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See detailPhase referencing in optical interferometry
Filho, Mercedes E; Garcia, Paulo; Duvert, Gilles et al

in Schöller, Markus; Danchi, William; Delplancke, Françoise (Eds.) Optical and Infrared Interferometry (2008, July 01)

One of the aims of next generation optical interferometric instrumentation is to be able to make use of information contained in the visibility phase to construct high dynamic range images. Radio and ... [more ▼]

One of the aims of next generation optical interferometric instrumentation is to be able to make use of information contained in the visibility phase to construct high dynamic range images. Radio and optical interferometry are at the two extremes of phase corruption by the atmosphere. While in radio it is possible to obtain calibrated phases for the science objects, in the optical this is currently not possible. Instead, optical interferometry has relied on closure phase techniques to produce images. Such techniques allow only to achieve modest dynamic ranges. However, with high contrast objects, for faint targets or when structure detail is needed, phase referencing techniques as used in radio interferometry, should theoretically achieve higher dynamic ranges for the same number of telescopes. Our approach is not to provide evidence either for or against the hypothesis that phase referenced imaging gives better dynamic range than closure phase imaging. Instead we wish to explore the potential of this technique for future optical interferometry and also because image reconstruction in the optical using phase referencing techniques has only been performed with limited success. We have generated simulated, noisy, complex visibility data, analogous to the signal produced in radio interferometers, using the VLTI as a template. We proceeded with image reconstruction using the radio image reconstruction algorithms contained in aips imagr (clean algorithm). Our results show that image reconstruction is successful in most of our science cases, yielding images with a 4 milliarcsecond resolution in K band. We have also investigated the number of target candidates for optical phase referencing. Using the 2MASS point source catalog, we show that there are several hundred objects with phase reference sources less than 30 arcseconds away, allowing to apply this technique. [less ▲]

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See detailSystem overview of the VLTI Spectro-Imager
Jocou, L.; Berger, J.-P.; Malbet, F. et al

in Schöller, Markus; Danchi, William; Delplancke, Françoise (Eds.) Optical and Infrared Interferometry (2008, July 01)

The VLTI Spectro Imager project aims to perform imaging with a temporal resolution of 1 night and with a maximum angular resolution of 1 milliarcsecond, making best use of the Very Large Telescope ... [more ▼]

The VLTI Spectro Imager project aims to perform imaging with a temporal resolution of 1 night and with a maximum angular resolution of 1 milliarcsecond, making best use of the Very Large Telescope Interferometer capabilities. To fulfill the scientific goals (see Garcia et. al.), the system requirements are: a) combining 4 to 6 beams; b) working in spectral bands J, H and K; c) spectral resolution from R= 100 to 12000; and d) internal fringe tracking on-axis, or off-axis when associated to the PRIMA dual-beam facility. The concept of VSI consists on 6 sub-systems: a common path distributing the light between the fringe tracker and the scientific instrument, the fringe tracker ensuring the co-phasing of the array, the scientific instrument delivering the interferometric observables and a calibration tool providing sources for internal alignment and interferometric calibrations. The two remaining sub-systems are the control system and the observation support software dedicated to the reduction of the interferometric data. This paper presents the global concept of VSI science path including the common path, the scientific instrument and the calibration tool. The scientific combination using a set of integrated optics multi-way beam combiners to provide high-stability visibility and closure phase measurements are also described. Finally we will address the performance budget of the global VSI instrument. The fringe tracker and scientific spectrograph will be shortly described. [less ▲]

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See detailPolar-interferometry: what can be learnt from the IOTA/IONIC experiment
Le Bouquin, Jean-Baptiste; Rousselet-Perraut, Karine; Berger, Jean-Philippe et al

in Schöller, Markus; Danchi, William; Delplancke, Françoise (Eds.) Optical and Infrared Interferometry (2008, July 01)

