Aims. We study the inner sub-AU region of the circumstellar environment of the UX Ori-type star KK Oph with near-infrared VLTI/AMBER interferometry. We are particularly interested in the inclination ...of the star-disk system, and we use this information to test the current standard picture for UX Ori stars. Methods. We recorded spectrally dispersed (R ~ 35) interferograms in the near-infrared H and K bands with the VLTI/AMBER instrument. The derived visibilities, closure phases, and the spectral energy distribution of KK Oph were compared with two-dimensional geometric and radiative transfer models (RADMC). Results. We obtained visibilities at four different position angles. Using two-dimensional geometric models, we derive an axis ratio ~3.0 corresponding to an inclination of ~70°. A fitted inclined ring model leads to a ring radius of 2.8 ± 0.2 mas, corresponding to 0.44 ± 0.03 AU at a distance of 160 pc, which is larger than the dust sublimation radius of ~0.1 AU predicted for a dust sublimation temperature of 1500 K. Our derived two-dimensional RADMC model consists of a circumstellar disk with an inclination angle of ~70° and an additional dust envelope. Conclusions. The finding of an ~70° inclined disk around KK Oph is consistent with the prediction that UX Ori objects are seen under large inclination angles, and orbiting clouds in the line of sight cause the observed variability. Furthermore, our results suggest that the orbit of the companion KK Oph B and the disk plane are coplanar.
Context. In long baseline interferometry, the raw fringe contrast must be calibrated to obtain the true visibility and then those observables that can be interpreted in terms of astrophysical ...parameters. The selection of suitable calibration stars is crucial for obtaining the ultimate precision of interferometric instruments like the VLTI. Potential calibrators must have spectro-photometric properties and a sky location close to those of the scientific target. Aims. We have developed software (SearchCal) that builds an evolutive catalog of stars suitable as calibrators within any given user-defined angular distance and magnitude around the scientific target. We present the first version of SearchCal dedicated to the bright-object case (sim162 mJy/beam and we detect 666 sources over an area of 132 square degrees. At 325 MHz, we have a resolution of 6.7'', a median similar to /aa/abs/2006/35/aa5018-06/img1.gif" ALT="$5\sigma sensitivity of 4 mJy/beam, and we detect 847 sources over an area of 15.3 square degrees. At 325 MHz we have detected a region of diffuse radio emission which is a cluster halo or relic candidate.
Context. The B-W method is used to determine the distance of Cepheids and consists in combining the angular size variations of the star, as derived from infrared surface-brightness relations or ...interferometry, with its linear size variation, as deduced from visible spectroscopy using the projection factor. The underlying assumption is that the photospheres probed in the infrared and in the visible are located at the same layer in the star whatever the pulsation phase. While many Cepheids have been intensively observed by infrared beam combiners, only a few have been observed in the visible. Aims. This paper is part of a project to observe Cepheids in the visible with interferometry as a counterpart to infrared observations already in hand. Methods. Observations of delta Cep itself were secured with the VEGA/CHARA instrument over the full pulsation cycle of the star. Results. These visible interferometric data are consistent in first approximation with a quasi-hydrostatic model of pulsation surrounded by a static circumstellar environment (CSE) with a size of theta sub(CSE)= 8.9 + or - 3.0 mas and a relative flux contribution of f sub(CSE)= 0.07 + or - 0.01. A model of visible nebula (a background source filling the field of view of the interferometer) with the same relative flux contribution is also consistent with our data at small spatial frequencies. However, in both cases, we find discrepancies in the squared visibilities at high spatial frequencies (maximum 2sigma) with two different regimes over the pulsation cycle of the star, phi= 0.0 - 0.8 and phi= 0.8-1.0. We provide several hypotheses to explain these discrepancies, but more observations and theoretical investigations are necessary before a firm conclusion can be drawn. Conclusions. For the first time we have been able to detect in the visible domain a resolved structure around delta Cep. We have also shown that a simple model cannot explain the observations, and more work will be necessary in the future, both on observations and modelling.
