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See detailComparison of robust detection techniques for local outliers in multivariate spatial data
Ernst, Marie ULg; Haesbroeck, Gentiane ULg

Conference (2014, August 22)

Spatial data are characterized by statistical units, with known geographical positions, on which non spatial attributes are measured. Spatial data may contain two types of atypical observations: global ... [more ▼]

Spatial data are characterized by statistical units, with known geographical positions, on which non spatial attributes are measured. Spatial data may contain two types of atypical observations: global and/or local outliers. The attribute values of a global outlier are outlying with respect to the values taken by the majority of the data points while the attribute values of a local outlier are extreme when compared to those of its neighbors. Usual outlier detection techniques may be used to find global outliers as the geographical positions of the data is not taken into account in this specific search. The detection of local outliers is more complex, especially when there are more than one non spatial attributes. This talk focuses on local detection with two main objectives. First, we will shortly review some of the local detection techniques that seem to perform well in practice. Among these, one can find robust ``Mahalanobis-type'' detection techniques and a wheighted PCA approach. We suggest an adaptation to one of these to further develop its local characteristic. Then, examples and simulations, based on linear model of co-regionalisation with Matern models, are reported and discussed in order to compare in an objective way the different detection techniques. [less ▲]

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See detailIn vivo skin fluorescence imaging in young Caucasian adults with early malignant melanomas
PIERARD, Gérald ULg; Hermanns-Lê, Trinh ULg; Pierard, Sébastien ULg et al

in Clinical, Cosmetic and Investigational Dermatology (2014), 7

Background: Human cutaneous malignant melanoma (CMM) is an aggressive cancer showing a dramatic worldwide increase in incidence over the past few decades. The most prominent relative epidemiological ... [more ▼]

Background: Human cutaneous malignant melanoma (CMM) is an aggressive cancer showing a dramatic worldwide increase in incidence over the past few decades. The most prominent relative epidemiological increase has been disclosed in young women. The aim of the study was to assess the effects of chronic sun exposures in order to rate the extend of melanocytic stimulations in the vicinity of CMM. Methods: The study was designed to evaluate the melanin distribution and density using ultraviolet light illumination. The present study was performed on surgical excision specimens of thin CMM lesion removed from the upper limbs of 55 Caucasian adults (37 women and 18 men). Two control groups comprised 23 men and 21 women of similar ages who had medium-size congenital melanocytic nevi, also present on the upper limbs. The peritumoral skin was scrutinized using a Visioscan® VC98 device, revealing the faint mosaic melanoderma (FMM) pattern that grossly indicates early signs of chronic photodamage in epidermal melanin units. Results: The median extent of relative FMM was significantly higher in the CMM male group. By contrast, the CMM female group showed a reverse bimodal distribution in FMM size. Only 12/37 (32.5%) of the CMM female group had an increased FMM size, whereas 25/37 (67.5%) of females with CMM had a global FMM extent in the normal range, relative to the controls. Conclusion: Thin CMM supervening in young women appear unrelated to repeat photoexposure. Other mechanisms are possibly involved. [less ▲]

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See detailLe poids d'août 1914 dans les relations belgo-allemandes (1914-1964)
Brüll, Christoph ULg

Conference (2014, August 20)

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See detailA multifractal analysis of air temperature signals based on the wavelet leaders method
Deliège, Adrien ULg; Nicolay, Samuel ULg

Conference (2014, August 20)

We present the wavelet leaders method (introduced by S. Jaffard) as a tool to study the Hölder regularity of signals, which is closely related to some functional spaces. We use the associated multifractal ... [more ▼]

We present the wavelet leaders method (introduced by S. Jaffard) as a tool to study the Hölder regularity of signals, which is closely related to some functional spaces. We use the associated multifractal formalism to show that surface air temperature signals are monofractal, i.e. these are regularly irregular. Then we use this result to establish a climate classification of weather stations in Europe which matches the Köppen-Geiger climate classification. This result could give rise to new criteria to determine the effectiveness of current climatic models. [less ▲]

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See detailCommémorations et souvenirs d'août 1914 à Liège
Lanneau, Catherine ULg

Conference (2014, August 20)

