References of "2007"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailThe Computation of Equating Errors in International Surveys in Education
Monseur, Christian ULg; Berezner, Alla

in Journal of Applied Measurement (2007), 8(3), 323-35

Since the IEA's Third International Mathematics and Science Study, one of the major objectives of international surveys in education has been to report trends in achievement. The names of the two current ... [more ▼]

Since the IEA's Third International Mathematics and Science Study, one of the major objectives of international surveys in education has been to report trends in achievement. The names of the two current IEA surveys reflect this growing interest: Trends in International Mathematics and Science Study (TIMSS) and Progress in International Reading Literacy Study (PIRLS). Similarly a central concern of the OECD's PISA is with trends in outcomes over time. To facilitate trend analyses these studies link their tests using common item equating in conjunction with item response modelling methods. IEA and PISA policies differ in terms of reporting the error associated with trends. In IEA surveys, the standard errors of the trend estimates do not include the uncertainty associated with the linking step while PISA does include a linking error component in the standard errors of trend estimates. In other words, PISA implicitly acknowledges that trend estimates partly depend on the selected common items, while the IEA's surveys do not recognise this source of error. Failing to recognise the linking error leads to an underestimation of the standard errors and thus increases the Type I error rate, thereby resulting in reporting of significant changes in achievement when in fact these are not significant. The growing interest of policy makers in trend indicators and the impact of the evaluation of educational reforms appear to be incompatible with such underestimation. However, the procedure implemented by PISA raises a few issues about the underlying assumptions for the computation of the equating error. After a brief introduction, this paper will describe the procedure PISA implemented to compute the linking error. The underlying assumptions of this procedure will then be discussed. Finally an alternative method based on replication techniques will be presented, based on a simulation study and then applied to the PISA 2000 data. [less ▲]

Detailed reference viewed: 41 (0 ULg)
Full Text
Peer Reviewed
See detailImportance of intertidal sediment processes and porewater exchange on the water column biogeochemistry in a pristine mangrove creek (Ras Dege, Tanzania)
Bouillon, Steven; Middelburg, Jack J.; Dehairs, Frank et al

in Biogeosciences (2007), 4

We sampled a tidal creek (Ras Dege, Tanzania) during a 24-h cycle to document the variations in a suite of creek water column characteristics and to determine the relative influence of tidal and ... [more ▼]

We sampled a tidal creek (Ras Dege, Tanzania) during a 24-h cycle to document the variations in a suite of creek water column characteristics and to determine the relative influence of tidal and biological driving forces. Since the creek has no upstream freshwater inputs, highest salinity was observed at low tide, due to evaporation effects and porewater seepage. Total suspended matter (TSM) and particulate organic carbon (POC) showed distinct maxima at periods of highest water flow, indicating that erosion of surface sediments and/or resuspension of bottom sediments were an important source of particulate material. Dissolved organic carbon (DOC), in contrast, varied in phase with water height and was highest at low tide. Stable isotope data of POC and DOC displayed large variations in both pools, and similarly followed the variations in water height. Although the variation of 13CDOC (−23.8 to −13.8‰) was higher than that of 13CPOC (−26.2 to −20.5‰), due to the different endmember pool sizes, the 13C signatures of both pools differed only slightly at low tide, but up to 9‰ at high tide. Thus, at low tide both DOC and POC originated from mangrove production. At high tide, however, the DOC pool had signatures consistent with a high contribution of seagrass-derived material, whereas the POC pool was dominated by marine phytoplankton. Daily variations in CH4, and partial pressure of CO2 (pCO2) were similarly governed by tidal influence and were up to 7- and 10-fold higher at low tide, which stresses the importance of exchange of porewater and diffusive fluxes to the water column. When assuming that the high dissolved inorganic carbon (DIC) levels in the upper parts of the creek (i.e. at low tide) are due to inputs from mineralization, 13C data on DIC indicate that the organic matter source for mineralization had a signature of −22.4‰. Hence, imported POC and DOC from the marine environment contributes strongly to overall mineralization within the mangrove system. Our data demonstrate how biogeochemical processes in the intertidal zone appear to be prominent drivers of element concentrations and isotope signatures in the water column, and how pathways of dissolved and particulate matter transport are fundamentally different. [less ▲]

Detailed reference viewed: 39 (8 ULg)
Peer Reviewed
See detailLocked-in syndrome et états de conscience altérée: comment détecter la conscience?
Vanhaudenhuyse, Audrey ULg

in Pellas, Frederique; Kiefer; Weiss (Eds.) et al Entretiens de Médecine Physique et de Réadaptation (2007)

