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See detailOptimal electron, phonon, and magnetic characteristics for low energy thermally induced magnetization switching
Atxitia, U.; Ostler, Thomas ULg; Chantrell, R. W. et al

in Applied Physics Letters (2015), 107(19), 192402

Using large-scale computer simulations, we thoroughly study the minimum energy required to ther- mally induced magnetization switching (TIMS) after the application of a femtosecond heat pulse in ... [more ▼]

Using large-scale computer simulations, we thoroughly study the minimum energy required to ther- mally induced magnetization switching (TIMS) after the application of a femtosecond heat pulse in transition metal-rare earth ferrimagnetic alloys. We find that for an energy efficient TIMS, a low ferrimagnetic net magnetization with a strong temperature dependence is the relevant factor for the magnetic system. For the lattice and electron systems, the key physics for efficient TIMS is a large electron-phonon relaxation time. Importantly, we show that as the cooling time of the heated elec- trons is increased, the minimum power required to produce TIMS can be reduced by an order of magnitude. Our results show the way to low power TIMS by appropriate engineering of magnetic heterostructures. [less ▲]

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See detailAb Initio Perspective on Stability and Aging in Phase Change Materials
Raty, Jean-Yves ULg

Scientific conference (2015, November 09)

Data recording with Phase Change Materials is a much studied topic as the writing/erasing characteristics, cyclability and downscaling properties of these materials allow for efficient data storage in ... [more ▼]

Data recording with Phase Change Materials is a much studied topic as the writing/erasing characteristics, cyclability and downscaling properties of these materials allow for efficient data storage in future generations of devices. Nevertheless, some aspects of phase change materials are limiting their performances and delaying their wider technological application. First, aging phenomena are common to all amorphous structures, but of special importance PCMs since it impedes the realization of multi-level memories. Different interpretations have been proposed, but we focus here on the structural relaxation of amorphous GeTe, chosen because it is the simplest system that is representative of the wider class of GST alloys, lying along the GeTe-Sb2Te3 composition line of the GeSbTe phase diagram. One difficulty encountered in the simulation of these amorphous systems is that the direct generation of an amorphous structure by quenching a liquid using Density Functional Theory (DFT) based Molecular Dynamics leads to one sample with a small number of atoms, and, hence of small number of atomic environments. Here we sample a large number of local atomic environments, corresponding to different bonding schemes, by chemically substituting different alloys, selected to favor different local atomic structures. This enables spanning a larger fraction of the configuration space relevant to aging. Our results support a model of the amorphous phase and its time evolution that involves an evolution of the local (chemical) order towards that of the crystal. On the other hand its electronic properties drift away from those of the crystal, driven by an increase of the Peierls-like distortion of the local environments in the amorphous, as compared to the crystal [1]. A second problem faced by PCMs is the fact that data recording is limited at high temperature due to the increased propensity to recrystallize. One approach to counter this is to stabilize the PCM using impurity atoms such as C or N. Using DFT and the analysis of the mechanical properties (constraints theory), we demonstrate how these impurity atoms modify the rigidity of the network, which is experimentally correlated with the activation energy for crystallization [2]. Finally, the crystal phase itself has been shown to have variable conductivities depending on the thermal history and annealing conditions. If this could be used profitably for multi-level recording, it also indicates that the crystal is undergoes some temporal evolution. Using DFT, we clarify the stability behavior of GST crystal and show that the metal-insulator transition is driven by the migration of intrinsic vacancies and an Anderson localization transition [3]. [1] J.Y Raty, W. Zhang, J. Luckas, C. Chen, R. Mazzarello, C. Bichara and M. Wuttig, Nat. Comm. (2015) [2] G. Ghezzi, J.Y. Raty, S. Maitrejean, A. Roule, E. Elkaim and F. Hippert, Applied Physics Letters, 99 (2011) 151906 [3] W. Zhang, A. Thiess, P. Zalden, R. Zeller, P. H. Dederichs, J-Y. Raty, M.Wuttig, S. Blügel et R. Mazzarello, Nature Materials 11 (2012) 952 [less ▲]

