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Purpose. Myocardial scar is directly related to the response to CRT after implantation. The extent of myocardial scar can be detected not only by cardiac magnetic resonance but also by two electrocardiographic scores: fragmented QRS (fQRS) and Selvester score (SSc). The aim of our study is to compare the role of baseline SSc and fQRS in predicting response to CRT in a cohort of heart failure patients with true left bundle branch block (LBBB). As a secondary endpoint, we assessed the association of both scores with overall and cardiac mortality, heart failure hospitalizations, ventricular arrhythmias requiring ICD intervention, and major adverse cardiovascular event (MACE). Methods. We evaluated fQRS and SSc of 178 consecutive HF patients with severe systolic dysfunction (LVEF ≤ 35%), NYHA class II-III despite optimal medical treatment, and true-LBBB. Response to CRT was defined as the improvement of LVEF of at least 10% or as the reduction of LVESV of at least 15% at a 6-month follow-up. Each endpoint was related to fQRS and SSc. Results. SSc ≥7 was significantly associated with the absence of echocardiographic response to CRT (OR: 0.327; 95% C.I. 0.155–0.689; p = 0.003 ), while the presence of fQRS at baseline ECG was not (OR: 1.133; 95% C.I. 0.539–2.381; p = 0.742 ). No correlation was found between SSc and overall mortality, cardiac death, ventricular arrhythmias, hospitalizations due to heart failure, or for MACE. Similar results were observed between fQRS and all secondary endpoints. Conclusion. In HF patients with true-LBBB and LVEF ≤35% eligible for CRT, myocardial scar assessed by calculating the SSc on preimplant ECG is an independent predictor of nonresponse after multiple adjustments. Neither SSc nor fQRS is associated with overall and cardiac death, ventricular arrhythmias, or hospitalization for heart failure at a 24-month follow-up.

Funding Acknowledgements NO FUNDING OnBehalf RHYTHM DETECT Registry Background The class of recommendation for S-ICD implantation in patients who have inadequate vascular access is I according to AHA-ACC-HRS Guidelines and IIb according to ESC Guidelines. Data are lacking about the use of S-ICD for patients in which a transvenous ICD is not a viable option because of the inability to deploy a transvenous lead. Purpose To describe current practice and to measure outcomes associated with S-ICD use in patients in which a transvenous ICD is not a viable option. Methods 942 consecutive patients underwent S-ICD implantation at 22 Italian centers from 2014 to 2019. We identified 101 (11%) patients who received S-ICD because of the reported impossibility of deploying a transvenous lead. Results 21 patients presented with inadequate vascular access but no previous device in place. One patient had a mechanical prosthesis in tricuspid position. The remaining 79 patients received the S-ICD after removal of a prior system implanted, and venous occlusion was diagnosed after lead extraction, or partially or completely failed lead removal. In 24 of these patients a functional transvenous pacing system was left in place for persisting pacing needs. Patients were 60 ± 15 years old, 85% were male, 77% had ischemic or non-ischemic dilated cardiomyopathy, ejection fraction was 36 ± 13%. At implantation, acute conversion test was performed in 64 patients and shock energy of ≤65J was successful in 62 (96.9%) patients. During a median follow-up of 18 months, 6 patients died for non-device related reasons and 1 patient underwent heart transplantation. One patient underwent device replacement for battery depletion and one patient underwent leadless pacemaker implantation. Minor complications (hematomas not requiring system revision) were reported in 2 patients. Appropriate therapies were delivered in 4 patients and 8 patients experienced inappropriate therapies (in 3 patients due to double counting during pacing); all resolved with device reprogramming. Conclusions: In current clinical practice, a minority of S-ICD patients receive the device because of inadequate vascular access. The profile of these patients is similar to that of the typical ICD population in the context of primary sudden death prevention, but many of them present with pacing indications. Acute and mid-term efficacy of S-ICD seemed high. Few complications occurred during follow-up. Particular attention must be paid to device programming for those patients with concomitant pacing systems, in order to prevent inappropriate therapies.

Background. Atrial fibrillation (AF) is the most frequent sustained arrhythmia found in clinical practice. Its prevalence significantly grows with age. The proportion of elderly individuals with depression varies between 4.2 and 10.6% according to the different criteria used for diagnosis. Interestingly, AF and depression synergistically act to increase mortality. Purpose. Aim of this study was to identify the clinical variables associated with depressive symptoms in elderly individuals with persistent AF. Methods. All patients consecutively admitted in a Day-Hospital setting to undergo electrical cardioversion of AF were enrolled in the study. No exclusion criteria were specified. Population was studied with instruments exploring neurocognitive performance (Mini-Mental State Examination - MMSE; range: 0-30; abnormal values 5). In this case, lower scores identified a healthier emotional profile. Results. Between January 2018 and August 2019, 111 patients were evaluated (age: 77 ± 9 years; women: 39.6%; weight: 78 ± 15 Kg; height: 171 ± 11 cm). Lone AF and brady- tachy- syndrome were diagnosed in 12.6% of cases. Hypertension and structural heart disease (coronary artery disease, heart failure, valvular heart disease) were responsible of the arrhythmia in 30.6% and 56.8% of patients, respectively. Left ventricular ejection fraction was 60 ± 12%, with a heart rate equal to 78 ± 17 bpm. MMSE and SPPB score were 28 ± 3 and 8.7 ± 2.9. An abnormal GDS score was observed in 19.8% of cases (mean: 3.0 ± 2.7). Interestingly, in univariate analysis, depressive symptoms increased with age (p = 0.002) and the CHA2DS2-VASc score ( =6: 4.4 ± 2.8; p Conclusions. In a population of elderly patients with persistent AF, the prevalence of depression is not negligible. Importantly, depressive symptoms are significantly associated with the CHA2DS2-VASs score, and, at multivariate analysis, with renal function, to live alone and physical performance. Paradoxically, after adjustment for these factors, GDS score decreases with age per se.

Civil engineering structures and infrastructures are inherently vulnerable to exceptional loads related to natural disasters, primarily earthquakes, tsunamis, strong winds, and floods [...]

This paper presents a novel type of foamed concrete that is termed “3D-printable lightweight foamed concrete” (3DP-LWFC). Unlike classical lightweight foamed concrete (C-LWFC), this novel material is able to keep its shape at the fresh state due to enhanced consistency and viscosity. This peculiarity lends itself to being implemented in automated extrusion production process and 3D printing applications without the use of formwork, which is particularly convenient in the building industry. These unique fresh state properties of 3DP-LWFC are demonstrated through a specific extrusion test conceived and used in this experimental campaign, and highlighted by comparison with results related to C-LWFC. Despite the remarkably different behavior of the novel material at the fresh state, the mechanical strength of 3DP-LWFC is even slightly higher than C-LWFC. This is demonstrated through a wide experimental campaign focused on the compressive and flexural strength of 3DP-LWFC, which includes different dry densities, curing conditions, cement types, water/cement ratios. Additionally, the effect of the mixing conditions on the mechanical strength of 3DP-LWFC, in particular the rotational speed of the mixer during the preparation of the paste, is also analyzed and discussed. It is found that the increase of mixing intensity from 1200 rpm to 3000 rpm resulted in a considerable increase of mechanical strength values of 3DP-LWFC, up to more than 70% for the compressive strength and up to around 100% for the flexural strength.