Detailed reference viewed: 2 (0 ULg)
See detailL'approche neuropsychologique: un autre regard sur les troubles des apprentissages chez l'enfant
Catale, Corinne ULg

Conference given outside the academic context (2007)

Detailed reference viewed: 17 (6 ULg)
Full Text
Peer Reviewed
See detailA type II-collagen derived peptide and its nitrated form as new markers of inflammation and cartilage degradation in equine osteochondral lesions.
Gangl, Monika; Deberg, Michelle ULg; Lejeune, Jean-Philippe ULg et al

in Research in Veterinary Science (2007), 82

Markers of cartilage breakdown enable studying the degradation of cartilage matrix in equine joint pathologies. This study was designed to determine the levels of Coll2-1, a peptide of the triple helix of ... [more ▼]

Markers of cartilage breakdown enable studying the degradation of cartilage matrix in equine joint pathologies. This study was designed to determine the levels of Coll2-1, a peptide of the triple helix of type II collagen, and Coll2-1NO(2), its nitrated form in the plasma of healthy horses (controls; n=37) and horses suffering from osteochondrosis (n=34). Clinical and arthroscopic scores were attributed reflecting the severity of lesions and were related to the plasma levels of Coll2-1 and Coll2-1NO(2). The median of Coll2-1 was significantly higher in the control group, whereas the mean of Coll2-1NO(2) showed significant elevation in the pathological group. However, the measurement means of scoring classes did not vary significantly. The markers were able to differentiate the group of horses suffering from osteochondrosis from the group of healthy horses. The elevation of Coll2-1NO(2) in the pathological group indicates an inflammation, mediated through reactive oxygen species and/or increased myeloperoxidase activity. [less ▲]

Detailed reference viewed: 35 (5 ULg)
See detailHousehod dynamics and the well-beeing after partnership dissolution
Bould, S.; Hartmann, P.; Schmaus, G. et al

Conference (2007)

Detailed reference viewed: 7 (0 ULg)
Full Text
Peer Reviewed
See detailGenetic diversity and joint-pedigree analysis of two importing Holstein populations.
Hammami, Hedi ULg; Croquet, Coraline; Stoll, Jean et al

in Journal of Dairy Science (2007), 90(7), 3530-41

Genetic diversity and relatedness between 2 geographically distant Holstein populations (in Luxembourg and Tunisia) were studied by pedigree analysis. These 2 populations have similar sizes and structures ... [more ▼]

Genetic diversity and relatedness between 2 geographically distant Holstein populations (in Luxembourg and Tunisia) were studied by pedigree analysis. These 2 populations have similar sizes and structures and are essentially importing populations. Edited pedigrees included 140,392 and 151,381 animals for Tunisia and Luxembourg, respectively. To partially account for pedigree completeness levels, a modified algorithm was used to compute inbreeding. The effective numbers of ancestors were derived from probabilities of gene origin for the 2 populations of cows born between 1990 and 2000. The 10 ancestors with the highest contributions to genetic diversity in the cow populations accounted for more than 32% of the genes. Eight of these 10 ancestors were the same in both populations. The rates of inbreeding were different in the 2 populations but were generally comparable to those found in the literature for the Holstein breed. Average inbreeding coefficients per year, estimated from the data, ranged from 0.91 and 0.50 in 1990 to 3.10 and 2.12 in 2000 for the Tunisian and Luxembourg populations, respectively. Genetic links have also strengthened with time. Average additive relationships between the 2 populations were as high as 2.2% in 2000. Results suggest that it would be possible to investigate genotype by environment interactions for milk traits using the Tunisian and Luxembourg dairy populations. [less ▲]

Detailed reference viewed: 60 (10 ULg)
Peer Reviewed
See detailVeszelyite: A New Blue-Green Maya Pigment
Garcia Moreno, Renata; Mathis, François ULg; Strivay, David ULg

Poster (2007)

Detailed reference viewed: 35 (1 ULg)
Full Text
Peer Reviewed
See detailOptimisation of extraction of phenolics and antioxidants from black currant leaves and buds and of stability during storage
Tabart, Jessica ULg; Kevers, Claire ULg; Sipel, Arnaud ULg et al

in Food Chemistry (2007), 105(3), 1268-1275

Health benefits of a diet rich in fruits and vegetables are attributed in part to their contents of phenolics and other antioxidant compounds. In this research, the extraction of phenolics and antioxidant ... [more ▼]

