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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)

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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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See detailPhotosynthetic trichomes contain a specific Rubisco with a modified pH9 dependent activity
Laterre, Raphaëlle; Pottier, Mathieu; Remacle, Claire ULg et al

in Plant Physiology (2017)

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See detailPhotonic photoanode for macroporous perovskite solar cells
Baron, Damien ULg; Dewalque, Jennifer ULg; Henrist, Catherine ULg et al

Poster (2017, March 01)

Organic-inorganic metal halide perovskite solar cells (PSCs) have reached power conversion efficiencies over 20%. Two archetypal PSC architectures are reported in the literature: mesoporous and planar ... [more ▼]

Organic-inorganic metal halide perovskite solar cells (PSCs) have reached power conversion efficiencies over 20%. Two archetypal PSC architectures are reported in the literature: mesoporous and planar PSCs. In the former one, a mesoporous TiO2 scaffold is incorporated into the cell. Because sizes of the mesopores are typically small compared to wavelengths of visible light, the scaffold barely scatters light. In this work, we propose to periodically structure a porous TiO2 scaffold incorporating pores with diameters comparable to wavelengths of visible light thanks to the use of colloidal crystal templating fabrication method. The resulting TiO2 scaffold filled with perovskite will constitute an opal-like photonic crystal incorporated in the solar cell, which will strongly interact with light. Through Finite Difference Time Domain (FDTD) simulations, we demonstrate that the photonic crystal induces resonances that can be exploited to modulate light harvesting in the macroporous TiO2 layer. Sunlight absorption by the PSC will be presented and discussed with dependency of pore sizes and number of opal layers. [less ▲]

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See detailInverse opal photoanodes: preparation and optical properties
Dewalque, Jennifer ULg; Spronck, Gilles ULg; Baron, Damien ULg et al

Conference (2017, March 01)

Perovskite compounds, used either in mesoscopic or planar solar cells, have allowed preparing highly efficient solid-state devices (>20%). In this study, we propose to design photoanodes with photonic ... [more ▼]

Perovskite compounds, used either in mesoscopic or planar solar cells, have allowed preparing highly efficient solid-state devices (>20%). In this study, we propose to design photoanodes with photonic structure in order to modulate light interaction. The periodic structure of porosity could add specific optical properties likely to increase light harvesting and reduce reflexion losses. Besides, current efficiencies reported for mesoscopic perovskite solar cells using an inorganic porous scaffold are slightly lower than those reported for planar perovskite cells mainly due to issues in perovskite infiltration. The control of the porous network architecture in terms of pore organization, size and connectivity could overcome this limitation. TiO2/perovskite and perovskite-only photoanodes with an inverse opal porous structure are prepared from templating techniques, using polystyrene beads as structuring agent. The photoanode microstructure is further characterized by scanning electron microscopy (SEM) and X-Ray diffraction (XRD). In parallel, light interaction is modeled in order to find the best compromise in terms of photonic architecture (pore size, organization, thickness…). [less ▲]

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See detailWASP-South transiting exoplanets: WASP-130b, WASP-131b, WASP-132b, WASP-139b, WASP-140b, WASP-141b & WASP-142b
Hellier, Coel; Anderson, D. R.; Collier Cameron, A. et al

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

We describe seven new exoplanets transiting stars of V = 10.1 to 12.4. WASP-130b is a "warm Jupiter" having an orbital period of 11.6 d, the longest yet found by WASP. It transits a V = 11.1, G6 star with ... [more ▼]

