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See detailHCCI engine modeling and experimental investigations - Part 2: The composition of a NO-PRF interaction mechanism and the influence of NO in EGR on auto-ignition
Machrafi, Hatim ULg; Guibert, Philippe; Cavadias, Simeon

in Combustion Science And Technology (2008), 180(7), 1245-1262

This article presents an investigation of the effect of NO in EGR on HCCI auto-ignition, by means of experiments and a NO-PRF interaction mechanism. The influence is investigated both numerically and ... [more ▼]

This article presents an investigation of the effect of NO in EGR on HCCI auto-ignition, by means of experiments and a NO-PRF interaction mechanism. The influence is investigated both numerically and experimentally. The numerical part is effected by a composition of a NO submechanism and the subsequent addition of this sub mechanism to a reduced validated n-heptane/iso-octane PRF mechanism, the latter of which is presented in a previous article, named article 1 (Machrafi et al., submitted 2006). The experimental part is effected on a CFR engine, operating at HCCI conditions, with an inlet temperature of 70 degrees C and a compression ratio of 10.2. Hereby n-heptane and PRF40 are used as the fuels, using different equivalence ratios in order to extend the interpretation domain. The NO adding concentration is experimentally varied between 0 and 160 ppm. The results showed that adding NO at low concentrations advances the ignition delays, the promoting reactions being more reactive than the inhibitory ones. The promoting effect seems to be at its maximum at an addition of 45 ppm concerning the fuel PRF40. At higher adding concentrations of NO the promoting effect becomes less and the inhibitory reactions become more reactive. The effect of NO on the auto-ignition of n-heptane seemed, however, to be unsignificant. The effect of NO was qualitatively well represented by the mechanism, while quantitatively the mechanism predicted a lower effect of NO at an addition of 45 ppm. [less ▲]

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See detailhCG: a pregnancy-related hormone stimulating angiogenesis and pericyte recruitment
Berndt, S; Blacher, Silvia ULg; Perrier d’Hauterive, S et al

Poster (2010)

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See detailHCMV seroprevalence and associated risk factors in pregnat women, Havana City, 2007 to 2008
Correa, C. B.; Kouri, V.; Verdasquera, D. et al

in Prenatal Diagnosis (2010), 30(9), 888-92

Objective To prenatally identify pregnant women at risk of developing congenital infection due to human cytomegalovirus (HCMV). Methods One thousand one hundred and thirty-one pregnant women from three ... [more ▼]

Objective To prenatally identify pregnant women at risk of developing congenital infection due to human cytomegalovirus (HCMV). Methods One thousand one hundred and thirty-one pregnant women from three municipalities from Havana City were serologically screened for HCMV infection (IgM/IgG, IgG avidity) from January 2007 to January 2008. Demographical, epidemiological, and clinical variables were correlated to serologic status to identify predictors of seroconversion in pregnancy. Results The majority of women were seropositive to HCMV (92.6%); 27 women (2.4%) developed HCMV active infection during pregnancy, defined by the detection of IgG+ and IgM+ (7 women), IgM+ and IgG− (2 women), and IgG seroconversion (18 women). Susceptibility of active HCMV infection during pregnancy was associated with maternal age <20 years and nulligravidity. Primary infection was detected in 20 pregnant women (1.8%), whereas 7 patients (0.6%) had active non-primary infection. Conclusion Although pregnant women in Cuba have high seroprevalence rates for HCMV, those younger than 20 years and nulligravidae are at risk of acquiring infection during pregnancy. [less ▲]

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See detailHCV genotype 4 in Belgium: epidemiological characteristics
REENAERS, Catherine ULg; DELWAIDE, Jean ULg; GERARD, Christiane ULg et al

in Acta Gastro-Enterologica Belgica (2004), (67), 03

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See detailHCV genotype 4 in Belgium: three distinct patterns among patients from European and African origin
Delwaide, Jean ULg; Reenaers, Catherine ULg; Gerard, Christiane ULg et al

in European Journal of Gastroenterology & Hepatology (2006), 18(7), 707-712

Background Considered uncommon in western countries some years ago, hepatitis C virus of genotype 4 is now spreading in some areas of Europe. This is assumed to be due to immigration from a region of high ... [more ▼]

