Biologically active Phytophthora mating hormone prepared by catalytic asymmetric total synthesis

A Phytophthora mating hormone with an array of 1,5-stereogenic centers has been synthesized by using our recently developed methodology of catalytic enantioselective conjugate addition of Grignard reagents. We applied this methodology in a diastereo- and enantioselective iterative route and obtained two of the 16 possible stereoisomers of Phytophthora hormone α1. These synthetic stereoisomers induced the formation of sexual spores (oospores) in A2 mating type strains of three heterothallic Phytophthora species, P. infestans, P. capsici, and P. nicotianae but not in A1 mating type strains. The response was concentration-dependent, and the oospores were viable. These results demonstrate that the biological activity of the synthetic hormone resembles that of the natural hormone α1. Mating hormones are essential components in the sexual life cycle of a variety of organisms. For plant pathogens like Phytophthora, sexual reproduction is important as a source of genetic variation. Moreover, the thick-walled oospores are the most durable propagules that can survive harsh environmental conditions. Sexual reproduction can thus greatly affect disease epidemics. The availability of synthetic compounds mimicking the activity of Phytophthora mating hormone will be instrumental for further unravelling sexual reproduction in this important group of plant pathogens.

Projected Destination Images on African Websites: Upgrading Branding Opportunities in the Global Tourism Value Chain

This paper explores whether websites that offer a global audience virtual access to watering holes in game parks afford African nations opportunities to diminish their international isolation as tourism destinations. The present analysis examines a sample of almost 450 tourism websites representing Rwanda, Uganda and Mozambique. Two aspects are studied in particular: the websites’ technical and social infrastructures, including website ownership and networks, and website content, i.e. the projected destination image and opportunities to bridge the main supplier-consumer gaps in the global tourism value chain. The findings indicate that there is substantial foreign involvement in Africa’s online tourism infrastructure; furthermore, that the current projected images tend to reproduce foreign stereotypes. It concludes that the potential for upgrading branding capabilities could be sourced in indigenous African cultural attributes, both high and low culture, and in contexts of the past and the contemporary

Virtual Tourism Destination Image: Glocal identities constructed, perceived and experienced

