Discrete event front tracking simulator of a physical fire spread model

International audienceSimulation of moving interfaces, like a fire front usually requires the resolution of a large scale and detailed domain. Such computing involves the use of supercomputers to process the large amount of data and calculations. This limitation is mainly due to the fact that large scale of space and time is usually split into nodes, cells or matrices, and the solving methods often require small time steps. This paper presents a novel method that enables the simulation of large scale/high resolution systems by focusing on the interface. Unlike the conventional explicit and implicit integration schemes, it is based on the discrete-event approach, which describes time advance in terms of increments of physical quantities rather than discrete time stepping. Space as well is not split into discrete nodes or cells, but we use polygons with real coordinates. The system is described by the behaviour of its interface, and evolves by computing collision events of this interface in the simulation. As this simulation technique is suited for a class of models that can explicitly provide rate of spread for a given configuration, we developed a specific radiation based propagation model of physical wildland fire. Simulations of a real large scale fire performed with an implementation of our method provide very interesting results in less than 30 seconds with a 3 metres resolution with current personal computers

Anti-oxidant potential and gap junction-mediated intercellular communication as early biological markers of mercuric chloride toxicity in MDCK cell line.

In this study, the early nephrotoxic potential of mercuric chloride (HgCl(2)) has been evaluated in vitro, by exposing a renal-derived cell system, the tubular epithelial Madin-Darby canine kidney (MDCK) cell line, to the presence of increasing HgCl(2) concentrations (0.1-100 microM) for different periods of time (from 4 to 72 h). As possible biological markers of the tubular-specific toxicity of HgCl(2) in exposed-MDCK cultures we analysed: (i) critical biochemical parameters related to oxidative stress conditions and (ii) gap-junctional function (GJIC). HgCl(2) cytotoxicity was evaluated by cell-density assay. The biochemical analysis of the pro-oxidant properties of the mercuric ion (Hg(2+)) was performed by evaluating the effect of the metal salt on the antioxidant status of the MDCK cells. The cell glutathione (GSH) content and the activity of glutathione peroxidase (Gpx) and catalase (Cat), two enzymes engaged in the H(2)O(2) degradation, were quantified. HgCl(2) influence on MDCK GJIC was analysed by the microinjection/dye-transfer assay. HgCl(2)-induced morphological changes in MDCK cells were also taken into account. Our results, proving that subcytotoxic (0.1-10 microM) HgCl(2) concentrations affect either the antioxidant defences of MDCK cells or their GJIC, indicate these critical functions as suitable biological targets of early mercury-induced tubular cell injury

First Record Along The Uruguayan Coast Of The Largest Sea Nettle Jellyfish, Chrysaora Plocamia (lesson, 1830) (cnidaria: Scyphozoa)

Chrysaora plocamia is one of the 15 species of the jellyfish genus Chrysaora. This species has an unusualdistribution pattern, occurring on both Atlantic and Pacific coasts of South America. It is distributed along the southeastern Pacific Ocean, encompassing coastal areas of Peru and Chile, and reaching the Patagonian coast of Argentina in the southwestern Atlantic. During two separate events, two large specimens of Chrysaora were collected on the east coast of Uruguay at La Paloma. Based on morphology and molecular data, these specimens were identified as Chrysaora plocamia. These records are described along with oceanographic features observed at that time. Unusual oceanographic and atmospheric conditions may explain the presence of these specimens 1,100 km north of the current northernmost known distribution. © 2016 Check List and Authors.12

A model for the spread of fire across a fuel bed incorporating the effects of wind and slope

International audienc

New experimental diagnostics in combustion of forest fuels: microscale appreciation for a macroscale approach

