126 research outputs found
CHEOPS's hunt for exocomets: photometric observations of 5 Vul
The presence of minor bodies in exoplanetary systems is in most cases
inferred through infra-red excesses, with the exception of exocomets. Even if
over 35 years have passed since the first detection of exocomets around beta
Pic, only ~ 25 systems are known to show evidence of evaporating bodies, and
most of them have only been observed in spectroscopy. With the appearance of
new high-precision photometric missions designed to search for exoplanets, such
as CHEOPS, a new opportunity to detect exocomets is available. Combining data
from CHEOPS and TESS we investigate the lightcurve of 5 Vul, an A-type star
with detected variability in spectroscopy, to search for non periodic transits
that could indicate the presence of dusty cometary tails in the system. While
we did not find any evidence of minor bodies, the high precision of the data,
along with the combination with previous spectroscopic results and models,
allows for an estimation of the sizes and spatial distribution of the
exocomets.Comment: Accepted for publication in MNRA
Tricaesium trisÂ(pyridine-2,6-dicarboxylÂato-κ3 O 2,N,O 6)lutetium(III) octaÂhydrate
Colourless block crystals of the title compound, Cs3[Lu(dipic)3]·8H2O [dipic is dipicolinate or pyridine-2,6-dicarboxylÂate, C7H3NO4] were synthesized by slow evaporation of the solvent. The crystal structure of this LuIII-complex, isostructural with the DyIII and EuIII complexes, was determined from a crystal twinned by inversion and consists of discrete [Lu(dipic)3]3− anions, Cs+ cations and water molÂecules involving hydrogen bonding. The Lu atom lies on a twofold rotation axis and is coordinated by six O atoms and three N atoms of three dipicolinate ligands. One Cs atom is also on a twofold axis. The unit cell can be regarded as successive layers along the crystallographic c-axis formed by [Lu(dipic)3]3− anionic planes and [Cs+, H2O] cationic planes. In the crystal structure, although the H atoms attached to water molÂecules could not be located, short O—O contacts clearly indicate the occurrence of an intricate hydrogen-bonded network through contacts with other water molÂecules, Cs cations or with the O atoms of the dipicolinate ligands
ITER LHe Plants Parallel Operation
AbstractThe ITER Cryogenic System includes three identical liquid helium (LHe) plants, with a total average cooling capacity equivalent to 75kW at 4.5K.The LHe plants provide the 4.5Â K cooling power to the magnets and cryopumps. They are designed to operate in parallel and to handle heavy load variations.In this proceedingwe will describe the presentstatusof the ITER LHe plants with emphasis on i) the project schedule, ii) the plantscharacteristics/layout and iii) the basic principles and control strategies for a stable operation of the three LHe plants in parallel
Intracardiac electrophysiology to characterize susceptibility to ventricular arrhythmias in murine models
Introduction: Sudden cardiac death (SCD) and ventricular fibrillation are rare but severe complications of many cardiovascular diseases and represent a major health issue worldwide. Although the primary causes are often acute or chronic coronary diseases, genetic conditions, such as inherited channelopathies or non-ischemic cardiomyopathies are leading causes of SCD among the young. However, relevant experimental models to study the underlying mechanisms of arrhythmias and develop new therapies are still needed. The number of genetically engineered mouse models with cardiac phenotype is growing, making electrophysiological studies in mice essential tools to study arrhythmogenicity and arrhythmia mechanisms and to test novel treatments. Recently, intracardiac catheterization via the jugular vein was described to induce and record ventricular arrhythmias in living anesthetized mice. Several strategies have been reported, developed in healthy wild-type animals and based on aggressive right ventricular stimulation.Methods: Here, we report a protocol based on programmed electrical stimulation (PES) performed in clinical practice in patients with cardiac rhythm disorders, adapted to two transgenic mice models of arrhythmia - Brugada syndrome and cardiolaminopathy.Results: We show that this progressive protocol, based on a limited number of right ventricular extrastimuli, enables to reveal different rhythmic phenotypes between control and diseased mice. In this study, we provide detailed information on PES in mice, including catheter positioning, stimulation protocols, intracardiac and surface ECG interpretation and we reveal a higher susceptibility of two mouse lines to experience triggered ventricular arrhythmias, when compared to control mice.Discussion: Overall, this technique allows to characterize arrhythmias and provides results in phenotyping 2 arrhythmogenic-disease murine models
The SOPHIE search for northern extrasolar planets XIV. A temperate (Teq ~ 300 K) super-earth around the nearby star Gliese 411
