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See detailIncreased sea ice cover disrupts food web structure in coastal Antarctica
Michel, Loïc ULg; Dubois, Philippe; Eleaume, Marc et al

Conference (2017, March 03)

Antarctica currently undergoes strong and contrasted impacts linked with climate change. While the West Antarctic Peninsula is one of the most rapidly warming regions in the world, resulting in sea ice ... [more ▼]

Antarctica currently undergoes strong and contrasted impacts linked with climate change. While the West Antarctic Peninsula is one of the most rapidly warming regions in the world, resulting in sea ice cover decrease, the sea ice cover of East Antarctica unexpectedly tends to increase, possibly in relation with changes in atmospheric circulation. Sea ice is a major environmental driver in Antarctica, and changes in sea ice cover are likely to influence benthic food web structure through several processes (modifications of benthic-pelagic coupling, disruption of benthic production and/or modifications of benthic community structure and therefore resource availability for benthic consumers). To date, regions where sea ice cover is decreasing have received more attention than regions where it is increasing. Here, on the other hand, we studied shallow (0-20 m) benthic food web structure on the coasts of Petrels Island (Adélie Land, East Antarctica) during an event of unusually high spatial and temporal (two successive austral summers without seasonal break-up) sea ice cover. Using time-tested integrative trophic markers (stable isotope ratios of carbon, nitrogen and sulfur) and state-of-the-art data analysis tools (bayesian ecological models), we studied the structure of the food web associated to benthic macroinvertebrates communities. In total, 28 macroinvertebrate taxa spanning most present animal groups (sponges, sea anemones, nemerteans, nematods, sipunculids, sessile and mobile polychaetes, gastropods, bivalves, pycnogonids, crustaceans, sea stars, sea urchins, brittle stars and sea cucumbers) and functional guilds (grazers, deposit feeders, filter feeders, predators, scavengers) were investigated. Our results indicate that the absence of seasonal sea ice breakup deeply influences coastal benthic food webs in Antarctica. We recorded marked differences from literature data, both in terms of horizontal (i.e. primary producers and resources supporting animal populations) and vertical (i.e. trophic level of the studied consumers) structure of the food web. Overall, sympagic (sea-ice associated) algae dominated the diet of many important consumers, and the trophic levels of invertebrates were low, suggesting omnivore consumers relied less on predation and/or scavenging than in normal environmental conditions. Surprisingly, few animals seemed to feed on the extremely abundant benthic biofilm, whose exceptional development was also presumably linked with the peculiar sea ice conditions. Interpretation of data was complicated by the peculiar ecophysiological features of Antarctic invertebrates, whose very low metabolic rates could be associated to low tissue turnover. However, comparison of data obtained in the austral summers of 2013-2014 (first year without seasonal breakup) and 2014-2015 (second year without seasonal breakup) clearly showed that the observed trends were linked with actual temporal changes in invertebrate feeding habits rather than with other potential ecological drivers. Our results provide insights about how Antarctic benthic consumers, which have evolved in an extremely stable environment, might adapt their feeding habits in response to sudden man-driven changes in environmental conditions and trophic resource availability. They also show that local and/or global trends of sea ice increase in Antarctica could cause strong changes in food web structure and therefore impact zoobenthic communities. This reinforces the view that, no matter their overall direction (i.e. increase or decrease), fluctuations in sea ice cover are likely to influence Antarctic benthic ecosystems' structure and functioning. [less ▲]

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See detailA meta-analysis of isotopic compositions of North Sea marine mammals
Damseaux, France ULg; Lepoint, Gilles ULg; Das, Krishna ULg

Conference (2017, March 03)

For over a decade, the North Sea has been undergoing significant changes due to global changes and overfishing. We conducted meta-analyses of previously published data on marine mammals sampled in the ... [more ▼]

