937 research outputs found
Probing the stellar population of seyfert galaxies: a near infrared perspective
We employ IRTF SpeX NIR (0.8--2.4mu m) spectra to investigate the stellar
population (SP), active galactic nuclei (AGN), featureless continuum (FC) and
hot dust properties in 9 Sy1 and 15 Sy2 galaxies. Both the {\sc starlight} code
and the hot dust as an additional base element were used for the first time in
this spectral range. Our synthesis shows significant differences between Sy1
and Sy2 galaxies: the hot dust component is required to fit the K-band spectra
of ~90% of the Sy1 galaxies, and only of ~25% of the Sy2; about 50% of the Sy2
galaxies require an FC component contribution >20%; this fraction increases to
about 60% in the Sy1. In about 50% of the Sy2, the combined FC and young
components contribute with more than 20%, while this occurs in 90% of the Sy1,
suggesting recent star formation in the central region. The central few hundred
parsecs of our galaxy sample contain a substantial fraction of intermediate-age
SPs with a mean metallicity near solar. Our SP synthesis confirms that the
1.1microns CN band can be used as a tracer of intermediate-age stellar
populations.Comment: To appear in IAU S262 proceedings, 4 pages, 4 figure
The adaptive optics lucky imager (AOLI): presentation, commissioning, and AIV innovations
Here we present the Adaptive Optics Lucky Imager (AOLI), a state-of-the-art
instrument which makes use of two well proved techniques, Lucky Imaging (LI)
and Adaptive Optics (AO), to deliver diffraction limited imaging at visible
wavelengths, 20 mas, from ground-based telescopes. Thanks to its revolutionary
TP3-WFS, AOLI shall have the capability of using faint reference stars. In the
extremely-big telescopes era, the combination of techniques and the development
of new WFS systems seems the clue key for success. We give details of the
integration and verification phases explaining the defiance that we have faced
and the innovative and versatile solutions for each of its subsystems that we
have developed, providing also very fresh results after its first fully-working
observing run at the William Herschel Telescope (WHT).Comment: 6 pages, 6 figures, conference. arXiv admin note: text overlap with
arXiv:1703.09354, arXiv:1608.0480
Exchange bias with Fe substitution in LaMnO_3
The exchange bias (EB) in LaMn_{0.7}Fe_{0.3}O_3 is observed by the negative
shift and training effect of the hysteresis loops, while the sample was cooled
in external magnetic field. The analysis of cooling field dependence of EB
gives the size of the ferromagnetic (FM) cluster ~ 25 Angstrom, where the
magnetic anisotropy of FM cluster is found two order of magnitude higher than
the FM bulk manganites. We propose that the nanoscale FM clusters are embedded
in the glassy magnetic host with EB at the FM/glassy magnetic interface.Comment: 6 figure
Metastatic renal cell carcinoma presenting as a paranasal sinus mass: the importance of differential diagnosis
Metastases in the paranasal sinuses are rare; renal cell carcinoma is the most common cancer that metastasizes to this region. We present the case of a patient with a 4-month history of a rapidly growing mass of the nasal pyramid following a nasal trauma, associated with spontaneous epistaxis and multiple episodes of hematuria. Cranial CT scan and MRI showed an ethmoid mass extending to the choanal region, the right orbit, and the right frontal sinus with an initial intracranial extension. Patient underwent surgery with a trans-sinusal frontal approach using a bicoronal incision combined with an anterior midfacial degloving; histological exam was compatible with a metastasis of clear cell renal cell carcinoma. Following histological findings, a total body CT scan showed a solitary 6 cm mass in the upper posterior pole of the left kidney identified as the primary tumor. Although rare, metastatic renal cell carcinoma should always be suspected in patients with nasal or paranasal masses, especially if associated with symptoms suggestive of a systemic involvement such as hematuria. A correct early-stage diagnosis of metastatic RCC can considerably improve survival rate in these patients; preoperative differential diagnosis with contrast-enhanced imaging is fundamental for the correct treatment and follow-up strategy
Weak Measurements of Light Chirality with a Plasmonic Slit
We examine, both experimentally and theoretically, an interaction of tightly
focused polarized light with a slit on a metal surface supporting
plasmon-polariton modes. Remarkably, this simple system can be highly sensitive
to the polarization of the incident light and offers a perfect
quantum-weak-measurement tool with a built-in post-selection in the
plasmon-polariton mode. We observe the plasmonic spin Hall effect in both
coordinate and momentum spaces which is interpreted as weak measurements of the
helicity of light with real and imaginary weak values determined by the input
polarization. Our experiment combines advantages of (i) quantum weak
measurements, (ii) near-field plasmonic systems, and (iii) high-numerical
aperture microscopy in employing spin-orbit interaction of light and probing
light chirality.Comment: 5 pages, 3 figure
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