Het opdoemend netwerk van mondiale hubs en stromen van geld, media, technologie en migratie, hebben geleid tot een algemene bewustwording rond oplopende spanningen tussen mondiale en locale identiteiten en imago’s. Dubai, het onderzoeksdecor van dit proefschrift, is een goed voorbeeld. Met internet en mobiele technologie bestaat het creëren van bestemmingsimago’s niet langer uit een eenzijdig pushproces van massacommunicatie. Steeds belangrijker worden dynamische interactieve processen van reflecteren, selecteren, debatteren en ervaren. Dit proefschrift construeert daarom een dynamisch toeristisch bestemmingsimago-ontwikkelingsmodel waarbij de driehoeksverhouding tussen plaatsidentiteit, geprojecteerd imago en gepercipieerd imago leidt tot een spanningsveld, welke wordt kortgesloten tijdens de reisbeleving, wanneer host (aanbod) en gast (vraag) elkaar ontmoeten. Op dat moment kunnen drie kloven in het model een negatief effect hebben op de klanttevredenheid, hetgeen in dit proefschrift empirisch wordt onderzocht door het meten van geprojecteerd en gepercipieerd imago. Dit wordt bewerkstelligd door een innovatieve methodologie gebaseerd op geautomatiseerde inhoudsanalyse. Het geprojecteerd imago is vestgesteld door middel van inhoudsanalyse op 20 in Dubai gevestigde toeristische websites, terwijl gepercipieerd imago is gemeten door middel van inhoudsanalyse op 1.100 online reacties op een kwalitatief imago-onderzoek. De resultaten tonen aan dat men in Dubai de drie kloven dient te overbruggen, aangezien de snelle ontwikkeling van Dubai als een mondiale hub soms voorbij gaat aan de verankering in de sterke lokale identiteit en het gevestigd imago. Een theoretische oplossing voor het overbruggen van de kloven wordt besproken en conceptueel toegepast in het concluderend hoofdstuk. Het is gebaseerd op de literatuur rond stedelijke of regionale merkontwikkeling en staaft de algemene bruikbaarheid van het model en de onderzoeksmethodologie zoals die in dit proefschrift ontwikkeld werden.Robert Govers, who was born on May 16, 1968 in The Hague, The Netherlands, is currently serving as research coordinator at the Flemish Center for Tourism Policy Studies of the University of Leuven, Belgium. Prior to this he worked in Dubai as a senior lecturer in tourism and marketing for four years, including two years at the Emirates Academy of Hospitality Management. Robert graduated with a Master’ s degree in Marketing from the Rotterdam School of Management, but also holds a Bachelor’ s degree in Information Management. Robert started his teaching career as a visiting lecturer at the Witwatersrand Technikon Johannesburg (RSA). After that he was a Research Associate for the Centre for Tourism Management at the Rotterdam School of Management. With Prof. dr. Frank M. Go, Robert is the author of Entrepreneurship in Tourism, a paperback published in Dutch. He also co-authored several journal articles and conference papers in the field of tourism, hospitality and quality management, e-commerce in tourism and tourism research and marketing. As a project manager, Robert has been involved in many consultancy projects for reputable organisations such as IATA, the European Commission, the Flemish Government and various Dutch ministries and tourism promotion boards.The emerging network of global hubs and flows of finance, media, technology and migration has raised awareness regarding the tensions between global and local identities and images. Dubai, as the central research background for this dissertation, is a good case in point. With internet and mobile technology, creating destination image is no longer a one-way ‘push’ process of mass communication, but rather a dynamic one of selecting, reflecting, sharing, and experiencing. This dissertation therefore constructs a dynamic tourism destination image formation model, which identifies a triadic tension between place identity, its projection and the perceived image. This tension is short circuited during the travel experience, when host (supply) meets guest (demand). At this instance, three potential gaps could negatively affect the level of satisfaction experienced in the host – guest encounter. The empirical research focuses on measuring projected and perceived images in order to test the way in which the gaps can be assessed. This is accomplished through an innovative methodology based on computerised content analysis. The projected image is measured through a content analysis of 20 Dubai based websites while the perceived images are gauged by content analysing 1.100 online responses to a qualitative image survey. The results indicate that for Dubai, the three gaps need bridging as there is a clear tension between its rapid development as a global hub and its strong local identity and image. A theoretical solution for bridging the gaps is discussed and conceptually applied in the concluding chapter. It is based on the destination branding literature and establishes the general usefulness of the model and its research methodology

A multidisciplinary approach to the study of the Chaotic Terrains on Mars

Chaotic terrains on Mars display common characteristics, such as irregular arrays of fractured and tilted blocks up to tens of kilometers in size and their occurrence in depressions of hundreds of meters deep. Moreover, they represent the source of the majority of the Hesperian outflow channels. These features spark the question which subsurface mechanism is responsible for the formation of chaotic terrains and release of major quantities of water in few. Morphological and hydrological observations fit well with a scenario of catastrophic water release from a buried sub-ice lake. In this scenario, the Chaotic Terrains would result from the collapse of sediments and ice covering the lake. The sub-ice lake would arise from slow melting of, and sedimentation on, a crater ice sheet. In order to investigate whether this scenario is feasible from a physical perspective, we perform a multidisciplinary study of the Chaotic Terrains. In particular, we perform a statistical analysis of their morphometric characteristics, and we investigate whether their surface morphology may be a consequence of the collapse of the infill of a crater. Based on their morphometric characteristics, we find that these landforms have a common origin. In particular, the investigated landforms show diameter-depth correlations similar to those that impact craters of equivalent diameters exhibit. We also find that the observed amount of collapse of the collected features is strongly correlated to their diameter. Furthermore, the linear relation between the minimum filling and pristine depth of craters, the constant ratio between collapse and the amount of filling and the fractured and chaotic aspect of the filling agree with melting and subsequent collapse of an ice layer below a sediment layer. We investigate whether this surface morphology may be a consequence of the collapse of the infill of a crater. We perform numerical simulations to evaluate the distribution of fractures within the crater and the influence of the crater size, infill thickness, and collapsing depth on the final morphology. The comparison between model predictions and the morphology of the Martian Chaotic Terrains shows strong statistical similarities in terms of both number of fractures and correlation between fractures and crater diameters. No or very weak correlation is observed between fractures and the infill thickness or collapsing depth. The strong correspondence between model results and observations suggests that the collapse of an infill layer within a crater is a viable mechanism for the peculiar morphology of the Martian Chaotic Terrains