We describe seven new exoplanets transiting stars of V = 10.1 to 12.4. WASP-130b is a "warm Jupiter" having an orbital period of 11.6 d, the longest yet found by WASP. It transits a V = 11.1, G6 star with [Fe/H] = +0.26. Warm Jupiters tend to have smaller radii than hot Jupiters, and WASP-130b is in line with this trend (1.23 Mjup; 0.89 Rjup). WASP-131b is a bloated Saturn-mass planet (0.27 Mjup; 1.22 Rjup). Its large scale height coupled with the V = 10.1 brightness of its host star make the planet a good target for atmospheric characterisation. WASP-132b is among the least irradiated and coolest of WASP planets, being in a 7.1-d orbit around a K4 star. It has a low mass and a modest radius (0.41 Mjup; 0.87 Rjup). The V = 12.4, [Fe/H] = +0.22 star shows a possible rotational modulation at 33 d. WASP-139b is the lowest-mass planet yet found by WASP, at 0.12 Mjup and 0.80 Rjup. It is a "super-Neptune" akin to HATS-7b and HATS-8b. It orbits a V = 12.4, [Fe/H] = +0.20, K0 star. The star appears to be anomalously dense, akin to HAT-P-11. WASP-140b is a 2.4-Mjup planet in a 2.2-d orbit that is both eccentric (e = 0.047) and with a grazing transit (b = 0.93) The timescale for tidal circularisation is likely to be the lowest of all known eccentric hot Jupiters. The planet's radius is large (1.4 Rjup), but uncertain owing to the grazing transit. The host star is a V = 11.1, [Fe/H] = +0.12, K0 dwarf showing a prominent 10.4-d rotational modulation. The dynamics of this system are worthy of further investigation. WASP-141b is a typical hot Jupiter, being a 2.7 Mjup, 1.2 Rjup planet in a 3.3-d orbit around a V = 12.4, [Fe/H] = +0.29, F9 star. WASP-142b is a typical bloated hot Jupiter (0.84 Mjup, 1.53 Rjup) in a 2.1-d orbit around a V = 12.3, [Fe/H] = +0.26, F8 star. [less ▲]

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See detailBioreducible cross-linked core polymer micelles enhance in vitro activity of methotrexate in breast cancer cells
Gulfam, Muhammad ULg; Matini, Teresa; Monteiro, Patrícia F et al

in Biomaterials Science (2017), 5(3), 532-550

Polymer micelles have emerged as promising carriers for controlled release applications, however, several limitations of micelle-based drug delivery have also been reported. To address these issues, we ... [more ▼]

Polymer micelles have emerged as promising carriers for controlled release applications, however, several limitations of micelle-based drug delivery have also been reported. To address these issues, we have synthesized a functional biodegradable and cytocompatible block copolymer based on methoxypoly (ethyleneglycol)-b-poly(ε-caprolactone-co-α-azido-ε-caprolactone) (mPEG-b-poly(εCL-co-αN3εCL)) as a precursor of reduction sensitive core-crosslinked micelles. The synthesized polymer was formulated as micelles using a dialysis method and loaded with the anti-inflammatory and anti-cancer drug metho- trexate (MTX). The micellar cores were subsequently crosslinked at their pendent azides by a redox- responsive bis(alkyne). The size distributions and morphology of the polymer micelles were assessed using dynamic light scattering (DLS) and transmission electron microscopy, and drug release assays were performed under simplified (serum free) physiological and reductive conditions. Cellular uptake studies in human breast cancer cells were performed using Oregon-green loaded core-crosslinked micelles. The MTX-loaded core-crosslinked micelles were assessed for their effects on metabolic activity in human breast cancer (MCF-7) cells by evaluating the reduction of the dye MTT 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide. The apoptosis inducing potential of MTX-loaded core-crosslinked micelles was analysed using Hoechst/propidium iodide (PI) and annexin-V/PI assays. The data from these experi- ments indicated that drug release from these cross-linked micelles can be controlled and that the redox- responsive micelles are more effective carriers for MTX than non-crosslinked analogues and the free drug in the cell-lines tested. [less ▲]

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See detailMagnetic reconnection during steady magnetospheric convection and other magnetospheric modes
Hubert, Benoît ULg; Gérard, Jean-Claude ULg; Milan, Steve E. et al

in Annales Geophysicae (2017), 35

We use remote sensing of the proton aurora with the IMAGE-FUV SI12 (Imager for Magnetopause to Aurora Global Exploration-Far Ultraviolet-Spectrographic Imaging at 121.8 nm) instrument and radar ... [more ▼]

