20 research outputs found
A two step synthesis of a key unit B precursor of cryptophycins by asymmetric hydrogenation
No full textSammet B, Brax M, Sewald N. A two step synthesis of a key unit B precursor of cryptophycins by asymmetric hydrogenation. Beilstein Journal of Organic Chemistry. 2011;7:243-245.A novel highly enantioselective two step access to a unit B precursor of cryptophycins in good yields from commercially available starting materials has been developed. The key step is an asymmetric hydrogenation using the commercially available [(COD)Rh-(R,R)-Et-DuPhos]BF4 catalyst. The synthetic route provides the advantage of less synthetic steps, proceeds with high yields and enantioselectivity, and avoids hazardous reaction conditions
Gel effect induced by mucilage in the pore space and consequences on soil physical properties
No full textWater uptake, respiration and exudation are some of the biological functions fulfilled by plant roots. They drive plant growth and alter the biogeochemical parameters of soil in the vicinity of roots, the rhizosphere. As a result, soil processes such as water fluxes, carbon and nitrogen exchanges or microbial activity are enhanced in the rhizosphere in comparison to the bulk soil. In particularly, the exudation of mucilage as a gel-like substance by plant roots seems to be a strategy for plants to overcome drought stress by increasing soil water content and soil unsaturated hydraulic conductivity at negative water potentials. Although the variations of soil properties due to mucilage are increasingly understood, a comprehensive understanding of the mechanisms in the pore space leading to such variations is lacking.
The aim of this work was to elucidate the gel properties of mucilage in the pore space, i.e. interparticulate mucilage, in order to link changes of the physico-chemical properties in the rhizosphere to mucilage. The fulfilment of this goal was confronted to the three following challenges: The lack of methods for in situ detection of mucilage in soil; The lack of knowledge concerning the properties of interparticulate mucilage; The unknown relationship between the composition and the properties of model substances and root mucilage produced by various species. These challenges are addressed in several chapters.
In a first instance, a literature review picked information from various scientific fields about methods enabling the characterization of gels and gel phases in soil. The variation of soil properties resulting from biohydrogel swelling in soil was named the gel effect. The combined study of water entrapment of gels and gel phases in soil and soil structural properties in terms of mechanical stability or visual structures proved promising to disentangle the gel effect in soil.
The acquired methodical knowledge was used in the next experiments to detect and characterize the properties of interparticulate gel. 1H NMR relaxometry allows the non-invasive measure of water mobility in porous media. A conceptual model based on the equations describing the relaxation of water protons in porous media was developed to integrate the several gel effects into the NMR parameters and quantify the influence of mucilage on proton relaxation. Rheometry was additionally used to assess mucilage viscosity and soil microstructural stability and ESEM images to visualize the network of interparticulate gel. Combination of the results enabled to identify three main interparticulate gel properties: The spider-web effect restricts the elongation of the polymer chains due to the grip of the polymer network to the surface of soil particles. The polymer network effect illustrates the organization of the polymer network in the pore space according to the environment. The microviscosity effect describes the increased viscosity of interparticulate gel in contrast to free gel. The impact of these properties on soil water mobility and microstructural stability were investigated. Consequences on soil hydraulic and soil mechanical properties found in the literature are further discussed.
The influence of the chemical properties of polymers on gel formation mechanism and gel properties was also investigated. For this, model substances with various uronic acid content, degree of esterification and amount of calcium were tested and their amount of high molecular weight substances was measured. The substances investigated included pectic polysaccharides and chia seed mucilage as model polymers and wheat and maize root mucilage. Polygalacturonic acid and low-methoxy pectin proved as non-suitable model polymers for seed and root mucilage as ionic interactions with calcium control their properties. Mucilage properties rather seem to be governed by weak electrostatic interactions between the entangled polymer chains. The amount of high molecular weight material varies considerably depending on mucilage´s origin and seems to be a straight factor for mucilage’s gel effect in soil. Additionally to the chemical characterization of the high molecular weight compounds, determination of their molecular weight and of their conformation in several mucilages types is needed to draw composition-property profiles. The variations measured between the various mucilages also highlight the necessity to study how the specific properties of the various mucilages fulfill the needs of the plant from which they are exuded.
