MediaDART: a decentralized framework for sharing multimedia content

This paper provides an overview of MediaDART, a framework for building online services for distributing and sharing digital media. Inspired by the participative model of Web 2.0, MediaDART relies on a scalable and decentralized architecture that can grow with the contribution of users. The architecture is based on an arbitrary number of nodes interconnected through a p2p network implementing a distributed hash table (DHT). The DHT provides resource storage and parallel resource processing for operations of feature extraction, adaptation and composition. MediaDART adopts application-level multicast based on distribution trees for delivery in streaming and implements algorithms to dynamically replicate resources across the network. The framework allows content description through user-defined tags. Tools for personalized content retrieval based on recommendation algorithms and user profiling are included too. This paper also describes two prototype applications and outlines further work.141-14

Occurrence of acute oesophageal necrosis (black oesophagus) in a single tertiary centre

Acute oesophageal necrosis (AON) is a rare condition characterised by the endoscopic finding of diffuse, circumferential, black mucosal pigmentation of the oesophagus, which typically stops at the gastro-oesophageal junction. This observational study aimed to assess the occurrence, clinical characteristics and outcomes of AON in a consecutive endoscopic cohort in a single tertiary university centre. A retrospective analysis of endoscopic data of upper gastrointestinal endoscopy (UGE) was carried out from 2008 to 2018. Out of 25,970 UGE, 16 patients (0.06%) had AON; 75.0% were men with a median age of 75 years. Almost all patients underwent diagnosis during emergency UGE performed for gastrointestinal bleeding, but one patient was diagnosed during elective UGE for persistent vomiting and diarrhoea. All patients reported one or more pre-existing comorbidities and concomitant acute events. Two patients had AON as the first presentation of Zollinger-Ellison syndrome (ZES). One patient developed an oesophageal stenosis, and another patient presented a relapse of AON. Mortality was 50%, but no patient died as a direct consequence of AON. AON is a rare cause of gastrointestinal bleeding diagnosed mainly during emergency UGE. Our study showed that ZES might manifest with this critical presentation, and endoscopists must be aware of this evidence

Out-of-plane capacity of cladding panel-to-structure connections in one-story R/C precast structures

AbstractThe interaction between cladding panels and the main structure is a crucial point to assess the seismic response, and above all the structural safety, of RC precast industrial building. In the past, connections were often designed to allow construction tolerances and to accommodate both thermal and wind-induced displacements. The lack of specific details to allow relative in-plane displacements between cladding panels and the main structure often led to the participation of cladding panels in the structure seismic-resistant system with consequent connection failures. In the last decades, a lot of experimental tests were performed to investigate the in-plane performance of panel connections, and some design recommendations have been developed accordingly. In the out-of-plane direction, the connections were often considered to be infinitely rigid and not to suffer any damage by the seismic load. This work deals with the out-of-plane response of panel-to-structure connections for vertical panels typical of industrial and commercial precast buildings. Both standard hammer-head strap and new devices, called SismoSafe, were investigated. Tests were performed in the Structures and Materials Testing Laboratory of the Department of Civil and Environmental Engineering of Florence, where a specific setup was designed to perform cyclic and monotonic tests on the connection devices. Standard connections showed a rather limited resistance, while the innovative connections exhibited a high out-of-plane resistance. Numerical analyses were also performed on a case study building to evaluate the distribution of the out-of-plane demand on the connections

Dynamic identification of selective steel storage pallet rack

Steel storage pallet racks are formed by cold formed steel members and are used worldwide for storage of palletized goods. The main racking system is called the “selective steel storage pallet rack”. Selective racks behave like bracing systems in the cross-aisle direction, with columns connected by diagonal braces. In the down-aisle direction, racks behave like moment resisting frames, whose stability and dynamic response is mainly affected by the beam-to-column connections and the column base plate connections. The paper presents a study on the dynamic cross-aisle and down-aisle behavior of selective steel storage pallet racks. The dynamic response of a three bays full scale rack system under three different load levels is investigated through pullback tests. In addition, the effect of the impact due to a forklift truck is simulated and the propagation in accelerations and strains between consecutive upright frames is analyzed. The objectives of the ongoing research activity are the evaluation of the natural frequency and damping coefficient of the system. Moreover, recommendations in type, number, and position of monitoring structural devices alerting the impact of forklifts and assessing damage on structural members are provided