For over a decade, the North Sea has been undergoing significant changes due to global changes and overfishing. We conducted meta-analyses of previously published data on marine mammals sampled in the North Sea to test the competition for food sources and spatial variations. The overall objective of this study was to assess the potential trophic changes of the grey seal, the harbour seal and the harbour porpoise. Data included δ13C and δ15N values measured in blood cells and muscles from the three species. SIBER, a trophic niche overlap quantification approach, highlighted potential competition between marine mammal species. The ellipse drawn for harbour seal data showed the highest δ15N values, reflecting its trophic position at the top of the food web. But the ellipse overlapping between the harbour seal and the grey seal of Germany was very important, showing a potential strong competition for food sources may be due to the overfishing. The harbour porpoise displayed a lower trophic position and a wide range of δ13C and δ15N values compared to harbour seal and grey seal as seen from its extended ellipse size. This may be due to a more opportunistic behaviour following the decline of some fish population in the North Sea. Surprisingly a group of grey seals sampled in Scotland present a very small ellipse size, presumably more selective in their prey choice, and showed the lowest δ15N values. Caution should be taken before comparing the trophic position of the groups of grey seals as the baseline differed between the two sampling areas. Low nitrates concentrations, higher latitudes, colder temperatures, deeper waters and rocky soils of the Scotland’s coasts of the North Sea cause a stratification phenomenon of the water column explaining the lower δ15N baseline in this area and so the spatial variation between these two groups of grey seals living in the North Sea. [less ▲]

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See detailStructure of Herbig AeBe disks at the milliarcsecond scale. A statistical survey in the H band using PIONIER-VLTI
Lazareff, B.; Berger, J.-P.; Kluska, J. et al

in Astronomy and Astrophysics (2017), 599

Context. It is now generally accepted that the near-infrared excess of Herbig AeBe stars originates in the dust of a circumstellar disk. Aims. The aims of this article are to infer the radial and vertical ... [more ▼]

Context. It is now generally accepted that the near-infrared excess of Herbig AeBe stars originates in the dust of a circumstellar disk. Aims. The aims of this article are to infer the radial and vertical structure of these disks at scales of order one au, and the properties of the dust grains. Methods. The program objects (51 in total) were observed with the H-band (1.6micron) PIONIER/VLTI interferometer. The largest baselines allowed us to resolve (at least partially) structures of a few tenths of an au at typical distances of a few hundred parsecs. Dedicated UBVRIJHK photometric measurements were also obtained. Spectral and 2D geometrical parameters are extracted via fits of a few simple models: ellipsoids and broadened rings with azimuthal modulation. Model bias is mitigated by parallel fits of physical disk models. Sample statistics were evaluated against similar statistics for the physical disk models to infer properties of the sample objects as a group. Results. We find that dust at the inner rim of the disk has a sublimation temperature Tsub~1800K. A ring morphology is confirmed for approximately half the resolved objects; these rings are wide delta_r>=0.5. A wide ring favors a rim that, on the star-facing side, looks more like a knife edge than a doughnut. The data are also compatible with a the combination of a narrow ring and an inner disk of unspecified nature inside the dust sublimation radius. The disk inner part has a thickness z/r~0.2, flaring to z/r~0.5 in the outer part. We confirm the known luminosity-radius relation; a simple physical model is consistent with both the mean luminosity-radius relation and the ring relative width; however, a significant spread around the mean relation is present. In some of the objects we find a halo component, fully resolved at the shortest interferometer spacing, that is related to the HAeBe class. [less ▲]

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See detailThe Borders of Nord-Pas-de-Calais: Camps, Actors and Insecurity
Da Silva, Amanda Carolina ULg

Scientific conference (2017, March 03)

I explore the securitization of the immigration process developed between France and the UK as units of the EU regional security complex. My main intention was to not only identify how both countries ... [more ▼]

I explore the securitization of the immigration process developed between France and the UK as units of the EU regional security complex. My main intention was to not only identify how both countries securitized immigration together, but also to identify the social consequences its produces for the city of Calais. The FR-UK immigration policy has been implemented in the city of Calais since 2002, and over time security apparatus has become more sophisticated, which sums up the transposition of the UK border and construction of refugee camps and jungles. As a result of this process, it was possible to identify the appearance of self-established camps, emergence of new actors, and rise of nationalism. I aim to highlight the relevance of bilateral policies developed between both countries and its impacts in Calais. From this, policies’ and migrants’ representations of emerging camps, new actors and nationalism will produce considerable changes in the city. [less ▲]