Background Considered uncommon in western countries some years ago, hepatitis C virus of genotype 4 is now spreading in some areas of Europe. This is assumed to be due to immigration from a region of high prevalence for this genotype and to propagation among drug users. In the south of Belgium, genotype 4 currently accounts for 10% of hepatitis C virus patients and its prevalence is increasing with time. Objective To better define the genotype 4 carriers' characteristics. Methods In a database comprising 1726 viraemic hepatitis C virus patients, the files of 85 genotype 4 carriers were reviewed. Results Beside the African (58%) and European drug user (15%) subgroups classically described, a third subgroup consisting of European nondrug users (26%) was identified as peculiar: these patients were older, had been mostly contaminated sporadically, presented a great diversity of subtypes, and were mainly of Italian origin. In this subgroup, contamination was supposed to be ancient, having occurred probably in Italy before immigration into Belgium. By contrast, European drug users were infected with only two subtypes (4c/4d and 4), an observation in favour of recent spread. Africans had a great diversity of subtypes, were young, and were mostly contaminated sporadically in their home countries. Despite their epidemiological differences, the clinical management, and in particular the rates of eligibility for treatment, were similar for these three groups. Conclusions Three different patterns of genotype 4 carriers were observed, corresponding to three different spreading profiles. They did not induce, however, different clinical management. [less ▲]

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See detailHCV genotype 5: an easy to treat population
REENAERS, Catherine ULg; DELWAIDE, Jean ULg; GERARD, Christiane ULg et al

in Acta Gastro-Enterologica Belgica (2004), 67

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See detailHCV genotypes 2 and 3: the predominant genotypes at the horizon 2020?
Delwaide, Jean ULg; Gerard, Christiane ULg; Vaira, Dolorès ULg et al

in Acta Gastro-Enterologica Belgica (2005, January), 68(1), 25

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See detailHCV screening in African (Malian) women : relevancy of the HCV NS3 epitope
BOUHARE, NOUHOUM; VAIRA, Dolorès ULg; GOTHOT, André ULg et al

Poster (2012)

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See detailHD 108: The mystery deepens with XMM-Newton observations
Nazé, Yaël ULg; Rauw, Grégor ULg; Vreux, Jean-Marie ULg et al

in Astronomy and Astrophysics (2004), 417(2), 667-677

In 2001, using a large spectroscopic dataset from an extensive monitoring campaign, we discovered that the peculiar Of star HD 108 displayed extreme line variations. This strange behaviour could be ... [more ▼]

In 2001, using a large spectroscopic dataset from an extensive monitoring campaign, we discovered that the peculiar Of star HD 108 displayed extreme line variations. This strange behaviour could be attributed to a variety of models, and an investigation of the high energy properties of HD 108 was needed to test the predictions from these models. Our dedicated XMM-Newton observation of HD 108 shows that its spectrum is well represented by a two temperature thermal plasma model with kT(1) similar to 0.2 keV and kT(2) similar to 1.4 keV. In addition, we find that the star does not display any significant short-term changes during the XMM-Newton exposure. Compared to previous Einstein and ROSAT detections, it also appears that HD 108 does not present long-term flux variations either. While the line variations continue to modify HD 108's spectrum in the optical domain, the X-ray emission of the star appears thus surprisingly stable: no simple model is for the moment able to explain such an unexpected behaviour. Thanks to its high sensitivity, the XMM-Newton observatory has also enabled the serendipitous discovery of 57 new X-ray sources in the field of HD 108. Their properties are also discussed in this paper. [less ▲]