This contribution focuses on the design and the characterization of innovative mix designs of high consistency mortars with biochar additions in different percentage with respect to the cement weight. Biochar is a by-product material that gives the cementitious mix a sustainable connotation from an environmental point of view. The mix designs presented here are characterized by a good dimensional stability in the fresh state, peculiarity that gives them the possibility to be extruded and so, to be used in automated construction processes. In addition to the mechanical properties (flexural and compressive strength), the assessment of the CO2 emission of representative mixes is presented. Different biochar content and maximum diameter of the aggregate are studied, obtaining interesting indications on these parameters to optimize mechanical properties. Finally, on the basis of the CO2 emission assessment, certain venues for future research work to minimize CO2 emissions are reported.

The frequency of premature atrial complexes (PACs) has been related with atrial fibrillation (AF) occurrence and adverse prognosis. Research objective was to evaluate whether temporal patterns of PACs are directly associated with AF onset in pacemaker patients with continuous monitoring of the atrial rhythm. Overall, 193 pacemaker patients (49% female, 72 ± 9 years old), enrolled in a national registry, were analyzed. Frequency of daily PACs was measured in a 14-day initial observation period, during which patients were in sinus rhythm. In the following period, temporal occurrence and frequency of daily PACs and eventual onset of AF were derived by pacemaker diagnostics. In the run-in period, median PACs frequency was 614 PACs/day (interquartile range 70–3056). Subsequently, in a median follow-up of 6 months, AF occurred in 109 patients, in particular in 37/96 (38.5%) patients with a PAC rate

Background Body mass index (BMI), age, left atrium (LA) dimension and left ventricular ejection fraction (LVEF) have been linked to post-operative atrial fibrillation (POAF) after cardiac surgery. The aim of this study was to better define the role of these risk factors. Methods This retrospective cohort study evaluated 249 patients (without prior atrial dysrhythmia) undergoing cardiac or aortic surgery. Prior to surgery, the following data were collected: age, BMI, LA diameter, LA area, LVEF, thyroid stimulating hormone (TSH), creatinine and the presence of arterial hypertension (AH) and diabetes. Intraoperative data such as operation time, total clamp time, cardiopulmonary bypass time, and presence of pericardial/pleural effusion were also collected. Only patients without pre- and post-surgery prophylactic anti-arrhythmic therapy were included. Results Patients with (N = 127, 51%) and without POAF (N = 122, 49%) were compared. No difference was observed for sex, LA diameter, LA area, LVEF, TSH, diabetes and use of ACE inhibitors or statins prior to intervention. Moreover, no difference was observed in terms of operation time, total clamp time, cardiopulmonary bypass time, and presence of pericardial/pleural effusion. However, patients with POAF were older (70.6 ± 10.7 vs. 60.4 ± 16.4 years, p = 0.001), had higher BMI (26.8 ± 4.5 vs. 24.9 ± 3.6 kg/m2, p = 0.001), higher baseline creatinine (1.06 ± 0.91 vs. 0.88 ± 0.32 mg/dL, p = 0.038) and a higher frequency of arterial hypertension (73.2% vs. 50%, p = 0.001) and Bentall procedure (24.4% vs. 9.8%, p = 0.023). Multivariate analysis showed that the only independent predictors of POAF were age (OR = 1.05, 95%CI 1.02–1.07, p = 0.001) and BMI (OR = 1.11 95%CI 1.03–1.2,p = 0.006). Conclusions These findings suggest that advanced age and a higher BMI are strong risk factors for POAF in patients without previous AF even in the presence of comparable LA dimensions and LVEF.

Unlike ordinary concrete, lightweight foamed concrete (LWFC) has the benefit of decreasing the self-weight of constructive elements while ensuring an efficient thermal insulation and acoustic absorption as well as high fire resistance. A novel version of LWFC has been recently developed by the authors, with the unique property of “extrudability” in a wide density range, meaning that its production process can be carried out without formworks and exploiting innovative 3D printing technologies. The present contribution is focused on the rheological behaviour of this innovative extrudable LWFC (ELWFC). The rheological behaviour in terms of yield stress of the ELWFC is studied via a rotational rheometer in two different modalities, namely constant shear rate and increasing shear rate. Comparison of the rheological behaviour between ELWFC and classical LWFC is also presented. Additionally, the dimensional stability of the cementitious paste at the fresh state having a given yield stress is assessed through an extrusion test. In particular, the experimental investigation is focused on a target dry density of 800 kg/m3, which is identified as a good compromise between insulating features and mechanical strengths. The experimental results show that the considered ELWFC, characterized by a zero slump in the extrusion test, has a yield stress of around 150 Pa (constant shear rate) and 130 Pa (increasing shear rate).

This papers aims at investigating the structural behavior of reinforced concrete (RC) beams with electric arc furnace (EAF) slag as full replacement of coarse natural aggregates. A few real scale EAF RC beams have been experimentally investigated under four-point bending tests in order to analyze their structural behavior in terms of peak load, deflections and crack patterns in comparison with traditional RC beams without recycled aggregates. Then, a numerical investigation has been carried out through two different three-dimensional finite element procedures: the former is a conventional step-by-step incremental analysis based on a nonlinear stress-strain law for concrete in compression and a post-failure response in tension based on a smeared-crack approach; the latter is an iterative, simplified methodology based on the application of the limit analysis theory. Comparison between numerical and experimental results is discussed and the main advantages and drawbacks of the two proposed numerical procedures are outlined.

The present study concerns the experimental investigation of foamed concretes with 1600 kg/m3 density that incorporate biochar additions in the mix. A series of small notched beams are prepared to determine the fracture energy in CMOD (crack mouth opening displacement) mode and the mechanical properties in terms of flexural and compressive strength. Besides the evaluation of such properties for classical foamed concrete, the influence of the addition of biochar in the lightweight cementitious paste is comparatively investigated. Two different concentrations of biochar are analyzed, namely 2% and 4% of the cement weight, and two different curing conditions are studied, namely in air and in water at controlled temperature for 28 days. The results demonstrate that better fracture behavior are obtained with 2% biochar and air curing conditions. The biochar additions in moderate concentrations (e.g. 2%) seems to make the fracture surface more tortuous, thus justifying the numerical outcomes, and does not impair the flexural strength. Further microstructural investigation is underway to confirm the experimental observations. This research paves the way for a promising construction material that is more environmentally friendly and sustainable than traditional materials used in the building industry.

