Mapping wildland-urban interfaces at large scales integrating housing density and vegetation aggregation for fire prevention in the South of France

Every year, more than 50,000 wildland fires affect about 500,000 ha of vegetation in southern European countries, particularly in wildland-urban interfaces (WUI). This paper presents a method to characterize and map WUIs at large scales and over large areas for wildland fire prevention in the South of France. Based on the combination of four types of building configuration and three classes of vegetation structure, 12 interface types were classified. Through spatial analysis, fire ignition density and burned area ratio were linked with the different types of WUI. Among WUI types, isolated WUIs with the lowest housing density represent the highest level of fire risk

Land cover analysis in wildland-urban interfaces according to wildfire risk: a case study in the South of France

Each year, forest fires destroy about 500,000 ha of vegetation in Europe, predominantly in the Mediterranean region. Many large fires are linked to the land transformations that have taken place in the Mediterranean region in recent decades that have increased the risk of forest fires. On the one hand, agricultural fallows and orchards are slowly being colonized by vegetation, and on the other hand, the forest is not sufficiently used, both of which result in increased accumulation of fuel. In addition, urbanization combined with forest extension results in new spatial configurations called wildland-urban interfaces (WUI). WUI are commonly defined as areas where urban areas meet and interact with rural lands, wildland vegetation and forests. Spatial analyses were performed using a WUI typology based on two intertwined elements, the spatial organization of homes and the structure of fuel vegetation. The organisation of the land cover in terms of representativeness, complexity or road density was evaluated for each type of WUI. Results showed that there were significant differences between the types of WUI in the study area. Three indicators (i) fire ignition density, derived from the distribution of fire ignition points, (ii) wildfire density, derived from the distribution of wildfire area and (iii) burned area ratio, derived from the proportion of the burned area to the total study area were then compared with each type of WUI. Assuming that the three indicators correspond to important aspects of fire risk, we showed that, at least in the south of France, WUI are at high risk of wildfire, and that of the different types of wildland-urban interfaces, isolated and scattered WUI were the most at risk. Their main land cover characteristics, i.e. low housing and road densities but a high density of country roads, and the availability of burnable vegetation such as forested stands and shrubland (garrigue) explain the high fire risk. Improving our knowledge of relationships between WUI environments and fire risk should increase the efficiency of wildfire prevention: to this end, suitable prevention actions and communication campaigns targeting the types of WUI at the highest risk are recommended

Mise au point d'une typologie de combustibles pour la Basse Provence calcaire

La typologie du combustible est un outil utilisé par les gestionnaires des milieux naturels soumis aux incendies dans de nombreux pays et massifs subissant ce risque. Cet outil permet d'intégrer le comportement du feu dans la gestion des milieux et dans la planification, à l'échelle d'un massif forestier. Ces typologies caractérisent la répartition verticale et horizontale de la végétation, ainsi que sa biomasse, éléments déterminants du comportement du feu, en milieu naturel. Le Cemagref d'Aix-en Provence, sur la base de près de 150 descriptions de végétation situées en Basse Provence calcaire, a bâti une typologie des structures de végétation et a pu caractériser le comportement du feu, dans chacun des onze types de combustibles construits

Observation of self-mode-locked pulses in terahertz quantum cascade lasers with real-time intracavity self-detection

Mode-locking operation and multimode instabilities in Terahertz (THz) quantum cascade lasers (QCLs) have been intensively investigated during the last decade. These studies have unveiled a rich phenomenology, owing to the unique properties of these lasers, in particular their ultrafast gain medium. Thanks to this, in QCLs a modulation of the intracavity field intensity gives rise to a strong modulation of the population inversion, directly affecting the laser current. In this work we show that this property can be used to monitor in real-time the temporal dynamics of multimode THz QCLs, using a self-detection technique combined with a broadband real-time oscilloscope. We study a 4.2THz QCL operating in free-running, and observe the formation of current pulses associated with trains of self-mode-locked optical pulses. Depending on the current pumping we find alternating regimes of unstable and stable pulse trains, respectively at the fundamental cavity repetition rate and its second harmonic. We interpret these measurements using a set of effective semiconductor Maxwell-Bloch equations that qualitatively reproduce the fundamental features of the laser dynamics, and also provide evidence in support of the solitonic nature of the observed pulses

Amélioration de la connaissance des causes d'incendie de forêt et mise en place d'une base de données géoréférencées

Dans le cadre du programme Forest Focus, le Cemagref d'Aix-en-Provence a réalisé un guide technique intitulé « Amélioration de la connaissance des causes de départ de feu de forêt » et l'agence MTDA a développé le prototype d'un module de saisie et de cartographie interactive des incendies de forêt. Cet article présente la méthode d'investigation de recherche des causes de départ de feu adaptée au contexte méditerranéen français ; un encadré concerne spécifiquement le module de saisie et de cartographie interactive permettant d'alimenter une base de données géoréférencées

Living on a flammable planet: interdisciplinary, cross-scalar and varied cultural lessons, prospects and challenges: Table 1.