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See detailHD 148937: A multiwavelength study of the third galactic member of the Of?p class
Nazé, Yaël ULg; Walborn, Nolan R.; Rauw, Grégor ULg et al

in Astronomical Journal (The) (2008), 135(5), 1946-1957

Three Galactic O-type stars belong to the rare class of Of? p objects: HD 108, HD 191612, and HD 148937. The first two stars show a wealth of phenomena, including strong X-ray emission, light variability ... [more ▼]

Three Galactic O-type stars belong to the rare class of Of? p objects: HD 108, HD 191612, and HD 148937. The first two stars show a wealth of phenomena, including strong X-ray emission, light variability, and dramatic periodic spectral variability. We present here the first detailed optical and X-ray study of the third Galactic Of? p star, HD 148937. Spectroscopic monitoring has revealed low-level variability in the Balmer and He II lambda 4686 lines, but constancy at He I and C III lambda 4650. The H alpha line exhibits profile variations at a possible periodicity of similar to 7 days. Model atmosphere fits yield T-eff = 41000 +/- 2000 K, log(g) = 4.0 +/- 0.1, M-sph less than or similar to 10(-7) M-circle dot yr(-1), and an overabundance of nitrogen by a factor of 4. At X-ray wavelengths, HD 148937 resembles HD 108 and HD 191612 in having a thermal spectrum dominated by a relatively cool component (kT = 0.2 keV), broad lines (>= 1700 km s(-1)), and an order-of-magnitude overluminosity compared to normal O stars (log[L-X(unabs) / L-BOL]similar to -6). [less ▲]

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See detailHD 150136: towards one of the most massive systems?
Mahy, Laurent ULg; Gosset, Eric ULg; Sana, Hugues et al

in Neiner, Coralie; Wade, G.; Meynet, G. (Eds.) et al Active OB stars: structure, evolution, mass loss and critical limits (2011, July 01)

We present the preliminary results of an intensive monitoring devoted to HD 150136. Already quoted as an O3+O6 binary, we detected a third O-type component physically linked to the system, making it one ... [more ▼]

We present the preliminary results of an intensive monitoring devoted to HD 150136. Already quoted as an O3+O6 binary, we detected a third O-type component physically linked to the system, making it one of the nearest (1.3 kpc) most massive systems known until now (~134M[SUB]solar[/SUB]). To determine the physical parameters of this system, we applied a disentangling program to study individually the three components. It allows us to constrain their spectral types and to derive a new orbital solution for the short-period system. [less ▲]

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See detailHD 150136: towards one of the most massive systems?
Mahy, Laurent ULg; Gosset, Eric ULg; Rauw, Grégor ULg et al

Poster (2010)

The improvement of the astronomical instrumentation allowed scientists to develop new analysis techniques to investigate binary and multiple stars. In this context, we present the preliminary results of ... [more ▼]

The improvement of the astronomical instrumentation allowed scientists to develop new analysis techniques to investigate binary and multiple stars. In this context, we present the preliminary results of an intense monitoring devoted to the triple system, HD 150136. Supposed to be the nearest O3 star (1.3 kpc), this object is also composed of two other early O-type stars, making it one of the most massive systems known until now (~ 134Mʘ). This multiple star is a non-thermal radio emitter and presents a colliding wind interaction zone. To determine the physical parameters of this system, we applied a disentangling program to study individually the three components. It allows us to revise their spectral classification and to derive a new orbital solution for the short-period system but also the first one for the entire system. [less ▲]

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See detailHD 151932 variability revisited
Vreux, Jean-Marie ULg; Manfroid, Jean ULg; Scuflaire, Richard ULg et al

in Astronomy and Astrophysics (1987), 180

The observation of variations in the blue absorption component of the He I lines as well as in the Si IV 4089 emission line of HD 151932 is reported. Possible explanations for these variations are ... [more ▼]

The observation of variations in the blue absorption component of the He I lines as well as in the Si IV 4089 emission line of HD 151932 is reported. Possible explanations for these variations are addressed, and it is concluded that none is satisfactory. The possibility of a periodicity in the variations is briefly considered. [less ▲]