The technique of direct intratumoral injection of permanent liquid agents has evolved significantly over the past few decades. The percutaneous direct puncture technique is being utilised more and more for embolisation of head and neck hypervascular lesions. We describe a case treated via the direct percutaneous transnasal (TN) puncture technique for embolisation of a sinonasal hypervascular tumour, performed in a 21-year-old male patient. Due to extensive vascularisation of the tumour, preoperative embolisation was requested by our otolaryngologist team in order to minimise intraoperative bleeding and reduce surgical morbidity. A primary attempt at trans-arterial embolisation through selective ophthalmic artery catheterisation was unsuccessful due to unfavourable anatomy. An extensive devascularisation of the nasal fossa lesion was obtained using a single injection of low-density polymeric embolic agent (SQUID®). Post-operative eradication was uneventful. Final histopathology exam revealed vascular tumour consistent with a rare sinonasal glomangiopericytoma. To our knowledge, this is the first reported case of a rare sinonasal glomangiopericytoma treated by direct TN injection, utilising the liquid polymer agent SQUID®.

Unsatisfactory numerical predictions may result from applying the classical modal analysis in conjunction with the response-spectrum-method (RSM) to nonclassically-damped systems such as base-isolated buildings. This inaccuracy is highlighted by comparing the conventional RSM outcomes with results from nonlinear time-history analyses consistent with that given spectrum. Indeed, some underlying assumptions of the conventional RSM are not really appropriate for base-isolated buildings, thus only approximate results are obtained, whereas either a complex-value modal analysis or the direct integration of the equations of motion should be undertaken to follow an exact approach to this problem. In an attempt to overcome the limitations of the conventional RSM as well as the mathematical difficulties and computational cost of the exact approach, in this paper an improved response-spectrum analysis procedure for base-isolated buildings is elaborated. Based upon the substructure approach, this procedure makes use of novel response spectra that quantify the effects of the base-isolation-system (BIS) to the superstructure while accounting for the dynamic interaction between BIS and superstructure. The developed procedure improves the conventional RSM in two aspects: (1) the seismic response of the base-isolated building is computed by applying the modal analysis to the superstructure only, which is typically considered as a classically damped system, rather than to the overall structure having nonclassical damping; (2) the BIS can potentially be modeled as a nonlinear subsystem with its actual hysteretic characteristics. The effectiveness of the proposed procedure and the improvements over the conventional RSM are scrutinized against time-history analyses with Monte Carlo simulated spectrum-compatible accelerograms.

The hysteretic behavior of friction concave isolators is affected by the variability of the friction coefficient experienced during a seismic event. This variability is a combined function of axial load, sliding velocity and temperature rise at the sliding surface, the latter being responsible for significant friction degradation. Experimental testing and corresponding numerical models are usually focused on the monodirectional performance of the friction isolators, although multi-directional paths occur in a real earthquake scenario. In this paper, the thermo-mechanical coupled (TMC) response of friction concave isolators when subjected to bidirectional excitation is investigated in both an analytical and a numerical framework. First, a simplified phenomenological model is presented that accounts for the friction degradation due to the distance traveled via a macroscale cycling variable, based on the assumption of a uniform heat flux at the sliding interface. Then, a more sophisticated numerical investigation is performed via a TMC finite element (FE) model. A customized subroutine has been developed and implemented into the FE code to account for the local variation of the friction coefficient due to the local temperature rise and sliding velocity. The mutual interaction between mechanical and thermal response is incorporated in the proposed computational approach: the friction-induced temperature rise on the contact points and the consequent friction degradation caused by heating phenomena are analyzed as two interconnected phenomena in a recursive fashion. The friction coefficient law at the sliding interface is adjusted step-by-step and is different from node to node on the basis of the temperature distribution. Validated against experimental data, the two proposed models are used within a parametric study to scrutinize some interesting features observed in the thermo-mechanical response of friction isolators.

This review of the literature on the use of mechanical thrombectomy (MT) in children with acute ischemic stroke from occlusion of the internal carotid artery and the proximal middle cerebral artery (MCA) compares the efficacy and safety of primary and secondary MT. We analyzed the data reported for 24 case reports from 20 relevant articles published up to 31 December 2016 and the data of a patient treated at our institution. Eighteen cases received primary MT and 7 received secondary MT. The proportions of complete MCA recanalization, small infarcts, and asymptomatic intracranial hemorrhage were similar in both MT groups (73% [11/15] vs. 67% [4/6], 58% [7/12] vs. 60% [3/5], and 15% [2/13] vs. 17% [1/6], respectively). The proportion of favorable neurological outcomes was higher for the primary MT group (69% [11/16] vs. 43% [3/7]). We found no substantial differences in efficacy and safety between primary and secondary MT for anterior circulation stroke in children.

Existing civil engineering structures having strategic importance, such as hospitals, fire stations, and power plants, often do not comply with seismic standards in force today, as they were designed and built based on past structural guidelines. On the other hand, due to their special importance, structural integrity of such buildings is of vital importance during and after earthquakes, which puts demands on strategies for their seismic protection. In this regard, seismic base isolation has been widely employed; however, the existing limited seismic joint between adjacent buildings may hamper this application because of the large displacements concentrated at the isolation floor. In this paper, we compare two possible remedies: the former is to provide supplemental damping in conventional base isolation systems and the latter consists in a combination of base isolation with supplemental rotational inertia. For the second strategy, a mechanical device, called inerter, is arranged in series with spring and dashpot elements to form the so-called tuned-mass-damper-inerter (TMDI) directly connected to an isolation floor. Several advantages of this second system as compared to the first one are outlined, especially with regard to the limitation of floor accelerations and interstory drifts, which may be an issue for nonstructural elements and equipment, in addition to disturbing occupants. Once the optimal design of the TMDI is established, possible implementation of this system into existing structures is discussed.

Malignant gliomas, the most frequent primary brain tumors, are characterized by a dismal prognosis. Reliable biomarkers complementary to neuroradiology in the differential diagnosis of gliomas and monitoring for post-surgical progression are unmet needs. Altered expression of several microRNAs in tumour tissues from patients with gliomas compared to normal brain tissue have been described, thus supporting the rationale of using microRNA-based biomarkers. Although different circulating microRNAs were proposed in association with gliomas, they have not been introduced into clinical practice so far. Blood samples were collected from patients with high and low grade gliomas, both before and after surgical resection, and the expression of miR-21, miR-222 and miR-124-3p was measured in exosomes isolated from serum. The expression levels of miR-21, miR-222 and miR-124-3p in serum exosomes of patients with high grade gliomas were significantly higher than those of low grade gliomas and healthy controls and were sharply decreased in samples obtained after surgery. The analysis of miR-21, miR-222 and miR-124-3p in serum exosomes of patients affected by gliomas can provide a minimally invasive and innovative tool to help the differential diagnosis of gliomas at their onset in the brain and predict glioma grading and non glial metastases before surgery.