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See detailThe notion of trade sanctions and the EU system
Colussi, Ilaria Anna ULg

Conference (2015, November 09)

The main rule in trade law is the freedom of trade. However, some limitations should be introduced for protecting non-economic interests, such as security. One of the ways for ensuring these interests is ... [more ▼]

The main rule in trade law is the freedom of trade. However, some limitations should be introduced for protecting non-economic interests, such as security. One of the ways for ensuring these interests is represented by national strategic trade control systems. In case of violation of these rules, sanctions should be provided. The contribution aims at analysing the existing sanctions in trade law area, distinguishing between "internal penalties", meant as the violation of export control regimes, and "external sanctions", referred to the violation of embargoes. The analysis is a comparative one, and focuses particularly on the EU level. [less ▲]

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See detailLe syndrome psychotique chez l'enfant
SCHOLL, Jean-Marc ULg

Conference given outside the academic context (2015)

Modules de formation sur « Le syndrome psychotique chez l'enfant ». La psychose chez l'enfant n'est diagnostiquée et traitée qu'après deux années d'évolution, et souvent davantage. Les milieux ... [more ▼]

Modules de formation sur « Le syndrome psychotique chez l'enfant ». La psychose chez l'enfant n'est diagnostiquée et traitée qu'après deux années d'évolution, et souvent davantage. Les milieux professionnels de l'enfance manquent de repères cliniques précis pour mieux appréhender les signes cliniques émergeants en période prodromiques ou dans les tableaux cliniques comportant essentiellement des symptômes négatifs, c'est-à-dire des pertes de certaines compétences. Ces tableaux cliniques reçoivent souvent de faux diagnostics ou passe relativement inaperçus alors que le pronostic sociale de l'enfant est en jeu. Les deux modules ici présentés donnent des repères cliniques sur la période d'émergence de cette maladie neurodéveloppementale et sur la reconnaissance des symptômes négatifs. [less ▲]

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See detailDiurnal cycle and multi-decadal trend of formaldehyde in the remote atmosphere near 46° N
Franco, Bruno ULg; Marais, Eloise A.; Bovy, Benoît ULg et al

in Atmospheric Chemistry & Physics Discussions (2015), 15

Only very few long-term trends of formaldehyde (HCHO) exist. Furthermore, many uncertainties remain as to its diurnal cycle, representing a large short-term variability superimposed on seasonal and inter ... [more ▼]

Only very few long-term trends of formaldehyde (HCHO) exist. Furthermore, many uncertainties remain as to its diurnal cycle, representing a large short-term variability superimposed on seasonal and inter-annual variations that should be accounted for when comparing ground-based observations to e.g., model results. In this study, we derive a multi-decadal time series (January 1988 – June 2015) of HCHO total columns from ground-based high-resolution Fourier transform infrared (FTIR) solar spectra recorded at the high-altitude station of Jungfraujoch (Swiss Alps, 46.5° N, 8.0° E, 3580 m a.s.l.), allowing for the characterization of the mid-latitudinal atmosphere for background conditions. First we investigate the HCHO diurnal variation, peaking around noontime and mainly driven by the intra-day insolation modulation and methane (CH4) oxidation. We also characterize quantitatively the diurnal cycles by adjusting a parametric model to the observations, which links the daytime to the HCHO columns according to the monthly intra-day regimes. It is then employed to scale all the individual FTIR measurements on a given daytime in order to remove the effect of the intra-day modulation for improving the trend determination and the comparison with HCHO columns simulated by the state-of-the-art chemical transport model GEOS-Chem v9-02. Such a parametric model will be useful to scale the Jungfraujoch HCHO columns on satellite overpass times in the framework of future calibration/validation efforts of space borne sensors. GEOS-Chem sensitivity tests suggest then that the seasonal and inter-annual HCHO column variations above Jungfraujoch are predominantly led by the atmospheric CH4 oxidation, with a maximum contribution of 25 % from the anthropogenic non-methane volatile organic compound precursors during wintertime. Finally, trend analysis of the so-scaled 27-year FTIR time series reveals a long-term evolution of the HCHO columns in the remote troposphere to be related with the atmospheric CH4 fluctuations and the short-term OH variability: +2.9 %/yr between 1988 and 1995, -3.7 %/yr over 1996-2002 and +0.8/% yr from 2003 onwards. [less ▲]

