Ultrasonic wave propagation in reticulated foams saturated by different gases: High frequency limit of the classical models

International audienceTransmission experiments are performed on high porosity reticulated polyurethane foams saturated by different gases at ultrasonic frequencies up to 800 kHz. An excess attenuation is observed at high frequencies, when the wavelength is not sufficiently large compared to the lateral dimensions of the fibers. At lower frequencies, these experiments lead by using classical models of equivalent fluids, to a fast and reliable method for determining the characteristic length $\Lambda$

Replication kinetics of neurovirulent versus non-neurovirulent equine herpesvirus type 1 strains in equine nasal mucosal explants

Equine herpesvirus type 1 (EHV-1) is the causative agent of equine herpes myeloencephalopathy, of which outbreaks are reported with increasing frequency throughout North America and Europe. This has resulted in its classification as a potentially emerging disease by the US Department of Agriculture. Recently, it was found that a single nucleotide polymorphism (SNP) in the viral DNA polymerase gene (ORF30) at aa 752 (N -> D) is associated with the neurovirulent potential of EHV-1. In the present study, equine respiratory mucosal explants were inoculated with several Belgian isolates typed in their ORF30 as D-752 or N-752, to evaluate a possible difference in replication in the upper respiratory tract. In addition, to evaluate whether any observed differences could be attributed to the SNP associated with neurovirulence, the experiments were repeated with parental Ab4 (reference neurovirulent strain), parental NY03 (reference non-neurovirulent strain) and their N/D revertant recombinant viruses. The salient findings were that EHV-1 spreads plaquewise in the epithelium, but plaques never cross the basement membrane (BM). However, single EHV-1-infected cells could be observed below the BM at 36 h post-inoculation (p.i.) for all N-752 isolates and at 24 h p.i. for all D-752 isolates, and were identified as monocytic cells and T lymphocytes. Interestingly, the number of infected cells was two to five times higher for D-752 isolates compared with N-752 isolates at every time point analysed. Finally, this study showed that equine respiratory explants are a valuable and reproducible model to study EHV-1 neurovirulence in vitro, thereby reducing the need for horses as experimental animals

Role of symmetric dimethylarginine in vascular damage by increasing ROS via store-operated calcium influx in monocytes

BACKGROUND: The guanidines asymmetric dimethylarginine (ADMA), a marker of endothelial dysfunction, and its counterpart symmetric dimethylarginine (SDMA), considered inert, are accumulated in chronic kidney disease (CKD). The present study evaluates their effect on monocyte function, since previous data demonstrated leukocyte activation by other guanidino compounds. METHODS: The effect of ADMA and SDMA on reactive oxygen species (ROS) production in human whole blood at baseline and after N-formyl-methionine-leucine-phenylalanine (fMLP) stimulation was evaluated. By using the fluorescent probe Fluo3-AM, the role of changes in monocytic cytoplasmic calcium ([Ca(2+)](i)) was studied. Thapsigargin, and removal followed by addition of extracellular Ca(2+) (Ca(2+)(ex)), was used to investigate the contribution of store-operated Ca(2+)-channels (SOCs). SKF96365 was used as a selective inhibitor of the SOCs. A pharmacologic intervention with captopril, known to affect Ca(2+) influx, was tested. RESULTS: SDMA enhanced ROS production in fMLP-stimulated monocytes using heparinized blood, and this effect was abolished in EDTA-anticoagulated blood. In the presence of SDMA, an increased Ca(2+) entry from the extracellular milieu resulted in an elevated amplitude of the peak [Ca(2+)](i) change triggered by fMLP. None of these effects were seen with ADMA. Depletion of the intracellular stores with thapsigargin in the absence of Ca(2+)(ex), followed by re-addition of Ca(2+)(ex) triggered a significantly larger Ca(2+) entry after SDMA treatment versus saline. This effect was prevented with SKF96365, as was the SDMA-enhanced oxidative burst after fMLP. Pre-incubation with captopril also reduced the increased ROS production seen with SDMA. CONCLUSIONS: SDMA, a uraemic retention solute considered inert, stimulates ROS production of monocytes by acting on Ca(2+) entry via SOCs. This pro-inflammatory effect may trigger vascular pathology and may be involved in altering the prevalence of cardiovascular disease in CKD

Analysis of the accuracy of continuous thermodilution cardiac output measurement - Comparison with intermittent thermodilution and Fick cardiac output measurement

Objective: To evaluate the accuracy of cardiac output measurement obtained by a new continuous thermodilution cardiac output (CCO) pulmonary artery catheter compared to intermittent thermodilution (TCO) and the direct Fick method. Design: Prospective open trial. Setting: University hospital, intensive care unit. Patients: 23 patients (15 surgical, 8 non-surgical) were monitored with the Intellicath pulmonary catheter. Cardiac output was evaluated by the three methods every 4 to 6 h as long as the pulmonary artery catheter was necessary (8 - 96 h). Results: The correlation coefficient between CCO and TCO was 0.92, no systematic bias was observed, and the relative error increased from 13.9% for a cardiac output of 2 l/min to 23.7% for an output of 10 l/min. When comparing CCO and Fick, the correlation coefficient was 0.89, no bias was detected, and the relative error increased from 20.4% for outputs of 2 l/min to 27.2% for outputs of 10 l/min. Conclusions: CCO provides clinically acceptable measurements. At high cardiac outputs, the difference with other methods increases and the results must be cautiously interpreted

Particle Monte Carlo modeling of single-event transient current and charge collection in integrated circuits

