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A Hysteresis model for timber joints with dowel-type fasteners
No full textPredicting the mechanical behaviour and the failure mechanism of timber joints with dowel-type fasteners requires consideration of several factors, including the geometrical and mechanical properties of the metal fastener, the physical properties of timber and the interaction between such elements. This paper proposes a numerical model where a joint is schematized as an elasto-plastic beam in a non-linear medium with a compression-only behaviour. Unlike the differential approach adopted by most of the hysteresis models published in literature, this model predicts the load-displacement response using simple mechanical relationships and basic input parameters. Furthermore, the model is capable of reproducing the effect of the cavity formed around the fastener by timber crushing, and simulates the hysteretic behaviour and the energy dissipation under cyclic conditions. Shear tests are reproduced on nailed steel-to-timber joints in Cross-Laminated Timber and results are compared to the experimental test data obtained on similar single fastener joints. Simulations lead to accurate predictions of both the mechanical behaviour (initial stiffness, maximum load-carrying capacity, global shape of the loading curve and of the hysteresis cycles) and the total energy dissipation observed in the tests
Studio sulla crioconservazione: dalle cellule somatiche alle cellule staminali
Full text linkThe challenging theme of cryopreservation was the focus of this PhD project. Different experimental approaches explored this topic in three ovine cell types of somatic, stem and germinal origin.
Skin fibroblasts were cryopreserved at 5°C/min. Cryomicroscopy analysis allowed to observe dynamics of ice formation and to calculate the probability of intracellular ice formation. Gene expression levels of some markers involved in metabolism, apoptosis and pathways of thermal stress were investigated at 0, 24 and 48 hours after thawing, showing that post-thaw in vitro culture could improve cryopreservation outcome.
The second experiment evaluated stem properties and differentiation capacity of primary isolated Wharton’s jelly cells and their ability to keep the original characteristics after cryopreservation. Three freezing methods were compared. According to gene expression and immunohistochemistry analysis, the slow and controlled freezing better retained the original cell characteristics than the other two studied methods.
Final experiment was a pilot study aimed to compare standard sperm freezing with a partial freeze-drying method (PFD). Cell motility and physical events as ice formation and the amount of the unfrozen fraction were evaluated via cryomicroscope and environmental scanning electron microscocope. Data showed that PFD was better in preserving motility and ensuring a higher unfrozen fraction, limiting severe damages related to ice growth and mechanical pressure
Rappresentazione di cartografia storica della città di Sassari in ambiente GIS Open Source
Full text linkThe aim of this research is to evaluate a methodology for the analysis of historical maps by applying open source GIS software.
Maps of “Città di Sassari” has been first collected, then, after proper editing using a graphic software, processed by a GIS (Geographic Information System). By comparing those systems with updated new maps has been possible to get final results. The cartography used is the one of “Città di Sassari” currently known. Both measured and derived maps were have been used. The former obtained through measurements and surveys performed on the ground by topographers while the latter through a series of re-elaborations performed by cartographers. As redards historical cartography we wanted to understand what was detected with elementary topographic tools, even before the advent of aerophotogrammetric technique.
Before entering into the real GIS, are presented those that are the basic maps that represent Sardinia, as well as a list, with related description, of the main detectors / cartographers and maps of Sassari.
The feasibility of employing an Open source software has been also part of the research except for the IT tools of office automation. The reason of such decision could be addressed almost exclusively by economic reasons, because studies about historical cartography are conducted mainly in academic fields, where, unfortunately, is almost lack of funds.
The research has had positive results, showing that free software can be used without reservations
Cultural ecologies of adaptive vs. maladaptive traits: a simple nonlinear model
No full textIn this paper, we generalize a model by Enquist and Ghirlanda [12] to analyze the “macro” dynamics of cumulative culture in a context where there is a coexistence of adaptive and maladaptive cultural traits. In particular, we introduce a different, nonlinear specification of the main processes at work in the cumulative culture dynamics: imperfect transmission of traits, generation of new traits, and switches from adaptive to maladaptive and vice-versa. We find that the system exhibits a variety of dynamic behaviors where the crucial force is the switching between the adaptive and maladaptive nature of a certain trait, with the other processes playing a modulating role. We identify in particular a number of dynamic regimes with distinctive characteristics
Environmental pollution as engine of industrialization
No full textThis paper analyzes the dynamics of a small open economy with two sectors (a farming sector and an industrial one), heterogeneous agents (workers and entrepreneurs) and free inter-sectoral labor mobility. Labor productivity in the first sector is negatively affected by environmental pollution generated by both sectors, whereas in the second sector it is positively affected by physical capital accumulated by entrepreneurs. Through a global analysis of the non-linear three-dimensional dynamic system of the model we derive conditions under which industrialization generates a decline in workers’ revenues in both sectors
Comparative development and reproduction of <i>Planococcus ficus</i> and <i>Planococcus citri</i> (Hemiptera: Pseudococcidae) on grapevine under field conditions
No full text1. Mealybugs are major pests in grape-growing areas worldwide, causing direct and indirect crop damage. The vine mealybug Planococcus ficus (Signoret) is a key pest in most of grape-producing countries, whereas the citrus mealybug Planococcus citri (Risso) is reported as being destructive in Brazilian and Spanish vineyards.