Comment, au fil des décennies, a-t-on célébré à Liège et dans sa région, le souvenir des événements d’août 1914, à commencer par la bataille de Liège et la résistance des forts ? Comment les autorités et ... [more ▼]

Comment, au fil des décennies, a-t-on célébré à Liège et dans sa région, le souvenir des événements d’août 1914, à commencer par la bataille de Liège et la résistance des forts ? Comment les autorités et les Liégeois eux-mêmes ont-ils contribué à construire la mémoire de ce mois tragique ? Comment, notamment, la presse locale a-t-elle rendu compte de ces manifestations ? Cette communication analyse l’évolution du contexte commémoratif liégeois de 1924 à 2004. Dans l’entre-deux-guerres, le souvenir d’août 1914 est extrêmement vif : les rescapés sont encore très nombreux, la germanophobie s'exprime avec force et le contexte international interfère puissamment sur la commémoration. Après la Seconde Guerre, un triple enjeu s’impose : gérer la concurrence ou la confusion de la mémoire et du souvenir entre les deux conflits mondiaux, entretenir la flamme de ce souvenir alors que le temps s’écoule et que les survivants se raréfient, et enfin appréhender un contexte international, lié notamment à la guerre froide, dans lequel l’Allemagne (de l’Ouest) est avant tout un partenaire politique et économique. En outre, dès les années 1970 mais surtout 1980, l'idée d'un tourisme mémoriel se fraie un chemin dans une région en pleine reconversion économique. [less ▲]

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See detailThe taste bud and the form. Ethnography of sensory labs
Vangeebergen, Thomas ULg

Conference (2014, August 20)

Sensory analyses present an opportunity to challenge classical dualism, especially when it is about taste. During long-term fieldworks, I accompanied several types of sensory expert panels, which had the ... [more ▼]

Sensory analyses present an opportunity to challenge classical dualism, especially when it is about taste. During long-term fieldworks, I accompanied several types of sensory expert panels, which had the mission to discriminate different sorts of products and define their respective sensory profile. I was interested to observe the period of training to understand how those people had acquired their expertise, and how their attention toward their own sensations were entangled to scientific infrastructures. Using sensory ethnographic methods, I assisted to the emergence of a particular world, in which the classical categories for science practices and taste perception were completely blurred. To establish a common truth, through sturdy and stable categories, appears to be compatible with personal moods and dispositions, singular and hedonic judgments, sociocultural grounded sensorium, contingent elements, and indeterminate parameters. Resorting to standard tests, educated and coached judges, statistical treatments, specific vocabulary, comparisons to physic-chemical analysis and various other apparatuses, these labs tempt to define and assess some food products. The goal of those examinations could be multiple: to outline consumers¿ feelings and choices, to check the quality of production, to search new applications, or to improve a current array. What interested me is the quest to an object practically exploitable in an industrial and commercial context, avoiding all kind of idiosyncratic experiences. In this presentation, I would tempt an analysis of those particular tests, focusing on the double bind of testing products and testing consumers, and searching to assess the causes of organoleptic variability. [less ▲]

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See detailMetropolitan governance rescaling in Belgium, France and United Kingdom. Studying boundaries of urban governments through the application of an analytical framework for institutional changes.
Breuer, Christophe ULg

Conference (2014, August 20)

Second tier European cities (small metropolis or regional cities) are subject to permanent reconfigurations of their governance. These changes are the response to both external and internal ... [more ▼]