25th European Symposium on the Reliability of Electron Devices, Failure Physics and Analysis (ESREF), Tech Univ Berlin, Berlin, GERMANY, SEP 29-OCT 02, 2014International audienceThis work describes a new computational approach for modeling the radiation-induced transient current and charge collection at circuit-level. Our methodology is based on a random-walk process that takes into account both diffusion and drift of radiation-induced minority carriers in a non-constant electric field both in space and time. The model has been successfully coupled either with an internal routine or with SPICE for circuit solving and feedback on the charge-collection process. It is illustrated here for a junction impacted by an ionizing particle and embedded in a CMOS inverter. (C) 2014 Elsevier Ltd. All rights reserved

Impact van geluid op welzijn, leefmilieu en volksgezondheid, in Vlaanderen

Met dit rapport wil het IST de algemene impact van omgevingsgeluid op de volksgezondheid, het welzijn en het leefmilieu van de mens in Vlaanderen laten onderzoeken. De aanleiding voor dit onderzoek vormden het maatschappelijk debat rond onder andere muziekgeluid en gehoorschade, slaapverstoring door landen en opstijgen rond luchthavens, geluidshinder door kinderopvang, maar ook recente beleidsinitiatieven zoals de Europese Richtlijn Omgevingsgeluid en de implementatie daarvan in Vlaanderen. Door deze verscheidenheid aan themas kan het breder kader en de onderliggende samenhang voor de leek vaag en onduidelijk worden. Het IST wil naast de impact van geluid ook het maatschappelijk debat rond geluidshinder en de gerelateerde maatschappelijke controversen in kaart laten. Dit rapport is opgebouwd rond een aantal onderzoeksvragen: 1. Hoe omschrijven internationaal erkende experten en expertenorganisaties de diversiteit aan effecten van geluid op de mens? Wat zijn bewezen en mogelijke effecten? Welke onderliggende mechanismen verklaren deze effecten en hoe relateren ze tot de fysische kenmerken van het geluid en de context en tijd waarin deze geluiden worden waargenomen? 2. Hoe vertaalt de problematiek rond geluidshinder en gezondheidsrisicos zich naar de Vlaamse context? En hoe reageert het beleid hierop? Wat is de resulterende wetgeving? Zijn er tekortkomingen, pijnpunten? Ook hier wil dit rapport eerder ingaan op de verbanden dan een expliciete opsomming te geven van de toestand van het milieuthema waarvoor verwezen wordt naar het geëigende beleidsdocument: MIRA. 3. Vermits geluid eenvoudig waarneembaar is – in tegenstelling tot andere leefmilieuthemas – is het maatschappelijk debat gefundeerd in accurate zij het subjectieve waarneming. Meer dan voor andere milieuthemas heeft het maatschappelijk debat dan ook een wetenschappelijke waarde. Wat kan er geleerd worden uit het maatschappelijk debat? Zijn er evoluties en trends in de manier waarop de burger omgaat met geluidshinder, slaapverstoring door geluid, enz.? Hoe worden controverses verklaard?status: publishe

Dossier 24: Impact van geluid op welzijn, leefmilieu en volksgezondheid, in Vlaanderen

Het maatschappelijke debat rond onder andere muziekgeluid en gehoorschade, slaapverstoring door landende en opstijgende vliegtuigen, geluidshinder bij kinderopvangplaatsen, maar ook recente beleidsinitiatieven zoals de Europese Richtlijn Omgevingsgeluid en de implementatie daarvan in Vlaanderen vormden de aanleiding voor dit onderzoek. Sinds enkele decennia beschouwen we omgevingslawaai niet enkel meer als louter vervelend. Wij zijn ons ook steeds meer bewust van de mogelijke gevolgen van lawaai voor de volksgezondheid en het algemeen welzijn en dat bewustzijn wordt ondersteund door een groeiende wetenschappelijke kennisbasis rond de effecten van geluid. Een verlaagde cognitieve performantie of een chronisch verhoogde bloeddruk zijn slechts enkele van de mogelijke negatieve effecten van een chronische, overmatige blootstelling aan geluid, die bovenop de reeds lang erkende slaapverstoring en geluidshinder komen. Het omgekeerde geldt ook. Een rustgevende omgeving met een aangenaam geluidsklimaat in de nabijheid van de woning kan een significant positief effect hebben op het algemeen stressniveau. Aandacht voor omgevingsgeluid is dan ook belangrijk voor wie een duurzame ontwikkeling van onze maatschappij nastreeft. Door de verscheidenheid aan thema’s kunnen het bredere kader en de onderliggende samenhang voor de leek vaag en onduidelijk worden. Redenen genoeg om een dossier over de problematiek op te stellen.status: publishe

Random-Walk Drift-Diffusion Charge-Collection Model For Reverse-Biased Junctions Embedded in Circuits

51st Annual IEEE International Nuclearand Space Radiation Effects Conference (NSREC), Paris, FRANCE, JUL 14-18, 2014International audienceA new computational model for charge transport based on parallelized random-walk drift-diffusion is proposed. This approach models the radiation-induced charge carriers as charge packets in a 3-D structure and the transport modeling are based on simple physical equations without any fitting parameter. This model has been dynamically coupled with a SPICE circuit simulator to take into account temporal variations of the electric fields in the charge collection process. Thus, the circuit electrical response modulates the charge collection efficiency. Three simulation cases have been explored and compared with TCAD simulations or radiation experiments in 65 nm technology to validate the accuracy of the proposed approach. These simulations demonstrate the capability of the proposed model to accurately estimate the soft error rate of complex structures, such as flip-flops over a large range of ionizing particle linear energy transfer. The proposed simulation methodology is also able to take into account charge-sharing phenomenon, and this point is highlighted by a specific investigation on the considered flip-flop