Periodic radial velocity variations in the nearby M-dwarf star Gl 411 are reported, based on measurements with the SOPHIE spectrograph. Current data do not allow us to distinguish between a 12.95-day period and its one-day alias at 1.08 days, but favour the former slightly. The velocity variation has an amplitude of 1.6 m s−1, making this the lowest-amplitude signal detected with SOPHIE up to now. We have performed a detailed analysis of the significance of the signal and its origin, including extensive simulations with both uncorrelated and correlated noise, representing the signal induced by stellar activity. The signal is significantly detected, and the results from all tests point to its planetary origin. Additionally, the presence of an additional acceleration in the velocity time series is suggested by the current data. On the other hand, a previously reported signal with a period of 9.9 days, detected in HIRES velocities of this star, is not recovered in the SOPHIE data. An independent analysis of the HIRES dataset also fails to unveil the 9.9-day signal. If the 12.95-day period is the real one, the amplitude of the signal detected with SOPHIE implies the presence of a planet, called Gl 411 b, with a minimum mass of around three Earth masses, orbiting its star at a distance of 0.079 AU. The planet receives about 3.5 times the insolation received by Earth, which implies an equilibrium temperature between 256 and 350 K, and makes it too hot to be in the habitable zone. At a distance of only 2.5 pc, Gl 411 b, is the third closest low-mass planet detected to date. Its proximity to Earth will permit probing its atmosphere with a combination of high-contrast imaging and high-dispersion spectroscopy in the next decade
Variable Nav1.5 Protein Expression from the Wild-Type Allele Correlates with the Penetrance of Cardiac Conduction Disease in the Scn5a+/− Mouse Model
BACKGROUND: Loss-of-function mutations in SCN5A, the gene encoding Na(v)1.5 Na+ channel, are associated with inherited cardiac conduction defects and Brugada syndrome, which both exhibit variable phenotypic penetrance of conduction defects. We investigated the mechanisms of this heterogeneity in a mouse model with heterozygous targeted disruption of Scn5a (Scn5a(+/-) mice) and compared our results to those obtained in patients with loss-of-function mutations in SCN5A. METHODOLOGY/PRINCIPAL FINDINGS: Based on ECG, 10-week-old Scn5a(+/-) mice were divided into 2 subgroups, one displaying severe ventricular conduction defects (QRS interval>18 ms) and one a mild phenotype (QRS53 weeks), ajmaline effect was larger in the severely affected subgroup. These data matched the clinical observations on patients with SCN5A loss-of-function mutations with either severe or mild conduction defects. Ventricular tachycardia developed in 5/10 old severely affected Scn5a(+/-) mice but not in mildly affected ones. Correspondingly, symptomatic SCN5A-mutated Brugada patients had more severe conduction defects than asymptomatic patients. Old severely affected Scn5a(+/-) mice but not mildly affected ones showed extensive cardiac fibrosis. Mildly affected Scn5a(+/-) mice had similar Na(v)1.5 mRNA but higher Na(v)1.5 protein expression, and moderately larger I(Na) current than severely affected Scn5a(+/-) mice. As a consequence, action potential upstroke velocity was more decreased in severely affected Scn5a(+/-) mice than in mildly affected ones. CONCLUSIONS: Scn5a(+/-) mice show similar phenotypic heterogeneity as SCN5A-mutated patients. In Scn5a(+/-) mice, phenotype severity correlates with wild-type Na(v)1.5 protein expression
Multifocal Ectopic Purkinje-Related Premature Contractions: A New SCN5A-Related Cardiac Channelopathy.: MEPPC: a new SCN5A-related cardiac channelopathy
International audienceOBJECTIVES: The aim of this study was to describe a new familial cardiac phenotype and to elucidate the electrophysiological mechanism responsible for the disease. BACKGROUND: Mutations in several genes encoding ion channels, especially SCN5A, have emerged as the basis for a variety of inherited cardiac arrhythmias. METHODS: Three unrelated families comprising 21 individuals affected by multifocal ectopic Purkinje-related premature contractions (MEPPC) characterized by narrow junctional and rare sinus beats competing with numerous premature ventricular contractions with right and/or left bundle branch block patterns were identified. RESULTS: Dilated cardiomyopathy was identified in 6 patients, atrial arrhythmias were detected in 9 patients, and sudden death was reported in 5 individuals. Invasive electrophysiological studies demonstrated that premature ventricular complexes originated from the Purkinje tissue. Hydroquinidine treatment dramatically decreased the number of premature ventricular complexes. It normalized the contractile function in 2 patients. All the affected subjects carried the c.665G>A transition in the SCN5A gene. Patch-clamp studies of resulting p.Arg222Gln (R222Q) Nav1.5 revealed a net gain of function of the sodium channel, leading, in silico, to incomplete repolarization in Purkinje cells responsible for premature ventricular action potentials. In vitro and in silico studies recapitulated the normalization of the ventricular action potentials in the presence of quinidine. CONCLUSIONS: A new SCN5A-related cardiac syndrome, MEPPC, was identified. The SCN5A mutation leads to a gain of function of the sodium channel responsible for hyperexcitability of the fascicular-Purkinje system. The MEPPC syndrome is responsive to hydroquinidine
Gender Difference in the Effects of COVID-19 Pandemic on Mechanical Reperfusion and 30-Day Mortality for STEMI: Results of the ISACS-STEMI COVID-19 Registry
Background. Several reports have demonstrated the impact of the COVID-19 pandemic on
the management and outcome of patients with ST-segment elevation myocardial infarction (STEMI).
