Seismic-proof buildings in developing countries

The use of \u201cductile seismic frames,\u201d whose proper seismic behavior largely depends upon construction details and specific design rules, may do not always lead to effective seismic resistant structures, as dramatically denounced by the famous Chinese artist Ai Weiwei in his artwork Straight. The artwork (96 t of undulating metal bars that were salvaged from schools destroyed by the 2008 Sichuan, China earthquake, where over 5,000 students were killed) is a clear denounce against the corruption yielding to shoddy construction methods. The issue of safe constructions against natural hazards appears even more important in developing countries where, in most cases, building structures are realized by non-expert workers, or even by simple \u201cpeople from the street,\u201d who does not have any technical knowledge on construction techniques and seismic engineering. In this paper, a brief history from the first frame structures to the more efficient wall-based structures is provided within Earthquake Engineering perspectives. The superior structural properties of box-type wall structures with respect to conventional frame structures envisage a change of paradigm from actual \u201cductility-based\u201d Earthquake Engineering (centered on frame structures) toward 100% safe buildings through a \u201cstrength-based\u201d design exploiting the use of box-type wall-based structures

Blended structural optimization for wire-and-arc additively manufactured beams

Current manufacturing techniques in the construction sector are slow, expensive and constrained in terms of architectural shapes. In other manufacturing sectors (such as automotive and aerospace) the use of automated construction systems significantly improved the safety, speed, quality and complexity of products. To realize real-scale structural elements for construction applications without ideally any geometrical constraints either in size or shape, the most suitable manufacturing solution for metallic elements is a directed energy deposition (DED) process referred to as wire-and-arc additive manufacturing (WAAM). The main advantage of WAAM relies on the possibility to create new shapes and forms following the breakthrough design tools for modern architecture as algorithm-aided design. At the same time, the printed part ensures high structural performances with reduced material use with respect to the conventional solution. The study presents a new approach called “blended” structural optimization, which blends topology optimization with basic principles of structural design and manufacturing constraints proper of WAAM technology, towards the realization of new efficient structural elements. The approach is applied to the case study of a I-type stainless steel beam on a multi-storey frame building. The approach could pave the way towards an efficient use of WAAM process to produce a new generation of structurally optimized elements for construction, with a more conscious use of the optimization tools and an efficient application of metal 3D printing

Cluster of legionnaires’ disease in an Italian prison

Background: Legionella pneumophila (Lp) is the most common etiologic agent causing Legionnaires’ Disease (LD). Water systems offer the best growth conditions for Lp and support its spread by producing aerosols. From 2015 to 2017, the Regional Reference Laboratory of Clinical and Environmental Surveillance of Legionellosis of Palermo monitored the presence of Lp in nine prisons in Western Sicily. During this investigation, we compared Lp isolates from environmental samples in a prison located in Palermo with isolates from two prisoners in the same prison. Methods: We collected 93 water samples from nine Sicilian prisons and the bronchoalveolar lavages (BALs) of two prisoners considered cases of LD. These samples were processed following the procedures described in the Italian Guidelines for the Prevention and Control of Legionellosis of 2015. Then, genotyping was performed on 19 Lp colonies (17 from water samples and 2 from clinical samples) using the Sequence-Based Typing (SBT) method, according to European Study Group for Legionella Infections (ESGLI) protocols. Results: Lp serogroup (sg) 6 was the most prevalent serogroup isolated from the prisons analyzed (40%), followed by Lp sg 1 (16%). Most of all, in four penitentiary institutions, we detected a high concentration of Lp >104 Colony Forming Unit/Liter (CFU/L). The environmental molecular investigation found the following Sequence Types (STs) in Lp sg 6: ST 93, ST 292, ST 461, ST 728, ST 1317 and ST 1362, while most of the isolates in sg 1 belonged to ST 1. We also found a new ST that has since been assigned the number 2451 in the ESGLI-SBT database. From the several Lp sg 1 colonies isolated from the two BALs, we identified ST 2451. Conclusions: In this article, we described the results obtained from environmental and epidemiological investigations of Lp isolated from prisons in Western Sicily. Furthermore, we reported the first cluster of Legionnaires’ in an Italian prison and the molecular typing of Lp sg 1 from one prison’s water system and two BALs, identified the source of the contamination, and discovered a new ST

Long-term seismometric monitoring of the two towers of Bologna (Italy): Modal frequencies identification and effects due to traffic induced vibrations

