean value in a non-Markovian dynamical regime, showing that, at variance
with what happens in the Born-Markov semigroup limiting case, heat can backflow from the environment to the system. After providing a condition for the occurrence of such phenomenon and a measure for its amount for a given dynamics, the relationship with suitable non-Markovianity estimators is sought in two paradigmatic models, namely the spin-boson and the quantum brownian motion. The results, collected in [ G. Guarnieri, C. Uchiyama, B. Vacchini, Phys. Rev. A 93, 012118 (2016); G. Guarnieri, J. Nokkala, R. Schmidt, S. Maniscalco, B. Vacchini, Phys. Rev. A 94, 062101 (2016)], on the one hand allow for the identification of parameter-regions where the heat backflow is absent or maximum. On the other hand they show that the occurrence of heat backflow represents a stricter condition than non-Markovianity, in the sense that non-Markovianity allows for the observation of heat flowing back from the environment to the system and, vice versa, a Markovian dynamics prevents its occurrence. This Thesis concludes with the formulation of a new family of lower bounds to the mean dissipated heat in an environmental-assisted erasure-protocol scenario where Landauer's principle applies. As originally conceived for classical systems, this principle states that every irreversible erasure of information stored in a system inevitably carries along an amount of heat dissipated into the environment which is expended to perform the action. Within the framework recently put forward in [D. Reeb, M. M. Wolf, New J. Phys. 16, 103011 (2014)],
which guarantees the validity of Landauer's principle in an open quantum systems scenario, we provide an asymptotically tight family of lower bounds to the dissipated heat which are also valid in the non-equilibrium setting. This construction is applied to an open system consisting of a three-level V-system, in which one transition is externally pumped by a laser field while the other is coupled through an XX-interaction to an environment consisting of a spin chain. Beside calculating all these quantities, an exact solution for the dynamics of such system is also provided. These results are collected in [G. Guarnieri, S. Campbell, J. Goold, S. Pigeon, M. Paternostro, B. Vacchini, in preparation]
La cappella gentilizia e le altre decorazioni trecentesche nel Palazzo Ducale di Mantova al tempo dei Gonzaga
No full textIl contributo tratta della decorazione trecentesca dei diversi ambienti di Palazzo Ducale di Mantova, delle sale dell’appartamento cosiddetto
della Guastalla al piano nobile, della cappella privata, oggi sala delle Imprese, dell’adiacente corridoio del Passerino e di alcune stanze al pianterreno. Ampiamente rimaneggiata e depauperata nel suo tessuto pittorico, la cappella gentilizia, in particolare, va senza dubbio annoverata tra le imprese di più alto profilo non solo del territorio mantovano, ma di tutta la pittura trecentesca padana. Considerazioni di natura tecnica e stilistica permettono di riconoscere l'attività di due pittori, entrambi di qualità, attivi ad un paio di decenni di distanza l'uno dall'altro, nel corso degli anni '30 e degli anni '50 del XIV secolo
La configuration institutionnelle du pouvoir judiciaire
No full textLes juridictions constituent l’un des piliers des systèmes politiques modernes. Elles sont en effet chargées de juger les litiges provenant de l’application des normes reconnues. Les juges – qui jouent évidemment un rôle crucial dans la résolution des conflits – tendent à jouir d’une position spéciale dans tous les systèmes politiques, et particulièrement dans les démocraties constitutionnelles. Dans de tels systèmes, les juges bénéficient de garanties plus fortes, prévues par des lois ordinaires et souvent également par des lois organiques et des normes constitutionnelles. Cependant, afin de déterminer les principes généraux gouvernant le statut des juges – et la configuration institutionnelle du pouvoir judiciaire – la façon dont les règles juridiques formelles sont appliquées doit également être prise en compte. De la sorte, les différences et les similitudes entre les pays – et les traditions juridiques – peuvent être clairement distinguées. En effet, dans les pays démocratiques, différentes traditions juridiques – emportant des conséquences notables quant au statut des juges – peuvent être identifiées
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