Baffles design of the PROBA-V wide FOV TMA
Mazzoli, Alexandra ; ; Houbrechts, Yvette et al
in Proceedings of ICSO 2010 - International Conference on Space Optics (Rhodes 2010, October) (2010)
Proba-V payload is a successor of the Vegetation instrument, a multispectral imager flown on Spot-4 and subsequently on Spot-5, French satellites for Earth Observation and defence. The instrument, with ... [more ▼]
Proba-V payload is a successor of the Vegetation instrument, a multispectral imager flown on Spot-4 and subsequently on Spot-5, French satellites for Earth Observation and defence. The instrument, with its wide field of view, is capable of covering a swath of 2200 km, which, in combination with a polar low Earth orbit, guarantees a daily revisit. The lifetime of Spot-5 expires in early 2013, and to ensure the continuity of vegetation data, BELSPO, the Belgian Federal Science Policy Office, supported the development of an instrument that could be flown on a Proba type satellite, a small satellite developed by the Belgian QinetiQ Space (previously known as Verhaert Space). The challenge of this development is to produce an instrument responding to the same user requirements as Vegetation, but with an overall mass of about 30 kg, while the Vegetation instrument mass is 130 kg. This development had become feasible thanks to a number of new technologies that have been developed since the nineties, when Vegetation was first conceived, namely Single Point Diamond Turning fabrication of aspherical mirrors and efficient VNIR and SWIR detectors. The Proba-V payload is based on three identical reflective telescopes using highly aspherical mirrors in a TMA (Three Mirrors Anastigmat) configuration. Each telescope covers a field of view of 34o to reach the required swath. One of the challenges in the development of the PROBA-V instrument is the efficient reduction of stray light. Due to the mass and volume constraints it was not possible to implement a design with an intermediate focus to reduce the stray light. The analysis and minimization of the in-field stray light is an important element of the design because of the large FOV and the surface roughness currently achievable with the Single Point Diamond Turning. This document presents the preliminary baffle layout designed for the Three Mirrors Anastigmatic (TMA) telescope developed for the Proba-V mission. This baffling is used to avoid 1st order stray light i.e. direct stray light or through reflections on the mirrors. The stray light from the SWIR folding mirror is also studied. After these preliminary analyses the mechanical structure of the TMA is designed then verified in term of vignetting and stray light. [less ▲]Detailed reference viewed: 110 (2 ULg)
Self-heating of bulk high temperature superconductors of finite height subjected to a large alternating magnetic field
; Fagnard, Jean-François ; et al
in Superconductor Science and Technology (2010), 23
In this work we study, both experimentally and numerically, the self-heating of a bulk, large YBCO pellet of aspect ratio (thickness / diameter) ~ 0.4 subjected to a large AC magnetic field. To ensure ... [more ▼]
In this work we study, both experimentally and numerically, the self-heating of a bulk, large YBCO pellet of aspect ratio (thickness / diameter) ~ 0.4 subjected to a large AC magnetic field. To ensure accurate temperature measurements, the sample was placed in an experimental vacuum chamber to achieve a small and reproducible heat transfer coefficient between the superconductor and the cryogenic fluid. The temperature was measured at several locations on the sample surface during the self-heating process. The experimentally determined temperature gradients are found to be very small in this arrangement (< 0.2 K across the radius of the superconductor). The time-dependence of the average temperature T(t) is found to agree well with a theoretical prediction based on the one-dimensional (1-D) Bean model, assuming a uniform temperature in the sample. A 2-D magneto-thermal model was also used to determine the space and time-dependent temperature distribution T(r, z, t) during the application of the AC field. The losses in the bulk pellet were determined using an algorithm based on the numerical method of Brandt, which was combined with a heat diffusion algorithm implemented using a finite-difference method. The model is shown to be able to reproduce the main trends of the observed temperature evolution of the bulk sample during a self-heating process. Finally, the 2-D model is used to study the effect of a non-uniform distribution of critical current density Jc(r, z) on the losses within the bulk superconductor. [less ▲]Detailed reference viewed: 70 (40 ULg)
History effect of light and temperature on monoterpenoid emissions from Fagus sylvatica L.
