FRAM for systemic accident analysis: a matrix representation of functional resonance

Due to the inherent complexity of nowadays Air Traffic Management (ATM) system, standard methods looking at an event as a linear sequence of failures might become inappropriate. For this purpose, adopting a systemic perspective, the Functional Resonance Analysis Method (FRAM) originally developed by Hollnagel, helps identifying non-linear combinations of events and interrelationships. This paper aims to enhance the strength of FRAM-based accident analyses, discussing the Resilience Analysis Matrix (RAM), a user-friendly tool that supports the analyst during the analysis, in order to reduce the complexity of representation of FRAM. The RAM offers a two dimensional representation which highlights systematically connections among couplings, and thus even highly connected group of couplings. As an illustrative case study, this paper develops a systemic accident analysis for the runway incursion happened in February 1991 at LAX airport, involving SkyWest Flight 5569 and USAir Flight 1493. FRAM confirms itself a powerful method to characterize the variability of the operational scenario, identifying the dynamic couplings with a critical role during the event and helping discussing the systemic effects of variability at different level of analysis

Ultrasonic consolidation (UC) debulking of thermosetting prepreg for autoclave curing of composite laminates

Debulking of prepreg (pre-impregnated resin system) layers during hand lay-up manufacturing of carbon fibre reinforced polymers (CFRP) is a key-step to reduce air content and maximise the mechanical properties of the final product. Debulking is usually performed using vacuum-bag cycles of 10–15 min applied after the lay-up of every three or five prepreg layers, leading to a considerable time-consuming process. In this work, the use of ultrasonic stimulation during vacuum is studied to improve the efficiency of the debulking process and reduce the number of operations in order to decrease the overall manufacturing time. Three CFRP laminates were laid-up using the proposed ultrasonic consolidation (UC) with three different exposition times (5, 10 and 15 min) and cured in autoclave. The UC debulking process consists in a vacuum cycle with ultrasonic waves sent to the uncured material through an ultrasonic transducer. In order to evaluate the efficiency of this process interlaminar shear strength (ILSS) and in-plane compressive properties were tested. Experimental results show for 15 min compressive properties comparable with the ones obtained from reference samples manufactured using the traditional debulking technique, and high improvements in terms of ILSS (>20%). Therefore, UC debulking process can be used during hand lay-up of prepreg in order to improve the interlaminar properties of the final part and reduce the debulking time by over 85%

A novel bistable energy harvesting concept

Bistable energy harvesting has become a major field of research due to some unique features for converting mechanical energy into electrical power. When properly loaded, bistable structures snap-through from one stable configuration to another, causing large strains and consequently power generation. Moreover, bistable structures can harvest energy across a broad-frequency bandwidth due to their nonlinear characteristics. Despite the fact that snap-through may be triggered regardless of the form or frequency of exciting vibration, the external force must reach a specific snap-through activation threshold value to trigger the transition from one stable state to another. This aspect is a limiting factor for realistic vibration energy harvesting application with bistable devices. This paper presents a novel power harvesting concept for bistable composites based on a 'lever effect' aimed at minimising the activation force to cause the snap through by choosing properly the bistable structures' constraints. The concept was demonstrated with the help of numerical simulation and experimental testing. The results showed that the actuation force is one order of magnitude smaller (3%–6%) than the activation force of conventionally constrained bistable devices. In addition, it was shown that the output voltage was higher than the conventional configuration, leading to a significant increase in power generation. This novel concept could lead to a new generation of more efficient bistable energy harvesters for realistic vibration environments

Unraveling VPS13A pathways: from Drosophila to human

Chorea-Acanthocytosis (ChAc) is a rare human neurodegenerative disease caused by homozygous mutations in the VPS13A gene. Until now no treatment is available and it is not known why mutations in this specific gene lead to neurodegeneration. We established and validated a suitable model organism, Drosophila melanogaster, to study ChAc. Drosophila melanogaster Vps13 mutants showed shortened life span, decreased climbing ability and the presence of vacuoles in the brain. Furthermore, Vps13 mutant flies were sensitive to proteotoxic stress and accumulated ubiquitylated proteins. We performed immunoprecipitation experiments coupled to mass spectrometry (IP-MS) in fly heads using control and Vps13 mutant flies to obtain a list of possible Vps13 interactors and Galectin was identified as a possible candidate. The Interaction between Vps13 and Galectin was validated via immunoprecipitation in cultured insect cells. In addition, we showed that human VPS13A is associated with mitochondria and, through its FFAT domain, interacting with the ER protein VAP-A. These results suggest a role in the formation of ER-mitochondria membrane contact sites. Interestingly, in cells treated with fatty acid, VPS13A translocates from mitochondria to newly synthesized lipid droplets influencing their motility and size. Our data are discussed and reveal an emerging role of VPS13A in preventing neurodegeneration

Analysis of A Sequence Nucleotide Polymorphism of STAT5A Gene in Garganica Goat Breed

STATs (signal transducer and activator of transcription) are a group of transcription factors that mediate actions of a variety of peptide hormones and cytokines within target cells (for example prolactin and growth hormone). In particular, STAT5A gene is a candidate marker for quantitative traits in farm animals. In this study, the STAT5A/Eco81I polymorphism was investigated with PCR-RFLP in a sample of Garganica goats. Garganica breed is an Italian goat breed that originates in the Gargano promontory, in Apulia region, by crossing the autochthonous population of goat with west European goats. Garganica breed show an exceptional ability to adapt to particularly difficult environments, as well as an extraordinary capacity to utilize poor pasture that would not otherwise be used. The investigated polymorphism is a substitution C→T at position 6852 within the exon 7 of the STAT5A gene. Only two out of three possible genotypes were identified in the population. The allelic frequencies of alleles C and T were 0.863 and 0.137 respectively and the population was kept in Hardy-Weinberg equilibrium. Moreover, some population genetic indices were also reported

Analysis of a sequence nucleotide polymorphism of STAT5A gene in Garganica goat breed

STATs (signal transducer and activator of transcription) are a group of transcription factors that mediate actions of a variety of peptide hormones and cytokines within target cells (for example prolactin and growth hormone). In particular, STAT5A gene is a candidate marker for quantitative traits in farm animals. In this study, the STAT5A/Eco81I polymorphism was investigated with PCR-RFLP in a sample of Garganica goats. Garganica breed is an Italian goat breed that originates in the Gargano promontory, in Apulia region, by crossing the autochthonous population of goat with west European goats. Garganica breed show an exceptional ability to adapt to particularly difficult environments, as well as an extraordinary capacity to utilize poor pasture that would not otherwise be used. The investigated polymorphism is a substitution C→T at position 6852 within the exon 7 of the STAT5A gene. Only two out of three possible genotypes were identified in the population. The allelic frequencies of alleles C and T were 0.863 and 0.137 respectively and the population was kept in Hardy-Weinberg equilibrium. Moreover, some population genetic indices were also reported