Health benefits of a diet rich in fruits and vegetables are attributed in part to their contents of phenolics and other antioxidant compounds. In this research, the extraction of phenolics and antioxidant compounds from black currant was optimised for different plant organs. The extraction solvent affected yield: aqueous acetone was better than methanol and acetate or glycine buffer. In aqueous buffer, maximum yields of total phenolics and antioxidant activities were obtained at pH 3. Extraction from lyophilised materials yielded extracts with higher phenolic contents and antioxidant activities. Stability of extracts made with acetate or glycine buffer was limited while the use of a mixture of acetone/acetic acid/water for extraction allowed a high phenolic content and antioxidant capacity in dry extract to be maintained for several months. This type of extract could be incorporated in functional food, beverage or dietary supplement. (c) 2007 Elsevier Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 83 (10 ULg)
Full Text
See detailLast two Millennia atmospheric lead and heavy metals inputs in a Belgian peat bog: regional to global Human impacts
De Vleeschouwer; Gerard; Goormaghtigh et al

Poster (2007)

Detailed reference viewed: 5 (0 ULg)
Full Text
Peer Reviewed
See detailCytogenetics of a new trispecies hybrid In cotton: [(Gossypium Hirsutum L. X G-Thurberi Tod.)(2) X G-Longicalyx Hutch. & Lee]
Konan, On.; D'Hont, A.; Baudoin, Jean-Pierre ULg et al

in Plant Breeding (2007), 126(2), 176-181

Detailed reference viewed: 33 (6 ULg)
See detailLa situation économique de la culture des céréales en Belgique
Burny, Philippe ULg

Conference (2007)

Detailed reference viewed: 2 (0 ULg)
Full Text
See detailZéro
Durand, Pascal ULg

in Durand, Pascal (Ed.) Les Nouveaux Mots du Pouvoir. Abécédaire critique (2007)

Detailed reference viewed: 30 (5 ULg)
Full Text
Peer Reviewed
See detailOrientation and Order of Self-Assembled p-Benzenedimethanethiol Films on Pt(111) Obtained by Direct Adsorption and via Alkanethiol Displacement
Silien, Christophe; Dreesen, Laurent ULg; Cecchet, Francesca et al

in Journal of Physical Chemistry C: Nanomaterials, Interfaces, and Hard Matter (2007), 111

Self-assembly of p-benzenedimethanethiol (p-BDMT) on Pt(111) has been investigated by high-resolution electron energy loss spectroscopy and sum-frequency generation spectroscopy. The molecules adsorb on ... [more ▼]

Self-assembly of p-benzenedimethanethiol (p-BDMT) on Pt(111) has been investigated by high-resolution electron energy loss spectroscopy and sum-frequency generation spectroscopy. The molecules adsorb on Pt-(111) like on gold, attached through one single thiol, leaving the second thiol moiety unreacted and exposed to the outer surface. Yet, the order of the p-BDMT self-assembled film is poor in comparison to alkanethiol SAMs. Displacement in solution of a preadsorbed pentanethiol (PTT) SAM by p-BDMT molecules proved to be a successful approach to achieve films of higher quality, where the size of the dithiol molecular domains tends toward the size measured for PTT. Nearly complete exchange is accomplished after 42 h. However, no significant exchange is observed when dodecanethiol replaces PTT. Displacing the alkanethiols by benzenethiol leads to the same conclusions, suggesting that the exchange processes are lessened as compared to gold. [less ▲]

Detailed reference viewed: 18 (1 ULg)
Full Text
Peer Reviewed
See detailTransport of the leaderless protein Ku on the cell surface of activated monocytes regulates their migratory abilities.
Paupert, Jenny ULg; Dauvillier, Stephanie; Salles, Bernard et al

in EMBO reports (2007), 8(6), 583-8

Recent evidence shows that the DNA repair protein Ku is expressed on the surface of a subset of cells, where it contributes to adhesion and invasion processes, and also to viral or bacterial entry into ... [more ▼]

Recent evidence shows that the DNA repair protein Ku is expressed on the surface of a subset of cells, where it contributes to adhesion and invasion processes, and also to viral or bacterial entry into target cells. Here, we show that Ku was expressed on the cell surface during activation of human monocytes and that its expression was independent of the conventional endoplasmic reticulum (ER)/Golgi secretory pathway. Ku inhibition, by blocking antibodies, decreases the migration of monocytes on fibronectin and laminin. On activation, nuclear Ku seems to move to the periphery of the cell and it shows a punctuate staining in the cytoplasm. The cytoplasmic distribution of Ku was shown to be unaltered by brefeldin A. Protease protection experiments show that Ku is contained within vesicles in activated monocytes. These data support a new role for Ku in the migration of monocytes into tissues, which depends on a tightly regulated pathway of intracellular redistribution. [less ▲]