Finally, the integration of molecular interactions in gel and interparticulate gel properties to explain the physical properties of the rhizosphere was discussed. This approach offers numerous perspectives to clarify for example how water content or hydraulic conductivity in the rhizosphere vary according to the properties of the exuded mucilage. The hypothesis that the gel effect is general for all soil-born exudates showing gel properties was considered. As a result, a classification of soil-born gel phases including roots, seeds, bacteria, hyphae and earthworm’s exuded gel-like material according to their common gel physico-chemical properties is recommended for future research. An outcome could be that the physico-chemical properties of such gels are linked with the extent of the gel effect, with their impact on soil properties and with the functions of the gels in soil.Wasseraufnahme, Atmung und Exsudation sind biologische Schlüsselfunktionen der Wurzeln höherer Pflanzen. Sie steuern das Pflanzenwachstum, indem sie die biogeochemischen Parameter des Bodens in unmittelbarer Nähe der Wurzeln, der Rhizosphäre, verändern. Folglich sind Bodenprozesse wie beispielsweise Wasserflüsse, Kohlen- und Stickstoffaustausch oder mikrobielle Aktivitäten in der Rhizosphäre im Vergleich zu freiem Boden begünstigt. Insbesondere die Exsudation von Mucilage durch die Pflanzenwurzeln scheint ein wichtiger Mechanismus zu sein, um Trockenstress vorzubeugen. Durch diese gelartige Substanz wird bei negativen Wasserpotentialen sowohl der Bodenwassergehalt als auch die ungesättigte hydraulische Leitfähigkeit erhöht. Die Veränderung der Bodeneigenschaften durch Mucilage ist Gegenstand aktueller Forschung. Ein umfassendes Verständnis der Mechanismen im Porenraum der Rhizosphäre ist bisher allerdings noch unzureichend.
Ziel dieser Arbeit war die Aufklärung der Gel-Eigenschaften von Mucilage im Porenraum der Rhizosphäre, um Veränderungen der physiko-chemischen Eigenschaften der Rhizosphäre auf dieses interpartikuläre Mucilage zurückzuführen. Dabei stellten sich drei Herausforderungen: Zunächst einmal mangelte es an Methoden zur in situ Detektion von Mucilage im Boden. Außerdem fehlten detaillierte Kenntnisse bezüglich der Eigenschaften von interpartikulärem Mucilage. Desweiteren war die Beziehung zwischen der Zusammensetzung und den Eigenschaften von Modelsubstanzen und wurzelstämmigem Mucilage verschiedener Spezies unbekannt. Diese Fragen werden in den verschiedenen Kapiteln der Arbeit thematisiert.
Zunächst erfolgte eine Literaturrecherche, um Informationen aus verschiedenen Wissenschaftsbereichen über Methoden zur Charakterisierung von Gelen und Gel-Phasen im Boden zusammenzustellen. Die Änderung von Bodeneigenschaften aufgrund vorhandener Biohydrogelphasen im Boden kann als „Gel-Effekt“ bezeichnet werden. Die kombinierte Studie von Wassereinschlüssen in Gelen und Boden-Gel-Phasen mit der Untersuchung struktureller Eigenschaften von Boden hinsichtlich der mechanischen Stabilität und visueller Strukturen, zeigte sich als vielversprechend, um den Gel-Effekt im Boden zu charakterisieren.