; ; et al
in Atmospheric Environment (2010), 44(27), 3261-3268
Monoterpenoid emissions from Fagus sylvatica L trees have been measured at light- and temperature-controlled conditions in a growth chamber, using Proton Transfer Reaction Mass Spectrometry (PTR-MS) and ... [more ▼]
Monoterpenoid emissions from Fagus sylvatica L trees have been measured at light- and temperature-controlled conditions in a growth chamber, using Proton Transfer Reaction Mass Spectrometry (PTR-MS) and the dynamic branch enclosure technique. De novo synthesized monoterpenoid Standard Emission Factors, obtained by applying the G97 algorithm (Guenther, 1997), varied between 2 and 32 mu g g(-1)DW h(-1) and showed a strong decline in late August and September, probably due to senescence. The response of monoterpenoid emissions to temperature variations at a constant daily light pattern could be well reproduced with a modified version of the MEGAN algorithm (Guenther et al., 2006), with a typical dependence on the average temperature over the past five days. The diurnal emissions at constant temperature showed a typical hysteretic behaviour, which could also be adequately described with the modified MEGAN algorithm by taking into account a dependence on the average light levels experienced by the trees during the past 10-13 h. The impact of the past light and temperature conditions on the monoterpenoid emissions from E sylvatica L was found to be much stronger than assumed in previous algorithms. Since our experiments were conducted under low light intensity, future studies should aim at confirming and completing the proposed algorithm updates in sunny conditions and natural environments. (C) 2010 Elsevier Ltd. All rights reserved. [less ▲]Detailed reference viewed: 26 (3 ULg)
Development of the National Forest Inventory in Luxembourg
Rondeux, Jacques ;
in Tomppo, Erkki; Gschwantner, Thomas; Lawrence, Mark (Eds.) et al National Forest Inventories - Pathways for common reporting (2010)Detailed reference viewed: 22 (6 ULg)
Verbal Learning in Alzheimer’s disease and Mild Cognitive Impairment: neuroanatomic correlates of acquisition and consolidation performances
Genon, Sarah ; Collette, Fabienne ; et al
in Proceedings of the Annual Meeting of the Belgian Association for Psychological Sciences (2010)
The aim of this study was to examine correlations between impaired memory acquisition/consolidation and brain metabolism at rest in Alzheimer’s disease. 44 confirmed Alzheimer patients (AD), 16 patients ... [more ▼]
The aim of this study was to examine correlations between impaired memory acquisition/consolidation and brain metabolism at rest in Alzheimer’s disease. 44 confirmed Alzheimer patients (AD), 16 patients with mild cognitive impairment (MCI) who converted to AD (MCI-C) (4-8 years of follow-up), 15 MCI patients who remained stable and 12 healthy elderly controls were administered the California Verbal Learning Task (CVLT) at entry. Acquisition and consolidation memory scores were calculated respectively as mean gained and total lost access across the 5 study-test trials (p = 0.05). Brain metabolism was measured by 18FDG-PET. Cognitive-metabolic correlations were performed with SPM8 (p<0.05 uncorrected). Mean gained access was significantly lower in the AD group than in the control and MCI-S group and was significantly lower in the MCI-C group than in the control group. Mean gained access was significantly correlated to metabolism in the left precentral gyrus and IPS fondus in the control group, in the left and right inferior parietal lobules in the MCI-S group and in the left hippocampus in the AD group. Total lost access was greater in AD patients compared to control participants. No significant correlation between total lost access and brain metabolism was found. The acquisition process is impaired in AD patients at a very early stage of the disease (MCI-C). This deficit is linked to metabolic changes in a frontoparieto-hippocampal learning network. In addition, consolidation process is specifically impaired in confirmed AD patients, while this deficit was not significantly correlated to brain metabolism in our participant groups. [less ▲]Detailed reference viewed: 76 (1 ULg)
A propos des Parcours d'Etude et de Recherche : foire aux idées, foire aux "enseignements"
Conference (2010)Detailed reference viewed: 2 (0 ULg)
Marker imputation with low-density marker panels in Dutch Holstein cattle.
; Druet, Tom
in Journal of Dairy Science (2010), 93(11), 5487-94
The availability of high-density bovine genotyping arrays made implementation of genomic selection possible in dairy cattle. Development of low-density single nucleotide polymorphism (SNP) panels will ... [more ▼]
The availability of high-density bovine genotyping arrays made implementation of genomic selection possible in dairy cattle. Development of low-density single nucleotide polymorphism (SNP) panels will allow the extension of genomic selection to a larger portion of the population. Prediction of ungenotyped markers, called imputation, is a strategy that allows using the same low-density chips for all traits (and for different breeds). In the present study, we evaluated the accuracy of imputation with low-density genotyping arrays in the Dutch Holstein population. Five different sizes of genotyping arrays were tested, from 384 to 6,000 SNP. According to marker density, the overall allelic imputation error rate obtained with the program DAGPHASE, which relies on linkage disequilibrium and linkage, ranged from 11.7 to 2.0%, and that obtained with the program CHROMIBD, which relies on linkage and the set of all genotyped ancestors, ranged from 10.7 to 3.3%. However, imputation efficiency was influenced by the relationship between low-density and high-density genotyped animals. Animals with both parents genotyped had particularly low imputation error rates: <1% with 1,500 SNP or more. In summary, missing marker alleles can be predicted with 3 to 4% errors with approximately 1 SNP/Mb (approximately 3,000 markers). The CHROMIBD program proved more efficient than DAGPHASE only at lower marker densities or when several genotyped ancestors were available. Future studies are required to measure the effect of these imputation error rates on accuracy of genomic selection with low-density SNP panels. [less ▲]Detailed reference viewed: 28 (3 ULg)
review of Luke Sunderland, Old French Narrative Cycles. Heroism between Ethics and Morality
in Medioevo Romanzo (2010), 34(2), 440-442Detailed reference viewed: 7 (0 ULg)
NAVA enhances ventilatory variability and diaphragmaticactivity/tidal volume coupling
; ; Desaive, Thomas et al
in Intensive Care Medicine (2010), 36(2), 326-326Detailed reference viewed: 26 (2 ULg)
Il ciclo di Guiron le Courtois. Strutture e testi nella tradizione manoscritta
Book published by SISMEL - Edizioni del Galluzzo (2010)Detailed reference viewed: 29 (4 ULg)
The temporal use of French ‘à travers (de)’: metaphorical transfer or cancellation of the spatial sense?