Second tier European cities (small metropolis or regional cities) are subject to permanent reconfigurations of their governance. These changes are the response to both external and internal transformations. On the one side, they are facing external pressures as increased competition between cities, European integration, legislative evolution or paradigm switch. On the other side, cities are dealing with internal problems: urban sprawl, socio-spatial segregation, actors’ fragmentation, financial issues, etc. These tensions renew themselves and take various shapes. They are wondering cities governance and ways to manage them. To cope with new challenges in a new context, cities are trying to reconfigure their collective action in a new spatiality and with new coordination modes. In this context, inherited institutional boundaries – that could be seen as obsolete or inadequate in a changing World – are particularly under pressure. Cities governments and their spatial limits are a central issue for researchers, politicians and urban actors, and a major component of the urban or metropolitan governance. Although second-tier cities are an essential part of the “polycentric system of European cities”, attention has essentially been focused on large metropolis and capital cities, where the problem occurred earlier. Furthermore, there is an extended literature on institutional change and the “rescaling”, but research mainly focused on the response of cities to economic changes; few analysis offer a good comprehension of particular trajectories and evolution of cities limits which are highly embedded in local context. These shortcomings make the reading of contemporary mutations particularly complex for local actors. Our paper presents our research on the development and the validation of an analytical framework to interpret changes in cities’ governments boundaries. We improved and used a framework based on institutional change and social change, which combined both institutional design theories and self-organization theories. The analytical framework had been tested on the last decades government limits changes of regional cities and small metropolis in France (Saint-Étienne, Metz), United Kingdom (Sheffield) and Belgium (Liège, Brussels). The research was carried on with historical and geographical data collected during research stays in each of these cities: historical evolution of cities limits, legislation’ development, urbanization trajectory, etc. The research leads to some conclusions. Firstly, it is possible to develop a generic analytical framework to identify and interpret mutations of city government limits. This framework helps to make a systematic identification of actors’ dynamics, internal or external pressure and spatial changes, and go ahead apparent dichotomy between quick adjustment and high stability of some governance configuration. Secondly, the analytical model shows there is a common scheme of city limits evolution, which is driven among others things by European common dynamics (specifically economic and political dynamic). Thirdly, despite similarities in cities government boundaries changes, the analytical model demonstrates the importance of local contexts to understand individual evolutions and the specific trajectory of a city’ limits. [less ▲]

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See detailEarthquake imprints on 400 years of marine sedimentation in the western Gulf of Corinth, Greece
Beckers, Arnaud ULg; Hubert, Aurelia ULg; Beck, Christian et al

Poster (2014, August 18)

The Corinth rift is one of the fastest spreading rifts on Earth. In the western tip of the Rift, no major historical earthquake (Mw≥6) is known for the last 300 yrs, while the geodetic extension rate is ... [more ▼]

The Corinth rift is one of the fastest spreading rifts on Earth. In the western tip of the Rift, no major historical earthquake (Mw≥6) is known for the last 300 yrs, while the geodetic extension rate is the highest of the whole Corinth Rift. The question of seismic hazard is consequently particularly relevant. In this framework, we investigated the offshore sediments in order to look for sedimentary signature of past earthquakes. 12 short gravity cores have been retrieved in different environments: two shelves (40 and 100 m deep), one sub-basin (180 m deep) and the deep Gulf axis (330 m deep). The cores are 0.5 to 0.85 m long, permitting to analyze up to 400 yrs of sedimentation. Several sedimentological analyses have been performed: magnetic susceptibility, grain-size, XRF, ASM. Chronology is based on 137Cs and 210Pb decay. In parallel, an in-depth analysis of existing and newly found documents has been done to re-interpret macroseismic intensity fields of historical earthquakes and to build an updated earthquake catalogue for the area. These new data allowed us to estimate a macroseismic intensity threshold for submarine slope failures in the area, based on 16 reported events. Sedimentary events have been identified in all cores. On the first shelf, despite a visually homogenous, silty, sedimentation, 3 events have been highlighted by high resolution grain-size analysis and 210Pb decay profile’s disturbances. The upper one could be a back-wash flow tsunami deposit. On the second shelf, 4 high-concentration density flow deposits occurred with a recurrence time of ~58 yrs. In the canyon and in the sub-basin, sandy turbidites occurred with recurrence times of ~26 and ~56 years respectively. The possible seismic origin of these deposits is discussed based on their sedimentary characteristics and the macroseismic intensities assessed for the sediments source areas for each core location. [less ▲]

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See detailRetrouvailles à vélo avec Dick Annegarn
Demoulin, Laurent ULg

E-print/Working paper (2014)

Le nouveau CD de Dick Annegarn, Vélo va (2014), offre à son auditeur, à travers un bel échantillon de dix chansons, un aperçu des différentes facettes de l’art de l’auteur-compositeur-interprète.