Early and Late Recurrences in AF CryoablationIntroduction Recurrences within the blanking period (early recurrences) are common after atrial fibrillation (AF) ablation by pulmonary vein isolation (PVI), but their clinical significance is still controversial. We aimed at evaluating the significance of within-blanking recurrences at 12-month follow-up after cryoballoon (CB) PVI, and to assess the real procedural success rate by continuous monitoring of cardiac rhythm. Methods and Results Sixty consecutive AF patients (34 paroxysmal, 56.7%) underwent their first CB-PVI at one Italian center (May 2013 to April 2015), and subsequent implantation of an implantable loop recorder (ILR). Overall, 12-month success rate after the blanking period was 55%. The shortest detected event was 7 minutes long. Late recurrences were more frequent in non-paroxysmal (19/26, 73.1%) than in paroxysmal AF (8/34, 23.5%; P

Background: Subcutaneous ICD (S-ICD) is a promising option for Hypertrophic Cardiomyopathy (HCM) patients at risk of Sudden Cardiac Death (SCD). However, its effectiveness in terminating ventricular arrhythmias in HCM is yet unresolved.Methods: Consecutive HCM patients referred for S-ICD implantation were prospectively enrolled. Patients underwent one or two attempts of VF induction by the programmer. Successful conversion was defined as any 65 J shock that terminated VF (not requiring rescue shocks). Clinical and instrumental parameterswere analyzed to study predictors of conversion failure.Results: Fifty HCMpatients (34males, 40 +/- 16 years) with amean BMI of 25.2 +/- 4.4 kg/m(2) were evaluated. Mean ESC SCD risk of was 6.5 +/- 3.9% and maximal LV wall thickness (LVMWT) was 26 +/- 6 mm. In 2/50 patients no arrhythmias were inducible, while in 7 (14%) only sustained ventricular tachycardia was induced and cardioverted. In the remaining 41 (82%) patients, 73 VF episodes were induced (1 episode in 14 and > 1 in 27 patients). Of these, 4 (6%) spontaneously converted. In 68/69 (98%) the S-ICD successfully cardioverted, but failed in 1 (2%) patient, who needed rescue defibrillation. This patient was severely obese (BMI 36) and LVMWT of 25 mm. VF was re-induced and successfully converted by the 80 J reversed polarity S-ICD.Conclusions: Acute DT at 65 J at the implant showed the effectiveness of S-ICD in the recognition and termination of VT/VF in all HCM patients except one. Extreme LVH did not affect the performance of the device, whereas severe obesity was likely responsible for the single 65 J failure. (C) 2017 Elsevier Ireland Ltd. All rights reserved.

In the field of stability of structures under nonconservative loads, the concept of follower force has long been debated by scientists due to the lack of actual experimental evidence. Bigoni and Noselli’s work [2] aimed to investigate flutter and divergence instability phenomena through a purely mechanical model with Coulomb friction represents a praiseworthy attempt to shed light on this issue. A two-degree-of-freedom (DOF) system, conceived as a variant of the Ziegler column, was set up experimentally. The follower load was induced by a frictional force acting on a wheel mounted at the column end, so that the rolling friction vanishes and the sliding frictional force keeps always coaxial to the column, thus representing a tangential follower force. Along this research line, in this contribution a model is elaborated that stems from the analysis of an elastically supported rigid plate that represents the behaviour of a bridge deck suspended on springs and subjected to a wind-induced force. The wind force has been simulated by a Coulomb friction force acting on a wheel mounted on the plate aerodynamic centre, so that the sliding friction force keeps perpendicular to the plate axis throughout the system motion, thus representing a follower force. To properly reproduce the wind force, the friction force is applied to the wheel by a lever mechanism wherein one of the two lever arms involves the plate rotation via a particular circular guide. The corresponding equations of motion of the bridge deck are derived in a completely dimensionless form. Depending on the mechanical characteristics of the plate and the magnitude of the friction force, stability, flutter or divergence phenomena may occur. The occurrence of these phenomena is numerically investigated by integration of the equations of motion. The development of an experimental framework of the model to corroborate these intuitions is the object of an ongoing research.

Background Atrial fibrillation (AF) is the most prevalent heart rhythm disorder in clinical practice and it is associated with poor quality of life and increased risks of heart failure, dementia, stroke, and death. Moreover AF management is a huge cost for healthcare systems. AF is irregular, typically originates from the pulmonary veins, and as such, requires cardioversion to terminate persistent episodes. AF is not susceptible to pace-termination, however, the MINERVA trial has shown that AF may transform in slower organized rhythms such as atrial flutter or atrial tachycardia, which can often be terminated by atrial anticahycardia pacing (ATP); in particular by Reactive ATP, a specific ATP feature which can be re-armed when atrial arrhythmias get slower or more regular. The MINERVA trial showed that the combination of ATP, preventive atrial pacing algorithms and minimal ventricular pacing (MVP) was associated with lower progression to persistent and permanent AF, compared with standard DDD pacing mode and to MVP mode, in pacemaker patients with clinical history of AF. Purpose We aimed to confirm MINERVA trial results in real-world clinical practice and to evaluate whether AF prevention was associated with preventive atrial pacing or solely with ATP. Indeed in our project atrial preventive pacing algorithms were not enabled and the pacing mode (DDD or MVP) was chosen according to patients' AV conduction characteristics. Methods Consecutive dual-chamber pacemaker patients with sinus node disease and device detected AT/AF were prospectively followed by 30 Italian cardiologic centers in an observational research. Clinical and device data were collected and reviewed by expert cardiologists to assess AT/AF occurrence through in clinic visit and/or remote transmissions of device data. Results A total of 239 patients (73 years old, 56% male) wearing a dual-chamber pacemaker with Reactive ATP were included in the project, followed for a median observation period of 13 months and compared with 1145 patients included in the MINERVA trial followed for a median observation period of 34 months and programmed with DDD pacing mode (383 patients), MVP (389 patients) and MVP+Reactive ATP+preventive algorithms (373 patients). As shown in the following figure incidence of 7 consecutive days of AF in the patients treated by DDD/MVP+Reactive ATP in real-world clinical practice was very similar to that found in the MINERVA trial arm programmed with MVP+Reactive ATP+preventive algorithms. Incidence of AF longer than 7 days Conclusions Our analysis performed in a population of sinus node disease patients with dual-chamber pacemakers confirmed MINERVA trial results in terms of prevention of long-lasting AF episodes. In particular these results confirm the benefit associated with the use of Reactive ATP, rather than preventive atrial pacing algorithms.

