203 research outputs found
Immediate results of percutaneous management of coarctation of the aorta: A 7-year single-centre experience.
Coarctation of the aorta (CoA) is often treated percutaneously. The aim of this study was to describe the immediate results of percutaneous management of native aortic coarctation (NaCoA) and recoarctation of the aorta (ReCoA) at our institution.
We identified all patients with NaCoA or ReCoA who underwent percutaneous dilatation by either balloon angioplasty (BAP) or endovascular stent implantation (ESI) between 2011 and 2017. Success was defined as a residual peak-to-peak gradient (PPG) <20 mmHg or a ≥50% reduction in the gradient if the pre-intervention PPG was <20 mmHg.
63 patients (median age 6.8 years, interquartile range [IQR] 0.4-14.2) were identified. Among 11 patients with NaCoA, 7 underwent BAP and 4 had ESI, and among 52 patients with ReCoA, 42 underwent BAP and 10 had ESI. In patients with NaCoA, BAP was successful in 71%, with median PPG decreasing from 32 mmHg (IQR 25-46) to 17 mmHg (IQR 4-23) (p = .02), and ESI was successful in 100%, with median PPG decreasing from 20 mmHg (IQR 14.5-40) to 2 mmHg (IQR 0-6) (p < .01). In patients with ReCoA, BAP was successful in 69%, with median PPG decreasing from 20 mmHg (IQR 16-31.3) to 9 mmHg (IQR 0-14.3) (p < .001), and ESI was successful in 100%, with median PPG decreasing from 18 mmHg (IQR 11.5-22.8) to 0 mmHg (IQR 0-3.5) (p < .01). ESI was more successful than BAP (p = .01). There was only one complication.
Percutaneous management of CoA is safe and effective in both NaCoA and ReCoA. Stent implantation is more effective than BAP
Lithium Diffusion & Magnetism in Battery Cathode Material LixNi1/3Co1/3Mn1/3O2
We have studied low-temperature magnetic properties as well as
high-temperature lithium ion diffusion in the battery cathode materials
LixNi1/3Co1/3Mn1/3O2 by the use of muon spin rotation/relaxation. Our data
reveal that the samples enter into a 2D spin-glass state below TSG=12 K. We
further show that lithium diffusion channels become active for T>Tdiff=125 K
where the Li-ion hopping-rate [nu(T)] starts to increase exponentially.
Further, nu(T) is found to fit very well to an Arrhenius type equation and the
activation energy for the diffusion process is extracted as Ea=100 meV.Comment: Submitted to Journal of Physics: Conference Series (2014
Gaia Eclipsing Binary and Multiple Systems. A study of detectability and classification of eclipsing binaries with Gaia
In the new era of large-scale astronomical surveys, automated methods of
analysis and classification of bulk data are a fundamental tool for fast and
efficient production of deliverables. This becomes ever more imminent as we
enter the Gaia era. We investigate the potential detectability of eclipsing
binaries with Gaia using a data set of all Kepler eclipsing binaries sampled
with Gaia cadence and folded with the Kepler period. The performance of fitting
methods is evaluated with comparison to real Kepler data parameters and a
classification scheme is proposed for the potentially detectable sources based
on the geometry of the light curve fits. The polynomial chain (polyfit) and
two-Gaussian models are used for light curve fitting of the data set.