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See detailBehavior of digital sequences through exotic numeration systems
Leroy, Julien ULg; Rigo, Michel ULg; Stipulanti, Manon ULg

in Electronic Journal of Combinatorics (2017), 24(1), 14436

Many digital functions studied in the literature, e.g., the summatory function of the base-k sum-of-digits function, have a behavior showing some periodic fluctuation. Such functions are usually studied ... [more ▼]

Many digital functions studied in the literature, e.g., the summatory function of the base-k sum-of-digits function, have a behavior showing some periodic fluctuation. Such functions are usually studied using techniques from analytic number theory or linear algebra. In this paper we develop a method based on exotic numeration systems and we apply it on two examples motivated by the study of generalized Pascal triangles and binomial coefficients of words. [less ▲]

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See detailMusical(ized) Biographies: Jackie Kay’s Trumpet and Caryl Phillips’s Dancing in the Dark
Mascoli, Giulia ULg

Conference (2017, March 03)

My paper deals with two musical(ized) biographies: Jackie Kay’s Trumpet (1998) and Caryl Phillips’s Dancing in the Dark (2005). These literary works share features, at once thematic, since the protagonist ... [more ▼]

My paper deals with two musical(ized) biographies: Jackie Kay’s Trumpet (1998) and Caryl Phillips’s Dancing in the Dark (2005). These literary works share features, at once thematic, since the protagonist is a musical performer, and formal, as both writers’ prose is drenched with musicality. The two narratives can thus be considered what Emily Petermann (2014) calls “musical novels”, as both display sonic and structural patterns as well as elements of improvisation (the imitation of orality; the use of different narrators and the inclusion of various types of texts such as lyrics, interviews, excerpts from newspapers, and the solo performances through improvised jazzy breaks and the repetition of the same lexical item). In my paper, I will take my cue from Eric Prieto, who writes that interart analogies should not be taken as ends in themselves, and I will try to show the purpose of such intermediality and how it can contribute to the biographical genre. Among other things, I will examine whether these musicalized biographies have, through their unusual forms, particular social and political relevance and how approaching them from this methodological angle can serve as interpretative aid. [less ▲]

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See detailStrategic Points in Aquaponics
Junge, Ranka; König, Bettina; Villarroel, Morris et al

in Water (2017), 9(182),

Detailed reference viewed: 22 (2 ULg)
See detailJesuit Festivals through words and images
De Marco, Rosa ULg

Scientific conference (2017, March 02)

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See detailExploiting random projections and sparsity with random forests and gradient boosting methods - Application to multi-label and multi-output learning, random forest model compression and leveraging input sparsity
Joly, Arnaud ULg

Doctoral thesis (2017)

Within machine learning, the supervised learning field aims at modeling the input-output relationship of a system, from past observations of its behavior. Decision trees characterize the input-output ... [more ▼]