The aim of the current analysis is to investigate the potential gender difference in the effects of the
COVID-19 pandemic on mechanical reperfusion and 30-day mortality for STEMI patients within the
ISACS-STEMI COVID-19 Registry. Methods. This retrospective multicenter registry was performed
in high-volume primary percutaneous coronary intervention (PPCI) centers on four continents and
included STEMI patients undergoing PPCIs in March–June 2019 and 2020. Patients were divided
according to gender. The main outcomes were the incidence and timing of the PPCI, (ischemia time
≥ 12 h and door-to-balloon ≥ 30 min) and in-hospital or 30-day mortality. Results. We included
16683 STEMI patients undergoing PPCIs in 109 centers. In 2020 during the pandemic, there was a
significant reduction in PPCIs compared to 2019 (IRR 0.843 (95% CI: 0.825–0.861, p < 0.0001). We did
not find a significant gender difference in the effects of the COVID-19 pandemic on the numbers of
STEMI patients, which were similarly reduced from 2019 to 2020 in both groups, or in the mortality
rates. Compared to prepandemia, 30-day mortality was significantly higher during the pandemic
period among female (12.1% vs. 8.7%; adjusted HR [95% CI] = 1.66 [1.31–2.11], p < 0.001) but not
male patients (5.8% vs. 6.7%; adjusted HR [95% CI] = 1.14 [0.96–1.34], p = 0.12). Conclusions. The
COVID-19 pandemic had a significant impact on the treatment of patients with STEMI, with a
16% reduction in PPCI procedures similarly observed in both genders. Furthermore, we observed
significantly increased in-hospital and 30-day mortality rates during the pandemic only among
females. Trial registration number: NCT 04412655
Age-Related Effects of COVID-19 Pandemic on Mechanical Reperfusion and 30-Day Mortality for STEMI : Results of the ISACS-STEMI COVID-19 Registry
Background: The constraints in the management of patients with ST-segment elevation
myocardial infarction (STEMI) during the COVID-19 pandemic have been suggested to have severely
impacted mortality levels. The aim of the current analysis is to evaluate the age-related effects of
the COVID-19 pandemic on mechanical reperfusion and 30-day mortality for STEMI within the
registry ISACS-STEMI COVID-19. Methods: This retrospective multicenter registry was performed
in high-volume PPCI centers on four continents and included STEMI patients undergoing PPCI
in March–June 2019 and 2020. Patients were divided according to age (< or ≥75 years). The main
outcomes were the incidence and timing of PPCI, (ischemia time longer than 12 h and door-to-balloon
longer than 30 min), and in-hospital or 30-day mortality. Results: We included 16,683 patients
undergoing PPCI in 109 centers. In 2020, during the pandemic, there was a significant reduction in
PPCI as compared to 2019 (IRR 0.843 (95%-CI: 0.825–0.861, p < 0.0001). We found a significant agerelated reduction (7%, p = 0.015), with a larger effect on elderly than on younger patients. Furthermore,
we observed significantly higher 30-day mortality during the pandemic period, especially among the
elderly (13.6% vs. 17.9%, adjusted HR (95% CI) = 1.55 [1.24–1.93], p < 0.001) as compared to younger
patients (4.8% vs. 5.7%; adjusted HR (95% CI) = 1.25 [1.05–1.49], p = 0.013), as a potential consequence
of the significantly longer ischemia time observed during the pandemic. Conclusions: The COVID-19
pandemic had a significant impact on the treatment of patients with STEMI, with a 16% reduction in
PPCI procedures, with a larger reduction and a longer delay to treatment among elderly patients,
which may have contributed to increase in-hospital and 30-day mortality during the pandemic
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