A higher-order active contour model of a `gas of circles' and its application to tree crown extraction

Many image processing problems involve identifying the region in the image domain occupied by a given entity in the scene. Automatic solution of these problems requires models that incorporate significant prior knowledge about the shape of the region. Many methods for including such knowledge run into difficulties when the topology of the region is unknown a priori, for example when the entity is composed of an unknown number of similar objects. Higher-order active contours (HOACs) represent one method for the modelling of non-trivial prior knowledge about shape without necessarily constraining region topology, via the inclusion of non-local interactions between region boundary points in the energy defining the model. The case of an unknown number of circular objects arises in a number of domains, e.g. medical, biological, nanotechnological, and remote sensing imagery. Regions composed of an a priori unknown number of circles may be referred to as a `gas of circles'. In this report, we present a HOAC model of a `gas of circles'. In order to guarantee stable circles, we conduct a stability analysis via a functional Taylor expansion of the HOAC energy around a circular shape. This analysis fixes one of the model parameters in terms of the others and constrains the rest. In conjunction with a suitable likelihood energy, we apply the model to the extraction of tree crowns from aerial imagery, and show that the new model outperforms other techniques

Reduced bio-efficacy of permethrin EC impregnated bednets against an Anopheles gambiae strain with oxidase-based pyrethroid tolerance

BACKGROUND: Insecticide-treated nets (ITNs) are an integral component of malaria control programmes in Africa. How much pyrethroid resistance in malaria vectors will impact on the efficacy of ITNs is controversial. The purpose of this study was to evaluate knockdown and killing effects of ITNs on a metabolic-based resistant or tolerant malaria vector strain. METHODS: Bio-efficacy of 500 mg/m(2 )permethrin EC treated bednets was assessed on the OCEAC laboratory (OC-Lab) strain of Anopheles gambiae s.s.. This strain is resistant to DDT and tolerant to pyrethroids, with elevated mixed function oxidases. The Kisumu reference susceptible strain of A. gambiae s.s. was used as control. Nets were impregnated in February 1998 and used by households of the Ebogo village. Then they were collected monthly over six months for Bio-assays (WHO cone test). Knockdown and mortality rates were compared between the OC-Lab and the Kisumu strains, by means of the Mantel-Haenszel chi-square test. RESULTS: During the whole trial, permethrin EC knockdown rates were impressive (mostly higher than 97%). No significant difference was observed between the two strains. However, the mortality rates were significantly decreased in the OC-Lab strain (40–80%) compared with that of the Kisumu strain (75–100%). The decrease of killing effect on the OC-Lab strain was attributed to permethrin EC tolerance, due to the high oxidase metabolic activity. CONCLUSION: These data suggested an impact of pyrethroid tolerance on the residual activity of ITNs. More attention should be given to early detection of resistance using biochemical or molecular assays for better resistance management

The LED Paradox: How Light Pollution Challenges Experts to Reconsider Sustainable Lighting

In the 21st century, the notion of “sustainable lighting” is closely associated with LED technology. In the past ten years, municipalities and private light users worldwide have installed light-emitting diodes in urban spaces and public streets to save energy. Yet an increasing body of interdisciplinary research suggests that supposedly sustainable LED installations are in fact unsustainable, because they increase light pollution. Paradoxically, blue-rich cool-white LED lighting, which is the most energy-efficient, also appears to be the most ecologically unfriendly. Biologists, physicians and ecologists warn that blue-rich LED light disturbs the circadian day-and-night rhythm of living organisms, including humans, with potential negative health effects on individual species and whole ecosystems. Can the paradox be solved? This paper explores this question based on our transdisciplinary research project Light Pollution—A Global Discussion. It reveals how light pollution experts and lighting professionals see the challenges and potential of LED lighting from their different viewpoints. This expert feedback shows that “sustainable LED lighting” goes far beyond energy efficiency as it raises complex design issues that imply stakeholder negotiation. It also suggests that the LED paradox may be solved in context, but hardly in principle

Designating Dark Sky Areas: Actors and Interests

The brighter prospect provided by the authors lies, firstly, in debunking simplistic assumptions about the universally positive value of artificial lighting. It presents one of the first state-of-the-art overviews of current debates on lighting among the humanities and social sciences, covering the fields of history, literature, economics, law, political science, geography and planning studies. Some are well established, such as concerns for safety and security in under-lit nocturnal environments, the extension of economic activities into the hours of darkness or commercial interests in advertising through lighting. Citizen participation which is common in many planning issues is not well established in the context of lighting. A promising avenue of research is to explore the multiple geographies of lighting whether material, institutional or representational and how these manifest themselves in specific local contexts. Artificial light is a great enabler of the 24-hour society, extending hours of social and economic activity into darkness

