Optimised design of nested oblong tube energy absorbers under lateral impact loading

Dynamic lateral crushing of mild steel (DIN 2393) nested tube systems was conducted using a ZWICK ROELL impact tester. The tests were performed with impact velocities ranging between 3 and 5 m/s, achieved using a fixed mass impinging onto the specimens under the influence of gravity. The various nested tube systems consisted of one standard and one optimised design. Their crushing behaviour and energy absorption capabilities were obtained and analysed. In addition to the experimental work, numerical simulations using the explicit code LS-DYNA were conducted; boundary conditions matching those observed in experiments were applied to the models. Results from the numerical method were compared against those obtained from experiments. An over-prediction in force-deflection responses was obtained from the numerical code. An attempt was made to explain this inconsistency on the basis of the formation of plastic hinges and the validity of strain rate parameters used in the Cowper Symonds relation. It was found that the optimised energy absorbers exhibited a more desirable force-deflection response than their standard counterparts due to a simple design modification which was incorporated in the optimised design

Formal Verification of Security Protocol Implementations: A Survey

Automated formal verification of security protocols has been mostly focused on analyzing high-level abstract models which, however, are significantly different from real protocol implementations written in programming languages. Recently, some researchers have started investigating techniques that bring automated formal proofs closer to real implementations. This paper surveys these attempts, focusing on approaches that target the application code that implements protocol logic, rather than the libraries that implement cryptography. According to these approaches, libraries are assumed to correctly implement some models. The aim is to derive formal proofs that, under this assumption, give assurance about the application code that implements the protocol logic. The two main approaches of model extraction and code generation are presented, along with the main techniques adopted for each approac

po 237 the pro oncogenic transcription factor stat3 regulates ca2 release and apoptosis from the endoplasmic reticulum via interaction with the ca2 channel ip3r3

Introduction Signal Transducer and Activator of Transcription (STAT) 3 is an oncogenic transcription factor found constitutively activated in several tumours, where it exerts its functions both as a canonical transcription factor and as a non-canonical regulator of energy metabolism and mitochondrial functions. These two activities rely on different post-translational activating events; the phosphorylation on Y705 is involved in nuclear activities, while that on S727 is relevant for mitochondrial functions. Mitochondrial STAT3 increases aerobic glycolysis and decreases ROS production, partly by interacting with the Electron Transfer Complexes (ETC). Material and methods By means of cell fractionations, we tested STAT3 localization to the Endoplasmic Reticulum (ER) in breast cancer cell lines dependent or not on STAT3 activity. We then measured Ca2+ release and apoptotic response in the same cells. The physical interaction between inositol 1,4,5-trisphosphate receptor type 3 (IP3R3) and STAT3 was demonstrated by co-IP either of the endogenous proteins or of their truncated/mutated forms, while STAT3 role in the degradation of IP3R3 was tested by serum starvation and refeeding experiments, followed by WB. Results and discussions We describe here the previously undetected abundant localization of STAT3 also to the ER. In this cellular compartment IP3R3, a Ca2+ channel that allows Ca2+ release from the ER and the mitochondrial associated membranes (MAMs) in response to IP3, regulates the balance between mitochondrial activation and Ca2+-triggered apoptosis. We observed that STAT3 within the ER physically interacts with IP3R3 and, via its phosphorylation on S727, it down-regulates Ca2+ release and apoptosis. Indeed, STAT3 silencing enhances both ER Ca2+ release and sensitivity to apoptosis following oxidative stress in STAT3-dependent mammary tumour cells, correlating with increased IP3R3 levels. In line with this, basal-like breast tumours, which frequently display constitutively active STAT3, show an inverse correlation between IP3R3 and STAT3 protein levels. Conclusion Our results indicate that S727-phosphorylated STAT3 contribute to mammary tumour aggressiveness, also by localising to the ER and regulating Ca2+ fluxes. STAT3-mediated enhanced IP3R3 degradation leads to decreased Ca2+ release and thus to resistance to apoptosis. This new non-canonical STAT3 role appears to be particularly relevant in basal-like breast cancers, adding a new mechanisms through which STAT3 exerts its well established pro-oncogenic anti-apoptotic role

A Formal Library for Elliptic Curves in the Coq Proof Assistant

International audienceA preliminary step towards the verification of elliptic curve cryptographic algorithms is the development of formal libraries with the corresponding mathematical theory. In this paper we present a formaliza-tion of elliptic curves theory, in the SSReflect extension of the Coq proof assistant. Our central contribution is a library containing many of the objects and core properties related to elliptic curve theory. We demonstrate the applicability of our library by formally proving a non-trivial property of elliptic curves: the existence of an isomorphism between a curve and its Picard group of divisors

Numerical and experimental investigation of a lightweight bonnet for pedestrian safety

