2,505 research outputs found
Method dependence of proline ring flexibility in the poly-L-proline type II polymer
Get PDFWe studied the sensitivity of the energetic and geometrical features of the proline ring (pyrrolidine) to the quantum mechanical computational approach by adopting the proline monomer, trimer, and polymer, as simplified collagen protein models. Within the Density Functional Theory (DFT) approach, we tested the ability of different functionals (GGA PBE and the hybrid B3LYP), added with a posteriori empirical dispersion corrections (D), to predict the conformational potential energy surface of the five-membered heterocycle pyrrolidine ring for the above models, dictating the collagen main features. We also compared the DFT-D results with those from the recently proposed cost-effective HF-3c method and our variant HF-3c-027, both based on Hartree-Fock Hamiltonian and Gaussian minimal basis set properly corrected for basis set superposition error, structure deficiencies, and dispersion interactions. We found that dispersion interactions are essential to destabilize specific conformers. While the HF-3c and its HF-3c-027 variant are unreliable to predict accurately the energy of the ring conformers, structures are accurate. Indeed, the cost-effective DFT-D//HF-3c-027 approach in which the energetic is from the accurate DFT-D method on HF-3c-027 structures provides energetic in line with that derived by the costly DFT-D//DFT-D approach, paving the way to simulate more realistic collagen models of much larger size. The adoption of either PBE or B3LYP functional for the electronic part of the DFTD method gives very similar results, recommending the first as the most cost-effective method for simulating large collagen models. The predicted most stable conformation computed for the periodic poly proline (type II) model allows for a higher flexibility, in agreement with experimental studies on collagen protein. The present results open the way to large-scale calculations of the collagen/hydroxyapatite system, crucial for understanding the atomistic details in bones and teeth
Revealing the Urban Plan. The Configurational Analysis as a Support for the Evaluation of Urban Plans and Projects
No full textEvent-Based Modelling and Simulation of Hospital Acquired Infection Propagation Dynamics by Contact Transmission in Hospital Wards
Get PDFIl percorso di ricerca presentato in questo lavoro si inserisce nell’ambito dello sviluppo dei sistemi di supporto alla decisione nel campo dell’Ingegneria del Territorio, nel caso particolare della gestione della conoscenza spaziale in condizioni di rischio.
L’oggetto di decisione in questo ambito è caratterizzato per essere un sistema complesso, composto di svariati sotto sistemi anch’essi complessi. La complessità è infatti una caratteristica propria di tutti i sistemi che comprendono elementi viventi e nella pianificazione territoriale l’agente umano o naturale è ubiquo.
Per poter sviluppare la ricerca si è scelto un settore problema che è quello della diffusione delle infezioni nei reparti ospedalieri. In particolare si è scelto di concentrarsi sulla trasmissione tramite contatto.
Questo tema è stato dimostrato essere una questione di rilevanza planetaria, da un punto di vista economico e ancor più per il rischio diretto alla salute umana.
Nella prima parte della tesi il tema è indagato, sia rispetto alle sue precipue caratteristiche, sia rispetto alle misure di controllo e prevenzione che esperti del settore hanno a disposizione ed attuano per contrastare il fenomeno.
Come le statistiche dimostrano le attuali strategie non sono sufficienti a evitare il verificarsi del fenomeno, né tantomeno potrebbero eliminarlo, quanto piuttosto sono delle contromisure più o meno efficaci ed intraprese quando il problema è conclamato, con tutte le nefaste conseguenze.
La ricerca di un più raffinata descrizione del problema, così da suggerire migliori strategie di intervento e supportare la presa di decisioni atte a prevenire l’insorgenza del fenomeno o a controllarlo, è auspicabile.
Per quanto la questione sia stata ampiamente indagata nei secoli soprattutto nel settore della epidemiologia, lo sviluppo di nuovi strumenti software basati sul paradigma del sistema multi agente può a nostro parere dare un contributo rilevante.
