637 research outputs found
Unruptured anterior communicating artery aneurysm with co-existing blister aneurysms: Case report and review of literature
Blister aneurysms are a separate class of vascular malformations with a unique etiopathogenesis and clinical profile, elusive to radiological imaging and complex to manage. Unless identified and managed appropriately they often lead increased morbidity intra and post operatively. They are commonly reported in internal carotid artery. We are reporting a rare case of intraoperatively diagnosed blister aneurysm of the anterior cerebral artery, the management options and the importance of constant vigilance in cases where the aneurysm appears unruptured intraoperatively
PRIMA General Observer Science Book
PRIMA (The PRobe for-Infrared Mission for Astrophysics) is a concept for a
far-infrared (IR) observatory. PRIMA features a cryogenically cooled 1.8 m
diameter telescope and is designed to carry two science instruments enabling
ultra-high sensitivity imaging and spectroscopic studies in the 24 to 235
microns wavelength range. The resulting observatory is a powerful survey and
discovery machine, with mapping speeds better by 2 - 4 orders of magnitude with
respect to its far-IR predecessors. The bulk of the observing time on PRIMA
should be made available to the community through a General Observer (GO)
program offering 75% of the mission time over 5 years. In March 2023, the
international astronomy community was encouraged to prepare authored
contributions articulating scientific cases that are enabled by the telescope
massive sensitivity advance and broad spectral coverage, and that could be
performed within the context of GO program. This document, the PRIMA General
Observer Science Book, is the edited collection of the 76 received
contributions.Comment: A. Moullet, T. Kataria, D. Lis, S. Unwin, Y. Hasegawa, E. Mills, C.
Battersby, A. Roc, M. Meixner are the editors of the PRIMA General Observer
Science Book. The book compiles 76 authored contributions. 399 page
Radial velocity eclipse mapping of exoplanets
Planetary rotation rates and obliquities provide information regarding the
history of planet formation, but have not yet been measured for evolved
extrasolar planets. Here we investigate the theoretical and observational
perspective of the Rossiter-McLauglin effect during secondary eclipse (RMse)
ingress and egress for transiting exoplanets. Near secondary eclipse, when the
planet passes behind the parent star, the star sequentially obscures light from
the approaching and receding parts of the rotating planetary surface. The
temporal block of light emerging from the approaching (blue-shifted) or
receding (red-shifted) parts of the planet causes a temporal distortion in the
planet's spectral line profiles resulting in an anomaly in the planet's radial
velocity curve. We demonstrate that the shape and the ratio of the
ingress-to-egress radial velocity amplitudes depends on the planetary
rotational rate, axial tilt and impact factor (i.e. sky-projected planet
spin-orbital alignment). In addition, line asymmetries originating from
different layers in the atmosphere of the planet could provide information
regarding zonal atmospheric winds and constraints on the hot spot shape for
giant irradiated exoplanets. The effect is expected to be most-pronounced at
near-infrared wavelengths, where the planet-to-star contrasts are large. We
create synthetic near-infrared, high-dispersion spectroscopic data and
demonstrate how the sky-projected spin axis orientation and equatorial velocity
of the planet can be estimated. We conclude that the RMse effect could be a
powerful method to measure exoplanet spins.Comment: 7 pages, 3 figures, 1 table, accepted for publication in ApJ on 2015
June 1
Method comparison studies of telomere length measurement using qPCR approaches:A critical appraisal of the literature
Use of telomere length (TL) as a biomarker for various environmental exposures and diseases has increased in recent years. Various methods have been developed to measure telomere length. Polymerase chain reaction (PCR)-based methods remain wide-spread for population-based studies due to the high-throughput capability. While several studies have evaluated the repeatability and reproducibility of different TL measurement methods, the results have been variable. We conducted a literature review of TL measurement cross-method comparison studies that included a PCR-based method published between January 1, 2002 and May 25, 2020. A total of 25 articles were found that matched the inclusion criteria. Papers were reviewed for quality of methodologic reporting of sample and DNA quality, PCR assay characteristics, sample blinding, and analytic approaches to determine final TL. Overall, methodologic reporting was low as assessed by two different reporting guidelines for qPCR-based TL measurement. There was a wide range in the reported correlation between methods (as assessed by Pearson's r) and few studies utilized the recommended intra-class correlation coefficient (ICC) for assessment of assay repeatability and methodologic comparisons. The sample size for nearly all studies was less than 100, raising concerns about statistical power. Overall, this review found that the current literature on the relation between TL measurement methods is lacking in validity and scientific rigor. In light of these findings, we present reporting guidelines for PCR-based TL measurement methods and results of analyses of the effect of assay repeatability (ICC) on statistical power of cross-sectional and longitudinal studies. Additional cross-laboratory studies with rigorous methodologic and statistical reporting, adequate sample size, and blinding are essential to accurately determine assay repeatability and replicability as well as the relation between TL measurement methods
Superconducting ground state study of valence skip compound AgSnSe
The valence-skipped superconductors are natural candidates for unconventional
superconductivity, as they can exhibit a negative effective, attractive
interaction for electron-pairing. This work reports comprehensive XRD,
magnetization, specific heat and muon spin rotation and relaxation measurements
