Experimental study of dynamic bending stiffness of ACSR overhead conductors

Abstract : Aeolian vibrations of transmission line conductors may cause fretting fatigue failure at or near the location of clamped devices. At these locations, the bending stiffness variation of the conductor has a large influence on its deformed shape and hence on its fatigue mechanics. Variable bending stiffness models could be integrated in non-linear finite element programs to obtain better mechanical behaviour predictions. However, there is very little data available in the literature to validate such numerical models. The objective of this paper is to present experimental data for the deformed shape of two types of ACSR conductors undergoing vibrations. The tests were performed on a 5.83 m test bench for various tensions, displacement amplitudes and frequencies. The displacement amplitude was measured at the vibration anti-node and at five locations near the squarefaced bushing. The results suggest a large stiffness variation near the bushing. This experimental study provides valuable data to compare with a numerical model of a vibrating conductor that includes variable bending stiffness

Bacterial Antagonistic Species of the Pathogenic Genus Legionella Isolated from Cooling Tower

Legionella pneumophila is the causative agent of Legionnaires' disease, a severe pneumonia. Cooling towers are a major source of large outbreaks of the disease. The growth of L. pneumophila in these habitats is influenced by the resident microbiota. Consequently, the aim of this study was to isolate and characterize bacterial species from cooling towers capable of inhibiting several strains of L. pneumophila and one strain of L. quinlivanii. Two cooling towers were sampled to isolate inhibiting bacterial species. Seven inhibitory isolates were isolated, through serial dilution plating and streaking on agar plates, belonging to seven distinct species. The genomes of these isolates were sequenced to identify potential genetic elements that could explain the inhibitory effect. The results showed that the bacterial isolates were taxonomically diverse and that one of the isolates may be a novel species. Genome analysis showed a high diversity of antimicrobial gene products identified in the genomes of the bacterial isolates. Finally, testing different strains of Legionella demonstrated varying degrees of susceptibility to the antimicrobial activity of the antagonistic species. This may be due to genetic variability between the Legionella strains. The results demonstrate that though cooling towers are breeding grounds for L. pneumophila, the bacteria must contend with various antagonistic species. Potentially, these species could be used to create an inhospitable environment for L. pneumophila, and thus decrease the probability of outbreaks occurring

Liver transplantation in the most severely ill cirrhotic patients: A multicenter study in acute-on-chronic liver failure grade 3

International audienceBACKGROUND & AIMS: Liver transplantation (LT) for the most severely ill patients with cirrhosis, with multiple organ dysfunction (accurately assessed by the acute-on-chronic liver failure [ACLF] classification) remains controversial. We aimed to report the results of LT in patients with ACLF grade 3 and to compare these patients to non-transplanted patients with cirrhosis and multiple organ dysfunction as well as to patients transplanted with lower ACLF grade. METHODS: All patients with ACLF-3 transplanted in three liver intensive care units (ICUs) were retrospectively included. Each patient with ACLF-3 was matched to a) non-transplanted patients hospitalized in the ICU with multiple organ dysfunction, or b) control patients transplanted with each of the lower ACLF grades (three groups). RESULTS: Seventy-three patients were included. These severely ill patients were transplanted following management to stabilize their condition with a median of nine days after admission (progression of mean organ failure from 4.03 to 3.67, p=0.009). One-year survival of transplanted patients with ACLF-3 was higher than that of non-transplanted controls: 83.9 vs. 7.9%, p\textless0.0001. This high survival rate was not different from that of matched control patients with no ACLF (90%), ACLF-1 (82.3%) or ACLF-2 (86.2%). However, a higher rate of complications was observed (100 vs. 51.2 vs. 76.5 vs. 74.3%, respectively), with a longer hospital stay. The notion of a "transplantation window" is discussed. CONCLUSIONS: LT strongly influences the survival of patients with cirrhosis and ACLF-3 with a 1-year survival similar to that of patients with a lower grade of ACLF. A rapid decision-making process is needed because of the short "transplantation window" suggesting that patients with ACLF-3 should be rapidly referred to a specific liver ICU. Lay summary: Liver transplantation improves survival of patients with very severe cirrhosis. These patients must be carefully monitored and managed in a specialized unit. The decision to transplant a patient must be quick to avoid a high risk of mortality