Within machine learning, the supervised learning field aims at modeling the input-output relationship of a system, from past observations of its behavior. Decision trees characterize the input-output relationship through a series of nested ``if-then-else'' questions, the testing nodes, leading to a set of predictions, the leaf nodes. Several of such trees are often combined together for state-of-the-art performance: random forest ensembles average the predictions of randomized decision trees trained independently in parallel, while tree boosting ensembles train decision trees sequentially to refine the predictions made by the previous ones. The emergence of new applications requires scalable supervised learning algorithms in terms of computational power and memory space with respect to the number of inputs, outputs, and observations without sacrificing accuracy. In this thesis, we identify three main areas where decision tree methods could be improved for which we provide and evaluate original algorithmic solutions: (i) learning over high dimensional output spaces, (ii) learning with large sample datasets and stringent memory constraints at prediction time and (iii) learning over high dimensional sparse input spaces. A first approach to solve learning tasks with a high dimensional output space, called binary relevance or single target, is to train one decision tree ensemble per output. However, it completely neglects the potential correlations existing between the outputs. An alternative approach called multi-output decision trees fits a single decision tree ensemble targeting simultaneously all the outputs, assuming that all outputs are correlated. Nevertheless, both approaches have (i) exactly the same computational complexity and (ii) target extreme output correlation structures. In our first contribution, we show how to combine random projection of the output space, a dimensionality reduction method, with the random forest algorithm decreasing the learning time complexity. The accuracy is preserved, and may even be improved by reaching a different bias-variance tradeoff. In our second contribution, we first formally adapt the gradient boosting ensemble method to multi-output supervised learning tasks such as multi-output regression and multi-label classification. We then propose to combine single random projections of the output space with gradient boosting on such tasks to adapt automatically to the output correlation structure. The random forest algorithm often generates large ensembles of complex models thanks to the availability of a large number of observations. However, the space complexity of such models, proportional to their total number of nodes, is often prohibitive, and therefore these modes are not well suited under stringent memory constraints at prediction time. In our third contribution, we propose to compress these ensembles by solving a L1-based regularization problem over the set of indicator functions defined by all their nodes. Some supervised learning tasks have a high dimensional but sparse input space, where each observation has only a few of the input variables that have non zero values. Standard decision tree implementations are not well adapted to treat sparse input spaces, unlike other supervised learning techniques such as support vector machines or linear models. In our fourth contribution, we show how to exploit algorithmically the input space sparsity within decision tree methods. Our implementation yields a significant speed up both on synthetic and real datasets, while leading to exactly the same model. It also reduces the required memory to grow such models by exploiting sparse instead of dense memory storage for the input matrix. [less ▲]

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See detailSemper Incertus: Authorization through Uncertainty in Hanif Kureishi’s My Ear at His Heart: Reading my Father
Munos, Delphine ULg

Conference (2017, March 02)

In Postcolonial Writers in the Global Literary Marketplace (2007), Sarah Brouillette discusses “the centrality of questions of biography in reception of postcolonial texts” (173). She argues that, as ... [more ▼]

In Postcolonial Writers in the Global Literary Marketplace (2007), Sarah Brouillette discusses “the centrality of questions of biography in reception of postcolonial texts” (173). She argues that, as against “the supposed dominant orthodoxy of anti-authorialism in literary studies” (173), successful marketing of postcolonial literature depends on – indeed requires – “biographical authenticity” so that postcolonial writers can figure valid interpreters of an authenticated location for an Anglo-American audience “schooled in multiculturalism.” Brouillette’s perception that the marketing of postcolonial writing depends on the coincidence between literary material and the biographical self of its author raises fascinating questions when it comes to examining ‘postcolonial’ biographies and autobiographies already relying on a “referential pact” (cf. Lejeune) because of their generic anatomy. Biographical fiction, then is a postcolonial nightmare come true, as the specificities of the genre endlessly displace the demand for “biographical authenticity” that is seen by Brouillette to condition the niche marketing of postcolonial literature. This paper looks at Hanif Kureishi’s My Ear at His Heart: Reading My Father (2004), in which the popular British Asian author narrativizes his ambivalent relationship with his father and retraces his father’s life from British India to the UK of the 1960s and 1970s. What is interesting is that Kureishi both relies on memory and on two unpublished ‘fictional’ texts by his late father to reconstruct the latter’s life, thus “imagining around [others’] imagination” (2004: 238), as he phrases it, that is, embracing fiction – not only memory – as a valid starting point for representing the life of his father. Susie Thomas writes that “It is a major irony that Kureishi, as a reader, approaches his father’s novels in a way that he would doubtless object to if his own fiction were raided for its autobiographical content” (2006: 189). My claim is that this “major irony” becomes a means, for Kureishi, of authorizing himself a place outside the ‘British Asian ghetto’ by playing up to the expectations of postcolonial niche marketing. [less ▲]

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See detailPouvoir politique et audace des juges
Grandjean, Geoffrey ULg

in Revue de la Faculté de Droit de l'Université de Liège (2017), (1), 231-237

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See detailLes peuplements à bouleau en forêt wallonne: reflet de la sylviculture du 20ème siècle
Dubois, Héloïse ULg; Latte, Nicolas ULg; Claessens, Hugues ULg

in FORÊT.NATURE (2017), 142

Le bouleau est présent sous des formes diverses dans nos forêts. La place qu’il occupe en forêt wallonne est souvent le reflet d’une méconnaissance et du peu d’estime que lui portaient les sylviculteurs ... [more ▼]