Das erworbene methodische Wissen wurde in den nächsten Untersuchungen angewendet, um die Eigenschaften von interpartikulären Gelen zu detektieren und zu charakterisieren. 1H NMR Relaxometrie erlaubt die nicht-invasive Bestimmung der Wassermobilität in porösen Medien. Ein konzeptuelles Modell wurde aus Gleichungen entwickelt, welche die Proton-Relaxation in gelhaltigen porösen Medien beschreiben. Dieses Modell berücksichtigt den beschriebenen Gel-Effekt bei der Wahl der NMR Parameter und quantifiziert den Einfluss von Mucilage auf die Proton-Relaxation. Darüber hinaus wurde mithilfe von Rheometrie die Viskosität von Mucilage sowie die mikrostrukturelle Bodenstabilität bestimmt. Mittels Rasterelektronenmikroskopie wurde die Netzwerkstruktur von interpartikulärem Gel visualisiert. Die kombinierte Auswertung dieser Ergebnisse identifizierte drei wichtige Eigenschaften von interpartikulärem Gel: Der „Spinnennetz-Effekt“ schränkt die Dehnung der Polymerketten aufgrund der Verbindung zwischen dem Polymer Netzwerk und der Oberfläche von Bodenpartikeln ein. Der „Polymer-Netzwerk-Effekt“ veranschaulicht die Anordnung des Polymernetzwerks im Porenraum gemäß der räumliche Umgebung. Der „Mikroviskositäts-Effekt“ beschreibt die erhöhte Viskosität von interpartikulärem Gel im Vergleich zu freiem Gel. Die Auswirkungen dieser Eigenschaften auf die Wassermobilität und auf die mikrostrukturelle Stabilität des Bodens wurden untersucht und daraus resultierende Konsequenzen für hydraulische und mechanische Eigenschaften des Bodens diskutiert.
Der Einfluss von den chemischen Eigenschaften von Polymeren auf Gel-Bildungsmechanismen und Gel-Eigenschaften wurde untersucht. Dafür wurden Modelsubstanzen mit verschiedenen Uronsäure-Gehalt, Veresterungsgrade und Calcium-Gehalt getestet und die Menge an Materialanteil mit hohem Molekulargewicht quantifiziert. Die untersuchten Modelsubstanzen waren verschiedenen Pektin Polymeren und Chia Samen Mucilage. Darüber hinaus wurde Mucilage aus Winterweizen und Mais Wurzeln isoliert und untersucht. Polygalakturonsäure und Niedermethyliertes Pektin erwiesen sich als nicht geeignete Modelpolymere für Samen und Wurzelmucilage, da ionische Wechselwirkungen mit Calcium ihre Eigenschaften dominieren. Die dem Mucilage zuzurechnenden Eigenschaften scheinen eher durch schwache elektrostatische Wechselwirkungen zwischen verstrickten Polymerketten beherrscht zu sein. Die Menge an Material mit hohem Molekulargewicht variiert deutlich, abhängig von dem Ursprung des Mucilages. Dies scheint ein bedeutender Faktor für den Gel-Effekt von Mucilage im Boden zu sein. Zusätzlich zu der chemischen Charakterisierung der hochmolekulargewichtigen Polymere ist die exakte Bestimmung der Molekularmassen und der Konformation in verschiedenen Mucilagesorten notwendig, um Zusammensetzungs-Eigenschafts-Profile aufzeichnen zu können. Die Abweichungen zwischen den verschiedenen Mucilagestypen, welche sich durch die Messungen ergeben, haben die Notwendigkeit weiterer Untersuchungen unterstrichen. Nur so lässt sich die Frage klären, wie die spezifischen Eigenschaften von verschiedenen Mucilagestypen auf die Bedürfnisse der Pflanze abgestimmt sind, der sie entstammen.