Si è quindi scelto di utilizzare un approccio di modellazione e simulazione Event-Based, che è un’evoluzione del sistema ad agenti puro. Esso si è dimostrato capace di rappresentare realisticamente complessi scenari di attività umane e d’uso di spazi tramite l’integrazione del classico approccio bottom-up con una architettura di alto livello per la pianificazione dei comportamenti degli agenti.
La conoscenza strutturata che si è generata nella fase di analisi del sistema problema è stata attribuita agli elementi del modello logico realizzato. Le caratteristiche che gli agenti erano in grado di esprimere sono state accordate al tema prescelto ed ampliate.
Inoltre nello sviluppo del modello si è voluto stressare le potenzialità dell’approccio scelto al fine di poter introitare interessanti considerazione di dettaglio. Il framework è stato esteso per rappresentare aspetti quali ad esempio la percezione del contesto da parte degli agenti e l’influenza delle condizioni ambientali sui loro comportamenti.
Il fine sotteso è stato quello di aumentare le capacità descrittive del l’approccio e di conseguenza l’espressività della simulazione verso una complessificazione che rendesse il modello più calzante alla realtà del fenomeno.
Rispetto ai modelli di letteratura quello qui presentato è stato costruito per superarne alcune limitazioni concettuali e strumentali soprattutto riguardanti l’inclusione dell’aspetto di diffusione spaziale della contaminazione, ancorché i dati attualmente disponibili in letteratura non sono sufficientemente fini per poter correttamente quantificare il peso delle interrelazioni fra le variabili considerate.
L’interpretazione del fenomeno rispetto alla sua relazione con gli spazi costruiti, sia fisici sia considerati nella comprensione di essi da parte degli agenti, è un aspetto innovativo che si è scelto di analizzare in collaborazione con il gruppo di ricerca del Prof. Yehuda E. Kalay presso la facoltà di architettura del Technion, (IL).
Dunque il comportamento degli agenti del sistema rispetto alla loro condizione e capacità di contaminazione è stato formulato attraverso una equazione discreta. Il modello e la equazione sono stati poi implementati in un ambiente di simulazione virtuale, Unity 3D e le funzioni logiche codificate in C#.
La simulazione di un caso di studio ipotetico e di scenari iniziali variamente settati è servita a verificare la bontà della modellazione e della formalizzazione, grazie alla possibilità di visualizzazione dinamica che offre lo strumento software.
Per quanto il modello necessiti di ulteriori passaggi di calibrazione, anche attraverso una campagna di data-collection mirata a raccogliere in maniera contestuale tutti i dati necessari come input per il sistema, gli scenari modellati e una prima analisi di sensitività ci offrono un certo grado di confidenza sulla bontà degli output.
Possiamo quindi affermare che il modello sviluppato può fungere da supporto alle decisioni per lo specifico fenomeno modellato ed ancor più conforta la nostra scelta della metodologia ad agenti per la modellazione di fenomeni complessi nel campo della pianificazione territoriale.
Come proseguo della ricerca ci si propone di migliorare la definizione della formulazione discreta adottata, estendendola al continuo così da rispecchiare la realtà ed è inoltre auspicabile l’applicazione del sistema ad un caso di studio reale che ci offra una base dati coerente con il modello proposto.The research aims presented in this study form part of a development of decision support systems for Land Engineering, particularly within the field of space knowledge management in risk conditions.
The aim of decision-making in this context is characterised by its being part of a complex system composed of different, equally complex sub-systems. Indeed, this complexity is a feature of all systems which include living elements and in any land planning scenario, a human or natural agent is ubiquitous.
In order to develop the research study, a problematic sector was chosen; the spread of infection in hospital wards. In particular, it was decided to concentrate specifically on transmission by contact.
This topic has proved to be of particular global importance, not only from an economic point of view but more importantly due to its direct risk to human health.
The first part of the thesis deals with an investigation of the topic’s principal characteristics as well as the control and prevention measures which are available to experts in the field and which are used to contrast this phenomenon.
As statistics demonstrate, current strategies are insufficient in preventing the occurrence of the phenomenon, much less eliminating it altogether, even if there are counter-measures which are relatively efficient in dealing with the problem once it has been officially declared, with all its ensuing ominous consequences.
