210 research outputs found
J004457+4123 (Sharov 21): not a remarkable nova in M31 but a background quasar with a spectacular UV flare
We announce the discovery of a quasar behind the disk of M31, which was
previously classified as a remarkable nova in our neighbour galaxy. The paper
is primarily aimed at the outburst of J004457+4123 (Sharov 21), with the first
part focussed on the optical spectroscopy and the improvement in the
photometric database. Both the optical spectrum and the broad band spectral
energy distribution of Sharov 21 are shown to be very similar to that of
normal, radio-quiet type 1 quasars. We present photometric data covering more
than a century and resulting in a long-term light curve that is densely sampled
over the past five decades. The variability of the quasar is characterized by a
ground state with typical fluctuation amplitudes of ~0.2 mag around B~20.5,
superimposed by a singular flare of ~2 yr duration (observer frame) with the
maximum at 1992.81 where the UV flux has increased by a factor of ~20. The
total energy in the flare is at least three orders of magnitudes higher than
the radiated energy of the most luminous supernovae, provided that it comes
from an intrinsic process and the energy is radiated isotropically. The profile
of the flare light curve appears to be in agreement with the standard
predictions for a stellar tidal disruption event where a ~10 M_sun giant star
was shredded in the tidal field of a ~2...5 10^8 M_sun black hole. The short
fallback time derived from the light curve requires an ultra-close encounter
where the pericentre of the stellar orbit is deep within the tidal disruption
radius. Gravitational microlensing provides an alternative explanation, though
the probability of such a high amplification event is very low.Comment: Accepted for publication in Astronomy and Astrophysics, 14 pages, 11
figure
The night-sky at the Calar Alto Observatory II: The sky at the near infrared
We present here the characterization of the night sky-brightness at the
near-infrared, the telescope seeing, and the fraction of useful time at the
Calar Alto observatory. For this study we have collected a large dataset
comprising 7311 near-infrared images taken regularly along the last four years
for the ALHAMBRA survey (J, H and Ks-bands), together with a more reduced
dataset of additional near-infrared images taken for the current study. In
addition we collected the information derived by the meteorological station at
the observatory during the last 10 years, together with the results from the
cloud sensor for the last ~2 years. We analyze the dependency of the
near-infrared night sky-brightness with the airmass and the seasons, studying
its origins and proposing a zenithal correction. A strong correlation is found
between the night sky-brightness in the Ks-band and the air temperature, with a
gradient of ~ -0.08 mag per 1 C degree. The typical (darkest) night
sky-brightness in the J, H and Ks-band are 15.95 mag (16.95 mag), 13.99 mag
(14.98 mag) and 12.39 mag (13.55 mag), respectively. These values show that
Calar Alto is as dark in the near-infrared as most of the other astronomical
astronomical sites in the world that we could compare with. Only Mauna Kea is
clearly darker in the Ks-band. The typical telescope seeing at the 3.5m is
~1.0" when converted to the V-band, being only slightly larger than the
atmospheric seeing measured at the same time by the seeing monitor, ~0.9".
Finally we estimate the fraction of useful time based on the relative humidity,
gust wind speed and presence of clouds. This fraction, ~72%, is very similar to
the one derived in Paper I, based on the fraction of time when the extinction
monitor is working.Comment: 15 pages, 6 figures, accepted to be published in PAS
Architecture of a consent management suite and integration into IHE-based regional health information networks
<p>Abstract</p> <p>Background</p> <p>The University Hospital Heidelberg is implementing a Regional Health Information Network (RHIN) in the Rhine-Neckar-Region in order to establish a shared-care environment, which is based on established Health IT standards and in particular Integrating the Healthcare Enterprise (IHE). Similar to all other Electronic Health Record (EHR) and Personal Health Record (PHR) approaches the chosen Personal Electronic Health Record (PEHR) architecture relies on the patient's consent in order to share documents and medical data with other care delivery organizations, with the additional requirement that the German legislation explicitly demands a patients' opt-in and does not allow opt-out solutions. This creates two issues: firstly the current IHE consent profile does not address this approach properly and secondly none of the employed intra- and inter-institutional information systems, like almost all systems on the market, offers consent management solutions at all. Hence, the objective of our work is to develop and introduce an extensible architecture for creating, managing and querying patient consents in an IHE-based environment.</p> <p>Methods</p> <p>Based on the features offered by the IHE profile Basic Patient Privacy Consent (BPPC) and literature, the functionalities and components to meet the requirements of a centralized opt-in consent management solution compliant with German legislation have been analyzed. Two services have been developed and integrated into the Heidelberg PEHR.</p> <p>Results</p> <p>The standard-based Consent Management Suite consists of two services. The Consent Management Service is able to receive and store consent documents. It can receive queries concerning a dedicated patient consent, process it and return an answer. It represents a centralized policy enforcement point. The Consent Creator Service allows patients to create their consents electronically. Interfaces to a Master Patient Index (MPI) and a provider index allow to dynamically generate XACML-based policies which are stored in a CDA document to be transferred to the first service. Three workflows have to be considered to integrate the suite into the PEHR: recording the consent, publishing documents and viewing documents.</p> <p>Conclusions</p> <p>Our approach solves the consent issue when using IHE profiles for regional health information networks. It is highly interoperable due to the use of international standards and can hence be used in any other region to leverage consent issues and substantially promote the use of IHE for regional health information networks in general.</p