In modelling the wildfire behaviour, good knowledge of the mechanisms and the kinetic parameters controlling the thermal decomposition of forest fuel is of great importance. The kinetic modelling is based on the mass-loss rate, which defines the mass-source term of combustible gases that supply the flames and influences the propagation of wildland fires. In this work, we investigated the thermal degradation of three different fuels using a multi-scale approach.Lab-scale experimental diagnostics such as thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), use of the cone calorimeter (CC) or Fire Propagation Apparatus (FPA) led to valuable results for modelling the thermal degradation of vegetal fuels and allowed several upgrades of pyrolysis models.However, this work remains beyond large-scale conditions of a wildland or forest fire. In an effort to elaborate on the kinetic models under realistic natural fire conditions, a mass-loss device specifically designed for the field scale has been developed. The paper presents primary results gained using this new device, during large-scale experiments of controlled fires. The mass-loss records obtained on a field scale highlight the influence of the chemical composition and the structure of plants. Indeed, two species with similar chemical and morphological characteristics exhibit similar mass-loss rates, whereas the third presents different thermal behaviour.The experimental data collected at a field scale led to a new insight about thermal degradation processes of natural fuel when compared to the kinetic laws established in TGA. These new results provide a global description of the kinetics of degradation of Mediterranean forest fuels. The results led to a proposed thermal degradation mechanism that has also been validated on a larger scale.</p

Lupus anticoagulant in patients without thrombotic or obstetric complications

El inhibidor lúpico (IL) es un criterio de laboratorio para síndrome antifosfolipídico (SAF); sin embargo, puede detectarse en individuos asintomáticos o estar asociado a otras situaciones clínicas. Presentamos un análisis retrospectivo de 2000 exámenes consecutivos para IL (TTPA, DRVVT), de los cuales 499 casos no presentaban criterios clínicos de SAF (trombosis o complicaciones obstétricas). Aplicando los criterios SSC-ISTH, hallamos IL+ en 27,3% (410/1501) y 43,3% (216/499) de los casos con y sin clínica de SAF respectivamente, analizándose en los casos no-SAF las características clínicas y de laboratorio. Contexto clínico de casos IL+ no-SAF: 18,0% asintomáticos, 34,3% sangrado (epistaxis, gingivorragia, equimosis, hematomas espontáneos) y 47,7% otras manifestaciones (infertilidad, insuficiencia renal crónica, desórdenes autoinmunes, cardiopatía isquémica, trombocitopenia inmune, entre otras). Otras alteraciones de laboratorio en casos IL+ no- SAF, con síntomas de sangrado: alteraciones plaquetarias, descenso de VWF:RCo y/o VWF:Ag, disthrombocytopeminución de FVIII, FII, FV, FVII, FXI o fibrinógeno (sólo o sumado a disminución de plaquetas o FX), inhibidor a-FV o hiperfibrinolisis fueron detectadas en el 55,4% de los casos. El análisis mostró IL+ en un número importante de estudios (216/2000) sin criterios de SAF (1,95% en individuos asintomáticos, 3,70% en pacientes con síntomas de sangrado y 5,15% en casos con otro contexto clínico). Los casos con IL+ y sangrado representan un desafío particular, al requerir evaluar otros posibles defectos subyacentes, que pudiesen justificar el comportamiento clínico. La detección e identificación de defectos combinados requiere de un análisis minucioso, a fin de alcanzar un diagnóstico correcto, esencial para tomar decisiones terapéuticas adecuadas.Despite lupus anticoagulant (LA) is a laboratory criterion for antiphospholipid syndrome (APS), it can be present in asymptomatic subjects or it can be associated with other clinical settings. We present a retrospective analysis of 2000 consecutive LA assays (APTT, DRVVT), 499 of them were performed in patients without APS clinical criteria (thrombosis or obstetric complications). According to SSC-ISTH criteria, LA+ was found in 27.3% (410/1501) and 43.3% (216/499) of cases with or without APS criteria respectively; in no-APS group, the analysis of clinical background and laboratory features was done. Clinical background of LA+ cases no-APS: 18.0% asymptomatic, 34.3% bleeding symptoms (epistaxis, gingivorrhagia, bruising, spontaneous hematomas) and 47.7% other clinical settings (infertility, chronic kidney disease, autoimmune disorders, ischemic heart disease, idiopathic thrombocytopenic purpura, among others). Other abnormal laboratory tests in LA+ cases no- APS with bleeding symptoms: platelet dysfunction; low VWF:RCo and/or VWF:Ag; decrease of FVIII, FII, FV, FVII, FXI or fibrinogen (alone or with low platelet count or low FX), a-FV inhibitor and hyperfibrinolysis were found in the 55.4% of the cases. The analysis showed LA+ in an important number of cases (216/2000) without APS criteria (1.95% in asymptomatic cases, 3.70% in patients with bleeding symptoms and 5.15% in cases with other clinical settings). Those LA+ cases with bleeding symptoms represent a particular challenge because other possible underlying defects have to be analysed in order to explain the clinical behaviour. The detection and identifications of combined defects required a careful analysis in order to achieve an accurate diagnosis, essential for therapeutic decisions.Fil: Remotti, L.. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; ArgentinaFil: Grosso, S. H.. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; ArgentinaFil: Ingratti, M. F.. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; ArgentinaFil: Vera Morandini, Maria Paula. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; ArgentinaFil: Woods, Adriana Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Bermejo, E. I.. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; ArgentinaFil: Sánchez Luceros, Analía Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; Argentina. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; ArgentinaFil: Meschengieser, S. S.. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; ArgentinaFil: Lazzari, María Ángela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Blanco, A. N.. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; Argentin