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See detailReinventing paternalism. The micropolitics of work in the mining companies of Central Africa
Rubbers, Benjamin ULg

Scientific conference (2015, November 09)

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See detailSTAtion of Reference and rEsearch on Change of local and global Anthropogenic Pressures on Mediterranean Ecosystems Drifts: The STARECAPMED project
Richir, Jonathan ULg; Abadie, Arnaud ULg; Binard, Marc ULg et al

Conference (2015, November 08)

The Marine and Oceanographic Research Station STARESO in the Calvi Bay, Corsica (France), is a unique tool in a preserved natural site that includes all the characteristic ecosystems of the Mediterranean ... [more ▼]

The Marine and Oceanographic Research Station STARESO in the Calvi Bay, Corsica (France), is a unique tool in a preserved natural site that includes all the characteristic ecosystems of the Mediterranean littoral. The station, established in 1970, has archived environmental data for decades. The STARECAPMED project, multidisciplinary, articulates itself around these two main features. Its objective is to understand how human activities can interact with the fundamental processes that govern the functioning of the different coastal ecosystems of a Mediterranean bay. The understanding of these interactions involves: (i) the identification of the anthropogenic pressures; (ii) the quantification of their impacts on the ecosystems; (iii) the prioritization of these impacts. STARECAPMED also aims to confirm the relevance of the use of the Calvi Bay as a reference in the study of local and global pressures and the changes they may cause on the structure and the functioning of Mediterranean coastal ecosytems. [less ▲]

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See detailL'ostéopathie: mythe ou réalité?
Henrotin, Yves ULg

Conference (2015, November 07)

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See detailPrise en charge non pharmacologique de la gonarthrose; actualités et perspectives
Henrotin, Yves ULg

Conference (2015, November 07)

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See detailPrévoir/prévenir la contamination : récit d’anticipation et hygiénisme
Stienon, Valérie ULg

Conference (2015, November 07)

Au croisement de la médecine, de l’urbanisme et du réformisme social, les théories hygiénistes influencent profondément les conceptions du vivre-ensemble au XIXe siècle en France. Au même moment, les ... [more ▼]

Au croisement de la médecine, de l’urbanisme et du réformisme social, les théories hygiénistes influencent profondément les conceptions du vivre-ensemble au XIXe siècle en France. Au même moment, les romans d’anticipation développent des préoccupations similaires à travers leurs visions de la communauté : conditions fragiles de la santé publique, mesures prophylactiques contre l’épidémie, mises à l’épreuve du corps social et des infrastructures urbaines. Émile Souvestre envisage l’allaitement des enfants à la vapeur (Le Monde tel qu’il sera, 1846), Jules Verne conçoit France-Ville comme la « cité du bien-être » centrée sur la propreté (Les Cinq Cents Millions de la Bégum, 1879), Léon Daudet satirise une autocratie médicale devenue meurtrière par l’application outrancière des lois d’hygiène (Les Morticoles, 1894) et Paul Adam présente l’organisation des villes selon les cycles de la reproduction, favorisant la femme enceinte mais rendant stérile le soldat (Les Lettres de Malaisie, 1898). Les convergences entre les théories hygiénistes et les récits d’anticipation reposent non seulement sur un discours social et idéologique privilégiant certaines topiques comme la contamination, mais aussi sur des formes d’expression spécifiques, l’hygiénisme ayant généré nombre d’écrits – du traité à l’essai – caractérisés par leur propre poétique. Poser des principes, édicter des lois, recenser les composantes du corps social, réformer les mœurs, cartographier la ville et catégoriser ses habitants : ces démarches cognitives et les rhétoriques qui leur sont associées transitent aussi par la fiction romanesque, qui les fait siennes. On propose d’examiner ce double aspect : entre théorie et application, entre discours social et roman, comment la fiction d’anticipation s’approprie-t-elle l’hygiénisme pour en confirmer les principes, les critiquer ou les réinventer ? Quelles sont les modalités de ce dialogue à la fois prédictif et prescriptif (intégration, citation, transposition) ? Enfin, une évolution est-elle perceptible au long de la seconde moitié du siècle ? [less ▲]