Background The benefit of cardiac resynchronization therapy (CRT) in patients (pts) with chronic kidney disease (CKD) remains controversial despite frequent use. Pts with impaired renal function have systematically been excluded from randomized clinical trials and therefore specific recommendations for the use of CRT in these pts are still lacking. Purpose Study objectives were to assess long-term outcomes and clinical/echocardiographic response in a large population of patients with moderate-to-severe impaired renal function implanted with a CRT device in accordance with the current standard of care. Methods We prospectively analyzed clinical, instrumental data and survival of pts with CKD who received a CRT device in the CRT-MORE registry from 2011 to 2014. Adverse events for the analysis of clinical outcome comprised death from any cause and nonfatal HF events requiring hospitalization after CRT implantation. LV reverse remodeling and Clinical Response (CR) were also evaluated at 12-month follow-up. Patients were stratified according to current definition of CKD stage: low-moderate CKD with a GFR = 45–59 mL/min (stage 3A); moderate CKD with a GFR = 30–44 mL/min (stage 3B) and severe CKD with a GFR = 15–29 mL/min (stage 4). Results Of the 922 consecutive patients enrolled in the registry, 416 (45%) pts had a moderate-to-severe impaired renal function (43% Stage 3A, 43% Stage 3B and 14% Stage 4). The mean follow-up was 935±506 days. By the end of the study, 85 pts had died and 47 pts had been hospitalized for HF. The combined end-point of death or HF hospitalization was reached by 121 (29%) pts. After 12 months the absolute LVEF improvement was greater than 10% in 37% of pts and 58% of pts displayed a positive clinical response. The percentage of pts who died was higher in the group of pts with severe CKD (32.8% vs 18.4%; p=0.012, compared to the group of pts with moderate CKD). On the contrary the percentage of pts who had at least one HF hospitalization was lower in the group with more severe CKD (2% vs 13%; p=0.011). According to CKD stage both LV remodeling (LVEF improvement ranging from 43.7% - 3A - to 30.8% - 4) and CR (positive response ranging from 63.9% - 3A - to 50% - 4) were higher in low-moderate stage and decreased with CKD severity. At multivariate Cox regression analysis adjusted for baseline confounders, CKD class at implantation [HR=1.5; 95% CI: 1.06–2.14; p=0.0219], chronic obstructive pulmonary disease [HR=1.89; 1.18–3.01; p=0.0077], persistent/permanent AF [HR=1.86; 1.15–3.01; p=0.0115] and male gender [HR=1.92; 1.07–3.46; p=0.0301] remained associated with death. Conclusions Among CKD patients in the CRT-MORE registry, severity of renal dysfunction at the time of CRT implantation was associated with worse prognosis, lower clinical response and LV reverse remodeling. Acknowledgement/Funding None

Background The frequency of premature atrial complexes (PACs) has been indirectly related with atrial fibrillation (AF) occurrence and adverse outcomes. Objective To evaluate whether temporal patterns of PACs are directly associated with AF onset in pacemaker patients with continuous monitoring of the atrial rhythm. Methods Overall, 193 pacemaker patients (49% female, 72±9 years old), enrolled in a national registry, were analyzed. Frequency of daily PACs was measured in a 14-day initial observation period, during which patients were in sinus rhythm. In the following period, temporal occurrence and frequency of daily PACs and eventual onset of AF were derived by pacemaker diagnostics. Results In the run-in period, median PACs frequency was 614 PACs/day (interquartile range=70–3056). Subsequently, in a median follow-up of 6 months, AF occurred in 109 patients, in particular in 37/96 (38.5%) patients with a PAC rate PACs changes daily trend before AF Conclusion PACs frequency increases in the 5–6 days preceding AF onset. A relative increase of the daily PACs is significantly associated with the risk of AF occurrence.

This work studies the advantageous features of the fluid inerter device for optimised structural control of buildings. Experimental data are first presented to characterise the fluid inerter dynamics, and validate the simplified analytical formulations. Building on these observations, the device is modelled as an inerter in parallel with a nonlinear dashpot representing a power law damping term. The latter dissipative effects are mainly induced by the pressure drops occurring in helical channels due to the fluid viscosity and density. Then, novel passive vibration control schemes are implemented for the earthquake protection of base-isolated buildings by combining the fluid inerter with a tuned mass damper system. To account for the uncertain nature of the earthquake input, the base acceleration is modelled as a Kanai–Tajimi filtered stationary random process. The optimal fluid inerter parameters, namely inertance and damping, are identified numerically by minimising stochastic performance indices relevant to displacement, acceleration, and energy-based measures of the structural response. The nonlinear damping behaviour of the fluid inerter is fully incorporated in the optimal design procedure via the statistical linearisation technique. Nonlinear response history analysis under an ensemble of 44 natural earthquake ground motions is carried out to assess the seismic performance of the system. Since inertance and damping are coupled characteristics in a real fluid inerter, design guidelines are finally outlined to determine the actual geometrical and mechanical properties of the device to achieve targeted parameters resulting from the optimisation procedure.

Diffuse gliomas are defined on the isocitrate dehydrogenase (IDH) gene (IDH) mutational mutational status. The most frequent IDH mutation is IDH1 R132H, which is detectable by immunohistochemistry; other IDH mutations are rare (10%). IDH mutant gliomas have better prognosis. Further, IDH wild-type low-grade (II/III) gliomas have clinical behaviors similar to those of glioblastoma (GBM) and it was suggested that they are submitted to similar post-surgical treatment. The incidence of IDH mutant gliomas (2%) and that of GBMs with non-canonical IDH mutations (< 1%) are very low in patients ≥ 55 years. For this reason, it was suggested that immunohistochemistry against IDH1 R132H is sufficient to classify GBM as IDH wild-type in this age group. However, no indication was provided for IDH mutational testing in low-grade diffuse gliomas. To address this issue, 273 diffuse gliomas were tested for IDH1 R132H immunohistochemistry. 2/4 diffuse astrocytomas (DAs), 4/9 anaplastic astrocytomas (AAs), 2/256 GBMs, and 4/4 oligodendrogliomas had positive staining. No other IDH mutations were found in immuno-negative low-grade cases by DNA sequencing. To validate our findings, we considered 311 diffuse gliomas in patients ≥ 55 years in The Cancer Genome Atlas database. Fifty-five out of 311 gliomas had IDH R132H mutations (9/16 DAs; 8/48 AAs; 3/211 GBMs; 35/36 oligodendrogliomas), one DA, and one oligodendroglioma had other IDH mutations. IDH mutant gliomas had significantly higher frequency of O-6-methylguanine-DNA methyltransferase promoter methylation (P = 0.0008) and longer overall survival (P