It is thus beneficial to present a research study which provides a more detailed description of the problem, proposing improved intervention strategies and supporting the decision-making required to prevent or control outbreaks of the phenomenon.
Although the subject has long been widely researched, above all in the field of epidemiology, the development of new software based on multi-agent paradigms can, in our opinion, play an important contributing role.
Thus, it was decided to use a modelling and Event-Based simulation approach, a development of the agent-based system. It proved capable of realistically representing complex human activity and use of space scenarios by integrating the classic bottom up approach with a high-level architecture to plan agent behaviour.
The structured knowledge generated during the system problem analysis phase have been attributed to elements of the completed logical model. Moreover, the characteristics that the agents were able to display were fitted with the pre-selected topic and extended.
During the development of the model, our aim was to stress the potential of the approach as a means to yielding interesting and detailed considerations. The framework was extended to include other features, for example agent perception of the situation or the influence of environmental conditions on his behaviour.
The underlying aim was to increase the descriptive capacity of the framework (and thus the expressive level of the simulation) to achieve a higher degree of complexity, so rendering the model more geared toward the reality of the phenomenon.
Compared with other examples in literature, our model was built to overcome a number of conceptual and instrumental limits, above all regarding the spatial spread of contamination. Even if current available data in literature is not detailed enough to allow for an accurate quantification of the weight of interrelations between the variables under study.
A further innovative feature is that of interpreting the phenomenon with regard to its relationship with built spaces, both in a physical sense as well as that perceived by agents. It was chosen to analyse this aspect in collaboration with Prof. Yehuda E. Kalay’s research group at the Faculty of Architecture of Technion (Israel).
The behaviour of system agents with regard to their conditions and contamination capacity was formulated by the use of a discrete equation. The model and equation were then implemented within a virtual simulation environment, Unity 3D, and the logical functions coded in c#.
The simulation of a hypothetical case study and scenarios with initial varied settings helped to verify the efficacy of the modelling and formalisation thanks to the possibility of dynamic visualisation provided by the tool software.
It is true that the model requires further calibration, which could also be through data collection to retrieve all the information necessary to feed the system. However, the modelled scenarios and an initial sensitivity analysis provide us with a certain degree of confidence about the validity of the output results.
We can thus state that the developed system may be used as decision-making support for this particular modelled phenomenon, thus justifying our choice of agent methodology in the modelling of complex phenomena in the field of urban planning.
As research continues, so improvements will be made in the definition of the discrete formula adopted, continuously extending it to reflect real life. A further aim is the application of the system to a real-life case study, providing us with a database in line with the proposed model
Modeling phosphorene and interacting with iron: lubricating effects compared to graphene
Get PDFPhosphorene, a single layer of black phosphorus, is attracting interest for several applications, among which tribology. Here, we investigate its possible use as a solid lubricant for iron-based materials by comparing its friction-reduction properties with MoS2 and graphene. Through first-principle calculations, we predict that phosphorene adheres more strongly to the native iron surface than the other considered 2D materials. The higher adhesion suggests that a stable and durable coverage of reactive surface regions can be obtained with phosphorene. Furthermore, our simulation uncovers the peculiar behavior of phosphorene to exfoliate into two atomic-thin layers upon interface intercalation. This capability makes phosphorene reduce the nano-asperity adhesion very efficiently thanks to the simultaneous passivation of the surface and countersurface. These results suggest that better performances could be obtained by phosphorene than other solid lubricants at low concentrations
Michele Taruffo: el magisterio y la obra ejemplares del genial procesalista «todoterreno»
No full textThe author reflects on Michele Taruffo’s extraordinarily important contribution to the renewal of both conventional procedural law scholarship and the theoretical background of law-court professionals. Taruffo’s contribution was achieved by means of introducing to mainstream culture in those circles the necessary knowledge of the underlying epistemic dimension, which was traditionally suppressed by the strictly legal one.El autor discurre acerca de la importantísima contribución de Michele Taruffo a la renovación del procesalismo convencional y del bagaje teórico de los profesionales de la jurisdicción, mediante la incorporación a la cultura dominante en tales medios del imprescindible conocimiento de la dimensión epistémica subyacente y tradicionalmente sofocada por la propiamente jurídica
A simplified methodology for risk analysis of historic centers: the World Heritage Site of San Gimignano, Italy
No full textPurpose
Worldwide, natural hazards are affecting urban cultural heritage and World Heritage Sites, exacerbating other environmental and human-induced threats deriving from deterioration, uncontrolled urbanization and unsustainable tourism. This paper aims to develop a disaster risk analysis in Italian historic centers because they are complex large-scale systems that are cultural and economic resources for the country, as well as fragile areas.
