The CRyogenic InfraRed Echelle Spectrograph (CRIRES) Upgrade project CRIRES
+
extended the capabilities of CRIRES. It transformed this VLT instrument into a cross-dispersed spectrograph to increase ...the wavelength range that is covered simultaneously by up to a factor of ten. In addition, a new detector focal plane array of three Hawaii 2RG detectors with a 5.3 μm cutoff wavelength replaced the existing detectors. Amongst many other improvements, a new spectropolarimetric unit was added and the calibration system has been enhanced. The instrument was installed at the VLT on Unit Telescope 3 at the beginning of 2020 and successfully commissioned and verified for science operations during 2021, partly remotely from Europe due to the COVID-19 pandemic. The instrument was subsequently offered to the community from October 2021 onwards. This article describes the performance and capabilities of the upgraded instrument and presents on sky results.
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Microcystic meningioma was originally classified as a subtype of meningioma by the World Health Organization classification of brain tumours in 1993, and accounts for 1.6% of intracranial ...meningiomas. This subtype is a variety of meningioma in which micro- and macro-cysts are diffuse. The morphologic characteristics are well defined, while the histogenetic mechanism that give rise to these patterns remain unclear.
The authors present an electron microscopic study of an unusual case of fronto-temporal microcystic meningioma, manifesting as history of headache, right paresis and dysphasia in a 73-year-old female. Computer tomography revealed a large hypodense mass in the left fronto-temporal region, with slight contrast enhancement.
Ultrastructural observation showed complex alterations among small vessels and intratumoral capillaries in a background of severe modification in vessel permeability.
This electronic microscopy study documented that growth of the cyst was due not only to accumulation of in extracellular fluid, but also to cytolysis consequent to ingravescent hydropic degeneration.
Seven cases of cerebellar haemangioblastoma, not associated with von Hippel-Lindau disease (sporadic haemangioblastomas), were studied by light and electron transmission microscopy. Morphological ...features that might provide information about the histogenesis of the tumour were examined. The ultrastructural data indicate both the common ancestry of the different cytotypes that make up the tumour, and the mesenchymal origin of the elements present, which were also documented by their capacity to synthesise lipid droplets in the cytoplasm (a process of lipidization similar to that of pre-adipocytes).
Recent surveys of wind energy areas offshore of Massachusetts and Rhode Island (USA) have demonstrated that they encompass habitat used by the Endangered North Atlantic right whale Eubalaena ...glacialis. Prior to 2011, little systematic survey effort had been conducted in the area. The Bureau of Ocean Energy Management and the state of Massachusetts supported 3.5 yr of twice-monthly aerial surveys by the Northeast Large Pelagic Survey Collaborative (NLPSC). Additional survey teams including the Northeast Fisheries Science Center and the Center for Coastal Studies have collected sightings data in the region. Data systematically collected by the NLPSC allowed analyses of monthly sightings rates, sightings per unit effort, and hot spots which provided information on current temporal and spatial use patterns. Abundance estimates for each season-year (i.e. a 3 mo period within a given survey year) were calculated. Behaviors observed included feeding and surface active groups. Photo-identification of whales since 2010 yielded a minimum count of 196 unique individuals (annual average = 35), or over one-third of the current population estimate. Analyses of demographics of these individuals revealed that 34 known calving females (30% of the total currently presumed alive) visited the study area. These results demonstrate consistent annual use of this area by a significant portion of the E. glacialis population, with a strong correlation between season and presence. These findings can inform management activities and development planning, and be used as a baseline dataset for assessing long-term impacts to the species.
An original model for the interpretation of the noise produced during the resistive transition of disordered granular superconductive films, induced by a slow temperature change, has been recently ...developed and tested on MgB 2 films. Both the amplitude and frequency behavior of the noise power spectrum, simulated on the basis of this model, are in very good agreement with the experimental data, practically without the introduction of adjustable parameters. The model is based on the onset of correlated transitions of large sets of grains, forming resistive layers through the film cross-section area during the transition process. The strong non-linear behavior and correlation of the grains produces abrupt resistance variations, giving rise to the large noise, of the 1/f 3 type, observed in experiments. Presently this model is tested under more general conditions, producing the resistive transition under an external magnetic field. The results show that the field reduces the grain critical current density but does not change the mechanism of the transition process. An alternative transition model, based on fluxoids depinning and motion, which would produce a much lower, 1/f type transition noise, can thus be excluded by the present analysis.
Context.
The nature of circumstellar envelopes (CSEs) around Cepheids is a matter of ongoing debate. The physical origin of their infrared (IR) excess could be shown to either be made up of a shell ...of ionized gas, a dust envelope, or a combination of both.
Aims.
This study is aimed at constraining the geometry and the IR excess of the environment of the bright long-period Cepheid
ℓ
Car (
P
= 35.5 days) at mid-IR wavelengths in order to understand its physical nature.
Methods.