2. We examined the adaptation of the citrus mealybug to grapevine by investigating its development, reproduction and life-history parameters under Mediterranean field conditions in comparison with those of P. ficus.
3. Both mealybug species developed and reproduced successfully on grapevine. However, P. ficus showed a shorter development time, larger female body size, and higher fecundity, fertility and survival than P. citri.
4. The life-history parameters further highlighted the different growth potential of vine and citrus mealybug populations because P. ficus exhibited a net reproductive rate and an intrinsic rate of increase two- to four-fold higher than that of P. citri. Furthermore, the vine mealybug population doubled its number in approximately half time with respect to the citrus mealybug.
5. Overall, the results of the present study show a better development and reproductive performance and a higher population growth potential of P. ficus compared with P. citri, indicating a higher capacity of the vine mealybug to develop on grapevine in Mediterranean vineyards
Malignancy-associated generalized perforating granuloma annulare
No full textNo abstract is available for this article
Studio del ruolo dell’effettore fitoplasmatico SAP11 nelle interazioni pianta-fitoplasma-vettore
Full text linkPhytoplasmas are insect-transmitted Prokariotes associated with several plant diseases. They are responsible for significant economic losses in several crops and are mainly spread through infected plant material and by insect vectors. The latter, during their feeding activity, acquire the pathogen from infected plants and then transmit it, after a latency period, to new healthy plants. This process has been considered as having a passive nature for a long time but a growing body of evidences suggests that Phytoplasmas are able to actively modulate this process. Indeed, they interact with plant metabolism and negatively affect defense response against insects. This thesis presents work done to identify the nature of this interaction and especially the component explained by the effector SAP11, a protein molecule secreted into plant by Phytoplasmas during pathogenic process and involved in plant-insect interaction. Previous studies have shown that SAP11 is able to manipulate plant metabolism, causing various developmental changes and contributing to show typical symptoms associated with the presence of Phytoplasmas. Additionally, SAP11 reduces plant defense response to insect vectors, allowing them to lay more eggs and to produce more nymphs. In this paper, the role of this effector in the Phytoplasma pathogenic process is analyzed, allowing to elucidate several fundamental points of this complex plant-pathogen-insect interaction
Potenziamento del settore turistico sardo attraverso la valorizzazione delle risorse locali mediante sistemi di mobile marketing e codici QR
Full text linkThe study focuses on the reciprocal relationship between spaces and the creation process of the territorial value, identifying the routes by which to increase the attractiveness of the places in order to augment their competitive profile. The esearch identifies the "authentic and high quality" tourism demanded by both national and international tourists and applies an analysis model which looks at the competitiveness of the destination based on the territories environmental and cultural resources. The elements enable the places to be defined and we can then consider the new ways of travelling and the corresponding segments of the market to which the Strategies of Tourism Destination Development should be directed.The research develops and applies an analysis model of the Customer Experience that examines tourists in the Internet age, through face-to-face interviews with 300 travellers, Content Analysis on almost 1,000 reviews and the popularity of search terms on Google Trends, providing a clear picture on the needs of tourists. The results of the survey allow us to define a tool for territorial development, called FoodExplorer, based on a digital information system to support the enhancement of the Sardinian tourism sector. The service is designed for the 2.0 tourist who appreciates the quality of the local products and, through a smartphone and a mobile marketing system mediated by QR code, is incentivized to discovery and learn about the territory
I Nuovi delitti contro l'ambiente
Full text linkQuesto lavoro analizza la recente riforma dei delitti ambientali attuata con la Legge 22 maggio 2015, n. 68, la quale ha introdotto nel codice penale italiano alcuni delitti contro l’ambiente, oltre ad aver apportato diverse altre importanti innovazioni.
Dopo aver esaminato il generale contesto normativo antecedente alla L. n. 68/2015, nonché la previsione di obblighi di criminalizzazione imposti dal diritto euro-unitario, l’attenzione si focalizzerà sull’esame dei singoli (ormai codificati) delitti ambientali: inquinamento ambientale ex art. 452-bis c.p., morte o lesioni come conseguenza del delitto di inquinamento ambientale ex art. 452-ter c.p, disastro ambientale ex art. 452-quater c.p., delitti colposi contro l’ambiente ex art. 452-quinquies c.p., traffico e abbandono di materiale ad alta radioattività ex art. 452-sexies c.p., impedimento del controllo ex art. 452-septies c.p., omessa bonifica ex art. 452-terdecies c.p.
Tali nuovi delitti risolvono alcuni problemi in passato determinati dalla mancanza di normativa in materia di protezione dell’ambiente all’interno del codice penale italiano, la quale lacuna costituisce la ragione per cui si era più volte dovuto far ricorso ad altre disposizioni di legge per sanzionare le diverse fattispecie di delitti ambientali