We report the first near-IR polar-interferometric observations, performed at the IOTA array using its integrated optics combiner IONIC. Fringes have been obtained on calibration stars and resolved late ... [more ▼]

We report the first near-IR polar-interferometric observations, performed at the IOTA array using its integrated optics combiner IONIC. Fringes have been obtained on calibration stars and resolved late-type giants. Optical modeling of the array and dedicated laboratory measures allowed us to confirm the good accuracy obtained on the calibrated polarized visibilities and closure phases. However, no evidences for polarimetric features at high angular resolution have been detected. The simulations and the results presented here open several perspectives for polar-interferometry, especially in the context of fibered, single-mode combiners. [less ▲]

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See detailEarth-like planets: science performance predictions for future nulling interferometry missions
Defrere, Denis ULg; Lay, O.; den Hartog, R. et al

in Schöller, Markus; Danchi, William; Delplancke, Françoise (Eds.) Optical and Infrared Interferometry (2008, July 01)

With the launch of planet-transit missions such as CoRoT and Kepler, it is expected that Earth-sized planets orbiting distant stars will be detected soon. This milestone will open the path towards the ... [more ▼]

With the launch of planet-transit missions such as CoRoT and Kepler, it is expected that Earth-sized planets orbiting distant stars will be detected soon. This milestone will open the path towards the definition of missions able to study the atmosphere of Earth-sized extrasolar planets, with the identification of bio-signatures as one of the main objectives. In that respect, both the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA) have identified nulling interferometry as one of the most promising techniques. Trying to minimize the cost and the technological risks while maximizing the scientific return, ESA and NASA recently converged towards a single mission architecture, the Emma X-array. In this paper, we present the expected science performance of this concept computed with two independent mission simulators. The impact of different observational parameters such as planet radius and exozodiacal cloud density is specifically addressed. [less ▲]

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See detailHydrogen-Deficient Compact Pulsators: The GW Virginis Stars and the Variable DB White Dwarfs
Quirion, P*-O; Dupret, Marc-Antoine ULg; Fontaine, G. et al

in Hydrogen-Deficient Stars (2008, July 01)

We review briefly the basic properties of the GW Vir stars and of the V777 Her stars. We describe the classical kappa-mechanism operating in the GW Vir stars and the effects of the chemical composition ... [more ▼]

We review briefly the basic properties of the GW Vir stars and of the V777 Her stars. We describe the classical kappa-mechanism operating in the GW Vir stars and the effects of the chemical composition and of the interaction between diffusion and mass loss on the boundaries of the instability domain of these objects in the log g - T[SUB]eff[/SUB] diagram. Because of the presence of an extensive superficial convection zone in pulsating DB (V777 Her) white dwarfs, oscillation modes are not excited through a similar classical kappa-mechanism in those stars but, instead, involve pulsation-convection interactions. We describe the effects of a time-dependent convection (TDC) treatment on the driving mechanism of the V777 Her stars. We show how convection deeply affects the excitation of modes via the entropy transport mechanism or S-mechanism. Provisional blue and red edges are calculated for the V777 Her stars and are found at T[SUB]eff[/SUB] ~= 28,500 K and ~= 20,500 K, respectively, for a 0.6 M[SUB]o[/SUB] star under the assumption of ML2 convection. [less ▲]

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See detailImproved parameters for the transiting planet HD 17156b: a high-density giant planet with a very eccentric orbit
Gillon, Michaël ULg; Triaud, A H M J; Mayor, M. et al

in Astronomy and Astrophysics (2008), 485

We report high-precision transit photometry for the recently detected planet HD 17156b. Using these new data with previously published transit photometry and radial velocity measurements, we perform a ... [more ▼]

