497 research outputs found
Stokes imaging polarimetry using image restoration: A calibration strategy for Fabry-P\'{e}rot based instruments
context: The combination of image restoration and a Fabry-P\'{e}rot
interferometer (FPI) based instrument in solar observations results in specific
calibration issues. FPIs generally show variations over the field-of-view,
while in the image restoration process, the 1-to-1 relation between pixel space
and image space is lost, thus complicating any correcting for such variations.
aims: We develop a data reduction method that takes these issues into account
and minimizes the resulting errors. methods: By accounting for the time
variations in the telescope's Mueller matrix and using separate calibration
data optimized for the wavefront sensing in the MOMFBD image restoration
process and for the final deconvolution of the data, we have removed most of
the calibration artifacts from the resulting data. results: Using this method
to reduce full Stokes data from CRISP at the SST, we find that it drastically
reduces the instrumental and image restoration artifacts resulting from cavity
errors, reflectivity variations, and the polarization dependence of flatfields.
The results allow for useful scientific interpretation. Inversions of restored
data from the sunspot AR11029 using the Nicole inversion code, reveal
strong (~10 km/s) downflows near the disk center side of the umbra.
conclusions: The use of image restoration in combination with an FPI-based
instrument leads to complications in the calibrations and intrinsic limitations
to the accuracy that can be achieved. We find that for CRISP, the resulting
errors can be kept mostly below the polarimetric accuracy of ~10^-3. Similar
instruments aiming for higher polarimetric and high spectroscopic accuracy,
will, however, need to take these problems into account. keywords: Techniques:
image processing, polarimetric, imaging spectroscopy, Sun: surface magnetism,
sunspots, activityComment: Astronomy and Astrophysics (accepted
3D modelling of geological and anthropogenic deposits at the World Heritage Site of Bryggen in Bergen, Norway
The landscape of many historic cities and the character of their shallow subsurface environments are
defined by a legacy of interaction between anthropogenic and geological processes. Anthropogenic
deposits and excavations result from processes ranging from archaeological activities to modern urban
development. Hence, in heritage cities, any geological investigation should acknowledge the role of past
and ongoing human activities, while any archaeological investigation should be conducted with geological
processes in mind. In this paper it is shown that 3D geological and anthropogenic models at different scales
can provide a holistic system for the management of the subsurface. It provides a framework for the
integration of other spatial and processmodels to help assess the preservationpotential for buried heritage.
Such an integrated framework model is thus contributing to a decision support system for sustainable
urban (re)development and regeneration in cities, while preserving cultural heritage. A collaborative
approach is proposed to enhance research and implementation of combined geological and archaeological
modelling for sustainable land use planning and heritage preservation, using York and Bryggen as prime
examples. This paper presents the status of 3D framework modelling at Bryggen in Norway as an example
Gating by ionic strength and safety check by cyclic-di-AMP in the ABC transporter OpuA
(Micro)organisms are exposed to fluctuating environmental conditions, and adaptation to stress is essential for survival. Increased osmolality (hypertonicity) causes outflow of water and loss of turgor and is dangerous if the cell is not capable of rapidly restoring its volume. The osmoregulatory adenosine triphosphate-binding cassette transporter OpuA restores the cell volume by accumulating large amounts of compatible solute. OpuA is gated by ionic strength and inhibited by the second messenger cyclic-di-AMP, a molecule recently shown to affect many cellular processes. Despite the master regulatory role of cyclic-di-AMP, structural and functional insights into how the second messenger regulates (transport) proteins on the molecular level are lacking. Here, we present high-resolution cryo-electron microscopy structures of OpuA and in vitro activity assays that show how the osmoregulator OpuA is activated by high ionic strength and how cyclic-di-AMP acts as a backstop to prevent unbridled uptake of compatible solutes
Quiet-Sun imaging asymmetries in NaI D1 compared with other strong Fraunhofer lines
Imaging spectroscopy of the solar atmosphere using the NaI D1 line yields
marked asymmetry between the blue and red line wings: sampling a quiet-Sun area
in the blue wing displays reversed granulation, whereas sampling in the red
wing displays normal granulation. The MgI b2 line of comparable strength does
not show this asymmetry, nor does the stronger CaII 8542 line. We demonstrate
the phenomenon with near-simultaneous spectral images in NaI D1, MgI b2, and
CaII 8542 from the Swedish 1-m Solar Telescope. We then explain it with
line-formation insights from classical 1D modeling and with a 3D
magnetohydrodynamical simulation combined with NLTE spectral line synthesis
that permits detailed comparison with the observations in a common format. The
cause of the imaging asymmetry is the combination of correlations between
intensity and Dopplershift modulation in granular overshoot and the sensitivity
to these of the steep profile flanks of the NaI D1 line. The MgI b2 line has
similar core formation but much wider wings due to larger opacity buildup and
damping in the photosphere. Both lines obtain marked core asymmetry from
photospheric shocks in or near strong magnetic concentrations, less from
higher-up internetwork shocks that produce similar asymmetry in the spatially
averaged CaII 8542 profile.Comment: Accepted by Astron & Astrophys. In each in-text citation the year
links to the corresponding ADS abstract pag
The solar chromosphere at high resolution with IBIS. I. New insights from the Ca II 854.2 nm line
(Abridged)
Aims: In this paper, we seek to establish the suitability of imaging
spectroscopy performed in the Ca II 854.2 nm line as a means to investigate the
solar chromosphere at high resolution.