The rise of human activities and the constant increase of vehicles traffic in the cities, and in particular of heavy vehicles such as buses and trucks, causes continues ambient vibrations that can detrimentally affect the conservation of built artifacts, especially historical constructions. The effects of urban vibrations on buildings and monuments are far from being fully investigated. In general, peak levels of traffic-induced vibrations are rarely high enough to be the main cause of heavy structural damages. On the other hand, they contribute to the process of deterioration by adding extra stresses\u2014through fatigue damage accumulation occurring as a result of long periods of exposure to low levels of vibration\u2014or by contributing to soil densification\u2014which can lead to the settlement of building foundations. As such, the estimation of threshold levels above which traffic-induced vibrations may cause damages to monumental buildings requires specific studies including long-time monitoring campaigns. Data from experimental campaign can, indeed, be used to extract information on the variation of dynamic properties of buildings, thus providing valuable pieces of information for a complete knowledge to plan effective preservation interventions. The present work aims to identify the effects of traffic induced urban vibrations on the two Towers of Bologna, particularly prone to fatigue-related damages and close to a high transit of vehicles, through a preliminary analysis of data from several dynamic monitoring campaigns conducted during the last years

Mindsets and Failures : Neural Differences in Reactions to Mistakes among 2nd Grade Finnish Girls

Mindsets have been identified as an important factor in explaining learning differences among students. Growth mindset students have been shown to recover from mistakes easier than fixed mindset students, and recent neuroscientific research has shown differences in the brain’s event-related potentials to errors in fixed and growth mindset participants. The purpose of this study was to examine and evaluate these differences in the Finnish elementary school context. To achieve this, event-related potentials of five fixed and five growth mindset 8-9-year-old female students were recorded during a go/no-go task. Differences between the two groups emerged, however, they were different from the results of some previous studies in the field. These findings are discussed in the light of earlier neuroscientific research related to mindsets, including limitations and suggestions for future research in the field.Peer reviewe

Comprehensive Review on the Dynamic and Seismic Behavior of Flat-Bottom Cylindrical Silos Filled With Granular Material

The seismic design of industrial flat-bottom ground-supported silos filled with granular material still presents several challenges to be addressed. They are related to the main aspects which differentiate silo structures containing granular material from other civil structural typologies: 1) the relatively low silo structure mass as compared to the ensiled content mass; 2) the granular nature of the ensiled material. Indeed, the internal actions in the structural members are governed by the complex dynamic interactions along the interfaces between granular content and silo wall or base, or even the internal interaction between particles. More in detail, even though the scientific interest in such complex interactions dates back to the middle of the 19th century, several issues are still unclear such as the dependency of the fundamental dynamic properties (period of vibration and damping ratio) on the characteristics of the dynamic excitation (intensity, frequency content, duration) or the amount of ensiled material mass activated during a seismic excitation and provoking extra pressures on the wall (effective mass). Therefore, most of current seismic code provisions for silos are grounded on rather approximate and simplified assumptions leading to often over-conservative evaluations. The present paper intends to provide a comprehensive summary of the mainly acknowledged experimental and theoretical advances in the dynamic and seismic behavior of silos, supporting the potential researcher in the field to understand the real differences between the code assumptions and recommendations and the actual conditions, as well as illustrating the open issues to be still further investigated

Room Temperature Coherent and Voltage Tunable Terahertz Emission from Nanometer-Sized Field Effect Transistors

We report on reflective electro-optic sampling measurements of TeraHertz emission from nanometer-gate-length InGaAs-based high electron mobility transistors. The room temperature coherent gate-voltage tunable emission is demonstrated. We establish that the physical mechanism of the coherent TeraHertz emission is related to the plasma waves driven by simultaneous current and optical excitation. A significant shift of the plasma frequency and the narrowing of the emission with increasing channel's current are observed and explained as due to the increase of the carriers density and drift velocity.Comment: 3 figure

Claimed Co-ethnics and Kin-State Citizenship in Southeastern Europe

The paper introduces the often neglected concept of 'claimed co-ethnics' in the analysis of citizenship policies. It argues that this is an interstitial category that further complicates the triadic nexus between national minorities, nationalising states and kin-states. The 'claimed co-ethnics' are defined as people who are recognised by the citizenship (or ethnizenship) conferring state as belonging to its main ethnic group, although they themselves do not embrace that definition. In addition to bringing the issue of claimed co-ethnics into focus, the paper elucidates how citizenship policies can affect groups that challenge the exact fit between ethnicity and nation, showing how national governments through particular citizenship policies and categorisation practices engage in the construction of these groups. The paper shows that the triadic nexus framework, which has had a strong influence on citizenship and minorities scholarship, needs to be revised to include unidirectional relations between the elements of the triadic nexus. The paper is based on the comparison between the cases of ethnic Vlachs (in the context of Albania and Greece) and Bunjevci (in the context of Serbia and Croatia).European Commission - Seventh Framework Programme (FP7

HAART in HIV+ naive elderly patients: immuno-virological response and clinical outcome

Purpose of the study Elderly patients (≥50 years) are increasing in the HIV population; HAART-related prolonged survival and late diagnosis of new HIV infections are possible reasons of this findings. It is debated whether older patients have a different response to HAART. The aim of this retrospective study was to evaluate efficacy of HAART and clinical outcome in a group of patients ≥50 year in comparison to a control group (<50 years-old)