Classification is performed with a combination of the t-SNE (t-distrubuted
Stochastic Neighbor Embedding) and DBSCAN (Density-Based Spatial Clustering of
Applications with Noise) algorithms. We find that approximately 68% of Kepler
Eclipsing Binary sources are potentially detectable by Gaia when folded with
the Kepler period and propose a classification scheme of the detectable sources
based on the morphological type indicative of the light curve, with subclasses
that reflect the properties of the fitted model (presence and visibility of
eclipses, their width, depth, etc.).Comment: 9 pages, 18 figures, accepted for publication in Astronomy &
Astrophysic
Magnetic Order in the 2D Heavy-Fermion System CePt2In7 studied by muSR
The low-temperature microscopic magnetic properties of the quasi-2D
heavyfermion compound, CePt2In7 are investigated by using a positive muon-spin
rotation and relaxation (?muSR) technique. Clear evidence for the formation of
a commensurate antiferromagnetic order below TN=5.40 K is presented. The
magnetic order parameter is shown to fit well to a modified BSC gap-energy
function in a strong-coupling scenario.Comment: Accepted in Journal of Physics: Conference Series (2014
Gaia eclipsing binary and multiple systems. Two-Gaussian models applied to OGLE-III eclipsing binary light curves in the Large Magellanic Cloud
The advent of large scale multi-epoch surveys raises the need for automated
light curve (LC) processing. This is particularly true for eclipsing binaries
(EBs), which form one of the most populated types of variable objects. The Gaia
mission, launched at the end of 2013, is expected to detect of the order of few
million EBs over a 5-year mission.
We present an automated procedure to characterize EBs based on the geometric
morphology of their LCs with two aims: first to study an ensemble of EBs on a
statistical ground without the need to model the binary system, and second to
enable the automated identification of EBs that display atypical LCs. We model
the folded LC geometry of EBs using up to two Gaussian functions for the
eclipses and a cosine function for any ellipsoidal-like variability that may be
present between the eclipses. The procedure is applied to the OGLE-III data set
of EBs in the Large Magellanic Cloud (LMC) as a proof of concept. The bayesian
information criterion is used to select the best model among models containing
various combinations of those components, as well as to estimate the
significance of the components.
Based on the two-Gaussian models, EBs with atypical LC geometries are
successfully identified in two diagrams, using the Abbe values of the original
and residual folded LCs, and the reduced . Cleaning the data set from
the atypical cases and further filtering out LCs that contain non-significant
eclipse candidates, the ensemble of EBs can be studied on a statistical ground
using the two-Gaussian model parameters. For illustration purposes, we present
the distribution of projected eccentricities as a function of orbital period
for the OGLE-III set of EBs in the LMC, as well as the distribution of their
primary versus secondary eclipse widths.Comment: 20 pages, 29 figures. Submitted to A&
A case of corticosteroid-dependent recurrent pericarditis with different response to two IL-1 blocking agents
Background: Recurrent pericarditis (RP) represents the most troublesome presentation of pericarditis and has a controversial pathogenesis that crosses infectious, auto-immune and auto-inflammatory pathways. It has been suggested that in some cases it might be an unrecognized auto-inflammatory disease. Recent studies have demonstrated that anakinra, an interleukin-1 receptor antagonist (IL-1RA), represents an effective treatment for the control of corticosteroid-dependent cases.
Objectives: To describe a case of cortico-dependent recurrent pericarditis with a different response to two IL-1 blocking agents, anakinra and canakinumab.
Methods: Case report
Results: 11 years old boy who was admitted to our hospital because of acute precordial pain, orthopnea, fever and increased levels of acute phase reactants. Acute pericarditis was confirmed by echocardiography and a treatment with prednisone was started with prompt clinical improvement. Pericarditis recurred twice during steroid tapering (1mg/kg/day and 0.5mg/kg/day respectively). After exclusion of infectious origin, therapy with anakinra (2mg/kg/day) was established (to avoid long term steroid side effects) followed by dramatic clinical response and normalisation of laboratory findings despite tapering and discontinuation of prednisone. Treatment with anakinra was discontinued after 5 months with recurrence of pericarditis one week later. Anakinra was resumed with an excellent response. Five months later, while being in complete remission, anakinra was replaced with canakinumab (2mg/kg/dose) due to patient’s intolerance of daily injections. One week later, the patient experienced a new episode of pericarditis requiring corticotherapy. Two more relapses occured during steroid tapering, after 6 weeks and 2 months, in spite of the uptitration of canakinumab to 4mg/kg/dose. Anakinra was restarted with prompt clinical and biological remission and prednisone was discontinuated without recurrence of pericarditis. After further four weeks follow-up under anakinra alone, the pericarditis is still in remission.