Methods: We utilize monochromatic images obtained with the Interferometric
BIdimensional Spectrometer (IBIS) at multiple wavelengths within the Ca II
854.2 nm line and over several quiet areas. We analyze both the morphological
properties derived from narrow-band monochromatic images and the average
spectral properties of distinct solar features such as network points,
internetwork areas and fibrils.
Results: The spectral properties derived over quiet-Sun targets are in full
agreement with earlier results obtained with fixed-slit spectrographic
observations, highlighting the reliability of the spectral information obtained
with IBIS. Furthermore, the very narrowband IBIS imaging reveals with much
clarity the dual nature of the Ca II 854.2 nm line: its outer wings gradually
sample the solar photosphere, while the core is a purely chromospheric
indicator. The latter displays a wealth of fine structures including bright
points, akin to the Ca II H2V and K2V grains, as well as fibrils originating
from even the smallest magnetic elements. The fibrils occupy a large fraction
of the observed field of view even in the quiet regions, and clearly outline
atmospheric volumes with different dynamical properties, strongly dependent on
the local magnetic topology. This highlights the fact that 1-D models
stratified along the vertical direction can provide only a very limited
representation of the actual chromospheric physics.Comment: 13 pages, 8 figures. Accepted in A&A. Revised version after referee's
comments. New Fig. 1 and 7. Higher quality figures in
http://www.arcetri.astro.it/~gcauzzi/papers/ibis.caii.pd
Nivolumab and ipilimumab in the real-world setting in patients with mesothelioma
Objectives: Nivolumab (anti-PD-1) plus ipilimumab (anti-CTLA-4) is a new first-line treatment combination for patients with pleural mesothelioma. Nivolumab-ipilimumab improved the survival, however, 30.3% of the patients suffered from grade 3–4 treatment related adverse events (TRAE's) and TRAE's led to discontinuation in 23.0% of all patients. Here, we present the first real-world data of nivolumab plus ipilimumab in patients with malignant mesothelioma treated in two mesothelioma expert centers. Methods: Clinical data of patients with mesothelioma treated with nivolumab and ipilimumab were prospectively collected. Clinical parameters were obtained every visit, CT scans were evaluated every 12 weeks and adverse events were assessed continuously during the treatment. Data on grade 2–5 TRAE's and activity (overall response rate (ORR), duration of response (DOR), disease control rate (DCR), median progression-free survival (mPFS) and median overall survival (mOS) were reported. Results: Between January 2021 and August 2022, 184 patients were treated with nivolumab plus ipilimumab. The median follow-up was 12.1 months (95 %CI 11.1 – 13.1). Grade 3–4 TRAEs were seen in 27.7 % of the patients and 25.0 % discontinued immunotherapy treatment early because of TRAE's. ORR was 21.7 % (95 % CI 15.7–27.7), median DOR was 5.7 months (IQR 3.2–8.7) and DCR at 12 weeks 56.0 % (95 % CI 48.8–63.2). The mPFS was 5.5 months (95 %CI 4.1–6.9), mOS was 14.1 months (95 % CI 11.1–18.2). Conclusions: Nivolumab plus ipilimumab had an equal efficacy in a real-world comparable population but also a high risk of TRAE's, leading to discontinuation of treatment in 25% of the patients.</p
Sustainability of Individual EndoAnchor Implants in Therapeutic Use to Treat Type Ia Endoleak After Endovascular Aneurysm Repair
Purpose: To investigate changes in penetration depths and angles of EndoAnchor implants with initially good penetration after therapeutic use in endovascular aneurysm repair. Materials and Methods: Patients were selected from the Aneurysm Treatment Using the Heli-FX Aortic Securement System Global Registry (ANCHOR; ClinicalTrials.gov identifier NCT01534819). Inclusion criteria were (1) EndoAnchor implantation to treat intraoperative or late type Ia endoleak and (2) at least 2 postoperative computed tomography angiography (CTA) scans. Exclusion criteria were the use of adjunct procedures. Based on these criteria, 54 patients (44 men) with 360 EndoAnchor implants were eligible for this analysis. Penetration depth of each EndoAnchor implant into the aortic wall was judged as (1) good (2-mm penetration), (2) borderline (</p
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