462 research outputs found
Explosion of a massive, He-rich star at z=0.16
We present spectroscopic and photometric data of the peculiar SN 2001gh,
discovered by the 'Southern inTermediate Redshift ESO Supernova Search'
(STRESS) at a redshift z=0.16. SN 2001gh has relatively high luminosity at
maximum (M_B = -18.55 mag), while the light curve shows a broad peak. An
early-time spectrum shows an almost featureless, blue continuum with a few weak
and shallow P-Cygni lines that we attribute to HeI. HeI lines remain the only
spectral features visible in a subsequent spectrum, obtained one month later. A
remarkable property of SN 2001gh is the lack of significant spectral evolution
over the temporal window of nearly one month separating the two spectra. In
order to explain the properties of SN 2001gh, three powering mechanism are
explored, including radioactive decays of a moderately large amount of 56Ni,
magnetar spin-down, and interaction of SN ejecta with circumstellar medium. We
favour the latter scenario, with a SN Ib wrapped in a dense, circumstellar
shell. The fact that no models provide an excellent fit with observations,
confirms the troublesome interpretation of the nature of SN 2001gh. A rate
estimate for SN 2001gh-like event is also provided, confirming the intrinsic
rarity of these objects.Comment: 11 pages, 8 figures, 3 tables. Accepted by MNRA
Epidemiology and outcomes of early versus late septic acute kidney injury in critically ill patients: A retrospective cohort study.
It was recently proposed to distinguish early from late sepsis-associated acute kidney injury (SA-AKI). We aimed to determine the relative frequency of these entities in critically ill patients and to describe their characteristics and outcomes.
We included in this retrospective cohort study all adult patients admitted for sepsis in a tertiary ICU between 2010 and 2020. We excluded those on chronic dialysis or without consent. We extracted serum creatinine, hourly urinary output, and clinical and socio-demographic data from medical records until day 7 or ICU discharge. AKI presence and characteristics were assessed daily using KDIGO criteria. We compared patients with early (occurring within 2 days of admission) or late (occurring between day 2 and day 7) SA-AKI. We conducted sensitivity analyses using different definitions for early/late SA-AKI.
Among 1835 patients, 1660 (90%) fulfilled SA-AKI criteria. Of those, 1610 (97%) had early SA-AKI, and 50 (3%) had late SA-AKI. Similar proportions were observed when only considering AKI with elevated sCr (71% vs. 3%), severe AKI (67% vs. 6%), or different time windows for early SA-AKI. Compared with early SA-AKI patients, those with late SA-AKI were younger (median age [IQR] 59 [49-70] vs. 69 [58-76] years, p < 0.001), had lower Charlson comorbidity index (3 [1-5] vs. 5 [3-7], p < 0.001) and lower SAPSII scores (41 [34-50] vs. 53 [43-64], p < 0.001). They had similar (24% vs. 26%, p = 0.75) in-hospital mortality.
AKI is almost ubiquitous in septic critically ill patients and present within two days of admission. The timing from ICU admission might not be relevant to distinguish different phenotypes of SA-AKI.
Ethics Committee Vaud, Lausanne, Switzerland (n°2017-00008)
Mission conjointe NMA/PRIFAS d´étude et de prospective dans Le Sudeste du Bresil, du 27 octobre au 10 novembre 1990.
bitstream/item/116959/1/1589.pd
Cytokine hemoadsorption with CytoSorb<sup>®</sup> in post-cardiac arrest syndrome, a pilot randomized controlled trial.
Hemoadsorption (HA) might mitigate the systemic inflammatory response associated with post-cardiac arrest syndrome (PCAS) and improve outcomes. Here, we investigated the feasibility, safety and efficacy of HA with CytoSorb <sup>®</sup> in cardiac arrest (CA) survivors at risk of PCAS.
In this pilot randomized controlled trial, we included patients admitted to our intensive care unit following CA and likely to develop PCAS: required norepinephrine (> 0.2 µg/kg/min), and/or had serum lactate > 6 mmol/l and/or a time-to-return of spontaneous circulation (ROSC) > 25 min. Those requiring ECMO or renal replacement therapy were excluded. Eligible patients were randomly allocated to either receive standard of care (SOC) or SOC plus HA. Hemoadsorption was performed as stand-alone therapy for 24 h, using CytoSorb <sup>®</sup> and regional heparin-protamine anticoagulation. We collected feasibility, safety and clinical data as well as serial plasma cytokines levels within 72 h of randomization.