Conclusion: We describe a case of steroid-dependent RP with a dramatic therapeutic response to IL-1RA (anakinra) but without response to IL-1β monoclonal antibody (canakinumab). This unexpected observation could suggest that Il-1α might have a role in the pathogenesis of RP. The definitive potential usefulness of each IL-1 blocking agent requires confirmation in prospective controlled trials
DISCOVERY OF TWO NEW THERMALLY BLOATED LOW-MASS WHITE DWARFS AMONG THE KEPLER BINARIES
We report the discovery of two new low-mass, thermally bloated, hot white dwarfs among the Kepler sample of eclipsing binaries. These are KIC 9164561 and KIC 10727668 with orbital periods of 1.2670 and 2.3058 days, respectively. The current primary in both systems is an A star of about 2 M[subscript ʘ]. This brings the number of similar binaries among the Kepler sample to six, and the two new systems have the shortest orbital periods among them. The white dwarf (WD) in KIC 9164561 has the largest thermal bloating, compared to its cold degenerate radius, of about a factor of 14. We utilize radial velocity measurements of the A star in KIC 9164561 to determine the WD mass rather accurately: 0.197 ± 0.005 M[subscript ʘ]. The mass of the WD in KIC 10727668 is based on the Doppler boosting signal in the Kepler photometry and is less accurately determined to be 0.266 ± 0.035 M[subscript ʘ]. Based on the inferred radii and effective temperatures of these two white dwarfs, we are able to make an independent theoretical estimate of their masses to within ~0.01 M[subscript ʘ] based on evolutionary models of their cooling history after they lose their hydrogen-rich envelopes. We also present evidence that there is a third body in the KIC 9164561 system with an orbital period of 8–14 yr.Spain. Ministerio de Economia y Competitividad (Grant ESP2013-48391-C4-2 R)National Aeronautics and Space Administration (Kepler Participating Scientist Program
HD 174884: a strongly eccentric, short-period early-type binary system discovered by CoRoT
Accurate photometric CoRoT space observations of a secondary seismological
target, HD 174884, led to the discovery that this star is an astrophysically
important double-lined eclipsing spectroscopic binary in an eccentric orbit (e
of about 0.3), unusual for its short (3.65705d) orbital period. The high
eccentricity, coupled with the orientation of the binary orbit in space,
explains the very unusual observed light curve with strongly unequal primary
and secondary eclipses having the depth ratio of 1-to-100 in the CoRoT 'seismo'
passband. Without the high accuracy of the CoRoT photometry, the secondary
eclipse, 1.5 mmag deep, would have gone unnoticed. A spectroscopic follow-up
program provided 45 high dispersion spectra. The analysis of the CoRoT light
curve was performed with an adapted version of PHOEBE that supports CoRoT
passbands. The final solution was obtained by simultaneous fitting of the light
and the radial velocity curves. Individual star spectra were derived by
spectrum disentangling. The uncertainties of the fit were derived by bootstrap
resampling and the solution uniqueness was tested by heuristic scanning. The
results provide a consistent picture of the system composed of two late B
stars. The Fourier analysis of the light curve fit residuals yields two
components, with orbital frequency multiples and an amplitude of about 0.1
mmag, which are tentatively interpreted as tidally induced pulsations. An
extensive comparison with theoretical models is carried out by means of the
Levenberg-Marquardt minimization technique and the discrepancy between models
and the derived parameters is discussed. The best fitting models yield a young
system age of 125 million years which is consistent with the eccentric orbit
and synchronous component rotation at periastron.Comment: 15 pages, 12 figures. Accepted for publication by A&
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