Origin of circular collapsed features in the Chryse region of Mars

The quasi-circular collapsed features occurring in the Chryse region of Mars share similar morphological charac- teristics, such as deeply collapsed quasi-circular areas with intensively fractured floor characterized by polygonal tilted blocks of highly variable size. We analyze statistical relations between diameter, maximum and minimum depth, and amount of collapse of several of these features. Based on their morphometric characteristics, we find that these features have a common origin. Different scenarios have been proposed to explain quasi-circular collapsed features. We find that the maximum depth and minimum amount of collapse are strongly correlated to diameter. Impact craters show the same relations, strongly suggesting that collapsed features originated as impact craters. Furthermore, the morphometric characteristics of the infill agree with melting and subsequent collapse of an ice layer below a sediment layer. This interpretation agrees with a buried sub-ice lake scenario. After the formation of an impact crater the increase in temperature resulting from the release of impact energy would induce melting of the surrounding cryosphere. The generated groundwater flows towards the crater, which represents a topograph- ically depressed area with low hydraulic head and produces a crater-lake. The volume of molten cryosphere and the amount of water flow is strictly related to the size of the impact crater: larger craters result in more melting and deeper lake. Due to low surface temperatures, the water lake freezes and sediments can be depositated at the top of the ice layer. The buried ice unit melts as result of the thermal insulation by the overburden in combination with the planetary heat loss, creating a subsurface lake. The system is no longer stable and the overburden collapses, resulting in massive expulsion of liquid water to the surface. Taking into account a uniformly distributed heat loss, the amount of melting is strictly affected by the crater size. This is a non-climatic mechanism for producing and storing abundant liquid water under martian conditions

Can Plate Bending Explain the Observed Faster Landward Motion of Lateral Regions of the Subduction Zone After Major Megathrust Earthquakes?

Greater landward velocities were recorded after six megathrust earthquakes in subduction zone regions adjacent to the ruptured portion. Previous explanations invoked either increased slip deficit accumulation or plate bending during postseismic relaxation, with different implications for seismic hazard. We investigate whether bending can be expected to reproduce this observed enhanced landward motion (ELM). We use 3D quasi-dynamic finite element models with periodic earthquakes. We find that afterslip downdip of the brittle megathrust exclusively produces enhanced trenchward surface motion in the overriding plate. Viscous relaxation produces ELM when a depth limit is imposed on afterslip. This landward motion results primarily from in-plane elastic bending of the overriding plate due to trenchward viscous flow in the mantle wedge near the rupture. Modeled ELM is, however, incompatible with the observations, which are an order of magnitude greater and last longer after the earthquake. This conclusion does not significantly change when varying mantle viscosity, plate elasticity, maximum afterslip depth, earthquake size, megathrust locking outside of the rupture, or nature and location of relevant model boundaries. The observed ELM consequently appears to reflect faster slip deficit accumulation, implying a greater seismic hazard in lateral segments of the subduction zone

Agriculture Beyond Food: Experiences from Indonesia

The ABF programme addresses one of today’s major societal challenges, how to achieve a sustainable and inclusive biobased economy, with high-level scientific research on the thin lines between food and non-food, commodities and waste products, livelihood opportunities and risks, and local and global economy. This book provides insights into the main issues and key questions relating to the biobased economy, reflects on the objectives of the ABF programme, and offers policy recommendations. It summarises the projects conducted within the three major clusters at the heart of the programme: migration and forest transformation, breakthroughs in biofuel production technology, and the commoditisation of an alternative biofuel crop. The book ends with a number of lessons learned from the ABF programme on interdisciplinary programming