We enrolled 21 patients, of whom 16 (76%) had out-of-hospital CA. Median (IQR) time-to-ROSC was 30 (20, 45) minutes. Ten were assigned to the HA group and 11 to the SOC group. Hemoadsorption was initiated in all patients allocated to the HA group within 18 (11, 23) h of ICU admission and conducted for a median duration of 21 (14, 24) h. The intervention was well tolerated except for a trend for a higher rate of aPTT elevation (5 (50%) vs 2 (18%) p = 0.18) and mild (100-150 G/L) thrombocytopenia at day 1 (5 (50%) vs 2 (18%) p = 0.18). Interleukin (IL)-6 plasma levels at randomization were low (< 100 pg/mL) in 10 (48%) patients and elevated (> 1000 pg/mL) in 6 (29%). The median relative reduction in IL-6 at 48 h was 75% (60, 94) in the HA group versus 5% (- 47, 70) in the SOC group (p = 0.06).
In CA survivors at risk of PCAS, HA was feasible, safe and was associated with a nonsignificant reduction in cytokine plasma levels. Future trials are needed to further define the role of HA after CA. Those studies should include cytokine assessment to enrich the study population.
NCT03523039, registered 14 May 2018
The Peculiar 2004 Superoutburst in the Helium Dwarf Nova, 2003aw
We conducted a time-resolved photometric campaign of the helium dwarf nova,
2003aw in 2004 May--June. 2003aw stayed at 14.7--15.7 mag for the first several
days during this campaign, which is the plateau phase of this superoutburst.
This variable then rapidly decayed to 18.0 mag, still brighter by about 2
mag than its quiescence magnitude, and maintained this brightness for about 20
days, having short flares of 2 mag. A long fading tail followed it. We
detected superhumps with a period of 0.02357(4) d [= 2036(3) s] during the
plateau phase. The whole light curve of the superoutburst in 2003aw, taking
into account the present data and those in the literature, perfectly resembles
that of the 1996-1997 superoutburst of the peculiar WZ Sge-type hydrogen-rich
dwarf nova, EG Cnc.Comment: 5 pages, 4 figures, PASJ Letter in pres
Recurrent mini-outbursts and a magnetic white dwarf in the symbiotic system FN Sgr
AIMS: We investigated the optical variability of the symbiotic binary FN Sgr,
with photometric monitoring during 55 years and with a high-cadence
Kepler light curve lasting 81 days. METHODS: The data obtained in the V and I
bands were reduced with standard photometric methods. The Kepler data were
divided into subsamples and analyses with the Lomb-Scargle algorithm. RESULTS:
The V and I band light curves showed a phenomenon never before observed with
such recurrence in any symbiotic system, namely short outbursts, starting
between orbital phase 0.3 and 0.5 and lasting about a month, with a fast rise
and a slower decline, and amplitude of 0.5-1 mag. In the Kepler light curve we
discovered three frequencies with sidebands. We attribute a stable frequency of
127.5 d (corresponding to an 11.3 minutes period) to the white dwarf
rotation. We suggest that this detection probably implies that the white dwarf
accretes through a magnetic stream, like in intermediate polars. The small
outbursts may be ascribed to the stream-disc interaction. Another possibility
is that they are due to localized thermonuclear burning, perhaps confined by
the magnetic field, like recently inferred in intermediate polars, albeit on
different timescales. We measured also a second frequency around 116.9 d
(corresponding to about 137 minutes), which is much less stable and has a
drift. It may be due to rocky detritus around the white dwarf, but it is more
likely to be caused by an inhomogeneity in the accretion disk. Finally, there
is a third frequency close to the first one that appears to correspond to the
beating between the rotation and the second frequency.Comment: Accepted for publication in Astronomy and Astrophysic
Two X-Ray Bright Cataclysmic Variables with Unusual Activities: GZ Cnc and NSV 10934
We report on a discovery of unexpected activities in two X-ray bright dwarf novae. GZ Cnc showed an anomalous clustering of outbursts in 2002, in contrast to a low outburst frequency in the past record. The activity resembles an increased activity seen in some intermediate polars or candidates. We identified NSV 10934, X-ray selected high-amplitude variable star, as a dwarf nova with unusually rapid decline. The outburst characteristics make NSV 10934 a twin of recently discovered intermediate polar (HT Cam) with dwarf nova-type outbursts. We propose that these activities in X-ray strong dwarf novae may be a previously overlooked manifestation of outburst activities in magnetic cataclysmic variables