The hysteretic behavior of friction isolators is affected by the variability of the friction coefficient caused by heating phenomena at the sliding interface. The aim of this paper is to investigate such heating phenomena through a series of full-scale experimental tests on a double curved surface slider. The prototype isolator is equipped with eight thermocouples placed in different points of the isolator, which are embedded in the sliding plate. The probes of the thermocouples are in contact with the stainless steel sheet covering the sliding plate, in such a manner that their measurements are representative of the temperature rise occurring at the sliding interface. By investigating different axial loads and sliding velocities, we discuss the measured temperature rise and its implications on the hysteretic behavior of the prototype isolator. Friction variation is observed in the cyclic response of the isolator, which reduces the energy dissipated per cycle and, consequently, may lead to some underestimations of the displacements occurring during real seismic events if a constant friction coefficient is assumed. The proposed data can be helpful to calibrate sophisticated thermo-mechanical finite element models, which is the object of ongoing research.

Background At the time of subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation, successful termination of ventricular fibrillation (VF) is confirmed. A previous study reported cases of prolonged time to therapy during defibrillation testing. Objectives We sought to evaluate the time to therapy, identify possible predictors of delay, and investigate the impact of delayed therapy on VF conversion. Methods We analyzed consecutive patients with S-ICDs who underwent initial conversion testing at a shock energy of 65 J in 53 Italian centers. Results We analyzed 570 patients (467 [82%] male; mean age 48 ± 15 years; mean body mass index 25 ± 6 kg/m2; mean ejection fraction 47% ± 17%). General anesthesia was used in 165 (29%) of patients, with sub- or intermuscular positioning of the generator in (422; 74%). Cardioversion was successful at 65 J in 557 (97.7%) of patients. In 12 patients (2.1%) the shock did not convert VF, and in 1 patient the shock was not delivered because of noise from entrapped subcutaneous air. All failures were successfully managed by reprogramming or repositioning the device. The mean time to therapy was 15 ± 3 seconds, and it exceeded 18 seconds in 51 patients (9%). Independent predictors of delayed therapy (18 seconds) were ejection fraction (odds ratio [OR] 0.98; 95% confidence interval [CI] 0.96–0.99; P = .016) and a 2× gain programmed (OR 3.66; 95% CI 1.44–9.30; P = .006). Effectiveness at 65 J was not associated with time to therapy (OR 1.13; 95% CI 0.97–1.32; P = .122). Conclusion In this analysis of a large population of patients with S-ICDs, delayed therapy during defibrillation testing occurred less frequently than previously reported and had no effect on VF conversion success. Delayed therapies seemed more common when a vector with a 2× gain was programmed.

Fluid viscous dampers (FVDs) are well-established supplemental energy dissipation devices that have been widely used for earthquake protection of structures. Optimal design, placement and sizing of FVDs have been extensively investigated in the last four decades. In this review paper, an overview of the most popular methodologies from the abundant literature in the field is presented. Key aspects and main characteristics of the different strategies to identify the optimal damping coefficients and the optimal placement of FVDs are scrutinized in a comparative manner. The optimal design problem is often solved through a numerical approach to a constrained optimization problem, by minimizing some performance criteria that are representative measures of the system response. With reference to two simple benchmark six-story shear-type structures subject to both a stochastic earthquake excitation and 44 natural ground motions extracted from the FEMA P695 record set, comparison of the seismic performance is carried out considering FVDs designed according to different methods — an overall number of 138 different design scenarios are incorporated in this comparative study. These methods are based either on a desired (target) damping ratio constraint or on a fixed total cost, here roughly related to the sum of the damping coefficients of the added FVDs. Some energy-based perspectives are also given in this review paper in order to interpret the seismic performance in terms of the amount of energy dissipated by the FVDs, out of the total input energy from the earthquake excitation.

A wide experimental campaign of 40 three-point-bending tests on small-scale foamed concrete beams in the low-to-medium density range (400–800 kg/m 3 ) is presented. The considered “extrudable foamed concrete” can keep its dimensional stability at fresh state. In order to increase the mechanical characteristics while preserving lightweight properties associated with the low densities, bi-directional grids of glass fibers are placed close to the bottom external face of the beams. Additionally, the use of short polymer fibers embedded within the cementitious matrix is investigated. Different specimen characteristics are explored, including: three curing conditions, three target dry densities, and two fiber contents. The presence of bi-directional grids increases the bending strength values for all the examined conditions: for 400 kg/m 3 the increase is up to 1700%, and for higher densities is, on average, 175%. The curing condition affects the failure mode: specimens cured in water with densities higher than 600 kg/m3 exhibit a premature failure of the grid reinforcement without separation from the concrete substrate , whereas in those cured in air and cellophane typical bond failures with detachment occur. Only for densities of 800 kg/m 3 the further addition of short polymer fibers produces non-negligible flexural strength increase of 31%, on average.

The Caughey-O’Kelly condition, which defines a specific property of the damping matrix with respect to the mass and stiffness matrix, is violated in several cases of interest in earthquake engineering (e.g. seismic base isolation, supplemental energy dissipation devices, etc.). In these circumstances, non-classically damped systems are associated with complex-valued natural modes of vibration, and the complex modal superposition approach can be invoked as a generalization of the real-valued classical modal analysis to decouple the equations of motion and to compute the earthquake response. In analogy to the classical modal analysis, measures that quantify the error resulting from truncating up to a certain mode are desirable, especially for structures with hundreds or thousands of degrees of freedom. The concept of modal participating mass ratio, widely used in classical modal analysis, is no longer applicable to non-classically damped systems. The authors introduce here two novel measures related to a generalized modal mass ratio and to a modal dissipation ratio of each mode in the complex modal analysis framework. These two real-valued measures, whose sum is equal to one when all the modes are present, should be simultaneously considered to anticipate the importance of each mode in the complex modal superposition approach. Therefore, they are useful to determine the number of modes to retain in a reduced-order model. These two measures and the novel concepts are illustrated through some simple numerical examples of free vibration response and earthquake response of non-classically damped systems, including structures equipped with fluid viscous dampers and base-isolated buildings.

The mechanical behavior of lightweight foamed concrete (LWFC) is markedly affected by microstructural properties, related to the distribution of air bubbles and development of hydration products. In this paper an experimental study on notched beams made of LWFC is carried out, wherein Crack Mouth Opening Displacement (CMOD) is also monitored to compute the fracture energy. To investigate the influence of the curing conditions, half of the specimens are cured in air and the other half in water. Experimental evidence on the load-CMOD curve reveals that foamed concrete absorbs a significant amount of energy before rupture, and curing conditions play a crucial role on the resulting mechanical properties and fracture energy. Both flexural strength and fracture energy are significantly higher in air curing conditions, while such pronounced difference is not so apparent in terms of compressive strength, although better results are still achieved for air-cured specimens. This is further investigated through images of crack paths across the tested beams obtained by Field Emission Scanning Electron Microscopy (FESEM): for all the samples cured in air the presence of diffuse micro-cracks was noted, while those in water show less microcracks but different hydration products.

