03.07: Robustness in fire of a new type of beam‐to‐column connection

In this paper a new type of beam‐to‐column connection is introduced, which is capable of absorbing both very large rotations and axial movements, due firstly to thermal elongation and subsequently to extreme weakening of the connected beam. The main idea is to connect the beam and column using a special connector bolted to the column flange using a face‐plate and to the beam web using a fin‐plate. Between these a highly ductile element, which is in this case a hollow circular tube, is included. This plays the crucial role in absorbing beam‐end movements occurring firstly during the expansion of the beam and secondly during its catenary behaviour at very high temperatures. This study aims to extend the research on this connection to structural case studies in the context of performance‐based structural fire engineering design. The connection has been modelled using different approaches, starting with 3‐D finite element modelling and proceeding to validated simplifications which feed into a component‐based model. In order to make calculations feasible, the mathematical model of the ductile component is developed and calibrated using the information provided by parametrized numerical FEM computations. The component model is developed to be capable of representing the hysteresis occurring due to deformation‐reversals as temperatures rise, as well as failure corresponding to fracture in tension. Thus, the component model is described as a function of displacement and temperature, including sufficiently realistic plastic deformation and fracture criteria. This model is then implemented into global FEM models and utilized to assemble the stiffness matrix of a special connector element used to join the beam and column nodes. This component‐based connection model is then applied in some comparative studies

Chatten - Fallstudien zur Verschränkung potenzieller Nutzungsmöglichkeiten und faktischer Aneignungsmuster

"Das Chatten via Internet und PC gilt als eine neuartige Form der Kommunikation, da weltweit und zeitgleich mit verschiedensten Personen im Modus der Anonymität kommuniziert werden kann. Der vorliegende Artikel setzt sich zum Ziel, Strukturpotenzialitäten des Mediums 'Chatten' kommunikationstypologisch zu bestimmen, um auf dieser Folie Spannungsfelder und Brüche zu faktischen Gebrauchsformen zu entfalten. Die Bestimmung solcher Potenzialitäten erfolgt auf der Basis interaktionstheoretischer Begriffe (v.a. Goffmans) und orientiert sich am Grundmodus jeglicher Interaktion, an der sog. 'Face to Face-Beziehung'. Die Bestimmung faktischer Gebrauchsformen basiert auf Gruppendiskussionen mit Chat-Experten. Hierzu werden zwei für das erhobene Material repräsentative und prototypische Ausschnitte aus einer Gruppendiskussion sprach- und deutungsmusteranalytisch ausgewertet. Es zeigt sich, da dass Chatten – zumindest in der privaten Kommunikation - als Mittel der Beziehungsanbahnung und Kontaktpflege genutzt wird, wo es Norm- und Kontrollentlastungsfunktionen übernimmt. Deutlich werden jedoch auch die Grenzen einer auf Anonymität basierenden Kommunikation: Werden alltagsanaloge und damit identitätsrelevante Beziehungen gesucht, zeigt sich, dass das In-Gebrauch- Nehmen des Mediums 'Chatten' eine sukzessive Veralltäglichung, mithin eine Unterwerfung unter die Regeln der Verpersönlichung von Kontakten mit sich bringt." (Autorenreferat)"Chatting via Internet and PC describes an innovative form of communication. Different users can communicate worldwide and coincidence of time in a modus of anonymity. The target of this article is to define the constitution of the medium 'Chatting;' typologically in communication for developing fields of tension and seclusion into practical using forms. The definition of such potentiality is ensued by the base of theoretical interaction (e.g. Goffmans) and is oriented at the ground of interactive mode, especially at the 'face-to-face-relationship.' The definition of practical using form is based on group discussion with chatting-experts. Two representative and prototypical cuts of the data of the group discussion will be evaluated through an analyization of the language and of the explanation. Chatting is used as an instrument for starting a relationship and it establishes contact in a private form, and meanwhile it assumes function of normal discharge and control discharge. The barrier of communication based of anonymity is defined: if common analogical relationships and therefore identity relevant relationships will be searched, thus showing that using the medium 'chatting' brings up a successive everyday occurrence, also a subjection to the rules of personality of contacts." (author's abstract

Bending behaviour of single-layered graphene nanosheets with vacancy defects

The paper at hand deals with the single layered graphene sheets. In particular, the influence of the vacancy location and the density of vacancies on the bending behavior are investigated. The nanomechanical model is based on the structural mechanics approach with covalent bonds modeled as beam finite elements. The used graphene sheet model is described in detail and the obtained results are presented and thoroughly discussed

Association of Delayed Surgery for Ankle Fractures and Patient-Reported Outcomes

Background: Several studies probe the association between prolonged time to surgery and postoperative complications in ankle fractures, but little is known about how a longer wait time affects clinical outcomes. The present study aims to assess the association between time from injury to surgery and patient-reported outcomes after operative treatment of severe ankle fractures. Method: Patients treated operatively for low-energy ankle fractures that also involve the posterior malleolus from 2014 to 2016 were included. Patient charts were reviewed for patient demographics, type of trauma, fracture characteristics, treatment given, and complications. Ankle function was evaluated on a follow-up visit by clinical examination, radiographs, and patient-reported outcome measures (Self-Reported Foot and Ankle Score [SEFAS], RAND-36, visual analog scale [VAS] of Pain, VAS of Satisfaction). We compared patients treated within 1 week to those treated later than a week from injury for analyses. Results: Follow-up visits of 130 patients were performed at mean 26 (SD 9) months after surgery. Patient demographics and fracture characteristics were similar between groups. Mean SEFAS was 34 (SD 10) in patients treated later than a week from injury vs 38 (SD 9) in those treated earlier (P = .012). Patients operated on later than 7 days from injury reported more pain (P = .008) and lower satisfaction than those treated earlier (P = .016). Conclusion: In this retrospective patient series of low-energy ankle fractures with posterior malleolar fragments, we found that waiting >7 days for definitive surgery was associated with poorer clinical outcomes and more pain compared with those who had surgery earlier.publishedVersio

Borna disease virus infects human neural progenitor cells and impairs neurogenesis.

Understanding the complex mechanisms by which infectious agents can disrupt behavior represents a major challenge. The Borna disease virus (BDV), a potential human pathogen, provides a unique model to study such mechanisms. Because BDV induces neurodegeneration in brain areas that are still undergoing maturation at the time of infection, we tested the hypothesis that BDV interferes with neurogenesis. We showed that human neural stem/progenitor cells are highly permissive to BDV, although infection does not alter their survival or undifferentiated phenotype. In contrast, upon the induction of differentiation, BDV is capable of severely impairing neurogenesis by interfering with the survival of newly generated neurons. Such impairment was specific to neurogenesis, since astrogliogenesis was unaltered. In conclusion, we demonstrate a new mechanism by which BDV might impair neural function and brain plasticity in infected individuals. These results may contribute to a better understanding of behavioral disorders associated with BDV infection