Archaeology and Archaeometry of a local production of Black Glazed Ware at Pompeii

International audienceThe paper focuses on a local production of Black Glazed ware attested in Pompeii between the mid-fourth and the early-third century B.C. The ceramics thereafter presented were found in a specific archaeological deposit termed as X B11, brought to light in stratigraphic excavations undertaken in the forum area in 1980/81 by P. Arthur on behalf of the local Superintendence

Instrumentation of wildland fire: Characterisation of a fire spreading through a Mediterranean shrub

International audienc

Fire spread experiment across Mediterranean shrub: Influence of wind on flame front properties

International audienceA previous termfirenext term spread experiment was conducted in the field under wind-blown conditions. The fuel consists of tall and dense Mediterranean shrub vegetation. The plot area was about 30 m wide and 80 m long. This experiment was conducted not only in order to increase the knowledge and understanding of the previous termfirenext term behaviour in the field but to provide data for the validation of physics based models of previous termfirenext term spread. In particular, the effects of wind on the geometric and thermal properties of the flame front in the field were investigated. The flame temperature along the vertical direction and the radiation emitted ahead of the flame front, were measured. The methodology employed in this experiment and some quantitative measurements of wind velocity and direction, flame geometric properties, are also presented and discussed. The measurements and observations exhibit that the behaviour of the previous termfirenext term and the flame structure character are very different from the one encountered at laboratory scale. These preliminary results show that large scale turbulence influence previous termfirenext term spread and affects the flame shape, temperature and radiation emission

TNF-α increases human melanoma cell invasion and migration in vitro: the role of proteolytic enzymes

Inflammatory mediators have been reported to promote malignant cell growth, invasion and metastatic potential. More specifically, we have recently reported that tumour necrosis factor alpha (TNF-a) increases melanoma cell attachment to extracellular matrix (ECM) substrates and invasion through fibronectin. In this study, we extend these investigations asking specifically whether the TNF-a effect on cell invasion and migration involves activation of proteolytic enzymes. We examined the effect of TNF-a on melanoma expression/activation of type IV gelatinases matrix metalloproteinases 2 and 9 (MMPs -2 and -9) and general proteolytic enzymes. Stimulation with TNF-a significantly increased both melanoma cell migration at 24 h ( þ 21%) and invasion through fibronectin ( þ 35%) but did not upregulate/activate the expression of latent MMP-2 constitutively produced by these cells and did not upregulate their general protease activity. However, the increased cell migration and invasion through fibronectin observed following stimulation with TNF-a were inhibited by the general protease inhibitor a2 macroglobulin. These findings suggest that the promigratory and proinvasive effect of TNF-a on this melanoma cell line may be mediated to some extent by induction of localised cell membrane-bound degradative enzyme activity, which is not readily detected in biochemical assays