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See detailHD 152248: Evidence for a colliding wind interaction
Sana, H.; Rauw, Grégor ULg; Gosset, Eric ULg

in Astronomy and Astrophysics (2001), 370

We present the results of a four year spectroscopic campaign on the early-type binary system HD 152248. Our analysis yields a new classification as O7.5III(f) + O7III(f), in contradiction with previous ... [more ▼]

We present the results of a four year spectroscopic campaign on the early-type binary system HD 152248. Our analysis yields a new classification as O7.5III(f) + O7III(f), in contradiction with previous classifications of the components as supergiants. We derive improved orbital elements and the corresponding masses (M_1=29.6 M[SUB]sun[/SUB] and M_2=29.9 M[SUB]sun[/SUB]) are somewhat larger than previously reported in the literature, although they are still significantly lower than the ones expected from evolutionary tracks. Both components of the system are close to filling their Roche lobe at periastron passage. We also investigate the equivalent width variations of the lines of the two components and we discuss their relation to the Struve-Sahade effect. Finally, we show that the line profile variability of the He Iil4686 and Halpha lines is consistent with a strong wind interaction between the two stars, quite as predicted by current colliding wind models. Based on data collected at the European Southern Observatory (La Silla, Chile) and at the Cerro Tololo Inter-American Observatory (Cerro Tololo, Chile). [less ▲]

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See detailHD 166181 = V815 Herculis, a Single-lined Spectroscopic Multiple System
Fekel, Francis C.; Barlow, D. J.; Scarfe, C. D. et al

in Astronomical Journal (The) (2005), 129

We have obtained extensive spectroscopic and velocity spectrometer observations of HD 166181, a previously known single-lined spectroscopic binary. Our improved orbit for the G6 V primary has a period of ... [more ▼]

We have obtained extensive spectroscopic and velocity spectrometer observations of HD 166181, a previously known single-lined spectroscopic binary. Our improved orbit for the G6 V primary has a period of 1.8098343 days and is circular. Although the lines of additional components have not been detected, radial velocity measurements confirm that the system has additional velocity variations with a period of 2092 days, or 5.73 yr. This long-period orbit has an eccentricity of 0.76. An analysis of the Hipparcos observations produces a well-determined astrometric orbit for the long-period system that has an inclination of 78°. Mass estimates of the components in this zero-age main-sequence multiple system indicate that the unseen secondary in the 5.73 yr orbit may also be a binary. Thus, HD 166181 is at least a triple system and possibly quadruple. [less ▲]

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See detailHD 167362, an object similar to Campbell's Hydrogen Envelope Star
Swings, Polydore ULg; Struve, Otto

in Proceedings of the National Academy of Sciences of the United States of America (1940), 26

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See detailHD 172256 Revisited
Heck, A.; Manfroid, Jean ULg; Percy, J. R.

in Information Bulletin on Variable Stars (1984), 2501

Not Available

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See detailHD 174884: a strongly eccentric, short-period early-type binary system discovered by CoRoT
Maceroni, C.; Montalban Iglesias, Josefa ULg; Michel, E. et al

in Astronomy and Astrophysics (2009), 508

Accurate photometric CoRoT space observations of a secondary seismological target, HD 174884, led to the discovery that this star is an astrophysically important double-lined eclipsing spectroscopic ... [more ▼]