Le bouleau est présent sous des formes diverses dans nos forêts. La place qu’il occupe en forêt wallonne est souvent le reflet d’une méconnaissance et du peu d’estime que lui portaient les sylviculteurs. Par une typologie des peuplements, l’article fait le tri parmi les contextes où se trouve le bouleau et discute de leurs potentialités sylvicoles dans un contexte changeant qui pourrait faire la part belle à cette essence vigoureuse et aux atouts variés. [less ▲]

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See detailBioavailability enhancement of itraconazole-based solid dispersions produced by hot melt extrusion in the framework of the Three Rs rule
Thiry, Justine ULg; Kok, Miranda ULg; Collard, Laurence ULg et al

in European Journal of Pharmaceutical Sciences (2017), 99

Solid dispersion formulations made of itraconazole (ITZ) and Soluplus® (polyethylene glycol, polyvinyl acetate and polyvinylcaprolactame-based graft copolymer abbreviated SOL) were produced using hot melt ... [more ▼]

Solid dispersion formulations made of itraconazole (ITZ) and Soluplus® (polyethylene glycol, polyvinyl acetate and polyvinylcaprolactame-based graft copolymer abbreviated SOL) were produced using hot melt extrusion. Since ITZ possesses a water solubility of less than 1 ng/mL, the aim of this work was to enhance the aqueous solubility of ITZ, and thereby improve its bioavailability. The three formulations consisted of a simple SOL/ITZ amorphous solid dispersion (ASD), an optimized SOL/ITZ/AcDiSol® (super-disintegrant) ASD and an equimolar inclusion complex of ITZ in hydroxypropyl-β-cyclodextrin (substitution degree = 0.63, CD) with SOL. The three formulations were compared in vitro and in vivo to the marketed product Sporanox®. The in vitro enhancement of dissolution rate was evaluated using a biphasic dissolution test. In vitro dissolution results showed that all three formulations had a higher percentage of ITZ released than Sporanox® with the following ranking: SOL/ITZ/CD > SOL/ITZ/AcDiSol® > SOL/ITZ > Sporanox®. The bioavailability of these four formulations was evaluated in rats. The bioanalytical method was optimized so that only 10 μL of blood was withdrawn from the rats using specific volumetric absorptive microsampling devices. This enabled to keep the same rats during the whole study, which was in accordance with the Three Rs rules (reduction, refinement and replacement). Furthermore, this technique allowed the suppression of inter-individual variability. Higher Cmax and AUC were obtained after the administration of all three formulations compared to the levels after the use of Sporanox® as follows: SOL/ITZ/AcDiSol® > SOL/ITZ/CD > SOL/ITZ > Sporanox®. The inversion in the ranking between SOL/ITZ/CD and SOL/ITZ/AcDiSol® made impossible the establishment of an in vitro–vivo correlation. Indeed, very different release rates were obtained in vitro and in vivo for the two optimized formulations. These results suggest that ITZ would be protected inside the core of the SOL micelles even during the absorption step at the intestine, while some agents present in the intestinal fluids could displace ITZ from the hydrophobic cavity of CD by competition. [less ▲]

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See detailCycle, cercle, compilation : le manuscrit Paris, BnF, fr. 12791
Lambert, Adélaïde ULg

Scientific conference (2017, March 01)

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See detailLes violences dans les relations amoureuses et dans les couples
Glowacz, Fabienne ULg

Scientific conference (2017, March 01)

Detailed reference viewed: 10 (0 ULg)
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See detailH0LiCOW - V. New COSMOGRAIL time delays of HE 0435-1223: H0 to 3.8 per cent precision from strong lensing in a flat ΛCDM model
Bonvin, V.; Courbin, F.; Suyu, S. H. et al

in Monthly Notices of the Royal Astronomical Society (2017), 465

We present a new measurement of the Hubble Constant H[SUB]0[/SUB] and other cosmological parameters based on the joint analysis of three multiply imaged quasar systems with measured gravitational time ... [more ▼]