We use remote sensing of the proton aurora with the IMAGE-FUV SI12 (Imager for Magnetopause to Aurora Global Exploration-Far Ultraviolet-Spectrographic Imaging at 121.8 nm) instrument and radar measurements of the ionospheric convection from the SuperDARN (Super Dual Aurora Radar Network) facility to estimate the open magnetic flux in the Earth's magnetosphere and the reconnection rates at the dayside magnetopause and in the magnetotail during intervals of steady magnetospheric convection (SMC). We find that SMC intervals occur with relatively high open magnetic flux (average ˜ 0.745 GWb, standard deviation ˜ 0.16 GWb), which is often found to be nearly steady, when the magnetic flux opening and closure rates approximately balance around 55 kV on average, with a standard deviation of 21 kV. We find that the residence timescale of open magnetic flux, defined as the ratio between the open magnetospheric flux and the flux closure rate, is roughly 4 h during SMCs. Interestingly, this number is approximately what can be deduced from the discussion of the length of the tail published by Dungey (1965), assuming a solar wind speed of ˜ 450 km s[SUP]-1[/SUP]. We also infer an enhanced convection velocity in the tail, driving open magnetic flux to the nightside reconnection site. We compare our results with previously published studies in order to identify different magnetospheric modes. These are ordered by increasing open magnetic flux and reconnection rate as quiet conditions, SMCs, substorms (with an important overlap between these last two) and sawtooth intervals. [less ▲]

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See detailLinking Forest Cover to Water Quality: A Multivariate Analysis of Large Monitoring Datasets
Brogna, Delphine; Michez, Adrien ULg; Jacobs, Sander et al

in Water (2017), 9(3), 176

Forested catchments are generally assumed to provide higher quality water. However, this hypothesis must be validated in various contexts as interactions between multiple land use and land cover (LULC ... [more ▼]

Forested catchments are generally assumed to provide higher quality water. However, this hypothesis must be validated in various contexts as interactions between multiple land use and land cover (LULC) types, ecological variables and water quality variables render this relationship highly complex. This paper applies a straightforward multivariate approach on a typical large monitoring dataset of a highly managed and densely populated area (Wallonia, Belgium; 10-year dataset), quantifying forest cover effects on nine physico-chemical water quality variables. Results show that forest cover explains about one third of the variability of water quality and is positively correlated with higher quality water. When controlling for spatial autocorrelation, forest cover still explains 9% of water quality. Unlike needle-leaved forest cover, broad-leaved forest cover presents an independent effect from ecological variables and explains independently 4.8% of water quality variability while it shares 5.8% with cropland cover. This study demonstrates clear independent effects of forest cover on water quality, and presents a method to tease out independent LULC effects from typical large multivariate monitoring datasets. Further research on explanatory variables, spatial distribution effects and water quality datasets could lead to effective strategies to mitigate pollution and reach legal targets. [less ▲]

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See detailTwo massive rocky planets transiting a K-dwarf 6.5 parsecs away
Gillon, Michaël ULg; Demory, Brice-Olivier; Van Grootel, Valérie ULg et al

in Nature Astronomy (2017), 1

HD 219134 is a K-dwarf star at a distance of 6.5 parsecs around which several low-mass planets were recently discovered[SUP]1,2[/SUP]. The Spitzer Space Telescope detected a transit of the innermost of ... [more ▼]

HD 219134 is a K-dwarf star at a distance of 6.5 parsecs around which several low-mass planets were recently discovered[SUP]1,2[/SUP]. The Spitzer Space Telescope detected a transit of the innermost of these planets, HD 219134 b, whose mass and radius (4.5 M[SUB]⊕[/SUB] and 1.6 R[SUB]⊕[/SUB] respectively) are consistent with a rocky composition[SUP]1[/SUP]. Here, we report new high-precision time-series photometry of the star acquired with Spitzer revealing that the second innermost planet of the system, HD 219134c, is also transiting. A global analysis of the Spitzer transit light curves and the most up-to-date HARPS-N velocity data set yields mass and radius estimations of 4.74 ± 0.19 M[SUB]⊕[/SUB] and 1.602 ± 0.055 R[SUB]⊕[/SUB] for HD 219134 b, and of 4.36 ± 0.22 M[SUB]⊕[/SUB] and 1.511 ± 0.047 R[SUB]⊕[/SUB] for HD 219134 c. These values suggest rocky compositions for both planets. Thanks to the proximity and the small size of their host star (0.778 ± 0.005 R[SUB]⊙[/SUB])[SUP]3[/SUP], these two transiting exoplanets — the nearest to the Earth yet found — are well suited for a detailed characterization (for example, precision of a few per cent on mass and radius, and constraints on the atmospheric properties) that could give important constraints on the nature and formation mechanism of the ubiquitous short-period planets of a few Earth masses. [less ▲]

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