Living with fire is a challenge for human communities because they are influenced by socio-economic, political, ecological and climatic processes at various spatial and temporal scales. Over the course of 2 days, the authors discussed how communities could live with fire challenges at local, national and transnational scales. Exploiting our diverse, international and interdisciplinary expertise, we outline generalizable properties of fire-adaptive communities in varied settings where cultural knowledge of fire is rich and diverse. At the national scale, we discussed policy and management challenges for countries that have diminishing fire knowledge, but for whom global climate change will bring new fire problems. Finally, we assessed major fire challenges that transcend national political boundaries, including the health burden of smoke plumes and the climate consequences of wildfires. It is clear that to best address the broad range of fire problems, a holistic wildfire scholarship must develop common agreement in working terms and build across disciplines. We must also communicate our understanding of fire and its importance to the media, politicians and the general public. This article is part of the themed issue ‘The interaction of fire and mankind’

Housing Arrangement and Location Determine the Likelihood of Housing Loss Due to Wildfire

Surging wildfires across the globe are contributing to escalating residential losses and have major social, economic, and ecological consequences. The highest losses in the U.S. occur in southern California, where nearly 1000 homes per year have been destroyed by wildfires since 2000. Wildfire risk reduction efforts focus primarily on fuel reduction and, to a lesser degree, on house characteristics and homeowner responsibility. However, the extent to which land use planning could alleviate wildfire risk has been largely missing from the debate despite large numbers of homes being placed in the most hazardous parts of the landscape. Our goal was to examine how housing location and arrangement affects the likelihood that a home will be lost when a wildfire occurs. We developed an extensive geographic dataset of structure locations, including more than 5500 structures that were destroyed or damaged by wildfire since 2001, and identified the main contributors to property loss in two extensive, fire-prone regions in southern California. The arrangement and location of structures strongly affected their susceptibility to wildfire, with property loss most likely at low to intermediate structure densities and in areas with a history of frequent fire. Rates of structure loss were higher when structures were surrounded by wildland vegetation, but were generally higher in herbaceous fuel types than in higher fuel-volume woody types. Empirically based maps developed using housing pattern and location performed better in distinguishing hazardous from non-hazardous areas than maps based on fuel distribution. The strong importance of housing arrangement and location indicate that land use planning may be a critical tool for reducing fire risk, but it will require reliable delineations of the most hazardous locations

Surface functionalisation of nanodiamonds for human neural stem cell adhesion and proliferation.

Biological systems interact with nanostructured materials on a sub-cellular level. These interactions may govern cell behaviour and the precise control of a nanomaterial's structure and surface chemistry allow for a high degree of tunability to be achieved. Cells are surrounded by an extra-cellular matrix with nano-topographical properties. Diamond based materials, and specifically nanostructured diamond has attracted much attention due to its extreme electrical and mechanical properties, chemical inertness and biocompatibility. Here the interaction of nanodiamond monolayers with human Neural Stem Cells (hNSCs) has been investigated. The effect of altering surface functionalisation of nanodiamonds on hNSC adhesion and proliferation has shown that confluent cellular attachment occurs on oxygen terminated nanodiamonds (O-NDs), but not on hydrogen terminated nanodiamonds (H-NDs). Analysis of H and O-NDs by Atomic Force Microscopy, contact angle measurements and protein adsorption suggests that differences in topography, wettability, surface charge and protein adsorption of these surfaces may underlie the difference in cellular adhesion of hNSCs reported here

Preparação e caracterização de um biocompósito obtido pela mistura de hidreto de titânio com nitrato de cálcio para implantes dentários

RESUMO Neste trabalho foram realizados estudos sobre a fabricação de um biocompósito à base de titânio para implantes dentários a partir da mistura de pó de hidreto de titânio (92%) com nitrato de cálcio (8% em volume). O pó de hidreto de titânio foi adicionado na solução aquosa de nitrato de cálcio, dissolvido por agitação mecânica, e em seguida os precursores foram misturados e dispersados/homogeneizados por ultrassom. Posteriormente, a mistura foi secada em evaporador rotativo, compactada com 600 MPa à temperatura ambiente, desmoldada e sinterizada em alto vácuo a 1200 oC durante 2 horas. Foi analisada a microestrutrura e fases formadas, as propriedades mecânicas, a rugosidade da superfície, a porosidade aberta, a molhabilidade da superfície e a citotoxicidade do biocompósito. As fases identificadas após a sinterização foram α-Ti e CaTiO3. O limite de resistência em compressão, o módulo de Young (E) e o ângulo de contato do biocompósito diminuíram significativamente com relação ao hidreto de titânio puro sinterizado nas mesmas condições. O limite médio de resistência em compressão do hidreto de titânio foi de 1794,67 MPa e do biocompósito foi de 481,36 MPa. O módulo de Young e o ângulo de contato do hidreto de titânio e do biocompósito foram de aproximadamente 112 GPa e 94 graus, e de 75 GPa e 83 graus, respectivamente. A rugosidade de superfície foi da mesma ordem de grandeza entre os materiais e ficou aproximadamente entre 1,4 e 1,5 µm (Ra) e 1,4 e 1,9 µm (Ra e Sa), medidas com rugosímetro de contato e com microscópio confocal a laser, respectivamente. A porosidade aberta do biocompósito sinterizado foi de aproximadamente três vezes maior do que aquela do hidreto de titânio sinterizado. Nos ensaios de citotoxicidade a porcentagem de células viáveis do biocompósito foi superior àquela do controle negativo e àquela do hidreto de titânio sinterizado