We report high-precision transit photometry for the recently detected planet HD 17156b. Using these new data with previously published transit photometry and radial velocity measurements, we perform a combined analysis based on a Markov Chain Monte Carlo approach. The resulting mass M[SUB]p[/SUB] = 3.09[SUP]+0.22[/SUP][SUB]-0.17[/SUB]~M_Jup and radius R[SUB]p[/SUB] = 1.23[SUP]+0.17[/SUP][SUB]-0.20[/SUB] R_Jup for the planet places it at the outer edge of the density distribution of known transiting planets with rho[SUB]p[/SUB] = 1.66[SUP]+1.37[/SUP][SUB]-0.60[/SUB] rho_Jup. The obtained transit ephemeris is T_Tr = 2 454 438.48271[SUP]+0.00077[/SUP][SUB]-0.00057[/SUB] + N × 21.21747[SUP]+0.00070[/SUP][SUB]-0.00067[/SUB] BJD. The derived plausible tidal circularization time scales for HD 17156b are larger than the age of the host star. The measured high orbital eccentricity e = 0.6719[SUP]+0.0052[/SUP][SUB]-0.0063[/SUB] can thus not be interpreted as the clear sign of the presence of another body in the system. Based on observations made with the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. Photometric measurements are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/485/871 [less ▲]

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See detailSAPS 3 admission score: an external validation in a general intensive care population
Ledoux, Didier ULg; Canivet, Jean-Luc ULg; Preiser, Jean-Charles ULg et al

in Intensive Care Medicine (2008)

OBJECTIVES: To validate the SAPS 3 admission score in an independent general intensive care case mix and to compare its performances with the APACHE II and the SAPS II scores. DESIGN: Cohort observational ... [more ▼]

OBJECTIVES: To validate the SAPS 3 admission score in an independent general intensive care case mix and to compare its performances with the APACHE II and the SAPS II scores. DESIGN: Cohort observational study. SETTING: A 26-bed general ICU from a Tertiary University Hospital. PATIENTS AND PARTICIPANTS: Eight hundred and fifty-one consecutive patients admitted to the ICU over an 8-month period. Of these patients, 49 were readmissions, leaving 802 patients for further analysis. INTERVENTION: None. MEASUREMENTS AND RESULTS: APACHE II, SAPS II and SAPS 3 variables were prospectively collected; scores and their derived probability of death were calculated according to their original manuscript description. The discriminative power was assessed using the area under the ROC curve (AUROC) and calibration was verified with the Hosmer-Lemeshow goodness-of-fit test. The AUROC of the APACHE II model (AUROC = 0.823) was significantly lower than those of the SAPS II (AUROC = 0.850) and SAPS 3 models (AUROC = 0.854) (P = 0.038). The calibration of the APACHE II model (P = 0.037) and of the SAPS 3 global model (P = 0.035) appeared unsatisfactory. On the contrary, both SAPS II model and SAPS 3 model customised for Central and Western Europe had a good calibration. However, in our study case mix, SAPS II model tended to overestimate the probability of death. CONCLUSION: In this study, the SAPS 3 admission score and its prediction model customised for Central and Western Europe was more discriminative and better calibrated than APACHE II, but it was not significantly better than the SAPS II. [less ▲]

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See detailCabergoline and the risk of valvular lesions in endocrine disease.
Lancellotti, Patrizio ULg; Livadariu, E.; Markov, M. et al

in European Journal of Endocrinology (2008), 159(1), 1-5

AIMS: The cardiac valvular risk associated with lower exposure to cabergoline in common endocrine conditions such as hyperprolactinemia is unknown. METHODS AND RESULTS: We performed a cross-sectional ... [more ▼]