We first used photometric observations in various bands (from the visible domain to the infrared) and
Spitzer
Space Telescope spectroscopy to constrain the IR excess of
ℓ
Car. Then we analyzed the VLTI/MATISSE measurements at a specific phase of observation in order to determine the flux contribution as well as the size and shape of the environment of the star in the
L
band. Finally, we tested the hypothesis of a shell of ionized gas in order to model the IR excess.
Results.
We report the first detection in the
L
band of a centro-symmetric extended emission around
ℓ
Car, of about 1.7
R
⋆
in full width at half maximum, producing an excess of about 7.0% in this band.This latter value is used to calibrate the IR excess found when comparing the photometric observations in various bands and quasi-static atmosphere models. In the
N
band, there is no clear evidence for dust emission from VLTI/MATISSE correlated flux and
Spitzer
data. On the other side, the modeled shell of ionized gas implies a more compact CSE (1.13 ± 0.02
R
⋆
) that is also fainter (IR excess of 1% in the
L
band).
Conclusions.
We provide new evidence supporting a compact CSE for
ℓ
Car and we demonstrate the capabilities of VLTI/MATISSE for determining common properties of CSEs. While the compact CSE of
ℓ
Car is likely to be of a gaseous nature, the tested model of a shell of ionized gas is not able to simultaneously reproduce the IR excess and the interferometric observations. Further Galactic Cepheid observations with VLTI/MATISSE are necessary for determining the properties of CSEs, which may also depend on both the pulsation period and the evolutionary state of the stars.
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Context. The nature of circumstellar envelopes (CSEs) around Cepheids is a matter of ongoing debate. The physical origin of their infrared (IR) excess could be shown to either be made up of a shell ...of ionized gas, a dust envelope, or a combination of both. Aims. This study is aimed at constraining the geometry and the IR excess of the environment of the bright long-period Cepheid ℓ Car ( P = 35.5 days) at mid-IR wavelengths in order to understand its physical nature. Methods. We first used photometric observations in various bands (from the visible domain to the infrared) and Spitzer Space Telescope spectroscopy to constrain the IR excess of ℓ Car. Then we analyzed the VLTI/MATISSE measurements at a specific phase of observation in order to determine the flux contribution as well as the size and shape of the environment of the star in the L band. Finally, we tested the hypothesis of a shell of ionized gas in order to model the IR excess. Results. We report the first detection in the L band of a centro-symmetric extended emission around ℓ Car, of about 1.7 R ⋆ in full width at half maximum, producing an excess of about 7.0% in this band.This latter value is used to calibrate the IR excess found when comparing the photometric observations in various bands and quasi-static atmosphere models. In the N band, there is no clear evidence for dust emission from VLTI/MATISSE correlated flux and Spitzer data. On the other side, the modeled shell of ionized gas implies a more compact CSE (1.13 ± 0.02 R ⋆ ) that is also fainter (IR excess of 1% in the L band). Conclusions. We provide new evidence supporting a compact CSE for ℓ Car and we demonstrate the capabilities of VLTI/MATISSE for determining common properties of CSEs. While the compact CSE of ℓ Car is likely to be of a gaseous nature, the tested model of a shell of ionized gas is not able to simultaneously reproduce the IR excess and the interferometric observations. Further Galactic Cepheid observations with VLTI/MATISSE are necessary for determining the properties of CSEs, which may also depend on both the pulsation period and the evolutionary state of the stars.
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Context. A complex environment exists in the inner few astronomical units of planet-forming disks. High-angular-resolution observations play a key role in our understanding of the disk structure and ...the dynamical processes at work. Aims. In this study we aim to characterize the mid-infrared brightness distribution of the inner disk of the young intermediate-mass star HD 163296 from early VLTI/MATISSE observations taken in the L - and N -bands. We put special emphasis on the detection of potential disk asymmetries. Methods. We use simple geometric models to fit the interferometric visibilities and closure phases. Our models include a smoothed ring, a flat disk with an inner cavity, and a 2D Gaussian. The models can account for disk inclination and for azimuthal asymmetries as well. We also perform numerical hydrodynamical simulations of the inner edge of the disk. Results. Our modeling reveals a significant brightness asymmetry in the L -band disk emission. The brightness maximum of the asymmetry is located at the NW part of the disk image, nearly at the position angle of the semimajor axis. The surface brightness ratio in the azimuthal variation is 3.5 ± 0.2. Comparing our result on the location of the asymmetry with other interferometric measurements, we confirm that the morphology of the r < 0.3 au disk region is time-variable. We propose that this asymmetric structure, located in or near the inner rim of the dusty disk, orbits the star. To find the physical origin of the asymmetry, we tested a hypothesis where a vortex is created by Rossby wave instability, and we find that a unique large-scale vortex may be compatible with our data. The half-light radius of the L -band-emitting region is 0.33 ±0.01 au, the inclination is 52° −7° +5° , and the position angle is 143° ± 3°. Our models predict that a non-negligible fraction of the L -band disk emission originates inside the dust sublimation radius for μ m-sized grains. Refractory grains or large (≳10 μ m-sized) grains could be the origin of this emission. N -band observations may also support a lack of small silicate grains in the innermost disk ( r ≲ 0.6 au), in agreement with our findings from L -band data.
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