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See detailMitigation strategies versus Adaptation strategies
Gengler, Nicolas ULg

Conference (2014, August 17)

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See detailMapping key pollutants in the English Channel region: the Channel Catchments Cluster (3C) cross-border project
Richir, Jonathan ULg; Pini, Jennifer; Watson, Gordon

Conference (2014, August 16)

The EU Water Framework Directive was a response to concerns about the previous disparate ways in which water quality was managed under Member State law and early European Directives. Within this context ... [more ▼]

The EU Water Framework Directive was a response to concerns about the previous disparate ways in which water quality was managed under Member State law and early European Directives. Within this context, the Interreg IVA France (Channel) England Region established the ‘sustainable environmental development of this common space’ as one of its priorities to integrate areas that face common problems. The wide variety of cooperative cross-border projects have brought together UK and French scientists and environmental managers to develop practical environmental management tools for the region (3Cs cluster). Using the Solent in the UK as a case study, maps of key pollutants (e.g. metals such as Zn and Cu) will be produced to assess their spatial diversity within the sediment. The incorporation of historical datasets will also provide a temporal component. The inclusion of bioavailable fractions (using sequential extraction methods) will enable the pollutants to be linked to the tissue concentrations of key benthic species such as the polychaete Nereis virens and possible impacts. Not only will this information provide a detailed account of the water quality of key areas of the English Channel, but it will also highlight the gaps in the data and sampling regimes that are necessary to achieve good environmental status for the future, thus ensuring more effective European environmental policy regarding the long-term protection and conservation of aquatic ecosystems. [less ▲]

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See detailMetropolitan governance of European medium-size cities. Linking cities trajectories and mode of governance.
Breuer, Christophe ULg

Conference (2014, August 16)

In the past few years, an increased attention has been paid to the effect of governance on regional development and trajectories. It is commonly argued by scholars and practitioners that governance is a ... [more ▼]

In the past few years, an increased attention has been paid to the effect of governance on regional development and trajectories. It is commonly argued by scholars and practitioners that governance is a key factor of regional competitiveness and differentiation. In this context, some institutions as the Organization for Economic Co-operation and Development (OECD), the United Nations (UN) or the European Commission (EC) claim that a better governance (or actually “good governance”) leads to better places to live, enhanced competitiveness and less segregation. In the same time, research, public efforts and investments has been focused on metropolitan regions as lever for economic development. If there is a consensus on the role of governance on metropolitan and urban development, researches mainly focused on cases analysis and bigger metropolis regions. Few empirical studies tried to link metropolitan governance and metropolitan trajectories in European Union, particularly for medium-size cities and metropolitan area (100.000 - 1.000.000 inhabitants), which represents a significant proportion of the European population and economy. Nowadays, some exploratory researches based on the Urban Audit (European Commission) and complementary surveys give us additional information on governance of such cities. In our research, we aimed to explore the link between metropolitan governance of medium-sized cities and their trajectories. We used latest data from the European Commission (Urban Audit, Perception survey, Regional Statistic Database - Eurostat) and additional sources for socio-economic, environmental and governance indicators (especially metropolitan governance typology). We integrated in our work previous researches on this topic. Our exploratory research pointed out pattern and similarities in European medium-sized cities governance and trajectories. Despite some difficulties to distinguish governance effects to other determinants of well-being and competitiveness, it opens questions on “governance matters” leitmotiv, public policy adequacy and innovation capacity in European cities. [less ▲]

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See detailNiche conservatism and conservation biology of Lepilemur in northwest Madagascar
Wilmet, Leslie ULg; Vermeulen, Cédric ULg; Schwitzer, Christoph et al

Conference (2014, August 14)

The main goals of our study is to verify the existence and extent of niche conservatism in three closely related species within the genus Lepilemur, and to draw conclusions on the applicability of ... [more ▼]