Detailed reference viewed: 7 (0 ULg)
Full Text
Peer Reviewed
See detailNumerical simulation of the fluid-structure interaction between air blast waves and free-standing plates
Kambouchev, Nayden; Noels, Ludovic ULg; Radovitzky, Raúl

in Computers & Structures (2007), 85(nov-14 Sp. Iss. SI), 923931

A numerical method is used to compute the flow field corresponding to blast waves of different incident profiles propagating in air and impinging on free-standing plates. The method is suitable for the ... [more ▼]

A numerical method is used to compute the flow field corresponding to blast waves of different incident profiles propagating in air and impinging on free-standing plates. The method is suitable for the consideration of compressibility effects in the fluid and their influence on the plate dynamics. The history of the pressure experienced by the plate is extracted from numerical simulations for arbitrary blast strengths and plate masses and used to infer the impulse per unit area transmitted to the plate. The numerical results complement some recent analytical solutions in the intermediate range of plate masses and arbitrary blast intensities where exact solutions are not available. The resulting beneficial effect of the fluid-structure interaction (FSI) in reducing transmitted impulse in the presence of compressibility effects is discussed. In particular, it is shown that in order to take advantage of the impulse reduction provided by the FSI effect, large plate displacements are required which, in effect, may limit the practical applicability of exploiting FSI effects in the design of blast-mitigating systems. (C) 2006 Elsevier Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 96 (6 ULg)
Full Text
Peer Reviewed
See detailLes ondes gravitationnelles
De Rop, Yves ULg

in Revue des Questions Scientifiques (2007), 178(1), 113-138

Detailed reference viewed: 45 (5 ULg)
Full Text
Peer Reviewed
See detailResidual doses in recent alluvial sediments from the ardenne (S Belgium)
Vandenberghe, D.; Derese, C.; Houbrechts, Geoffrey ULg

in Geochronometria (2007), 28

We report on our first investigations into the potential of optical dating for determining the rate of river flood sedimentation in the Ardenne region (S Belgium). Two samples collected from a recent ... [more ▼]

We report on our first investigations into the potential of optical dating for determining the rate of river flood sedimentation in the Ardenne region (S Belgium). Two samples collected from a recent alluvial deposit were used to investigate the extent of resetting in different particle size fractions of quartz (4-11 mu m, 63-90 mu m, 90-125 mu m, 125-180 mu m, 180-212 mu m and 212-250 mu m) as well as in polymineral fine (4-11 mu m) grains. Both samples show satisfactory OSL and IRSL characteristics. The IRSL signals from the polymineral fine grains yield an equivalent dose (D-e) of 3-4 Gy, while a D-e of 0.3-0.6 Gy was measured using large aliquots of quartz. Small aliquot analyses of 63-90 mu m and 212-250 mu m quartz grains confirm that the coarser fraction contains more grains with lower D-e's. Furthermore, for a modern sample (< 3 years old), similar to 60% of the aliquots yields a D-e consistent with zero, indicating that these contain only well-bleached grains. These findings suggest that it might be possible to extract the true burial dose from dose distributions measured using small aliquots of coarse-grained (e.g. 212-250 mu m) quartz. [less ▲]

Detailed reference viewed: 17 (7 ULg)
Full Text
Peer Reviewed
See detailOptimization of superconducting critical parameters by tuning the size and magnetization of arrays of magnetic dots
Silhanek, Alejandro ULg; Gillijns, W.; Milosevic, M. V. et al

in Physical Review. B, Condensed Matter and Materials Physics (2007), 76(10),

We investigate the nucleation of superconductivity in an Al film deposited on top of an array of micromagnets with perpendicular anisotropy by dc transport measurements. The absolute control of the ... [more ▼]

We investigate the nucleation of superconductivity in an Al film deposited on top of an array of micromagnets with perpendicular anisotropy by dc transport measurements. The absolute control of the magnetic state of the ferromagnets enabled us to explore the superconductor-normal-metal phase boundary as a function of the magnetization M of the dots. For a given external homogeneous field H, the magnetization of the dots can be tuned in such a way to optimize the field and current compensation in the sample, thus yielding a clear enhancement of the upper critical field H-c2. In addition, we theoretically demonstrate that the critical current I-c for a given temperature could be further enhanced by properly adjusting the size of the magnetic dots. These results are fully corroborated by the Ginzburg-Landau theory as well as analytic estimates. [less ▲]

Detailed reference viewed: 5 (0 ULg)