Representing Semantified Biological Assays in the Open Research Knowledge Graph
In the biotechnology and biomedical domains, recent text mining efforts
advocate for machine-interpretable, and preferably, semantified, documentation
formats of laboratory processes. This includes wet-lab protocols, (in)organic
materials synthesis reactions, genetic manipulations and procedures for faster
computer-mediated analysis and predictions. Herein, we present our work on the
representation of semantified bioassays in the Open Research Knowledge Graph
(ORKG). In particular, we describe a semantification system work-in-progress to
generate, automatically and quickly, the critical semantified bioassay data
mass needed to foster a consistent user audience to adopt the ORKG for
recording their bioassays and facilitate the organisation of research,
according to FAIR principles.Comment: In Proceedings of 'The 22nd International Conference on Asia-Pacific
Digital Libraries
The OpenCitations Data Model
A variety of schemas and ontologies are currently used for the
machine-readable description of bibliographic entities and citations. This
diversity, and the reuse of the same ontology terms with different nuances,
generates inconsistencies in data. Adoption of a single data model would
facilitate data integration tasks regardless of the data supplier or context
application. In this paper we present the OpenCitations Data Model (OCDM), a
generic data model for describing bibliographic entities and citations,
developed using Semantic Web technologies. We also evaluate the effective
reusability of OCDM according to ontology evaluation practices, mention
existing users of OCDM, and discuss the use and impact of OCDM in the wider
open science community.Comment: ISWC 2020 Conference proceeding
Analysis of the Interaction Effects in the Southern Galaxy Pair Tol1238-364 and ESO381-G009
In the context of the connection among galaxy-galaxy interaction, starbursts
and nuclear activity, we present and discuss a quantitative morphological
analysis based on BVR images and a detailed spectroscopic investigation of two
interacting galaxies, the Seyfert 2 Tol1238-364 (IC 3639) and its companion
ESO381-G009, forming a triple system with ESO381-G006. Broad-band optical
photometry is complemented by Halpha imaging, which provides information about
the distribution of star forming regions across the galaxies. Long-slit
spectroscopic data obtained at different position angles of the slit are
employed to determine the physical conditions of circumnuclear and extranuclear
regions. A mixture of thermal and non-thermal ionizing radiation is found in
the surroundings of the nucleus of Tol1238-364 and the energy budget supports
the presence of a circumnuclear starburst.Several regions in both the galaxies
show anomalous line ratios: additional ionization by shock-heating and low
ionization of some extranuclear HII regions are suggested as possible
explanations. An analysis of the emission-line profiles reveals the presence of
a broad Halpha component in the nuclear region of Tol1238-364. Independent
estimates of the star formation rates (SFR) were obtained through
flux-calibrated Halpha-images and FIR emission in the four IRAS bands. Overall
SFR densities have been compared with the SFR densities derived from Halpha
emission in the individual regions of the galaxies sampled by long-slit
spectra. In both galaxies an enhancement of the star formation activity with
respect to isolated galaxies is revealed. The prevalence of starburst or
nuclear activity has been examined through FIR color indices. The interaction
scenario is discussed on the basis of the observed galaxy properties.Comment: Tentatively scheduled for publication in ApJS, v184 n2 October 2003
issue. A version with full resolution figures is available as unedited
preprint at http://www.journals.uchicago.edu/ApJ/future.htm
M31N 2007-11d: A Slowly-Rising, Luminous Nova in M31
We report a series of extensive photometric and spectroscopic observations of
the luminous M31 nova M31N 2007-11d. Our photometric observations coupled with
previous measurements show that the nova took at least four days to reach peak
brightness at R~14.9 on 20 Nov 2007 UT. After reaching maximum, the time for
the nova to decline 2 and 3 magnitudes from maximum light (t_2 and t_3) was
~9.5 and ~13 days, respectively, establishing that M31N 2007-11d was a
moderately fast declining nova. During the nova's evolution a total of three
spectra were obtained. The first spectrum was obtained one day after maximum
light (5 days post-discovery), followed by two additional spectra taken on the
decline at two and three weeks post-maximum. The initial spectrum reveals
narrow Balmer and Fe II emission with P Cygni profiles superimposed on a blue
continuum. These data along with the spectra obtained on the subsequent decline
clearly establish that M31N 2007-11d belongs to the Fe II spectroscopic class.
