117,501 research outputs found
Presentazione
No full textPresentando il lavoro di ricerca di Daniela Bosia sul Buxus, lo scritto – partendo dalla presenza tecnologicamente innovativa del materiale utilizzato da Depero - individua in modo sintetico alcuni possibili fuochi di indagine relativi alla presenza del Secondo Futurismo a Torino.
Introducing the research work of Daniela Bosia about Buxus the article - starting from the innovative technological presence of the material used by Depero – synthetically identifies some possible research topics about the presence of Secondo Futurismo in Turin
Systematic numerical investigation of the role of hierarchy in heterogeneous bio-inspired materials
No full textIt is well known that hierarchical structure is an important feature in biological materials to optimise various properties, including mechanical ones. It is however still unclear how these hierarchical architectures can improve material characteristics, for example strength. Also, the transposition of these structures from natural to artificial bioinspired materials remains to be perfected. In this paper, we introduce a numerical method to evaluate the strength of fibre-based heterogeneous biological materials and systematically investigate the role of hierarchy. Results show that hierarchy indeed plays an important role and that it is possible to “tune” the strength of bio-inspired materials in a wide range of values, in some cases improving the strength of non-hierarchical structures considerably
Numerical implementation of multiple peeling theory and its application to spider web anchorages
No full textAdhesion of spider web anchorages has been studied in recent years, including the specific functionalities achieved through different architectures. To better understand the delamination mechanisms of these and other biological or artificial fibrillar adhesives, and how their adhesion can be optimized, we develop a novel numerical model to simulate the multiple peeling of structures with arbitrary branching and adhesion angles, including complex architectures. We validate the numerical model by comparing predictions with the recently developed Multiple Peeling Theory (MPT), which extends the energy-based single peeling theory of Kendall, finding excellent agreement even for complex structures. In particular we numerically confirm that a multiple peeling problem can be treated as the superposition of single peeling configurations even for complex structures. Finally, we apply the developed numerical approach to study spider web anchorages, showing how their function is achieved through optimal geometrical configurations
The influence of substrate roughness, patterning, curvature, and compliance in peeling problems
No full textNMP is supported by the European Commission under the Graphene FET Flagship (WP14 'Polymer composites' No. 604391) and FET Proactive 'Neurofibres' grant No. 732344. FB is supported by 'Neurofibres' grant No. 732344
Emergence of the interplay between hierarchy and contact splitting in biological adhesion highlighted through a hierarchical shear lag model
No full textContact unit size reduction is a widely studied mechanism as a means to improve adhesion in natural fibrillar systems, such as those observed in beetles or geckos. However, these animals also display complex structural features in the way the contact is subdivided in a hierarchical manner. Here, we study the influence of hierarchical fibrillar architectures on the load distribution over the contact elements of the adhesive system, and the corresponding delamination behaviour. We present an analytical model to derive the load distribution in a fibrillar system loaded in shear, including hierarchical splitting of contacts, i.e. a ‘‘hierarchical shear-lag’’ model that generalizes the well-known shear-lag model used in mechanics. The influence on the detachment process is investigated introducing a numerical procedure that allows the derivation of the maximum delamination force as a function of the considered geometry, including statistical variability of local adhesive energy. Our study suggests that contact splitting generates improved adhesion only in the ideal case of extremely compliant contacts. In real cases, to produce efficient adhesive performance, contact splitting needs to be coupled with hierarchical architectures to counterbalance high load concentrations resulting from contact unit size reduction, generating multiple delamination fronts and helping to avoid detrimental non-uniform load distributions. We show that these results can be summarized in a generalized adhesion scaling scheme for hierarchical structures, proving the beneficial effect of multiple hierarchical levels. The model can thus be used to predict the adhesive performance of hierarchical adhesive structures, as well as the mechanical behaviour of composite materials with hierarchical reinforcements
Guida al recupero dell'architettura rurale del G.A.L. Langhe Roero Leader
No full textLa Guida al recupero dell'architettura tradizionale del G.A.L. Langhe Roero Leader nasce in attuazione dell'intervento A)1 dell'Azione 3.2. "Interventi di tutela e valorizzazione architettonica e paesaggistica" prevista dal Piano di Sviluppo Locale di cui il G.A.L. si è dotato, finanziato all'interno del programma di iniziativa comunitaria Leader Plus. La Guida è riferita a un territorio collinare vasto, che comprende una cinquantina di Comuni delle Langhe e del Roero, ed è stata perciò impostata in modo da fornire linee di indirizzo, consigli più che imposizioni, per affrontare gli interventi di recupero dell'architettura rurale della tradizione di questa zona suggestiva della Provincia di Cuneo. Una trattazione più specifica e restrittiva, in effetti, avrebbe potuto risultare "pericolosa": le caratteristiche costruttive degli edifici e dei manufatti rurali, infatti, possono assumere peculiarità legate ad ambiti locali anche estremamente ristretti, non riconducibili a caratteri generali. La Guida è organizzata in sezioni tematiche: Elementi del Paesaggio, Centri storici, Materiali della tradizione costruttiva, Tipologie edilizie, Elementi costruttivi. In particolare, la sezione "Tipologie edilizie" riporta, per ciascun tipo di fabbricato individuato (nuclei rurali, edifici a impianto a "L" o a "C", edifici in linea e isolati, fabbricati di produzione e di servizio come stalle, fienili, depositi, ciabot, pozzi e forni, manufatti edilizi diversi, quali i muri di sostegno e le pavimentazioni esterne), una descrizione dei caratteri generali e alcune indicazioni, redatte sotto forma di linee guida, per un recupero dell'esistente compatibile con l'ambiente e il paesaggio e per l'impostazione di progetti di nuova costruzione. La sezione "Elementi costruttivi", invece, è organizzata in sotto-sezioni, ciascuna delle quali corrisponde a un elemento costruttivo individuato (murature, coperture, aperture, elementi di collegamento e di distribuzione, orizzontamenti), del quale vengono descritte le diverse articolazioni e le varianti costruttive presenti sul territorio, i possibili fenomeni di degrado ricorrenti, con indicazione di criteri generali di intervento e, talvolta, di qualche esempio di intervento. La trattazione di ogni elemento individuato è completata da specifiche schede di compatibilità degli interventi che riportano, per le principali varianti dell'elemento presenti sul territorio, indicazioni sintetiche sugli interventi ritenuti ammissibili, non ammissibili o critici rispetto alle istanze di tutela e di valorizzazione del costruito, del paesaggio e dell'ambient
The advantage of periodic over constant signalling in microRNA-mediated regulation
No full textCells may exploit oscillatory gene expression to encode biological information. Temporal features of oscillations, such as pulse frequency and amplitude, are determinant for the outcome of signalling pathways. However, little effort has been devoted to unveiling the role of pulsatility in the context of post-transcriptional gene regulation, where microRNAs act by binding to RNAs and regulate their expression. Here, we study the effects of periodic against constant microRNA synthesis within minimal microRNA-target networks. We find that there is a repressive advantage of pulsatile over constant microRNA synthesis, and that the extent of repression depends on the frequency of pulses, thus uncovering frequency preference behaviours. We show that the preference for specific input frequencies is determined by relative microRNA and target kinetic rates and can lead to exclusive frequency-dependent repression on distinct RNA species, thereby highlighting a potential mechanism of selective dynamical target regulation. Moreover, we show that frequencies observed in periodically expressed microRNAs, such as those involved in circadian rhythms and development, can be selectively favored. Our findings might have implications for experimental studies aimed at understanding how periodic patterns drive biological responses through microRNA-mediated signalling and provide suggestions for validation in synthetic networks
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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