Poster (2010)Detailed reference viewed: 10 (1 ULg)
The use of French ‘à travers (de)’ for describing a movement along a curved surface: peripheral membership or anomaly?
Conference (2010)Detailed reference viewed: 7 (0 ULg)
Validation of a new French-language triage algorithm : the ELISA scale.
Jobe, Jérôme ; Ghuysen, Alexandre ; et al
in Critical Care (2010), 14(Suppl1), 277Detailed reference viewed: 39 (14 ULg)
Bilan des connaissances sur les dommages piscicoles engendrés par les prises d'eau industrielles et les centrales hydroélectriques dans les cours d'eau de la Province de Liège.
Philippart, Jean-Claude ; Ovidio, Michaël ; Poncin, Pascal
Report (2010)Detailed reference viewed: 72 (16 ULg)
La “Cantata per la nascita del Delfino” di Vincenzo Monti e Domenico Cimarosa
in Quintili, Paolo (Ed.) Vivere tra città e campagna. I piaceri della Villa dal secolo XVIII al XXI (2010)Detailed reference viewed: 16 (0 ULg)
Functionalization of carbon xerogels for the preparation of Pd/C catalysts by grafting of Pd complex
; ; Job, Nathalie et al
in Studies in Surface Science and Catalysis (2010), 175Detailed reference viewed: 26 (1 ULg)
Génération de maillages éléments finis d’ordre élevé
Master's dissertation (2010)Detailed reference viewed: 16 (0 ULg)
Microtomographic investigation of a yeast grain porous structure
; Léonard, Angélique ; et al
in Journal of Food Engineering (2010), 97Detailed reference viewed: 38 (7 ULg)
Association of admission plasma D-dimer concentration with diagnosis and outcome in horses with colic.
Cesarini Latorre, Carlota ; ; et al
in Journal of veterinary internal medicine / American College of Veterinary Internal Medicine (2010), 24(6), 1490-7
BACKGROUND: Coagulopathies detected in horses with gastrointestinal problems seem to be associated with poor outcome. Plasma D-Dimer concentration is a sensitive test for assessing coagulopathies ... [more ▼]
BACKGROUND: Coagulopathies detected in horses with gastrointestinal problems seem to be associated with poor outcome. Plasma D-Dimer concentration is a sensitive test for assessing coagulopathies. HYPOTHESIS: Plasma D-Dimer concentration tested on admission is related to diagnosis and outcome in horses with colic. ANIMALS: Four hundred and ninety three horses referred for evaluation of abdominal pain. METHODS: Prospective observational clinical study. Horses were grouped according to diagnosis (medical and surgical intestinal obstructions, ischemic disorders with and without intestinal resection, enteritis, peritonitis), outcome (survivors, nonsurvivors), and number of coagulopathies (normal profile, 1 or 2 coagulopathies, subclinical disseminated intravascular coagulation [DIC]). Blood samples were collected on admission and plasma D-Dimer concentration, clotting times (PT and aPTT), and antithrombin activity were determined. Positive likelihood ratios (LR+) were calculated for evaluation of D-Dimer cut-off values, which were later tested in a logistic regression model. RESULTS: Horses with enteritis or peritonitis had significantly (P<.001) higher plasma D-Dimer concentrations and more severe coagulopathies on admission than horses with other diagnoses. Nonsurvivors also had significantly (P<.001) higher plasma D-Dimer concentrations at presentation than did survivors, and those horses with subclinical DIC on presentation had an odds ratio (OR) 8.6 (95% confidence interval [CI], 3.3-22.5, P<.001) for nonsurvival. Finally, D-Dimer concentrations>4,000 ng/mL had a LR+ of 5.9 and an OR 8.8 (95% CI, 4.5-17.1, P<.001) for nonsurvival. CONCLUSION AND CLINICAL IMPORTANCE: Plasma D-Dimer concentration measured on admission can be used to facilitate diagnosis and outcome prediction in horses with colic. A potential cut-off value for nonsurvival was found at approximately 4,000 ng/mL. [less ▲]Detailed reference viewed: 8 (0 ULg)