A topic of great consideration in current vehicle development in Europe is pedestrian protection. The enforcement of a new regulation trying to decrease the injuries to head, pelvis, and leg of pedestrian impacted by cars, is imposing great changes in vehicles' front design. In the present work a design solution for the bonnet, which is the main body part interacting with the human head during a car to pedestrian collision, is proposed. This solution meets the stiffness and safety targets, takes into account the manufacturing and recyclability requirements and gives a relevant contribution to vehicle lightweight. Thus this proposed solution puts in evidence that safety and lightweight are not incompatible targets. The amount of potential injury to the pedestrian head is evaluated, as prescribed by the standard test procedures, by means of a headform launched on the bonnet. However, the standard approach based on the head injury criterion (HIC) value only is reported to be largely unsatisfactory: therefore, a new experimental methodology for the measurement of the translational and the rotational accelerations has been developed, and the experimental results are reported. This would be a starting point for the evolution of currently adopted injury criteria to increase the safety of the vulnerable road user

Card-Based Cryptography Meets Formal Verification

Card-based cryptography provides simple and practicable protocols for performing secure multi-party computation (MPC) with just a deck of cards. For the sake of simplicity, this is often done using cards with only two symbols, e.g., ♣ and ♡. Within this paper, we target the setting where all cards carry distinct symbols, catering for use-cases with commonly available standard decks and a weaker indistinguishability assumption. As of yet, the literature provides for only three protocols and no proofs for non-trivial lower bounds on the number of cards. As such complex proofs (handling very large combinatorial state spaces) tend to be involved and error-prone, we propose using formal verification for finding protocols and proving lower bounds. In this paper, we employ the technique of software bounded model checking (SBMC), which reduces the problem to a bounded state space, which is automatically searched exhaustively using a SAT solver as a backend. Our contribution is twofold: (a) We identify two protocols for converting between different bit encodings with overlapping bases, and then show them to be card-minimal. This completes the picture of tight lower bounds on the number of cards with respect to runtime behavior and shuffle properties of conversion protocols. For computing AND, we show that there is no protocol with finite runtime using four cards with distinguishable symbols and fixed output encoding, and give a four-card protocol with an expected finite runtime using only random cuts. (b) We provide a general translation of proofs for lower bounds to a bounded model checking framework for automatically finding card- and length-minimal protocols and to give additional confidence in lower bounds. We apply this to validate our method and, as an example, confirm our new AND protocol to have a shortest run for protocols using this number of cards

Persistent interaction patterns across social media platforms and over time

Growing concern surrounds the impact of social media platforms on public discourse1–4 and their influence on social dynamics5–9, especially in the context of toxicity10–12. Here, to better understand these phenomena, we use a comparative approach to isolate human behavioural patterns across multiple social media platforms. In particular, we analyse conversations in different online communities, focusing on identifying consistent patterns of toxic content. Drawing from an extensive dataset that spans eight platforms over 34 years—from Usenet to contemporary social media—our findings show consistent conversation patterns and user behaviour, irrespective of the platform, topic or time. Notably, although long conversations consistently exhibit higher toxicity, toxic language does not invariably discourage people from participating in a conversation, and toxicity does not necessarily escalate as discussions evolve. Our analysis suggests that debates and contrasting sentiments among users significantly contribute to more intense and hostile discussions. Moreover, the persistence of these patterns across three decades, despite changes in platforms and societal norms, underscores the pivotal role of human behaviour in shaping online discourse

Ultra-fast Microwave Synthesis of ZnO Nanowires and their Dynamic Response Toward Hydrogen Gas

Ultra-fast and large-quantity (grams) synthesis of one-dimensional ZnO nanowires has been carried out by a novel microwave-assisted method. High purity Zinc (Zn) metal was used as source material and placed on microwave absorber. The evaporation/oxidation process occurs under exposure to microwave in less than 100 s. Field effect scanning electron microscopy analysis reveals the formation of high aspect-ratio and high density ZnO nanowires with diameter ranging from 70 to 80 nm. Comprehensive structural analysis showed that these ZnO nanowires are single crystal in nature with excellent crystal quality. The gas sensor made of these ZnO nanowires exhibited excellent sensitivity, fast response, and good reproducibility. Furthermore, the method can be extended for the synthesis of other oxide nanowires that will be the building block of future nanoscale devices

Resistindo ao desenvolvimento neocolonial: a luta do povo de Andalgalá contra projetos megamineiros

A América Latina vem experimentando uma nova era de declarada fé dos governos no mito do desenvolvimento, em articulação com a expansão de políticas extrativistas exportadoras em um contexto de renovada dependência. A face mais dramática do extrativismo na região tem sido a crescente presença de corporações mineiras transnacionais apoiadas por governos nacionais e regionais e por instituições internacionais financeiras e de apoio ao desenvolvimento, e intensamente resistidas por movimentos sociais populares. Neste artigo apresentamos o caso de Andalgalá (uma pequena cidade na Província de Catamarca, na Argentina) e as lutas do povo contra corporações mineiras transnacionais e seus aliados. Na tradição da Filosofia da Libertação e do método ana-dialético de Dussel, nos engajamos com o que tem sido denominado "comunidades argentinas do NÃO", expressando sua oposição a formas neocoloniais de desenvolvimento e gestão. Neste artigo estamos especificamente interessados em compreender como dois dispositivos gerencialistas usados pelas corporações mineiras, responsabilidade social corporativa (RSC) e pactos de governança, impactam a luta do povo. Acima de tudo, este artigo oferece instantâneos de batalhas na linha de frente do extrativismo. Esperamos ter dado voz àquelas pessoas que normalmente não são ouvidas, criando um espaço para suas visões sobre um tipo diferente de desenvolvimento.</jats:p