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See detail) The spatial variability of trace element bioaccumulation processes: Tools to environmental management
Richir, Jonathan ULg; Lejeune, Lejeune; Lepoint, Gilles ULg et al

Conference (2015, November 07)

As transitional environments, coastal meadows are particularly vulnerable to pollution. Trace elements remain contaminants of concern because of their persistence, their ability to accumulate in biota and ... [more ▼]

As transitional environments, coastal meadows are particularly vulnerable to pollution. Trace elements remain contaminants of concern because of their persistence, their ability to accumulate in biota and their toxicity. Local, regional, national and cross-border programs are thus initiated to monitor their environmental occurrence. Sentinel organisms, or bioindicators, have been widely used to this end since they accumulate the bioavailable and thus potentially toxic fraction of contaminants. In the framework of the STARECAPMED project, the accumulation of trace elements in the seagrass Posidonia oceanica (L.) Delile was studied at different spatial scales: along a radial (100 m scale), in a bay (1 km scale), along the French Mediterranean littoral (10-100 km scale) and along the whole Mediterranean coastline (100-1000 km scale). Results showed that the contamination of the sampled shoots could vary as much at opposite scales. This benthic primary producer accumulates contaminants sequestered in the sediments, in addition to their dissolved fraction in the water column. The sediments also offer a time integration of coastal pollution and thus amplify the pollution signal recorded by the seagrass, resulting in the observed spatial variability. These results demonstrate that the in-depth knowledge of the ecology of the monitored bioindicator and the interactions it shares with its environment cannot be ignored. Such failure could lead to erroneous interpretations of the levels of contamination of monitored sites, and points out the need to define a sampling strategy based on the monitoring objectives and the selected bioindicator. [less ▲]

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See detailThe trace element contamination of coastal waters: A holistic approach to environmental monitoring surveys
Richir, Jonathan ULg; Gobert, Sylvie ULg

Conference (2015, November 07)

Sustained monitoring programs are necessary to evidence the efficacy of regulatory controls on pollutant discharges and to assess the health status of ecosystems. Within this perspective, this study aimed ... [more ▼]

Sustained monitoring programs are necessary to evidence the efficacy of regulatory controls on pollutant discharges and to assess the health status of ecosystems. Within this perspective, this study aimed to monitor the coastal trace element contamination of the whole Mediterranean, using Posidonia oceanica (L.) Delile as bioindicator. But sustainable coastal management also requires the development of appropriate classification systems intended, among other purposes, for environmental managers and policy makers. The combined utilization of several complementary monitoring tools - water quality scale, pollution index, spatial analysis - successfully led to the development of such an operational classification system: it allowed to assess contamination threats and to depict contamination gradients of the entire Mediterranean, while assessing more regional and local impacts. Consequently, such holistic approaches should be privileged to accurately monitor the contamination rate of coastal waters and to transfer relevant information on this composite problem to environmental managers and policy makers. [less ▲]

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See detailEquine cadaver ligaments : A new promising source of stem cells
Shikh Al Sook, Mohamad Khir ULg; Gabriel, Annick ULg; Salouci, Moustafa et al

Scientific conference (2015, November 07)

Detailed reference viewed: 136 (70 ULg)
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See detailDo changes in atmospheric CO2 concentration affect aphid alarm signaling?
Boullis, Antoine ULg; Appeldoorn, Claire; Oostrom, Marjolein et al

Conference (2015, November 06)

