Earthquake Protection of Existing Structures with Limited Seismic Joint: Base Isolation with Supplemental Damping versus Rotational Inertia

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

Improving the dynamic performance of base-isolated structures via tuned mass damper and inerter devices: A comparative study

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analysis of dynamic instabilities in bridges under wind action through a simple friction based mechanical model

Abstract 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

Key factors affecting the compressive strength of foamed concrete

This contribution aims to highlight, from an experimental point of view, the key factors affecting the compressive strength of foamed concrete. An experimental campaign has been conducted on a broad group of cubic specimens made of foamed concrete under compression tests at 28 days. In addition to the obvious influence of the density on the achievement of the compressive strength, other factors have been studied. In particular, three different curing conditions, three foaming agents with either synthetic or protein nature, two different cement types, and three water/cement ratios have been included in this experimental investigation. As a result of this experimental campaign, it has been found that the not only the density, but also the foaming agent and the water/cement ratio play a major role in the strength achievement of the foamed concrete. It is also demonstrated that the combination of the foaming agent with a particular water/cement ratio is a crucial parameter affecting the compressive strength of this material

Anti-VEGF Therapy in Breast and Lung Mouse Models of Cancers

Cancer is the second leading cause of death in the world after cardiovascular diseases. Some types of cancer cells often travel to other parts of the body through blood circulation or lymph vessels, where they begin to grow. This process is recognized as metastasis. Angiogenesis is the formation of new blood vessels from existing vessel. Normally angiogenesis is a healthy process, that helps the body to heal wounds and repair damaged body tissues, whereas in cancerous condition this process supports new blood vessels formation that provide a tumor with its own blood supply, nutrients and allow it to grow. The most important proximal factor for angiogenesis is the vascular endothelial growth factor VEGF. Angioinhibition is a form of targeted therapy that uses drugs to stop tumors from making new blood vessels. Therefore, in this paper we analyse the importance of VEGF as target of cancer therapy, analysing murine models

Critical assessment of CO2 emission of different concretes: foamed, lightweight aggregate, recycled and ordinary concrete

Construction materials contribute to about 75% of the CO2 emission of all the construction processes. Concrete is one of the most widely used construction materials and is thus primarily responsible for CO2 emission. In particular, 8 − 9% of global greenhouse gas (GHG) emission are produced by concrete. CO2 emissions can be considerably reduced in the construction phase through a careful selection of materials with low environmental impact or through specific admixtures. In this study, different concretes are taken into consideration, including foamed concrete, lightweight aggregate concrete, recycled concrete and ordinary concrete. A series of mix designs of these four classes of concrete, characterized by a comparable mechanical strength or a comparable density, are taken from the relevant literature and compared to one another in terms of CO2 emission. Some guidelines or possible research lines aimed at reducing CO2 emission are finally outlined in this contribution

FP906PHOSPHORUS IN CHRONIC KIDNEY DISEASE PATIENTS FROM 1669 TO 2014

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Cervical mucus proteome in endometriosis

Additional file 1: Table S1. Identified proteins in CM in the group of controls and in patients affected by endometriosis

Squeezing out predictions with leptogenesis from SO(10)

We consider the see-saw mechanism within a non-supersymmetric SO(10) model. By assuming the SO(10) quark-lepton symmetry, and after imposing suitable conditions that ensure that the right-handed (RH) neutrino masses are at most mildly hierarchical (compact RH spectrum) we obtain a surprisingly predictive scenario. The absolute neutrino mass scale, the Dirac and the two Majorana phases of the neutrino mixing matrix remain determined in terms of the set of already measured low energy observables, modulo a discrete ambiguity in the signs of two neutrino mixing angles and of the Dirac phase. The RH neutrinos mass spectrum is also predicted, as well as the size and sign of the leptogenesis CP asymmetries. We compute the cosmological baryon asymmetry generated through leptogenesis and obtain the correct sign and a size compatible with observations.Comment: 18 pages, 2 figures; minor changes, version accepted for publication in PR

A critical appraisal of epidemiological studies comes from basic knowledge: a reader's guide to assess potential for biases

Scientific literature may be biased because of the internal validity of studies being compromised by different forms of measurement error, and/or because of the selective reporting of positive and 'statistically significant' results. While the first source of bias might be prevented, and in some cases corrected to a degree, the second represents a pervasive problem afflicting the medical literature; a situation that can only be 'corrected' by a change in the mindset of authors, reviewers, and editors. This review focuses on the concepts of confounding, selection bias and information bias, utilising explanatory examples and simple rules to recognise and, when possible, to correct for them. Confounding is a mixing of effects resulting from an imbalance of some of the causes of disease across the compared groups. It can be prevented by randomization and restriction, and controlled by stratification, standardization or by using multivariable techniques. Selection bias stems from an absence of comparability among the groups being studied, while information bias arises from distorted information collection techniques. Publication bias of medical research results can invalidate evidence-based medicine, when a researcher attempting to collect all the published studies on a specific topic actually gathers only a proportion of them, usually the ones reporting 'positive' results. The selective publication of 'statistically significant' results represents a problem that researchers and readers have to be aware of in order to face the entire body of published medical evidence with a degree of scepticism