Accurate photometric CoRoT space observations of a secondary seismological target, HD 174884, led to the discovery that this star is an astrophysically important double-lined eclipsing spectroscopic binary in an eccentric orbit (eË 0.3), unusual for its short 3.65705° orbital period. The high eccentricity, coupled with the orientation of the binary orbit in space, explains the very unusual observed light curve with strongly unequal primary and secondary eclipses having the depth ratio of 1-to-100 in the CoRoT â seismoâ passband. Without the high accuracy of the CoRoT photometry, the secondary eclipse, 1.5 mmag deep, would have gone unnoticed. A spectroscopic follow-up program provided 45 high dispersion spectra. The analysis of the CoRoT light curve was performed with an adapted version of PHOEBE that supports CoRoT passbands. The final solution was obtained by a simultaneous fitting of the light and the radial velocity curves. Individual star spectra were obtained by spectrum disentangling. The uncertainties of the fit were achieved by bootstrap resampling and the solution uniqueness was tested by heuristic scanning. The results provide a consistent picture of the system composed of two late B stars. The Fourier analysis of the light curve fit residuals yields two components, with orbital frequency multiples and an amplitude of ~0.1 mmag, which are tentatively interpreted as tidally induced pulsations. An extensive comparison with theoretical models is carried out by means of the Levenberg-Marquardt minimization technique, and the discrepancy between the models and the derived parameters is discussed. The best fitting models yield a young system age of 125 million years which is consistent with the eccentric orbit and synchronous component rotation at periastron. Based on photometry collected by the CoRoT space mission and spectroscopy obtained with the CORALIE spectrograph attached to the 1.2 m Euler telescope at ESO, La Silla, Chile. The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Programs, Austria, Belgium, Brazil, Germany and Spain. Postdoctoral fellow of the Fund for Scientific Research of Flanders (FWO). [less ▲]

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See detailHD 192163 variability revisited - A very short period WR binary or a pulsating star?
Vreux, Jean-Marie ULg; Andrillat, Y.; Gosset, Eric ULg

in Astronomy and Astrophysics (1985), 149

The present reexamination of emission line variations in HD 192163 on the basis of 23 spectra takes into account stratification effects in the atmosphere of the WR stars, as well as the necessity for a ... [more ▼]

The present reexamination of emission line variations in HD 192163 on the basis of 23 spectra takes into account stratification effects in the atmosphere of the WR stars, as well as the necessity for a high N/R ratio. Because of the peculiar shape of the profiles, the wavelength shifts are measured by comparing the position of every observation to a nearly noise-free profile that is taken as reference. The most probable period supported by the present data is either 0.45 or 0.31 days; these two periods are one-day aliases of each other. [less ▲]

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See detailHD 203608, a quiet asteroseismic target in the old galactic disk
Mosser, B.; Deheuvels, S.; Michel, Eric et al

in Astronomy and Astrophysics (2008), 488

Context: We conducted a 5-night observing run with the spectrometer harps at the ESO 3.6-m telescope in August 2006, to continue exploring the asteroseismic properties of F-type stars. In fact, Doppler ... [more ▼]

Context: We conducted a 5-night observing run with the spectrometer harps at the ESO 3.6-m telescope in August 2006, to continue exploring the asteroseismic properties of F-type stars. In fact, Doppler observations of F-type on the main sequence are demanding and remain currently limited to a single case (HD 49933). Comparison with photometric results obtained with the CoRoT space mission (Convection, Rotation and planetary Transits) on similar stars will be possible with an enhanced set of observations. Aims: We selected the 4th magnitude F8V star HD 203608 to investigate the oscillating properties of a low-metallicity star of the old galactic disk. Methods: We reduced the spectra with the on-line data reduction software provided by the instrument. We developed a new statistical approach for extracting the significant peaks in the Fourier domain. Results: The oscillation spectrum shows a significant excess power in the frequency range [1.5, 3.0 mHz]. It exhibits a large spacing of about 120.4 muHz at 2.5 mHz. Variations of the large spacing with frequency are clearly identified, which require an adapted asymptotic development. The modes identification is based on the unambiguous signature of 15 modes with l = 0 and 1. Conclusions: These observations show the potential diagnostic of asteroseismic constraints. Including them in the stellar modeling significantly enhances the precision on the physical parameters of HD 203608, resulting in a much more precise position in the HR diagram. The age of the star is now determined in the range 7.25±0.07 Gyr. Based on observations obtained with the harps échelle spectrometer mounted on the 3.6-m telescope at ESO-La Silla Observatory (Chile), programme 077.D-0720. Data corresponding to Figs. [see full textsee full textsee full text], [see full textsee full textsee full text], and Table [see full textsee full textsee full text] are 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/488/635 [less ▲]

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