André Lagarde, contes occitans: Quercorb, Pays d'Olmes, Volvestre, édités et présentés par Josiane Bru, Toulouse, Editions de l' Escòla Occitana, 2005

Il est inhabituel –et sans doute aussi incongru– de rendre compte d’un livre dont on est à ce point partie prenante. Il est aussi inhabituel dans les Estudos de Literatura Oral comme dans d’autres revues internationales, de rendre compte d’un ouvrage de contes occitans, publiés dans leur langue d’origine et sans traduction dans une langue officielle. La proximité des langues latines, qui permet la lecture de cette abondante collecte, le permet cependant

Observations sur une chape rouge de l'ancienne abbaye de Saint-Papoul (Aude)

International audiencePreliminary study on the technique and dating of a remarkable cope whose base fabricseems to come from the mid-17th century, while the fabric of the orphreys and hoodseems to have been made in the East during the first half of the 18th century.Première étude sur la technique et la datation d’une chape insigne dont le tissu de fondsemble du milieu du XVIIe siècle tandis que le tissu des orfrois et du chaperon aurait étéexécuté en Orient durant la première moitié du XVIIIe siècle

Essai sur le conte de tradition orale

Cet ouvrage de Nicole Belmont nous donne l'opportunité de revenir sur l’œuvre de ce chercheur dont de nombreux travaux concernent le conte populaire et la problématique de l’oral et de l’écrit

Von Autobahnauffahrten und Szenekneipen : Theorien und Forschung zu Standortwahl und Standortfaktoren ; eine Wissenschaft des Ungefähren im Mantel der Genauigkeit?

Die unternehmerische Standortwahl in all ihren Facetten, zu denen Neuerrichtungen ebenso gehören wie Erweiterungen, Rückbau, Verlagerungen und Schließungen, hat erheblichen Einfluss auf die Entwicklung von Städten und Regionen. Entsprechend groß ist das Interesse an wissenschaftlichem Erkenntnisgewinn und politischer Handlungsorientierung. Dies wird an der Vielzahl von Studien und theoretischen Erklärungsansätzen zur unternehmerischen Standortwahl ebenso deutlich wie an der Häufigkeit darauf basierender Argumentationen, etwa im Rahmen kommunaler Entwicklungskonzepte. Die Prozesse der unternehmerischen Standortwahl sind trotz der bereits 200 Jahre währenden theoretischen Auseinandersetzung sowie zahlreicher empirischer Studien jedoch längst nicht abschließend geklärt. Zudem werden durch fortlaufende, tief greifende und komplexe Veränderungen der wirtschaftlichen und gesellschaftlichen Rahmenbedingungen – u.a. Prozesse der Globalisierung, des wirtschaftlichen Strukturwandels und des demografischen Wandels – immer wieder neue Fragen aufgeworfen, denen es in Theorie und Forschung nachzugehen gilt. In der Auseinandersetzung mit Prozessen der Standortwahl spielen Standortfaktoren – also Eigenschaften, durch die sich ein Raum von anderen Räumen unterscheidet und die damit die Standortwahl von Unternehmen beeinflussen – eine prominente Rolle sowohl in theoretischen Modellen als auch in einer kontinuierlich wachsenden Anzahl empirischer Studien und darauf basierenden Argumentationen und Handlungsansätzen für die Praxis. Hier setzt die vorliegende Arbeit an, indem sie einen Überblick zentraler theoretischer Grundlagen bietet, die Bandbreite und Wandelbarkeit von Standortfaktoren beleuchtet sowie eine Vielzahl von Studien im Detail und – soweit möglich – vergleichend betrachtet. Vor dem Hintergrund aktueller wirtschaftlicher und gesellschaftlicher Wandlungsprozesse werden Thesen zur Bedeutungsentwicklung von Standortfaktoren aufgegriffen und gegenüber den empirischen Befunden geprüft. Dabei setzt sich die Arbeit kritisch mit der empirischen Erforschung von Standortfaktoren auseinander und formuliert Empfehlungen zu deren Weiterentwicklung. Online-Version im Universitätsverlag der TU Berlin (www.univerlag.tu-berlin.de) erschienen.Companies’ locational decisions impact the development of cities and regions considerably. When analysing processes of locational decision-making, factors to do with location play a central role. This paper sheds light on the scope and variance of such locational factors, provides an overview of essential theoretical approaches and takes an in-depth and – to the extent possible – comparative look at numerous studies on locational factors. In taking a critical approach to research on locational factors, the paper provides recommendations for its further development