(SR) on a valence-skipped compound: AgSnSe. The temperature dependence
of the electronic specific heat () and of the upper critical field
() provide evidence of two-gap superconductivity, which is also
confirmed by our transverse-field SR measurements. Our zero-field SR
measurements suggest preserved time-reversal symmetry in the superconducting
ground state of AgSnSe.Comment: 8 pages, 6 figure
EDGE: The direct link between mass growth history and the extended stellar haloes of the faintest dwarf galaxies
Ultra-faint dwarf galaxies (UFDs) are commonly found in close proximity to
the Milky Way and other massive spiral galaxies. As such, their projected
stellar ellipticity and extended light distributions are often thought to owe
to tidal forces. In this paper, we study the projected stellar ellipticities
and faint stellar outskirts of tidally isolated ultra-faints drawn from the
'Engineering Dwarfs at Galaxy Formation's Edge' (EDGE) cosmological simulation
suite. Despite their tidal isolation, our simulated dwarfs exhibit a wide range
of projected ellipticities (), with many possessing
anisotropic extended stellar haloes that mimic tidal tails, but owe instead to
late-time accretion of lower mass companions. Furthermore, we find a strong
causal relationship between ellipticity and formation time of an UFD, which is
robust to a wide variation in the feedback model. We show that the distribution
of projected ellipticities in our suite of simulated EDGE dwarfs matches well
with that of 21 Local Group dwarf galaxies. Given the ellipticity in EDGE
arises from an ex-situ accretion origin, the agreement in shape indicates the
ellipticities of some observed dwarfs may also originate from a similar
non-tidal scenario. The orbital parameters of these observed dwarfs further
support that they are not currently tidally disrupting. If the baryonic content
in these galaxies is still tidally intact, then the same may be true for their
dark matter content, making these galaxies in our Local Group pristine
laboratories for testing dark matter and galaxy formation models.Comment: 10 pages, 4 figures; submitted to MNRA
In-flight calibration of the Cluster PEACE sensors
The Plasma Electron and Current Experiment (PEACE) instruments operate on all four of the Cluster spacecraft and measure the 3-D velocity distribution of electrons in the energy range from 0.59 eV to 26.4 keV during each spacecraft spin. Pitch angle distributions and moments of the velocity distribution are also produced. As the mission has progressed, the efficiency of the detectors has declined. Several factors may play a role in this decline such as exposure to radiation, high electron fluxes and spacecraft thruster firings. To account for these variations, continuous in-flight calibration work is essential. The purpose of this paper is to describe the PEACE calibration parameters, focussing in particular on those that vary over time, and to describe the methods which are used to determine their evolution
Spitzer phase curve observations and circulation models of the inflated ultra-hot Jupiter WASP-76b
The large radii of many hot Jupiters can only be matched by models that have
hot interior adiabats, and recent theoretical work has shown that the interior
evolution of hot Jupiters has a significant impact on their atmospheric
structure. Due to its inflated radius, low gravity, and ultra-hot equilibrium
temperature, WASP-76b is an ideal case study for the impact of internal
evolution on observable properties. Hot interiors should most strongly affect
the non-irradiated side of the planet, and thus full phase curve observations
are critical to ascertain the effect of the interior on the atmospheres of hot
Jupiters. In this work, we present the first Spitzer phase curve observations
of WASP-76b. We find that WASP-76b has an ultra-hot day side and relatively
cold nightside with brightness temperatures of / at 3.6~\micron and / at 4.5~\micron, respectively. These results provide evidence
for a dayside thermal inversion. Both channels exhibit small phase offsets of
at 3.6~\micron and at
. We compare our observations to a suite of general
circulation models that consider two end-members of interior temperature along
with a broad range of frictional drag strengths. Strong frictional drag is
necessary to match the small phase offsets and cold nightside temperatures
observed. From our suite of cloud-free GCMs, we find that only cases with a
cold interior can reproduce the cold nightsides and large phase curve amplitude
at 4.5~\micron, hinting that the hot interior adiabat of WASP-76b does not
significantly impact its atmospheric dynamics or that clouds blanket its
nightside.Comment: 24 pages, 10 Figures, 5 Tables. Accepted to AJ. Co-First Author
Successful treatment of recalcitrant cutaneous sarcoidosis with fumaric acid esters
BACKGROUND: Sarcoidosis is a multisystem disease of unknown origin characterized by the formation of noncaseating granulomas, in particular in the lungs, lymph nodes, eyes, and skin. Systemic treatment for cutaneous sarcoidosis can be used for large disfiguring lesions, generalized involvement, or recalcitrant lesions that did not respond to topical therapy. CASE PRESENTATIONS: We report three patients with recalcitrant cutaneous sarcoidosis who were treated with oral fumaric acid esters (FAE). Three female patients presented with cutaneous sarcoidosis that have proved to be refractory to various therapies, including corticosteroids and chloroquine. We treated the patients with FAE in tablet form using two formulations differing in strength (Fumaderm(® )initial, Fumaderm(®)). Dosage of FAE was performed according to the standard therapy regimen for psoriasis patients. After treatment with FAE (4–12 months), a complete clearance of skin lesions was achieved in the three patients. The side effects observed in this trial correspond to the well-known spectrum of adverse effects of FAE (flush, minor gastrointestinal complaints, lymphopenia). CONCLUSIONS: On the basis of our findings FAE therapy seems to be a safe and effective regimen for patients with recalcitrant cutaneous sarcoidosis. Nevertheless further investigations are necessary to confirm our preliminary results
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