The main goals of our study is to verify the existence and extent of niche conservatism in three closely related species within the genus Lepilemur, and to draw conclusions on the applicability of conservation protocols to a broader array of Lepilemur species. The genus is an exemplary of the mammalian fauna of Madagascar which high biological diversity is under increasingly severe threat from anthropogenic degradation of its forest habitats. This study focuses particularly on three poorly-known Lepilemur taxa: L. sahamalazensis, L. dorsalis and L. mittermeieri, uplisted into one of the threatened categories of the IUCN Red List.The genus is particularly negatively affected by deforestation and habitat fragmentation and all have a small distribution range, fairly small total populations. Their pattern of distribution appears to have been established through vicariant speciation, probably driven by changes in the configuration of the hydrographic system. Such a pattern permits to expect a high level of niche conservatism. We present here our preliminary results of an exploratory mission on 1) evaluation of Lepilemur abundance in forest patches on the Ampasindava Peninsula, the Sahamalaza Peninsula and the Manongarivo Special Reserve 2) sleeping sites characteristics of the three studied species. [less ▲]

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See detailVirus indexing and sanitation of international banana collection: insights from a 5-year collaborative effort
De Clerck, Caroline ULg; Parmenter, Kathleen; Vandenhouwe, Ines et al

Conference (2014, August 14)

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See detailContribution à l'exploration de la structure des sols par microtomographie aux rayons X : vers une amélioration de la modélisation hydropédologique
Beckers, Eléonore ULg

Doctoral thesis (2014)

The aim of this thesis is to tend towards a better representation of soil water horizontal fluxes in hydropedological modelling. Tillage practices result in soil structural modifications which impact soil ... [more ▼]

The aim of this thesis is to tend towards a better representation of soil water horizontal fluxes in hydropedological modelling. Tillage practices result in soil structural modifications which impact soil hydrodynamic behaviour. This study takes place in this context, aiming to understand these modifications using X-ray microtomography (µCT), which allows a more fundamental analysis of soil. Indeed, this tool becomes a key in the field of soil science, giving a direct insight of the internal structure of soil. Besides, anisotropy studies are still rare as tiresome, and this work shows that the current hydrological models are anyway unable to represent it correctly: when it is taken into account, it rests on the hypothesis of a simple ratio between vertical and horizontal conductivity functions. First, microtomography is used supplementary to usual methods for the establishment of hydrodynamic functions near saturation. We showed that the retention curve designed with µCT information is more realistic since it leads to a better estimation of unsaturated hydraulic conductivity. However, these results could be doubtful depending on the different µCT acquisition or processing choices and hypothesis. Particularly, the thresholding step is crucial. Consequently, we propose a new global thresholding method based on the visible part of soil sample porosity. This method has been tested and validated in the context of the present study. This step allows us to use microtomography results to increase our knowledge of soil structure. A principal component analysis on soil pores structural parameters confirms that connectivity, specific surface, volume and radius are key factors for the differentiation of soil horizons texturally similar but structurally different. Our results show that structural parameters have to be taken into account to improve hydropedological modelling, especially if pores orientation is considered. We described thus the relevant parameters that can be obtained with µCT and which could help to better model water fluxes in soil while discussing the remaining limits and uncertainties, about upscaling issues notably. [less ▲]

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See detailExactitude du positionnement numérique des axes de ruissellement dans les bassins versants agricoles
Ouedraogo, Mohamar ULg

Doctoral thesis (2014)

Des études récentes menées en Belgique estiment les dommages causés par les inondations et les coulées boueuses entre 12,5 et 122 millions d’euros par an pour les infrastructures publiques, et entre 1,6 ... [more ▼]

