1,735 research outputs found

    Stress Analysis of an Endosseus Dental Implant by BEM and FEM

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    In this work the Boundary Element Method (BEM) and the Finite Element Method (FEM) have been used for an elastic-static analysis of both a Branemark dental implant and a generic conic threaded implant, modelled either in the complete mandible or in a mandibular segment, under axial and lateral loading conditions. Two different hypotheses are considered with reference to degree of osteo-integration between the implant and the mandibular bone: perfect and partial osteointegration. The BEM analysis takes advantage of the submodelling technique, applied on the region surrounding the implant. Such region is extracted from the overall mandible and the boundary conditions for such submodel are obtained from the stress analysis realised on the complete mandible. The obtained results provide the localisation of the most stressed areas at the bone-implant interface and at the mandibular canal (containing the alveolar nerve) which represent the most critical areas during mastication. This methodology, enriched with the tools necessary for the numerical mandible reconstruction, is useful to realise sensitivity analysis of the stress field against a variation of the localisation, inclination and typology of the considered implant, in order to assess the optimal implant conditions for each patient under treatment. Due to the high flexibility in the pre- and post-processing phase and accuracy in reproducing superficial stress gradients, BEM is more efficient than FEM in facing this kind of problem, especially when a linear elastic constitutive material law is adopted

    Workers’ Aging Management—Human Fatigue at Work: An Experimental Offices Study

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    The aging issue in the work context is becoming a significant element of the future sustainability of service and industrial companies. It is well known that with increasing worker age the problem of maintaining the performance and the safety level when fatigue increases is a crucial point, and fatigue increases with the age. Due to social and political developments, especially in Western countries, the retirement age is increasing and companies operate with a higher workforce mean age. Therefore, the problem of recognizing and measuring fatigue has become a key aspect in the management of aging. Note that in the scientific engineering field, the problem of fatigue evaluation when a worker is performing his/her work activities is an important issue in the industrial and service world and especially in the context of the researchers that are investigating the human reliability assessment. As it is clear from the literature, the industrial operations management are suffering from some misleading concepts that only the medicine scientific context can clarify. Therefore, the aim of this paper is to define what are the open issues and the misleading concepts present in the classical fatigue evaluation methods, and second to define two experimental curves of fatigue that will help the decision makers to minimize the impact of fatigue on the workers, thus maximizing the sustainability of the working tasks assigned. This aim is achieved by examining the medical literature about the measurement of a particular kind of fatigue related to the circadian cycle, i.e., the cognitive one; after that, a survey about the possible technologies for measurements is performed. On the basis of technology selection, an experiment on real work activities is performed and some remarkable results about the fatigue in the workers observed and the technology use and its limitations are defined

    Towards Digital Twin Implementation for Assessing Production Line Performance and Balancing

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    The optimization of production processes has always been one of the cornerstones for manufacturing companies, aimed to increase their productivity, minimizing the related costs. In the Industry 4.0 era, some innovative technologies, perceived as far away until a few years ago, have become reachable by everyone. The massive introduction of these technologies directly in the factories allows interconnecting the resources (machines and humans) and the entire production chain to be kept under control, thanks to the collection and the analyses of real production data, supporting the decision making process. This article aims to propose a methodological framework that, thanks to the use of Industrial Internet of Things—IoT devices, in particular the wearable sensors, and simulation tools, supports the analyses of production line performance parameters, by considering both experimental and numerical data, allowing a continuous monitoring of the line balancing and performance at varying of the production demand. A case study, regarding a manual task of a real manufacturing production line, is presented to demonstrate the applicability and the effectiveness of the proposed procedure

    Long-term outcome of low-activity radioiodine administration preceded by adjuvant recombinant human TSH pretreatment in elderly subjects with multinodular goiter

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    <p>Abstract</p> <p>Background</p> <p>Large multinodular goiter (MNG) in elderly people is a common finding which can require intervention. The long-term effect of radioiodine therapy on thyroid volume (TV) and function after recombinant human (rh) TSH pre-treatment was evaluated.</p> <p>Methods</p> <p>After baseline evaluation, 40 subjects over 60 years old with a large MNG were treated with <sup>131</sup>I up to the activity of 600 MBq. Nineteen patients were pretreated with rhTSH (0.1 mg on 2 consecutive days; group 1) while 21 subjects underwent treatment without rhTSH pretreatment (group 2). TV was monitored every 6–12 months by ultrasonography. The median follow-up period was 36 months.</p> <p>Results</p> <p>At the baseline, the groups matched in terms of TV, 24-h radioiodine uptake (RAIU), urinary iodine and neck complaints. The number of subjects pretreated with anti-thyroid drugs was significantly (P = 0.01) greater in group 2 than in group 1; TSH was more suppressed (P = 0.003) and f-T3 was more elevated (P = 0.005) in group 2 than in group 1 patients. RhTSH increased 24-h RAIU in group 1 up to the baseline level observed in group 2. The <sup>131</sup>I activity administered was similar in both groups. Adverse events were slight and similar in both groups. A permanent post-radioiodine toxic condition was reported only in 2 patients in group 2. After radioiodine therapy, hypothyroidism was observed in significantly more group 1 patients than group 2 patients (P = 0.002). While TV was reduced in both groups, the percentage TV reduction recorded at the last examination was significantly higher (P = 0.03) in group 1 than in group 2. MNG-related complaints were significantly reduced in both group 1 (P = 0.0001 vs baseline) and group 2 (P = 0.001) patients.</p> <p>Conclusion</p> <p>Low radioiodine activities after pretreatment with low-dosage rhTSH are able to reduce TV and improve MNG-related symptoms in elderly subjects.</p