Experiments on the residence time distribution (RTD) and axial dispersion for the continuous flow of sand and broken rice, through a pilot scale rotary kiln at room temperature and equipped with ...lifters, are reported. Factors such as the rotational speed, the kiln slope, the material flow rate and the exit dam height have been studied. Furthermore, two profiles of lifters were used: straight lifters (SL) and rectangular lifters (RL). Thus, under varying conditions the RTDs were obtained by the typical stimulus response test using a tracer and the corresponding axial dispersion coefficients were determined. The validity of the axial dispersion model was assessed in this study, and the model was found to match well with the experimental data. A large number of experiments were conducted, enabling a correlation to be developed to predict the axial dispersion coefficient of the solid particles within the kiln. Comparisons with reported models are also discussed. The second part of this study will be concerned with the experimental kiln hold-up and the mean residence time (MRT) of solid particles.
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•We study effects of lifter shape, materials and operating parameters on the RTD.•Pe is determined by fitting the experimental data with the axial dispersion model.•Compared to the straight lifters, the rectangular shape introduces more back-mixing.•We develop a correlation to predict the axial dispersion coefficient.
Context. Among optical stellar interferometers, the CHARA Array located at Mt Wilson in California offers the potential of very long baselines (up to 330 m) and the prospect of coupling multiple beam ...combiners. This paper presents the principle and the measured performance of VEGA, Visible spEctroGraph and polArimeter installed in September 2007 at the coherent focus of the array. Aims. With 0.3 ms of arc of spatial resolution and up to $30 000$ of spectral resolution, VEGA intends to measure fundamental parameters of stars, to study stellar activities and to image and analyze circumstellar environments. We describe the observing modes that have been implemented for this spectro-polarimeter and show actual performances measured on the sky during the first observing runs. Methods. The astrophysical programs are described in relation to the observing modes of the instrument, the presentation of the spectrograph and of the interface table is shown and finally the data is presented. We discuss the perspectives of further development in the framework of the CHARA Array. Results. We show that VEGA/CHARA is fully operational. The current limiting magnitude is nearly 7 but the results depend on the observing conditions (seeing, spectral resolution, etc.). We have validated the stability of the instrumental visibility at the level of 1 to 2% over half an hour and of the instrumental polarization for various declinations. Some examples of squared visibility and differential visibility are presented. Conclusions. The spectro-polarimeter VEGA has been installed and successfully tested on CHARA. It will permit stellar physics studies at unprecedented spectral and spatial resolutions.
This phase II study assessed the safety and efficacy of everolimus, an oral mammalian target of rapamycin inhibitor in advanced transitional carcinoma cell (TCC) after failure of platinum-based ...therapy.
Thirty-seven patients with advanced TCC received everolimus 10 mg/day until progressive disease (PD) or unacceptable toxicity. The primary end point was the disease control rate (DCR), defined as either stable disease (SD), partial response (PR), or complete response at 8 weeks. Angiogenesis-related proteins were detected in plasma and changes during everolimus treatment were analyzed. PTEN expression and PIK3CA mutations were correlated to disease control.
Two confirmed PR and eight SD were observed, resulting in a DCR of 27% at 8 weeks. Everolimus was well tolerated. Compared with patients with noncontrolled disease, we observed in patients with controlled disease a significant higher baseline level of angiopoietin-1 and a significant early plasma decrease in angiopoietin-1, endoglin, and platelet-derived growth factor-AB. PTEN loss was observed only in patients with PD.
Everolimus showed clinical activity in advanced TCC. The profile of the plasma angiogenesis-related proteins suggested a role of the everolimus antiangiogenic properties in disease control. PTEN loss might be associated with everolimus resistance.
Although many more eyes of children with retinoblastoma are salvaged now compared to just 10 years ago, the control of vitreous seeding remains a challenge. The introduction of intravitreal injection ...of melphalan has enabled more eyes to be salvaged safely but with definite retinal toxicity. Intensive treatment with high-dose intravitreal topotecan may be a strategy to control tumor burden because of its cell cycle-dependent cytotoxicity and the proven safety in humans. Therefore, we evaluated the ocular and systemic safety of repeated high-dose intravitreal injections of topotecan in rabbits.
Systemic and ocular toxicity was assessed in non-tumor-bearing rabbits after four weekly injections of three doses of topotecan (10 μg, 25 μg, and 50 μg) or vehicle alone. Animals were evaluated weekly for general and ophthalmic clinical status. One week after the last injection, vitreous and plasma samples were collected for drug quantification and the enucleated eyes were subjected to histological assessment.