Des études récentes menées en Belgique estiment les dommages causés par les inondations et les coulées boueuses entre 12,5 et 122 millions d’euros par an pour les infrastructures publiques, et entre 1,6 et 16,5 millions d’euros par an pour les habitations. La carte des zones à risque potentiel de ruissellement concentré est l’un des outils mis en place par la Wallonie pour lutter contre ces phénomènes de plus en plus fréquents. Cependant, la résolution (10 × 10 m) du MNT utilisé pour extraire les axes de ruissellement est trop faible pour prendre en compte les détails de la microtopographie (travail du sol, résidus de cultures, cultures…) des parcelles agricoles. De plus, elle ne tient pas compte des incertitudes inévitables, présentes dans les données altimétriques utilisées. L’objectif de cette thèse est d’envisager l’utilisation des nouvelles technologies d’acquisition des données altimétriques de haute densité (plusieurs points/m²), i.e., le scanner laser terrestre (TLS) et la photogrammétrie à partir d’un véhicule non piloté (VNP) pour créer un modèle numérique de terrain (MNT) de meilleure exactitude et de haute résolution spatiale (maille de dimensions ± 1 x 1 m). Cela permet de tenir compte de la variabilité altimétrique des parcelles agricoles, et d’analyser son impact sur le positionnement numérique des axes de ruissellement. Dans un premier temps, un TLS et un VNP à voilure fixe ont été utilisés pour acquérir des données altimétriques sur un bassin versant agricole de 12 ha. Deux logiciels photogrammétriques ont permis de générer le MNTPSC (Agisoft PhotoScan) et le MNTMCM (MicMac) ; tandis que des traitements statistiques ont été nécessaires pour supprimer les erreurs systématiques présentes dans les nuages de points obtenus au TLS avant de les fusionner pour générer le MNTTLS. La comparaison des MNT avec des points de contrôle (GCP) positionnés au récepteur GNSS (Global Navigation Satellite System) en mode RTK (Real Time Kinematic) a montré que le MNTTLS est le plus exact avec un RMSE (Root Mean Square Error) de 4,5 cm, suivi par le MNTMCM et le MNTPSC avec des RMSE valant respectivement 9,0 et 13,9 cm. Dans un second temps, la méthode de Monte Carlo a été utilisée pour générer à partir du MNTTLS, des MNT équiprobables. L’extraction des axes de ruissellement à partir des MNT équiprobables a permis de définir pour chaque maille du MNT, la probabilité d’appartenir à l’axe de ruissellement, et de définir une zone contenant l’axe de ruissellement extrait du MNTTLS avec une probabilité définie. Une telle zone peut être utilisée pour la mise en place de solutions telles que les bandes et les chenaux enherbés. La comparaison des algorithmes de suppressions des dépressions fermées d’une part, et des algorithmes d’extraction de la direction de l’eau d’autre part, a montré peu de différence au niveau de la probabilité d’appartenance des mailles à l’axe de ruissellement lorsque le MNT est de haute résolution spatiale (± 1 m). Enfin, les analyses statistiques ont montré que les altitudes des GCP utilisés dans la méthode de Monte Carlo sont influencées par l’état d’ameublissement et par la rugosité des sols des parcelles agricoles. Les études futures, e.g., à l’échelle de la Wallonie, devront prendre en compte l’impact de ces erreurs. [less ▲]

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See detailBarley (Hordeum distichon L.) roots produce volatile aldehydes via the lipoxygenase/hydroperoxide lyase pathway with a strong age-dependent pattern
Delory, Benjamin ULg; Delaplace, Pierre ULg; du Jardin, Patrick ULg et al

Conference (2014, August 13)

In chemical ecology, the roles played by root-emitted volatile organic compounds (VOCs) in biotic interactions and the quantitative analysis of such chemicals in root tissues remain poorly documented. In ... [more ▼]

In chemical ecology, the roles played by root-emitted volatile organic compounds (VOCs) in biotic interactions and the quantitative analysis of such chemicals in root tissues remain poorly documented. In this context, this study aims at using a fully automated gas chromatography – mass spectrometry methodology allowing both identification and accurate quantification of VOCs produced by roots of a monocotyledonous plant species at five selected developmental stages from germination to the end of tillering. Results show that barley roots mainly produce four volatile aldehydes, namely hexanal, (E)-hex-2-enal, (E)-non-2-enal and (E,Z)-nona-2,6-dienal. These molecules are well-known linoleic and linolenic acid derivatives produced via the lipoxygenase/hydroperoxide lyase pathway of higher plants. Our findings contrast with analyses documented on aboveground barley tissues that mainly emit C6 aldehydes, alcohols and their corresponding esters. Multivariate statistical analyses performed on individual VOC concentrations indicate quantitative changes in the volatile profile produced by barley roots according to plant age. Barley roots produced higher total and individual VOC concentrations when young seminal roots emerged from the coleorhizae compared to older phenological stages. Moreover, results also show that the C6/C9 volatile aldehyde ratio was the lowest at the end of tillering while the maximum mean value of this ratio was reached in seven day-old barley roots. [less ▲]

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