The Use of a Pendulum Dynamic Mass Absorber to Protect a Trilithic Symmetric System from the Overturning

The trilith consists of two vertical elements (columns) supporting a horizontal element (lintel). The understanding of the dynamic behaviour of triliths is an important step towards their preservation and starts with the knowledge of the dynamics of rigid blocks. A passive method based on a dynamic mass absorber is used to protect a trilith from overturning. The protection system is modelled as a pendulum, hinged on the lintel, with the mass lumped at the end. The equations of rocking motion, uplift and the impact conditions are obtained for the coupled system trilith-mass absorber. An extensive parametric analysis is performed with the aim to compare the behaviour of the system with and without the pendulum, under impulsive one-sine (or one-cosine) base excitations. In order to point out the effectiveness of the protection system, overturning spectra, providing the amplitude of the excitation versus its frequency, are obtained. The pendulum mass absorber results effective in avoiding overturning in specific ranges of the frequency of the excitation. However, outside these ranges the mass absorber never compromises the safety of the trilith

Structural disconnection as a general technique to improve the dynamic and seismic response of structures: a basic model

Abstract The Base Isolation ( BI ) and the Tuned Mass Damper ( TMD ) represent two different techniques to reduce vibrations in building structures. Both these techniques may be considered as descending from an appropriate "disconnection" carried out on a given structure, whose global mass is subdivided in two parts, with a substantial difference in stiffness. The present work aims to study the characteristics of the disconnection and its effectiveness in reducing the dynamic response of a building structure subject to a base excitation. A simple 2- DOF "archetype" model has been developed to describe structural systems where a disconnection has been performed. This model has a constant total mass while stiffness and mass ratios, related to the two degrees of freedom, are taken as main variable parameters. Two distinct reference schemes ( BI -scheme and TMD -scheme) have been adopted in order to identify the specific part of the structure (respectively upper or lower) whose dynamic response should take advantage from the disconnection. A measurement of such advantage has been then proposed by means of different "gain parameters", related to each scheme. The behavior of the gain parameters has been depicted in various maps, each one defined for different base accelerations

probability models to assess the seismic safety of rigid block like structures and the effectiveness of two safety devices

Abstract When subject to earthquakes, some objects and structures, such as statues, obelisks, storage systems, and transformers, show a dynamic behavior that can be modeled considering the object/structure as a rigid block. Several papers have studied the dynamic behavior of both stand-alone rigid blocks and systems where rigid blocks have been paired with safety devices to prevent or delay the overturning of the blocks. Although the safety devices have generally been proven to be effective, their effectiveness changes substantially varying the parameters that characterize the system and the seismic input. This paper compares the seismic responses of stand along rigid blocks with those of blocks coupled with two candidate safety devices: an isolating base and a pendulum mass damper. To account for the relevant uncertainties, probabilistic seismic demand models are developed using a Bayesian approach. The probabilistic models are then used along with the overturning capacities of the blocks to construct fragility curves that give a prediction of the probability of overturning occurrence as a function of some characteristics of the blocks, of the safety devices, as well as of the seismic excitation, i.e. the slenderness of the body and the peak ground acceleration. The data needed to develop the probabilistic model are obtained integrating the nonlinear equations of motion of the two systems subject to selected ground motions. In the end, some numerical examples are proposed

Natural History and Management of Familial Paraganglioma Syndrome Type 1: Long-Term Data from a Large Family

Head and neck paragangliomas are the most common clinical features of familial paraganglioma syndrome type 1 caused by succinate dehydrogenase complex subunit D (SDHD) mutation. The clinical management of this syndrome is still unclear. In this study we propose a diagnostic algorithm for SDHD mutation carriers based on our family case series and literature review. After genetic diagnosis, first evaluation should include biochemical examination and whole-body imaging. In case of lesion detection, nuclear medicine examination is required for staging and tumor characterization. The study summarizes the diagnostic accuracy of different functional imaging techniques in SDHD mutation carriers. 18F-3,4-dihydroxyphenylalanine (18F-DOPA) positron emission tomography (PET)-computed tomography (CT) is considered the gold standard. If it is not available, 123I-Metaiodobenzylguanidine (MIBG) could be used also for predicting response to radiometabolic therapy. 18F-fluoro-2-deoxy-D-glucose (18F-FDG) PET-CT has a prognostic role since high uptake identifies more aggressive cases. Finally, 68Ga-peptides PET-CT is a promising diagnostic technique, demonstrating the best diagnostic accuracy in our and in other published case series, even if this finding still needs to be confirmed in larger studies. Periodic follow-up should consist of annual biochemical and ultrasonographic screening and biannual magnetic resonance examination to identify biochemical silent tumors early

Escherichia coli Nissle 1917 in ulcerative colitis treatment: Systematic review and meta-analysis