We present a new measurement of the Hubble Constant H[SUB]0[/SUB] and other cosmological parameters based on the joint analysis of three multiply imaged quasar systems with measured gravitational time delays. First, we measure the time delay of HE 0435-1223 from 13-yr light curves obtained as part of the COSMOGRAIL project. Companion papers detail the modelling of the main deflectors and line-of-sight effects, and how these data are combined to determine the time-delay distance of HE 0435-1223. Crucially, the measurements are carried out blindly with respect to cosmological parameters in order to avoid confirmation bias. We then combine the time-delay distance of HE 0435-1223 with previous measurements from systems B1608+656 and RXJ1131-1231 to create a Time Delay Strong Lensing probe (TDSL). In flat Λ cold dark matter (ΛCDM) with free matter and energy density, we find H[SUB]0[/SUB] =71.9^{+2.4}_{-3.0} {km s^{-1} Mpc^{-1}} and Ω _{Λ }=0.62^{+0.24}_{-0.35}. This measurement is completely independent of, and in agreement with, the local distance ladder measurements of H[SUB]0[/SUB]. We explore more general cosmological models combining TDSL with other probes, illustrating its power to break degeneracies inherent to other methods. The joint constraints from TDSL and Planck are H[SUB]0[/SUB] = 69.2_{-2.2}^{+1.4} {km s^{-1} Mpc^{-1}}, Ω _{Λ }=0.70_{-0.01}^{+0.01} and Ω _k=0.003_{-0.006}^{+0.004} in open ΛCDM and H[SUB]0[/SUB] =79.0_{-4.2}^{+4.4} {km s^{-1} Mpc^{-1}}, Ω _de=0.77_{-0.03}^{+0.02} and w=-1.38_{-0.16}^{+0.14} in flat wCDM. In combination with Planck and baryon acoustic oscillation data, when relaxing the constraints on the numbers of relativistic species we find N[SUB]eff[/SUB] = 3.34_{-0.21}^{+0.21} in N[SUB]eff[/SUB]ΛCDM and when relaxing the total mass of neutrinos we find Σm[SUB]ν[/SUB] ≤ 0.182 eV in m[SUB]ν[/SUB]ΛCDM. Finally, in an open wCDM in combination with Planck and cosmic microwave background lensing, we find H[SUB]0[/SUB] =77.9_{-4.2}^{+5.0} {km s^{-1} Mpc^{-1}}, Ω _de=0.77_{-0.03}^{+0.03}, Ω _k=-0.003_{-0.004}^{+0.004} and w=-1.37_{-0.23}^{+0.18}. [less ▲]

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See detailH0LiCOW - IV. Lens mass model of HE 0435-1223 and blind measurement of its time-delay distance for cosmology
Wong, Kenneth C.; Suyu, Sherry H.; Auger, Matthew W. et al

in Monthly Notices of the Royal Astronomical Society (2017), 465

Strong gravitational lenses with measured time delays between the multiple images allow a direct measurement of the time-delay distance to the lens, and thus a measure of cosmological parameters ... [more ▼]

Strong gravitational lenses with measured time delays between the multiple images allow a direct measurement of the time-delay distance to the lens, and thus a measure of cosmological parameters, particularly the Hubble constant, H[SUB]0[/SUB]. We present a blind lens model analysis of the quadruply imaged quasar lens HE 0435-1223 using deep Hubble Space Telescope imaging, updated time-delay measurements from the COSmological MOnitoring of GRAvItational Lenses (COSMOGRAIL), a measurement of the velocity dispersion of the lens galaxy based on Keck data, and a characterization of the mass distribution along the line of sight. HE 0435-1223 is the third lens analysed as a part of the H[SUB]0[/SUB] Lenses in COSMOGRAIL's Wellspring (H0LiCOW) project. We account for various sources of systematic uncertainty, including the detailed treatment of nearby perturbers, the parametrization of the galaxy light and mass profile, and the regions used for lens modelling. We constrain the effective time-delay distance to be D_{Δ t}= 2612_{-191}^{+208} Mpc, a precision of 7.6 per cent. From HE 0435-1223 alone, we infer a Hubble constant of H[SUB]0[/SUB] = 73.1_{-6.0}^{+5.7} km s^{-1 Mpc^{-1}} assuming a flat ΛCDM cosmology. The cosmographic inference based on the three lenses analysed by H0LiCOW to date is presented in a companion paper (H0LiCOW Paper V). [less ▲]