Schließlich wurde diskutiert, wie die Betrachtung von molekularen Wechselwirkungen im Gel und interpartikulären Gel-Eigenschaften das Verständnis über die physikalischen Eigenschaften der Rhizosphäre erweitert. Dieser Ansatz ist vielversprechend, um zum Beispiel der Wassergehalt oder die hydraulische Leitfähigkeit entsprechend die Eigenschaften vom exudierten Mucilage zu klären. Darüber hinaus liegt die Vermutung nahe, dass der Gel-Effekt allgemein für alle Bodenexsudate mit Gel-Charakter Gültigkeit besitzt. Eine Klassifizierung natürlicher Boden-Gel-Phasen einschließlich der von Wurzeln, Samen, Bakterien, Hyphen oder Regenwürmern exsudierten, gelartigen Materialien nach ihren gemeinsamen physiko-chemischen Gel-Eigenschaften wird für die zukünftige Forschung empfohlen. Als Ergebnis könnten die physiko-chemische Eigenschaften von solchen Gelen zum Gel-Effekt den Auswirkungen auf die Bodeneigenschaften und den Funktionen von den Gelen im Boden zugeschrieben worden
Microhydrological Niches in Soils : How Mucilage and EPS Alter the Biophysical Properties of the Rhizosphere and Other Biological Hotspots
No full textISSN:1539-166
Effect of mucilage on water properties in the rhizosphere monitored by 1 H-NMR relaxometry
No full textKonstruktiivinen mytopoetiikka J. R. R. Tolkienin legendaariossa
No full textAbstractThis doctoral dissertation discusses constructive mythopoetics in J. R. R. Tolkien’s legendarium, the mythopoetic logics and elements on which Tolkien’s texts and his fantasy world are constructed.My aim in this research is to create a reading of Tolkien’s fiction that shows that it is possible to discern a mythopoetic code in Tolkien’s legendarium. My hypothesis is that Tolkien’s mythopoetic fiction aims to be coherent on the levels of languages, myths, and inter- and intratextual background. This coherence can be found throughout the various texts and fragments of Tolkien’s fiction. From the cosmogonical creation myth of The Silmarillion, to the fairy-story lightness of The Hobbit and the quest fantasy of The Lord of the Rings, Tolkien’s fiction has its roots in the mythopoetic logics of his theory of creative writing (or myth-making). Tolkien is the sub-creator; he is creating myths and building his own world. For Tolkien, God is the primary creator, but the author is the (sub-)creator of his own creation. This is consistent throughout Tolkien’s legendarium, despite the fact that whilst creating his fiction, Tolkien is “pretending” to be a translator of mythical pseudo-historical documents.In the main chapters, my research logics trace the inner timeline of Tolkien’s legendarium. Starting from the creation of the world, I move onto the long fall and struggle and to the end of the world. When discussing the theme of creation, I focus on the concept of creation on the intratextual level of Tolkien’s legendarium as well as on Tolkien’s aesthetics of creative work. In the end of the dissertation, I turn my attention also to the creative work of the reader.My theoretical approach is influenced by both Northrop Frye’s constructive theory of literature and Benjamin Harshav’s theory of constructive poetics. I discuss the creative methods of speculative historical epic and the dichotomies of beginning and end, good and evil, mortality and immortality, spiritual and physical, and visibility and invisibility, as well as how these elements are manifested in Tolkien’s mythopoetic vision. The structure of Tolkien’s constructive mythopoetics is illuminated through the grand concepts of the Creation, the Existence, the Fall and the Struggle.TiivistelmäVäitöskirjani käsittelee konstruktiivista mytopoetiikkaa J. R. R. Tolkienin legendaariossa. Työ keskittyy ennen kaikkea mytopoeettiseen logiikkaan ja elementteihin, joiden kautta Tolkienin tekstit ja hänen luomansa fantasiamaailma rakentuvat.Tutkimukseni muodostaa Tolkienin fiktion luennan, joka osoittaa, että Tolkienin legendaariolle voidaan löytää mytopoeettinen koodi. Tämä koodi havainnollistaa, että Tolkienin mytopoeettinen fiktio luo koherentin ja uskottavan kokonaisuuden kielen, myyttien sekä inter- ja intratekstuaalisten vaikutussuhteiden kautta. Tämä yhteenkuuluvuus ja koodi on nähtävissä, vaikka Tolkienin legendaarion osat ovat keskenään perin erilaisia, eri kirjallisuuslajeihin kuuluvia ja vaikka osa on julkaistu vain fragmentteina