Many trials demonstrated the beneficial effects on hospitalizations and mortality of cardiac resynchronization therapy (CRT). The purpose of this study was to evaluate CRT effects on functional performance and cognition, two determinants of disability, frailty development and survival.All consecutive patients receiving a CRT device were evaluated at baseline and at the 6-month follow-up. Functional profile was assessed with the Short Physical Performance Battery (SPPB), a measure exploring balance, gait, strength and endurance, highly predictive of incident disability and mortality. The Mini-Mental State Examination (MMSE) was used to study the cognitive profile.We enrolled 54 patients; two of them died during the follow-up, two refused to continue the study. Age was 67±10years (men: 80%, LVEF: 28±5%); medical therapy was optimized (ACE-I/ARB: 84%, beta-blockers: 80%). After 6months, CRT was associated with the improvement of LVEF (35±8 vs. 28±5%, p0.001) and NYHA Class (1.8±0.6 vs. 2.6±0.5, p0.001), and with the reduction of left ventricular end-systolic diameter (50±9 vs. 57±9mm, p0.001). SPPB improved in its total score (10.3±2.0 vs. 9.1±2.7, p0.001) and in the scores exploring gait speed and strength and endurance. These changes were associated with a better cognitive profile (MMSE score: 27.0±3.5 vs. 25.9±4.8, p=0.009). Advanced age was an independent predictor of improved functional performance and cognition.CRT is associated with higher functional and cognitive profile after only 6months of therapy. These findings let us hypothesize a powerful effect of treatment to slow disability and frailty development in heart failure.

AIMS Heart failure patients show impaired left ventricular rotation and twist. In patients undergoing cardiac resynchronization therapy (CRT) significance of preimplant left ventricular rotational timing between different ventricular regions is unknown. We thoroughly evaluated, in patients eligible for CRT, baseline left ventricular rotational mechanics, also assessing segmental rotational timing, and investigated whether the presence of rotational dyssynchrony may be associated with echocardiographic response. METHODS By two-dimensional speckle-tracking echocardiography, baseline peak apical and basal rotation, peak twist, and time-related parameters, such as delays between opposite segments at base and apex, were assessed in 55 CRT patients and 11 healthy participants. RESULTS At 6 months, 30 (54%) patients were echocardiographic responders. Left ventricular rotation and twist had no association with response. All time-related parameters were significantly altered in CRT patients. Maximum basal and apical segments delay, and anteroseptal-posterior delays at base and apex, were longer in responders than in nonresponders (P

BACKGROUND SonR sensor signal correlates well with myocardial contractility expressed in terms of left ventricular (LV) dP/dt max. The aim of our study was to evaluate the changes in myocardial contractility during isometric effort in heart failure patients undergoing cardiac resynchronization therapy (CRT) with right atrial SonR sensor. METHODS Thirty-one patients (19 men, 65 ± 7 years, LV ejection fraction [LVEF] 28% ± 5%, in sinus rhythm) were implanted with a CRT-defibrillator (CRT-D) device equipped with SonR sensor, which was programmed in VVI mode at 40 beats/min. Twenty-four hours after implantation, each patient underwent a noninvasive hemodynamic evaluation at rest and during isometric effort, including: (1) measurement of beat-to-beat endocavitary SonR signal; (2) echocardiographic assessment; and (3) continuous measurement of blood pressure with Nexfin method (BMEYE, Amsterdam, the Netherlands). The following contractility parameters were considered: (1) mean value of beat-to-beat SonR signal; (2) mean value of LV dP/dt by Nexfin system; and (3) fractional shortening (FS) by echocardiography. RESULTS At the third minute of the isometric effort, mean value of SonR signal significantly increased from baseline (P < 0.001). Similarly, mean value of both LV dP/dt by Nexfin and FS significantly increased compared to the resting condition (P < 0.001; P < 0.001). While in 27 (88%) patients SonR signal increased at the third minute of the isometric effort, in four (12%) patients SonR signal decreased. In these patients, both LV dP/dt by Nexfin and FS consensually decreased. CONCLUSIONS In CRT patients, SonR sensor is able to detect changes in myocardial contractility in a consensual way like noninvasive methods such as Nexfin system and echocardiography.

OBJECT The goal of this study was to evaluate advantages, risks, and failures of Gamma Knife radiosurgery (GKRS) in a large series of pediatric and adolescent patients with cerebral arteriovenous malformations (cAVMs) who were followed up for at least 36 months. METHODS Since February 1993, 100 pediatric and adolescent patients (≤ 18 years of age) with cAVMs have undergone GKRS at the authors’ institution and were followed up for at least 36 months. Forty-six patients were boys and 54 were girls; the mean age was 12.8 years (range 3–18 years). Hemorrhage, either alone or combined with seizure, was the clinical onset in 70% of cases. The mean pre-GK cAVM volume was 2.8 ml; 92% of cAVMs were Spetzler-Martin (S-M) Grades I–III. Most lesions (94%) were in eloquent or deep-seated brain regions, according to S-M classification. The parameters for mean and range in treatment planning were prescription isodose 53.8% (40%–90%); prescription dose (PD) 20.2 Gy (9.0–26.4 Gy); maximal dose (MD) 37.8 Gy (18–50 Gy); and number of shots 4.7 (1–17). On the day of GKRS, stereotactic CT or stereotactic MRI and digital subtraction angiography were used. RESULTS Obliteration rate (OR) was angiographically documented in 75 of 84 cases (89.3%) after single-session GKRS, with actuarial ORs at 3 and 5 years of 68.0% and 88.1%, respectively. A repeat treatment was performed in 7 patients (6 with obliteration), and 16 patients with cAVMs underwent staged treatment (9 of them were angiographically cured). Thus, the overall OR was 90%, with actuarial ORs at 3, 5, and 8 years of 59.0%, 76.0%, and 85.0%, respectively. Permanent symptomatic GK-related complications were observed in 11% of cases, with surgical removal of enlarged mass seen on post-RS imaging needed in 5 cases. Hemorrhage during the latency period occurred in 9% of patients, but surgical evacuation of the hematoma was required in only 1 patient. One patient died due to rebleeding of a brainstem cAVM. Radiosurgery outcomes varied according to cAVM sizes and doses: volumes ≤ 10 ml and PDs > 16 Gy were significantly associated with higher ORs and lower rates of permanent complication and bleeding during the latency period. CONCLUSIONS The data from this study reinforce the conclusion that GKRS is a safe and effective treatment for pediatric and adolescent cAVMs, yielding a high OR with minimal permanent severe morbidity and no mortality. The very low frequency of severe hemorrhages during the latency period further encourages a widespread application of RS in such patients. Univariate analysis found that modified RS-based cAVM score, nidus volume, PD, integral dose, S-M grade, and preplanned treatment (the last 2 parameters were also confirmed on multivariate analysis) significantly influenced OR. Lower S-M grades and single-session planned treatments correlated with shorter treatment obliteration interval on univariate analysis. This statistical analysis suggests that a staged radiosurgical treatment should be planned when nidus volume > 10 ml and/or when the recommended PD is ≤ 16 Gy.