Weight, hair loss, or changes in hematologic values were absent during the study period across all animal groups. Eyes injected with all topotecan doses or vehicle showed no signs of anterior segment inflammation, clinical or histologic evidence of damage to the retina, and ERG parameters remained unaltered throughout the study. Vitreous and plasma topotecan lactone concentrations were undetectable.
Four weekly intravitreal injections of topotecan up to 50 μg in the animal model or a 100 μg human equivalent dose were not toxic for the rabbit eye. High doses of topotecan may show promising translation to the clinic for the management of difficult-to-treat retinoblastoma vitreous seeds.
Active pre-main-sequence binaries with separations of around 10 stellar radii present a wealth of phenomena unobserved in common systems. The study of these objects is extended from classical T Tauri ...stars to the Herbig Ae star HD 104237. The primary has a mass 2.2 ± 0.2 M and secondary 1.4 ± 0.3 M. Spectrointerferometry with the VLTI/AMBER in the K-band continuum and the Brγ line is presented.
It is found that the K-band continuum squared visibilities are compatible with a circumbinary disc with a radius of ∼0.5 AU. However, a significant fraction (∼50 per cent) of the flux is unresolved and not fully accounted by the stellar photospheres. The stars probably do not hold circumstellar discs, in addition to the circumbinary disc, due to the combined effects of inner magnetospheric truncation and outer tidal truncation. This unresolved flux likely arises in compact structures inside the tidally disrupted circumbinary disc.
Most ( 90 per cent) of the Brγ line emission is unresolved. The line-to-continuum spectroastrometry shifts in time, along the direction of the Lyα jet known to be driven by the system. The shift is anticorrelated with the Brγ equivalent width. It is shown that the unresolved Brγ emission cannot originate in the jet but instead is compatible with stellar emission from the orbiting binary components. The increase in the absolute value of the equivalent width of the line takes place at periastron passage; it could arise in an accretion burst, a flare or in the increase in effective size of the emission region by the interaction of the magnetospheres. The binary longitude of the ascending node is found to be Ω = (235 ± 3)° and the orbit retrograde.
The origin of the jet is revisited. The tidal disruption of the circumstellar discs creates difficulties to ejection models that rely on stellar magnetosphere and disc coupling. A scenario of a stellar wind collimated by a circumbinary disc wind is suggested.
Up-scaling tracer experiments were carried out in a pilot-scale rotary kiln twice as big as the kiln used in the first two Parts of this study. Internal fixtures such as grid, or lifter structure ...arranged in 3 and 6 rows of single throughout lifters were used. The effects of these removable fixtures and other usual operating conditions, namely, mass flow rate of granular biomass materials, rotational speed and slope of the kiln on the residence time distribution (RTD), the mean and variance of residence time (MRT and VRT), the hold-up (HU), the Peclet number (Pe) and corresponding axial dispersion coefficient (D), were investigated. Scaling-up rules were derived for the MRT, HU volume fraction and D from the results of a comprehensive experimental work. Good agreement was found between the experimental data and the calculated values. The wide size distribution of the beech chips used in the present study allows analysis of particle segregation, which may further increase understanding of the flow characteristics of granular materials, notably within flighted rotary kilns. The results show that while significantly increasing the dispersion, ipso facto, enhancing the mixing, the lifters limit the extent of particle segregation.
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•Effects of operating conditions on the flow characteristics of biomass are analyzed.•Up-scaling rules are proposed for three main solid transport characteristics.•The presence of lifters is found to reduce effects of particle segregation.
Experiments were carried out on a pilot scale rotary kiln equipped with lifters at room temperature to investigate the effects of the kiln slope, rotational speed, mass flow rate of materials, and ...exit dam height on the hold-up and the mean residence time (MRT). The MRT was determined from the residence time distribution measurements as detailed in Part I of this work. Two granular solids having different properties were used: sand and broken rice. Furthermore, two shapes of lifters were compared to determine the influence of lifter geometry: straight lifters (SL) and rectangular lifters (RL). A new model to predict the MRT was established by means of a dimensional analysis. The correlation not only gave good agreement with the experimental data from the present study, but also demonstrated good predictive performances when applied to published experimental data of other kilns; the model is applicable for inclined kilns that process materials in cascading (tumbling) motion, whether or not equipped with lifters or fitted with dams at the outlet end.
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•The presence of lifters increase significantly the hold-up within the kiln.•The larger of the two materials used (broken rice) generally have lower residence time.•We develop a model for the mean residence time by means of a dimensional analysis.
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