hänen kuolemansa jälkeen. Tolkienin mytopoeettinen logiikka ja luovan kirjoittamisen teoria näkyvät aina Silmarillion-teoksen kosmogonisesta luomismyytistä kevyen satumaiseen Hobittiin tai aina seikkailufantasiaan Taru Sormusten Herrasta. Tekijänä Tolkien näyttäytyy teoksissaan “alempana luojana” (sub-creator), joka kehittää myyttejä ja rakentaa fantasiamaailmaansa. Tolkienille Jumala on “ylempi luoja”, johon kirjailija vertautuu fiktion tasolla.Väitöskirjani tutkimuslogiikka seuraa Tolkienin legendaarion aikajärjestystä. Aloitan työni maailmanluomisesta, siirryn tämän jälkeen ns. pitkään tappioon ja haipumiseen sekä aina maailmanloppuun saakka. Luomisen teemaa käsitellessäni päähuomioni on sekä Tolkienin legendaarion teosten sisäisessä kertomuksessa että hänen kirjallisen luomisensa estetiikassa. Väitöskirjan loppupuolella käännän huomiotani myös lukijan “luomistyöhön” teoksia lukiessa.Käyttämääni teoreettiseen näkökulmaan ovat vaikuttaneet erityisesti Northrop Fryen konstruktiivinen kirjallisuusteoria sekä Benjamin Harshavin konstruktiivinen poetiikka. Käsittelyssäni ovat myös spekulatiivisen historiallisen epiikan metodit sekä hyvän ja pahan, kuolevaisuuden ja kuolemattomuuden, henkisen ja fyysisen sekä näkyvän ja näkymättömän vastakkainasetteluparit, ja ennen kaikkea se, kuinka nämä vastakkainasetteluparit ja elementit näyttäytyvät Tolkienin mytopoeettisessa visiossa. Tolkienin fiktion konstruktiivinen mytopoetiikka havainnollistuu metafyysisten ja temaattisten käsitteiden Luominen (Creation), Olemassaolo (Existence), Lankeamus (Fall) ja Ponnistelu (Struggle) kautta.Academic dissertation to be presented with the assent of the Doctoral Training Committee of Human Sciences of the University of Oulu for public defence in Keckmaninsali (HU106), Linnanmaa, on 13 November 2015, at 12 noonAbstract
This doctoral dissertation discusses constructive mythopoetics in J. R. R. Tolkien’s legendarium, the mythopoetic logics and elements on which Tolkien’s texts and his fantasy world are constructed.
My aim in this research is to create a reading of Tolkien’s fiction that shows that it is possible to discern a mythopoetic code in Tolkien’s legendarium. My hypothesis is that Tolkien’s mythopoetic fiction aims to be coherent on the levels of languages, myths, and inter- and intratextual background. This coherence can be found throughout the various texts and fragments of Tolkien’s fiction. From the cosmogonical creation myth of The Silmarillion, to the fairy-story lightness of The Hobbit and the quest fantasy of The Lord of the Rings, Tolkien’s fiction has its roots in the mythopoetic logics of his theory of creative writing (or myth-making). Tolkien is the sub-creator; he is creating myths and building his own world. For Tolkien, God is the primary creator, but the author is the (sub-)creator of his own creation. This is consistent throughout Tolkien’s legendarium, despite the fact that whilst creating his fiction, Tolkien is “pretending” to be a translator of mythical pseudo-historical documents.
In the main chapters, my research logics trace the inner timeline of Tolkien’s legendarium. Starting from the creation of the world, I move onto the long fall and struggle and to the end of the world. When discussing the theme of creation, I focus on the concept of creation on the intratextual level of Tolkien’s legendarium as well as on Tolkien’s aesthetics of creative work. In the end of the dissertation, I turn my attention also to the creative work of the reader.
My theoretical approach is influenced by both Northrop Frye’s constructive theory of literature and Benjamin Harshav’s theory of constructive poetics. I discuss the creative methods of speculative historical epic and the dichotomies of beginning and end, good and evil, mortality and immortality, spiritual and physical, and visibility and invisibility, as well as how these elements are manifested in Tolkien’s mythopoetic vision. The structure of Tolkien’s constructive mythopoetics is illuminated through the grand concepts of the Creation, the Existence, the Fall and the Struggle.Tiivistelmä
Väitöskirjani käsittelee konstruktiivista mytopoetiikkaa J. R. R. Tolkienin legendaariossa. Työ keskittyy ennen kaikkea mytopoeettiseen logiikkaan ja elementteihin, joiden kautta Tolkienin tekstit ja hänen luomansa fantasiamaailma rakentuvat.