The hydraulic realization of the inerter, called fluid inerter, is a piston-cylinder device designed to convey a fluid through an external helical channel, thus producing rotational inertia of a fluid mass. This paper proposes a novel base-isolation scheme that combines friction pendulum isolators with a Tuned Fluid Inerter (TFI), wherein a grounded fluid inerter benefits from the interaction with an auxiliary set of low-damping rubber isolators as tuning elements. Based on experiments on a small-scale prototype, the fluid inerter is modeled as a linear inerter in parallel with a nonlinear dashpot, whose power-law damping term is related to the pressure drops in the helical channel. Instead, the hysteretic behavior of friction pendulum isolators is described by a standard Coulomb-type frictional model. Optimal design of the fluid inerter is performed within a probabilistic framework, by modeling the base acceleration as a Kanai-Tajimi filtered random process and handling the nonlinearities of fluid inerter and friction isolators through statistical linearization. An extensive parametric study is conducted to assess the influence of different characteristics of isolators and earthquake excitation and, above all, of the nonlinearity of the fluid inerter. The effectiveness of the TFI is demonstrated through nonlinear response history analysis under a suite of 100 ground-motion records. The proposed isolation scheme not only significantly reduces the displacement demand of the isolators, but also mitigates the acceleration and interstory drift response of the superstructure. Moreover, the benefits of the inherent nonlinear damping effect produced by the fluid inerter proves to be particularly effective to reduce the peak response under pulse-like ground motions that may occur in near-field earthquake events, which indeed represent critical excitations for structures with friction isolators.

Subcutaneous implantable defibrillators (S-ICD) are attractive for preventing sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM) as they mitigate risks of transvenous leads, although they may increase the risk of inappropriate shock (IAS). We retrospectively collected data on

This contribution is focused on the properties of a particular type of foamed concrete, the extrudable foamed concrete, which is characterized by the dimensional stability in the green state, that is the ability to maintain its shape in the fresh state (green strength). In particular, after an overview of both the compressive and the indirect tensile strength, the effect of density on thermal conductivity values is presented. Interestingly, the thermal conductivity of this particular kind of lightweight cementitious material is lower compared to both classical foamed concrete and aerated autoclaved concrete (AAC) at comparable density. Moreover, the remarkable inherent green strength makes this material potentially suitable for in situ 3D printing applications in co-extruded elements with both thermal insulation and structural purposes.

This paper presents the first results of an ongoing experimental campaign focused on foamed concrete. The dependence of the compressive strength upon dry density, water content, curing conditions, cement type and, most importantly, foaming agents employed in the cement paste is here investigated. In particular, this experimental study comprises more than 100 foamed concrete specimens with a fixed water/cement ratio and dry densities ranging from around 350 up to 850 kg/m3, two cement types, three foaming agents with either protein or synthetic nature, and curing conditions in water at 30 °C, in air as well as within a cellophane sheet at environmental temperature. Unlike most of the research studies in which the water/cement ratio is adjusted on the basis of the stability and the consistence of the foam concrete mix, in this experimental investigation this ratio is fixed constant for all the analyzed design densities. This specimen preparation has made it possible to highlight different behaviors of the employed foaming agents having different nature, which is not fully described in other similar studies of the relevant literature, especially for the range of low densities analyzed in this work. The variability of the compressive strength measured is ascribed to a different stability behavior of the foams generated by foaming agents having different nature during the mixing phase with the cement paste. It is found that the increase of the compressive strength with the density is more or less described by a linear trend and is more pronounced when protein foaming agents are employed in the mix design.

The earthquake-resilient design of a reinforced concrete framed building is presented in this paper as a case study. A non-conventional application of the base isolation in conjunction with a tuned-mass-damper (TMD) located at basement, below the isolation floor, is studied for improving the seismic performance of the building. The seismic base isolation is implemented below the first story, with low-damping rubber isolators mainly placed throughout the perimeter of the building. At the center of the building a large-mass TMD is inserted, which consists of a box filled with large aggregate concrete. The box is located at basement and is connected to the base isolation system via an auxiliary set of lead-core rubber isolators, the latter playing the role of damper and spring elements of the TMD. The TMD box is disconnected from the ground via low-friction flat sliding devices. Optimal design parameters of the auxiliary TMD isolators are detected by minimizing an objective function that is based on the stochastic dynamic analysis of a simplified three-degree-of-freedom system comprising the main structure, the base isolation and the TMD. Four different objective functions are investigated, including the main structure displacement relative to the ground, the interstory displacements, the total acceleration and an energy-based indicator. The effectiveness of this design philosophy and of the related optimization procedure, first time applied to a real case, is demonstrated via nonlinear time-history analyses with simulated accelerograms being consistent with the response spectrum of the installation site. Advantages of this structural system over both the fixed-base building and the conventional application of the base isolation are shown in terms of a variety of response indicators summarizing the seismic performance of the building, including the deformation of the isolators, the displacement demand of the structure, the base shear, the interstory drifts, and the shear forces and bending moments on the beam-column members.

The stochastic linearization technique (SLT), in its conventional force-based Gaussian version (FB-G-SLT), is widely adopted in the literature to handle the nonlinear power-law constitutive behavior of fluid viscous dampers (FVDs), either for evaluating the system response, or within optimal design strategies. In this note, the authors prove that, for the kind of nonlinearity induced by FVDs, this version of FB-G-SLT is not the best choice, especially if the velocity-related response is of major importance in an optimal design process. As an example, the energy dissipated by the devices depends upon the square of the velocity at the ends of the dampers. Among six different formulations of SLT examined in this note, an equal-energy non-Gaussian SLT (EE-NG-SLT) is found to be superior to the FB-G-SLT since it more satisfactorily captures the nonlinear response of the structure as predicted by Monte Carlo simulations. This alternative EE-NG-SLT, without requiring higher computational effort than the FB-G-SLT, is therefore recommended, especially when energy-based (or, in general, velocity-related) objective functions are used in the optimization problem of nonlinear viscous dampers.