AIMS: The cardiac valvular risk associated with lower exposure to cabergoline in common endocrine conditions such as hyperprolactinemia is unknown. METHODS AND RESULTS: We performed a cross-sectional, case-control echocardiographic study to assess the valvular status in 102 subjects receiving cabergoline for endocrine disorders and 51 matched control subjects. Cabergoline treatment ranged from 12 to 228 months, with a cumulative dose of 18-1718 mg. Valvular regurgitation was equally prevalent in both groups and was almost exclusively mild. Two cabergoline-treated subjects had moderate mitral regurgitation; there was no relationship between cabergoline dose and the presence or severity of mitral valve regurgitation (P=NS). Mitral valve tenting area was significantly greater in the cabergoline group when compared with the control subjects (P=0.03). Mitral valve leaflet thickening was observed in 5.9% of cabergoline-treated subjects; no relationship with the cumulative cabergoline dose was found. No patient had aortic or tricuspid valvular restriction. CONCLUSION: No significantly increased risk of clinically relevant cardiac valve disorders was found in subjects treated with long-term cabergoline therapy at the doses used in endocrine practice. While exposure to cabergoline appears to be safe during low-dose long-term therapy, an association with subclinical changes in mitral valve geometry cannot be completely excluded. [less ▲]

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See detailA working methodology for the total water determination in inulin by the volumetric Karl Fischer titration.
Ronkart, Sébastien; Blecker, Christophe ULg; Fougnies, C. et al

Poster (2008, July)

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See detailImpact of physical properties of inulin on stability during moisture sorption.
Ronkart, Sébastien; Paquot, Michel ULg; Fougnies, C. et al

Poster (2008, July)

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See detailImpact of the spray drying conditions on inulin's physical properties
Ronkart, Sébastien; Blecker, Christophe ULg; Deroanne, Claude et al

Poster (2008, July)

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See detailGenetic parameters of stearoyl coenzyme-A desaturase 9 activity estimated by test-day model
Arnould, Valérie ULg; Gengler, Nicolas ULg; Soyeurt, Hélène ULg

in Journal of Dairy Science (2008, July), 91(E-Suppl. 2), 542

Dairy and beef products account for a large part of fat intake in human nutrition and therefore can be linked to dietary diseases. The stearoyl Coenzyme-A desaturase 9 (delta-9) gene was identified as a ... [more ▼]

Dairy and beef products account for a large part of fat intake in human nutrition and therefore can be linked to dietary diseases. The stearoyl Coenzyme-A desaturase 9 (delta-9) gene was identified as a potential functional candidate gene affecting milk fat composition in dairy cattle. The objective of this research was to estimate the genetic parameters of delta-9 activity indicator traits and to study the relationship between delta-9 activity as described by these indicator traits and common milk production traits. A total of 126,331 test-day records were obtained from 14,259 Holstein (> 84% Holstein gene) heifers belonging to 105 herds. The studied traits were milk yield, percentages of fat and protein, content of monounsaturated fatty acids, and 3 ratios reflecting the delta-9 activity (C14:1/ C14:0; C16:1/C16:0 and C18:1/C18). The used model was a multiple-trait random regressions test-day model and included as fixed effects: herd x date of test, class of age, and month x year. Random effects were herd x year of calving, permanent environmental, additive genetic, and residual effects. The fatty acid contents were estimated by mid-infrared spectrometry. Delta-9 activity varied within year and lactation. The obtained heritability estimates of delta-9 as well as the genetic and phenotypic correlation varied also through lactation. This study suggests potential improvements of delta-9 activity and subsequently milk fat composition can be achieved by animal management but also by breeding and animal selection. [less ▲]

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See detailGenetic parameters of stearoyl coenzyme-A desaturase 9 activity estimated by test-day model
Arnould, Valérie ULg; Gengler, Nicolas ULg; Soyeurt, Hélène ULg

Conference (2008, July)

Dairy and beef products account for a large part of fat intake in human nutrition and therefore can be linked to dietary diseases. The stearoyl Coenzyme-A desaturase 9 (delta-9) gene was identified as a ... [more ▼]