Peek polymer in orthodontics : a pilot study on children

The purpose of the study has been making the orthodontic space maintainers in PEEK polymer (Polyetheretherketone) through a digital workflow. New digital technologies are taking hold in diagnosis, therapy and in dental laboratories. The digital world can help dentist in diagnosis and therapy: -diagnosis through the acquisition of radiographic images (CBCT) or scanners which allow the creation of 3D digital models ? about therapy thanks to dental CAD CAM system. It consists of design devices through an dedicated software CAD and then realize devices through CAM system. We used digital system to improve the quality of the treatment and reduce costs. Peek polymer, subject of studies in recent years, thanking to its characteristics, resulted useful for this study. According to a nine month- follow up the devices were found comfortable, satisfying, personalized and minimally visible for the patients. These devices were found suitable to maintain the space. About material, thanks to its dimensional stability, mechanical strength but specially, thanks to its biocompatibility, PEEK was found as a very good material to build space maintainers. The workflow allowed a simulation of the treatment plan with a better collaboration and acceptance of the patient. Digital system reduced the systematic mistakes during the various phases and the production time. The digital system saved space creating a virtual plaster casts collection

The application of a fluoride-and-vitamin D solution to deciduous teeth promotes formation of persistent mineral crystals: a morphological ex-vivo study

Background: The use of effective, low-cost, and easy-to-use products for early caries management will avoid loss of dental vitality and impairment in oral function. The ability of fluoride to re-mineralize dental surfaces has been widely reported as well as vitamin D demonstrated to have significant potential in improving the remineralization of early lesions on enamel surfaces. The aim of the present ex vivo study was to evaluate the effect of a fluoride and vitamin D solution in terms of formation of mineral crystals on the enamel of primary teeth, and their permanence over time on dental surfaces. Methods: Sixteen extracted deciduous teeth were cut to obtain 64 specimens that were divided into two groups. The first consisted of immersion of specimens for 4 days in a fluoride solution (T1); in the second group, the specimens were immersed for 4 days (T1) in fluoride and Vitamin D solution, and for a further 2 (T2) and 4 days (T3) in saline solution. Then, samples were morphologically analyzed by using Variable Pressure Scanning Electron Microscope (VPSEM) and underwent 3D surface reconstruction. Results: After a 4-day immersion in both solutions, octahedral-shaped crystals were formed on the enamel surface of primary teeth, demonstrating any statistically significant differences in terms of number, size, and shape. Moreover, the binding of the same crystals seemed to be strong enough to be maintained until 4 days in saline solution. However, a partial dissolution was observed in a time-dependent manner. Conclusions: A topical application of fluoride and Vitamin D promoted the formation of persistent mineral crystals on enamel surfaces of deciduous teeth and should be further studied to be potentially used as an alternative strategy in preventive dentistry

Frequency Dependence of Piles' Dynamic Stiffness

Technical BriefTechnical Brief 6: The evaluation of the dynamic behavior of deep foundations for Turbomachinery Modules is not a simple task due to uncertainties in the evaluation of the soil shear modulus and the approximations introduced with published literature formulas for complex stiffness (impedance) functions of piles. The direct measurement of the dynamic response of full scale piles can be an efficient method to reduce considerably these uncertainties and to get a reliable evaluation of the dynamic response of deep foundations. The above should also positively impact both the risks and the engineering schedule in the execution phase of the projects, reducing the dynamic analysis cases. The authors present herein the results of full-scale dynamic tests on piles, which have been performed by applying sinusoidal forces to their top