Background & Aims: Escherichia coli Nissle 1917 (EcN) has been recommended as a therapeutic tool for ulcerative colitis (UC) treatment. However, to date, no meta-analysis has been performed on this topic. Methods. We performed a literature search on PubMed, MEDLINE, Science Direct and EMBASE. We evaluated success rates for induction of remission, relapse rates and side effects, expressed as Intention-To-Treat. Odd ratios (OR), pooled OR and 95% confidence intervals (CI) were calculated, based on the Mantel-Haenszel method. Heterogeneity was assessed by using the χ2 and I2 statistics and, if present, a random-effects model was adopted. Results. We selected six eligible trials, with 719 patients, 390 assigned to the study group and 329 to the control group. EcN induced remission in 61.6% of cases, while in the control group (mesalazine) the remission was achieved in 69.5% of cases, with a mean difference of 7.9%. The pooled OR was 0.92 (95% CI 0.15-9.66, p=0.93). A single study showed a better performance of EcN than the placebo. A relapse of the disease occurred in 36.8% in the EcN group and in 36.1% in the control group (mesalazine), with a mean difference of 0.8%, OR=1.07, with a 95% CI of 0.70-1.64 (p=0.74). Side effects were comparable (OR=1.44, 95% CI 0.80-2.59, p=0.22). Conclusions. EcN is equivalent to mesalazine in preventing disease relapse, thus confirming current guideline recommendations. EcN seems to be as effective as controls in inducing remission and therefore, its use cannot be recommended as in one study the comparison was performed against placebo. Further studies may be helpful for this subject

The quality of life in extracorporeal life support survivors: single-center experience of a long-term follow-up

Objective: To evaluate the health-related quality of life on a very long-term follow-up in patients treated with extracorporeal membrane oxygenation (ECMO) during neonatal and pediatric age. Design: Prospective follow-up study. Setting: Pediatric Intensive Care Unit of a tertiary-care University-Hospital. Patients: Out of 20 neonates and 21 children treated with ECMO in our center, 24 patients underwent short-term neurological follow-up. Twenty of them underwent long-term neurological follow-up. Intervention: Short-term follow-up was performed at 18 months and consisted in clinical evaluation, electroencephalography, and neuroimaging. Long-term follow-up was performed in 2017, at the mean period 19.72 years from ECMO (median 20.75, range 11.50-24.08) and consisted in a standardized questionnaires self-evaluation (PedsQL 4.0 Generic Core Scale) of health-related quality of life and an interviewed about the presence of organ morbidity, school level, or work position. Measurements and main results: Sixty-one percent (25/41) of the patients survived within 30 days after ECMO treatment. Short-term follow-up was performed in 24 patients (1 patient but died before the evaluation): 21 patients (87%) showed a normal neurological status, and 3 developed severe disability. Long-term follow-up was performed in 20 long-term survivors (3 patients were not possible to be contacted and considered lost to follow-up): mean age of patients at long-term follow-up was 21.23 (median 20.96, range 13.33-35.58) years; 90% (18/20) of them have no disability with a complete normal quality of life and 95% have no cognitive impairment. Conclusions: ECMO represents a life-saving treatment for infants and children with respiratory and/or heart failure; survivors show a good quality of life comparable to healthy peers

Trends of Liver Stiffness in Inflammatory Bowel Disease with Chronic Hepatitis C

Concomitant inflammatory bowel disease (IBD) and hepatitis C virus (HCV) infection is a relevant comorbidity since IBD itself exposes to a high risk of liver damage. We aimed to evaluate liver stiffness (LS) in IBD-HCV after antiviral treatment. We enrolled IBD patients with HCV. All patients at baseline underwent LS measurement by elastography. Patients who were eligible for antiviral therapy received direct antiviral agents (DAAs) and sustained viral response was evaluated at the 12th week. A control group was selected within IBD patients without HCV. One year later, all IBD-HCV patients and controls repeated LS measurement. Twenty-four IBD-HCV patients and 24 IBD controls entered the study. Only twelve out of 24 received DAAs and all achieved sustained viral response (SVR). All IBD subjects were in remission at enrollment and maintained remission for one year. After one year, IBD patients who eradicated HCV passed from a liver stiffness of 8.5 ± 6.2 kPa to 7.1 ± 3.9, p = 0.13. IBD patients who did not eradicate HCV worsened liver stiffness: from 7.6 ± 4.4 to 8.6 ± 4.6, p = 0.01. In the IBD control group, stiffness decreased from 7.8 ± 4.4 to 6.0 ± 3.1, p < 0.001. In conclusion, HCV eradication is able to stop the evolution of liver fibrosis in IBD, while failure to treat may lead to its progression. A stable IBD remission may improve LS even in non-infected subjects

Screening and diagnostic breast MRI: how do they impact surgical treatment? Insights from the MIPA study

To report mastectomy and reoperation rates in women who had breast MRI for screening (S-MRI subgroup) or diagnostic (D-MRI subgroup) purposes, using multivariable analysis for investigating the role of MRI referral/non-referral and other covariates in driving surgical outcomes. The MIPA observational study enrolled women aged 18–80 years with newly diagnosed breast cancer destined to have surgery as the primary treatment, in 27 centres worldwide. Mastectomy and reoperation rates were compared using non-parametric tests and multivariable analysis

Voltage Control in Low-Voltage Grids Using Distributed Photovoltaic Converters and Centralized Devices

This paper studies the application of distributed and centralized solutions for voltage control in low voltage (LV) grids with high photovoltaic (PV) penetration. In traditional LV grids, the coordination of distributed PV converters and a centralized device would require massive investments in new communication and control infrastructures. The alternative of exploiting distributed PV converters for voltage control is discussed, showing that it can help to stabilize the voltage in the grid connection points also without coordination between them and/or with a centralized unit. The goal of this paper is to investigate how the setup of the voltage controllers inside PV inverters affects the operation of these controllers taking into account the limits for reactive power injection. In addition, the interaction of distributed PV converters with centralized devices (static var compensators and on load tap changers) is analyzed to assess whether additional benefits may come in these cases