Design/methodology/approach
A heritage-oriented qualitative methodology for risk assessment is proposed based upon the formalization of risk as a function of hazard, vulnerability and exposure, taking into account the values of cultural heritage assets.
Findings
This work provides a contribution to the body of knowledge in the Italian context of disaster risk mitigation on World Heritage Sites, opening for further research on the monitoring and maintenance of the tangible heritage assets. The application to the site of San Gimignano proves the effectiveness of the methodology for proposing preventive measures and actions that ensure the preservation of cultural values and a safer built environment.
Originality/value
The application of a value-based simplified approach to risk analysis is a novelty for historic centers that are listed as World Heritage Sites
Adhesion, Friction and Tribochemical Reactions at the Diamond-Silica Interface
Get PDFDiamond-based coatings are employed in several technological applications,
for their outstanding mechanical properties, biocompatibility, and chemical
stability. Of significant relevance is the interface with silicon oxide, where
phenomena of adhesion, friction, and wear can affect drastically the
performance of the coating. Here we monitor such phenomena in real-time by
performing massive ab initio molecular dynamics simulations in tribological
conditions. We take into account many relevant factors that can play a role,
i.e. the diamond surface orientation and reconstruction, silanol density, as
well as, the type and concentration of passivating species. The large systems
size and the long simulations time, put our work at the frontier of what can be
currently done with fully ab initio molecular dynamics. The results of our work
point to full hydrogenation as an effective way to reduce both friction and
wear for all diamond surfaces, while graphitization is competitive only on the
(111) surface. Overall we expect that our observations will be useful to
improve technological applications where the silica-diamond interface plays a
key role. Moreover, we demonstrate that realistic and accurate in silico
experiments are feasible nowadays exploiting HPC resources and HPC optimized
software, paving the way to a more general understanding of the relationship
between surface chemistry and nanoscale-tribology
Looking for Japan in contemporary Italy
No full textPh. D.Includes bibliographical referencesIncludes vitaby Michele Monserrat
The Author Reply. Letter to the Editor
No full textThe Author reply to the Letter sent to the Editor about a previus article on low anterior resection
Il trionfo della morte di Palermo. Un'allegoria della modernità
No full textOriginariamente collocato nel cortile dell’Ospedale Grande e Nuovo in Palazzo Sclafani, il Trionfo della morte – ora custodito nella Galleria di Palazzo Abatellis, a Palermo – è una straordinaria enciclopedia iconografica medievale e moderna, di cui non conosciamo l’autore.
Il libro di Michele Cometa è una guida all’interpretazione del tessuto narrativo di questo formidabile affresco. Le molteplici fonti pittoriche e letterarie che ne costituiscono la trama convergono nel tratteggiare – evocando la peste nera che imperversava in Europa da più di un secolo – una sorta di confutazione iconologica del retribuzionismo medievale. Le pene mondane, infatti, non sono qui più riconducibili al peccato, ma si stemperano in una melanconia tutta modernaOriginally located in the courtyard of the Great and New Hospital in Palazzo Sclafani, the Triumph of Death - now housed in the Gallery of Palazzo Abatellis, in Palermo - is an extraordinary medieval and modern iconographic encyclopedia, of which we do not know the author.
Michele Cometa's book is a guide to interpreting the narrative fabric of this formidable fresco. The multiple pictorial and literary sources that make up the plot converge in outlining - evoking the black plague that raged in Europe for more than a century - a sort of iconological refutation of medieval retribution. In fact, worldly pains are no longer attributable to sin, but are dissolved in a wholly modern melancholy
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