    Seismological monitoring of the February 2007 effusive eruption of the Stromboli volcano

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    On February 27, 2007, the Stromboli volcano, which has usually been characterized by moderate explosive activity, started an effusive eruption with a small lava flow down the NW flank. The permanent broadband network installed on the island allowed the revealing of anomalies in the seismicity before the effusive eruption and for the phenomena to be followed over time, thus obtaining meaningful information about the eruption dynamics. During the effusive phase, a major explosion occurred on March 15, 2007. On that occasion, two strainmeters deployed on the volcano in the previous year recorded a strain increment before the blast. After this explosion, which further destabilized the upper part of the edifice, swarms of Long-Period (LP) and hybrid events were recorded. The characteristics and locations of these events suggest that they were associated with the fracturing processes that affected the summit area of the cone. During the effusive phase, changes in the Very Long Period (VLP) event location were recorded. This type of events accompanied the change in the eruptive style, providing information about the magmatic conduit involved in their seismogenetic processes. The effusive phase stopped on April 2, 2007, and the typical Strombolian activity restarted some months later

    Mutations impairing GSK3-mediated MAF phosphorylation cause cataract, deafness, intellectual disability, seizures, and a down syndrome-like facies

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    Transcription factors operate in developmental processes to mediate inductive events and cell competence, and perturbation of their function or regulation can dramatically affect morphogenesis, organogenesis, and growth. We report that a narrow spectrum of amino-acid substitutions within the transactivation domain of the v-maf avian musculoaponeurotic fibrosarcoma oncogene homolog (MAF), a leucine zipper-containing transcription factor of the AP1 superfamily, profoundly affect development. Seven different de novo missense mutations involving conserved residues of the four GSK3 phosphorylation motifs were identified in eight unrelated individuals. The distinctive clinical phenotype, for which we propose the eponym Aymé-Gripp syndrome, is not limited to lens and eye defects as previously reported for MAF/Maf loss of function but includes sensorineural deafness, intellectual disability, seizures, brachycephaly, distinctive flat facial appearance, skeletal anomalies, mammary gland hypoplasia, and reduced growth. Disease-causing mutations were demonstrated to impair proper MAF phosphorylation, ubiquitination and proteasomal degradation, perturbed gene expression in primary skin fibroblasts, and induced neurodevelopmental defects in an in vivo model. Our findings nosologically and clinically delineate a previously poorly understood recognizable multisystem disorder, provide evidence for MAF governing a wider range of developmental programs than previously appreciated, and describe a novel instance of protein dosage effect severely perturbing developmen

    Geophysical monitoring of Stromboli volcano: insight into recent volcanic activity

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    Stromboli is an open conduit strato-volcano of the Aeolian archipelago (Italy), characterized by typical Strom-bolian explosive activity, lasting for several centuries, and by the emission of huge amounts of gas. The normalactivity of Stromboli is characterized by some hundreds of moderate explosions per day. Major explosions, whichlaunch scoria up to hundreds of meters from the craters, lava flows and paroxysmal explosions, which producelarge ballistic blocks, sometimes take place. During the effusive eruption in 2002 - 2003, which caused a tsunamiwith waves of about 10 meters high along the coasts of the Island, the monitoring system was enhanced. In 2006INGV has added two Sacks-Evertson borehole volumetric dilatometers to the surveillance system, in order to mon-itor changes in the local strain field by measuring areal strain. Today we have a large amount of geophysical dataand observations that allow us to better understand how this volcano works. After a period of low explosive activitystarted in mid-2014, Stromboli has shown a more intense explosive activity in the last few months. During the re-cent phase of increased activity, the geophysical monitoring system detected four major explosions occurred on 26July, 23 October, 1 November and 1 December 2017, respectively. The current phase of reawakening of Strombolivolcano has led the Italian civil protection authorities to decree the "attention" alert level (yellow) on the Island.PublishedVienna, Austria1IT. Reti di monitoraggio e sorveglianz
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