The properties of M31N 2007-11d are discussed within the context of other
luminous novae in M31, the Galaxy, and the LMC. Overall, M31N 2007-11d appears
to be remarkably similar to Nova LMC 1991, which was another bright,
slowly-rising, Fe II nova. A comparison of the available data for luminous
extragalactic novae suggest that the >~4 day rise to maximum light seen in M31N
2007-11d may not be unusual, and that the rise times of luminous Galactic
novae, usually assumed to be <~2 days, may have been underestimated.Comment: Accepted for publication in The Astrophysical Journal (28 pages, 6
figures
First optical identification of a suprsoft X-ray source in M31
We propose the first association of an optical counterpart with a luminous
supersoft X-ray source in M31, RX J0044.0+4118, observed with ROSAT in July
1991. The PSPC position is at 1.6" angular distance from a candidate nova in
outburst in September of 1990. This is interesting because the incidence of
classical novae among supersoft X-ray sources is an open question. The proposed
optical counterpart was measured at R~17.7 in September of 1990, and it had
faded to R>19.2 when it was observed again after 70 days.
The light curve was too sparsely monitored for definite conclusions on the
speed class of the nova. No other variable objects with V<23.5 were found in
the ROSAT spatial error box. We evaluate that the probability that a classical
or recurrent nova was in outburst in the ROSAT error box in the few years
preceding the observation is very small, so the proposed identification is
meaningful. We also show evidence that the associated supersoft X-ray source
turned off in the third year after the outburst.Comment: To appear in Astronomy and Astrophysic
Effects of Short Term Adiponectin Receptor Agonism on Cardiac Function and Energetics in Diabetic db/db Mice.
Objective
Impaired cardiac efficiency is a hallmark of diabetic cardiomyopathy in models of type 2 diabetes. Adiponectin receptor 1 (AdipoR1) deficiency impairs cardiac efficiency in non-diabetic mice, suggesting that hypoadiponectinemia in type 2 diabetes may contribute to impaired cardiac efficiency due to compromised AdipoR1 signaling. Thus, we investigated whether targeting cardiac adiponectin receptors may improve cardiac function and energetics, and attenuate diabetic cardiomyopathy in type 2 diabetic mice.
Methods
A non-selective adiponectin receptor agonist, AdipoRon, and vehicle were injected intraperitoneally into Eight-week-old db/db or C57BLKS/J mice for 10 days. Cardiac morphology and function were evaluated by echocardiography and working heart perfusions.
Results
Based on echocardiography, AdipoRon treatment did not alter ejection fraction, left ventricular diameters or left ventricular wall thickness in db/db mice compared to vehicle-treated mice. In isolated working hearts, an impairment in cardiac output and efficiency in db/db mice was not improved by AdipoRon. Mitochondrial respiratory capacity, respiration in the presence of oligomycin, and 4-hydroxynonenal levels were similar among all groups. However, AdipoRon induced a marked shift in the substrate oxidation pattern in db/db mice towards increased reliance on glucose utilization. In parallel, the diabetes-associated increase in serum triglyceride levels in vehicle-treated db/db mice was blunted by AdipoRon treatment, while an increase in myocardial triglycerides in vehicle-treated db/db mice was not altered by AdipoRon treatment.
Conclusion
AdipoRon treatment shifts myocardial substrate preference towards increased glucose utilization, likely by decreasing fatty acid delivery to the heart, but was not sufficient to improve cardiac output and efficiency in db/db mice
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