Tutkimukseni muodostaa Tolkienin fiktion luennan, joka osoittaa, että Tolkienin legendaariolle voidaan löytää mytopoeettinen koodi. Tämä koodi havainnollistaa, että Tolkienin mytopoeettinen fiktio luo koherentin ja uskottavan kokonaisuuden kielen, myyttien sekä inter- ja intratekstuaalisten vaikutussuhteiden kautta. Tämä yhteenkuuluvuus ja koodi on nähtävissä, vaikka Tolkienin legendaarion osat ovat keskenään perin erilaisia, eri kirjallisuuslajeihin kuuluvia ja vaikka osa on julkaistu vain fragmentteina hänen kuolemansa jälkeen. Tolkienin mytopoeettinen logiikka ja luovan kirjoittamisen teoria näkyvät aina Silmarillion-teoksen kosmogonisesta luomismyytistä kevyen satumaiseen Hobittiin tai aina seikkailufantasiaan Taru Sormusten Herrasta. Tekijänä Tolkien näyttäytyy teoksissaan “alempana luojana” (sub-creator), joka kehittää myyttejä ja rakentaa fantasiamaailmaansa. Tolkienille Jumala on “ylempi luoja”, johon kirjailija vertautuu fiktion tasolla.
Väitöskirjani tutkimuslogiikka seuraa Tolkienin legendaarion aikajärjestystä. Aloitan työni maailmanluomisesta, siirryn tämän jälkeen ns. pitkään tappioon ja haipumiseen sekä aina maailmanloppuun saakka. Luomisen teemaa käsitellessäni päähuomioni on sekä Tolkienin legendaarion teosten sisäisessä kertomuksessa että hänen kirjallisen luomisensa estetiikassa. Väitöskirjan loppupuolella käännän huomiotani myös lukijan “luomistyöhön” teoksia lukiessa.
Käyttämääni teoreettiseen näkökulmaan ovat vaikuttaneet erityisesti Northrop Fryen konstruktiivinen kirjallisuusteoria sekä Benjamin Harshavin konstruktiivinen poetiikka. Käsittelyssäni ovat myös spekulatiivisen historiallisen epiikan metodit sekä hyvän ja pahan, kuolevaisuuden ja kuolemattomuuden, henkisen ja fyysisen sekä näkyvän ja näkymättömän vastakkainasetteluparit, ja ennen kaikkea se, kuinka nämä vastakkainasetteluparit ja elementit näyttäytyvät Tolkienin mytopoeettisessa visiossa. Tolkienin fiktion konstruktiivinen mytopoetiikka havainnollistuu metafyysisten ja temaattisten käsitteiden Luominen (Creation), Olemassaolo (Existence), Lankeamus (Fall) ja Ponnistelu (Struggle) kautta
mucilage
No full textBackground: Gaseous matter exchanges in soil are determined by the connectivity of the pore system which is easily clogged by fresh root exudates. However, it remains unclear how a hydrogel (e.g., mucilage) affects soil pore tortuosity and gas diffusion properties when drying.Aims: The aim of this viewpoint study is to extend the understanding of gas exchange processes in the rhizosphere by (a) relating it to the patterns formed by drying mucilage within pore space and (b) to give a concept of the effect of drying mucilage on soil gas diffusivity using the combination of experimental evidence and simulations.Methods: To describe the effect of mucilage on soil gas exchanges, we performed gas diffusion experiments on dry soil–mucilage samples and took images of glass beads mixed with mucilage to visualize the formation of mucilage after drying, using Environmental Scanning Electron Microscopy. Finally, we set up simulations to characterize the geometric distribution of mucilage within soil during the drying process.Results: Experiments of gas diffusion show that mucilage decreases gas diffusion coefficient in dry soil without significantly altering bulk density and porosity. Electron microscopy indicates that during drying mucilage forms filaments and interconnected structures throughout the pore space reducing gas phase connectivity. The evolution of these geometric structures is explained via pore scale modelling based on identifying the elastic strength of rhizodeposition during soil drying.Conclusion: Our results suggest that releasing mucilage may be a plant adaption strategy to actively alter gas diffusion in soil
Visualising product-service system business models
No full textCopyright © 2014. Copyright in each paper in this conference’s proceedings is the property of
the author(s). Permission is granted to reproduce copies of these works for purposes relevant
to the above conference, provided that the author(s), source and copyright notice are included