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See detailH0LiCOW. VI. Testing the fidelity of lensed quasar host galaxy reconstruction
Ding, Xuheng; Liao, Kai; Treu, Tommaso et al

in Monthly Notices of the Royal Astronomical Society (2017), 465

The empirical correlation between the mass of a supermassive black hole (M_BH) and its host galaxy properties is widely considered to be an evidence of their co-evolution. A powerful way to test the co ... [more ▼]

The empirical correlation between the mass of a supermassive black hole (M_BH) and its host galaxy properties is widely considered to be an evidence of their co-evolution. A powerful way to test the co-evolution scenario and learn about the feedback processes linking galaxies and nuclear activity is to measure these correlations as a function of redshift. Unfortunately, currently M_BH can only be estimated in active galaxies at cosmological distances. At these distances, bright active galactic nuclei (AGNs) can outshine the host galaxy, making it extremely difficult to measure the host's luminosity. Strongly lensed AGNs provide in principle a great opportunity to improve the sensitivity and accuracy of the host galaxy luminosity measurements as the host galaxy is magnified and more easily separated from the point source, provided the lens model is sufficiently accurate. In order to measure the M_BH-L correlation with strong lensing, it is necessary to ensure that the lens modelling is accurate, and that the host galaxy luminosity can be recovered to at least a precision and accuracy better than that of the typical M_BH measurement. We carry out extensive and realistic simulations of deep Hubble Space Telescope observations of lensed AGNs obtained by our collaboration. We show that the host galaxy luminosity can be recovered with better accuracy and precision than the typical uncertainty in M_BH(˜0.5 dex) for hosts as faint as 2-4 mag dimmer than the AGN itself. Our simulations will be used to estimate bias and uncertainties in the actual measurements to be presented in a future paper. [less ▲]

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See detailLacustrine clay mineral assemblages as a proxy for land-use and climate changes over the last 4 kyr: The Amik Lake case study, Southern Turkey
El Ouahabi, Meriam ULg; Hubert, Aurelia ULg; Fagel, Nathalie ULg

in Quaternary International (2017), 1/15

Lake sediments are sensitive to landscape changes and most of these changes seem to be modulated by land-use (anthropogenic factors) coupled to palaeoenvironmental/palaeoclimatic changes. In its detrital ... [more ▼]

Lake sediments are sensitive to landscape changes and most of these changes seem to be modulated by land-use (anthropogenic factors) coupled to palaeoenvironmental/palaeoclimatic changes. In its detrital fraction, the lacustrine sediments record the history of soil erosion within its catchment via the inputs of clays and others detrital products. Within a Mediterranean context, the study investigates the upper sediments infilling the central part of the Amik basin in southern Turkey. This tectonic basin was occupied and exploited by modern human at least since 6000-7000 BC. We focus on the clay mineralogy (x-ray diffraction on oriented aggregates) and magnetic susceptibility measurements (Bartington) of the sedimentary record in the area over the last 4000 years, to assess environmental changes in relation with the different land uses and/or weathering during the successive Bronze, Iron, Roman, Islamic/Ottoman and Modern civilizations. The clay fraction of Amik Lake sediments comprises smectite, kaolinite, illite, chlorite and chlorite/smectite mixed layers that are the inherited clay phases. A relative change in abundance and crystallinity and chemistry of illite attests that environmental conditions evolved in the Amik Plain from the Bronze to Modern Age in relation with climates and/or land-use changes. The history of the Amik Lake reveals different soil erosion episode. The most intense erosion phase occurred during the Bronze/Iron Ages as indicated by the clay and magnetic susceptibility proxies. The Roman period was an exceptional period with soil erosion products arriving from the watershed, probably due the water channelization. A reduction of soil erosion occurred during the post Roman period until nowadays. Significant pedogenesis transformations are evidenced, especially during the Islamic/Ottoman periods suggesting intense chemical weathering conditions related to climate change. [less ▲]

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