The effects of global atmospheric changes on vegetation and associated insect populations are increasingly studied, but how these gases affect the interactions between herbivore insects and their natural ... [more ▼]

The effects of global atmospheric changes on vegetation and associated insect populations are increasingly studied, but how these gases affect the interactions between herbivore insects and their natural enemies is less clear. As the efficacy of natural enemies is governed largely by behavioral mechanisms, changes in the behavior of insect prey defenses can change the dynamics of insect populations. The impact of increases in atmospheric carbon dioxide (CO2) concentrations on aphid population dynamic is well documented. However, few publications about their chemical ecology are reported. Aphids are using many chemical signals to communicate with each other or with their environment. For example aphids produce an alarm pheromone to signal the presence of a natural enemy in the colony. For our experiments, aphids Acyrthosiphon pisum (Harris) were reared on Vicia faba L. in home-made Plexiglas® chambers, allowing us to control the CO2 concentration, temperature and humidity. Aphids were reared under both ambient (aCO2 ≈ 400 ppm) and elevated (eCO2 ≈ 800 ppm) CO2 concentration for several generations. Here we quantified the emission of (E)-β-Farnesene (EβF - main compound of alarm pheromone) released by predated aphids reared under ambient or elevated CO2 concentration, with two different methods: a real-time analysis, and the total amount analysis. The EβF content of whole aphid bodies was also analyzed, as well as the escape behavior of aphid colony according to the growing conditions of aphid populations. These results will be discussed in terms of biological control in future climate. [less ▲]

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See detailComposite dark matter and direct-search experiments
Wallemacq, Quentin ULg

in International Journal of Modern Physics D : Gravitation, Astrophysics & Cosmology (2015), 24

The results of the direct searches for dark matter are reinterpreted in the framework of composite dark matter, i.e. dark matter particles that form neutral bound states, generically called “dark atoms” ... [more ▼]

The results of the direct searches for dark matter are reinterpreted in the framework of composite dark matter, i.e. dark matter particles that form neutral bound states, generically called “dark atoms”. Two different scenarios are presented: milli-interacting dark matter and dark anti-atoms. In both of them, dark matter interacts sufficiently strongly with terrestrial matter to be stopped in it before reaching underground detec- tors, which are typically located at a depth of 1 km. As they drift towards the center of the earth because of gravity, these thermal dark atoms are radiatively captured by the atoms of the active medium of underground detectors, which causes the emission of photons that produce the signals through their interac- tions with the electrons of the medium. This provides a way of reinterpreting the results in terms of electron recoils instead of nuclear recoils. The two models involve milli-charges and are able to reconcile the most contradictory experiments. We determine, for each model, the regions in the parameter space that reproduce the experiments with positive results in con- sistency with the constraints of the experiments with negative results. [less ▲]

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See detailFE2 approach for the modelling of coupled hydro-mechanical behaviour of partially saturated coalbeds
Bertrand, François ULg

Diverse speeche and writing (2015)

Présentation de projet de thèse au comité FRIA

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See detailCHANGEMENT CLIMATIQUE: CAUSES ET CONSEQUENCES (2015) - ANALYSE HOLISTIQUE -
Ozer, Pierre ULg

Scientific conference (2015, November 06)

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See detailAnalyse multifractale de la divergence de séries d'ondelettes
Esser, Céline ULg

Scientific conference (2015, November 06)

Dans cet exposé, nous étudions la divergence ponctuelle de séries d'ondelettes dans un espace de Besov. Nous obtenons une borne supérieure pour la dimension de Hausdorff de l'ensemble des points ayant un ... [more ▼]

Dans cet exposé, nous étudions la divergence ponctuelle de séries d'ondelettes dans un espace de Besov. Nous obtenons une borne supérieure pour la dimension de Hausdorff de l'ensemble des points ayant un taux de divergence donné, et nous montrons que cette borne est optimale en utilisant les notions de résidualité et de prévalence. Il s'agit d'un travail en collaboration avec S. Jaffard. [less ▲]