on each copy. For other uses, including extended quotation, please contact the author(s).The paper addresses the issue of how to visualise innovative business models at various stages of the design and development process. The focus is on a particular type of business model, defined Product-Service Systems (PSSs), characterised by an integrated product-service offering, but can be generalised to other business model innovations. The paper presents a visualisation system based on a formalised business model ontology and a set of visualisation tools, and discusses how it can be used to enhance internal and external communication and improve dialogue and co-design activities inside the company and with external stakeholders
Open Source Software reference implementations for standards issued by different standards setting organisations : availability, perceptions and practices
No full textSoftware reference implementations of ICT standards have an important role for verifying that a standard is implementable, supporting interoperability testing among other implementations, and providing feedback to the standard development process. Providing reference implementations and widely used implementations of a standard as Open Source Software promotes wide deployment in software systems, interoperability, longevity of systems and associated digital assets, and avoidance of different lock-in effects. In this paper results are reported on the availability of, and perceptions and practices concerning, reference implementations and widely deployed implementations provided as Open Source Software for standards issued by different standards setting organisations. Specifically, findings draw from observations and analyses related to software implementations for identified standards and policy statements, issued by ETSI, IEC, IEEE, IETF, ISO, ITU-T, OASIS, and W3C.CC BY 4.0 DEEDCorresponding author: [email protected] research has been financially supported by the Swedish Knowledge Foundation (KK-stiftelsen) and participating partner organisations in the SUDO project.</p
A fault-based probabilistic seismic hazard model for Lebanon, controlling parameters and hazard levels
No full textInternational audienceThe present work develops a comprehensive probabilistic seismic hazard study for Lebanon, a country prone to a high seismic hazard since it is located along the Levant fault system. The historical seismicity has documented devastating earthquakes which have struck this area. Contrarily, the instrumental period is typical of a low-to-moderate seismicity region. The source model built is made of a smoothed seismicity earthquake forecast based on the Lebanese instrumental catalog, combined with a fault model including major and best-characterized faults in the area. Earthquake frequencies on faults are inferred from geological as well as geodetic slip rates. Uncertainties at every step are tracked and a sensitivity study is led to identify which parameters and decisions most influence hazard estimates. The results demonstrate that the choice of the recurrence model, exponential or characteristic, impacts the most the hazard, followed by the uncertainty on the slip rate, on the maximum magnitude that may break faults, and on the minimum magnitude applied to faults. At return periods larger than or equal to 475 years, the hazard in Lebanon is fully controlled by the sources on faults, and the off-fault model has a negligible contribution. We establish a source model logic tree populated with the key parameters, and combine this logic tree with three ground-motion models (GMMs) potentially adapted to the Levant region. A specific study is led in Beirut, located on the hanging-wall of the Mount Lebanon fault to understand where the contributions come from in terms of magnitudes, distances and sources. Running hazard calculations based on the logic tree, distributions of hazard estimates are obtained for selected sites, as well as seismic hazard maps at the scale of the country. Considering the PGA at 475 years of return period, mean hazard values found are larger than 0.3 g for sites within a distance of 20-30 km from the main strand of the Levant Fault, as well as in the coastal region in-between Saida and Tripoli (≥ 0.4 g considering the 84th percentile). The study provides detailed information on the hazard levels to expect in Lebanon, with the associated uncertainties, constituting a solid basis that may help taking decisions in the perspective of future updates of the Lebanese building code