Dairy and beef products account for a large part of fat intake in human nutrition and therefore can be linked to dietary diseases. The stearoyl Coenzyme-A desaturase 9 (delta-9) gene was identified as a potential functional candidate gene affecting milk fat composition in dairy cattle. The objective of this research was to estimate the genetic parameters of delta-9 activity indicator traits and to study the relationship between delta-9 activity as described by these indicator traits and common milk production traits. A total of 126,331 test-day records were obtained from 14,259 Holstein (> 84% Holstein gene) heifers belonging to 105 herds. The studied traits were milk yield, percentages of fat and protein, content of monounsaturated fatty acids, and 3 ratios reflecting the delta-9 activity (C14:1/ C14:0; C16:1/C16:0 and C18:1/C18). The used model was a multiple-trait random regressions test-day model and included as fixed effects: herd x date of test, class of age, and month x year. Random effects were herd x year of calving, permanent environmental, additive genetic, and residual effects. The fatty acid contents were estimated by mid-infrared spectrometry. Delta-9 activity varied within year and lactation. The obtained heritability estimates of delta-9 as well as the genetic and phenotypic correlation varied also through lactation. This study suggests potential improvements of delta-9 activity and subsequently milk fat composition can be achieved by animal management but also by breeding and animal selection. [less ▲]

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See detailStudy of the stability and the physical property changes of amorphous inulin during moisture adsorption
Ronkart, S.; Paquot, Michel ULg; Fougnies, C. et al

Poster (2008, July)

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See detailLes aventures du transcendantal. Dialectique et politique de la pensée chez Merleau-Ponty
Janvier, Antoine ULg

in Archives du Groupe de recherches matérialistes (2008)

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See detailAPPLYING L. MANEVITCH’S COMPLEXIFICATION – AVERAGING METHOD TO ANALYZE CONDITIONS FOR OPTIMAL TARGETED ENERGY TRANSFER IN COUPLED OSCILLATORS WITH ESSENTIAL STIFFNESS NONLINEARITY
Sapsis, Themistoklis; Quinn, D. Dane; Gendelman, Oleg et al

in International Conference on Nonlinear Phenomena in Polymer Solids and Low-Dimensional Systems. Moscou, 2008 (2008, July)

We study targeted energy transfer (TET) [1] from a linear damped oscillator (LO) to a light attachment with essential stiffness nonlinearity, caused by 1:1 transient resonance capture (TRC). First, we ... [more ▼]

We study targeted energy transfer (TET) [1] from a linear damped oscillator (LO) to a light attachment with essential stiffness nonlinearity, caused by 1:1 transient resonance capture (TRC). First, we study the underlying Hamiltonian dynamics and show that for sufficiently weak damping, the nonlinear damped transitions of the system are strongly influenced by the underlying topological structure of periodic and quasiperiodic orbits of the hamiltonian system. Then, we formulate conditions that lead to effective or even optimal TET from the linear system to the nonlinear attachment. Direct analytical treatment of the governing strongly nonlinear damped equations of motion is performed by applying L. Manevitch’s complexification – averaging (CX-A) method [2] to perform slow-fast partition of the transient responses, and analytically model the dynamics in the region of optimal TET. This analysis determines the characteristic time scales of the dynamics that influence the capacity of the nonlinear attachment to passively absorb and locally dissipate broadband energy from the linear oscillator in an optimal fashion. [less ▲]

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See detailEvidence for short-term variations in two O-type stars
De Becker, Michaël ULg; Linder, Natacha ULg; Rauw, Grégor ULg

in Information Bulletin on Variable Stars (2008), 5841

Only a few O-type stars are known to display short-term (a fraction of a day) variations. Intense spectroscopic monitoring of the ON8V star HD 13268 revealed low amplitude variations with periods of ... [more ▼]

Only a few O-type stars are known to display short-term (a fraction of a day) variations. Intense spectroscopic monitoring of the ON8V star HD 13268 revealed low amplitude variations with periods of several hours. In addition, observations of the SB1 system HD 15137 revealed variations on a time scale of a few hours. We consider these stars to be a good candidates for non radial pulsations, even though variations related to inhomogeneities in a circumstellar disk can not be rejected. [less ▲]

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