Inverse anisotropic diffusion from power density measurements in two dimensions
This paper concerns the reconstruction of an anisotropic diffusion tensor
from knowledge of internal functionals
of the form with for
solutions of the elliptic equation on a two
dimensional bounded domain with appropriate boundary conditions. We show that
for I=4 and appropriately chosen boundary conditions, may uniquely and
stably be reconstructed from such internal functionals, which appear in
coupled-physics inverse problems involving the ultrasound modulation of
electrical or optical coefficients. Explicit reconstruction procedures for the
diffusion tensor are presented and implemented numerically.Comment: 27 pages, 6 figure
An Intermediate Luminosity Transient in NGC300: The Eruption of a Dust-Enshrouded Massive Star
[abridged] We present multi-epoch high-resolution optical spectroscopy,
UV/radio/X-ray imaging, and archival Hubble and Spitzer observations of an
intermediate luminosity optical transient recently discovered in the nearby
galaxy NGC300. We find that the transient (NGC300 OT2008-1) has a peak absolute
magnitude of M_bol~-11.8 mag, intermediate between novae and supernovae, and
similar to the recent events M85 OT2006-1 and SN2008S. Our high-resolution
spectra, the first for this event, are dominated by intermediate velocity
(~200-1000 km/s) hydrogen Balmer lines and CaII emission and absorption lines
that point to a complex circumstellar environment, reminiscent of the yellow
hypergiant IRC+10420. In particular, we detect broad CaII H&K absorption with
an asymmetric red wing extending to ~1000 km/s, indicative of gas infall onto a
massive and relatively compact star (blue supergiant or Wolf-Rayet star); an
extended red supergiant progenitor is unlikely. The origin of the inflowing gas
may be a previous ejection from the progenitor or the wind of a massive binary
companion. The low luminosity, intermediate velocities, and overall similarity
to a known eruptive star indicate that the event did not result in a complete
disruption of the progenitor. We identify the progenitor in archival Spitzer
observations, with deep upper limits from Hubble data. The spectral energy
distribution points to a dust-enshrouded star with a luminosity of about 6x10^4
L_sun, indicative of a ~10-20 M_sun progenitor (or binary system). This
conclusion is in good agreement with our interpretation of the outburst and
circumstellar properties. The lack of significant extinction in the transient
spectrum indicates that the dust surrounding the progenitor was cleared by the
outburst.Comment: Submitted to ApJ; emulateapj style; 39 pages; 26 figure
The beta Pictoris association: Catalog of photometric rotational periods of low-mass members and candidate members
We intended to compile the most complete catalog of bona fide members and
candidate members of the beta Pictoris association, and to measure their
rotation periods and basic properties from our own observations, public
archives, and exploring the literature. We carried out a multi-observatories
campaign to get our own photometric time series and collected all archived
public photometric data time series for the stars in our catalog. Each time
series was analyzed with the Lomb-Scargle and CLEAN periodograms to search for
the stellar rotation periods. We complemented the measured rotational
properties with detailed information on multiplicity, membership, and projected
rotational velocity available in the literature and discussed star by star. We
measured the rotation periods of 112 out of 117 among bona fide members and
candidate members of the beta Pictoris association and, whenever possible, we
also measured the luminosity, radius, and inclination of the stellar rotation
axis. This represents to date the largest catalog of rotation periods of any
young loose stellar association. We provided an extensive catalog of rotation
periods together with other relevant basic properties useful to explore a
number of open issues, such as the causes of spread of rotation periods among
coeval stars, evolution of angular momentum, and lithium-rotation connection.Comment: Forthcoming article, Received: 20 June 2016 / Accepted: 09 September
2016; 40 pages, 2 figures. The online figures A1-A73 are available at CD
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