147 research outputs found
On the nature of CP Pup
We present new X-ray and optical spectra of the old nova CP Pup (nova Pup 1942) obtained with Chandra and the Cerro Tololo Inter American Observatory (CTIO) 4 m telescope. The X-ray spectrum reveals a multitemperature optically thin plasma reaching a maximum temperature of 36^{+19}_{-16} keV absorbed by local complex neutral material. The time-resolved optical spectroscopy confirms the presence of the ?1.47 h period, with cycle-to-cycle amplitude changes, as well as of an additional long-term modulation which is suggestive either of a longer period or of non-Keplerian velocities in the emission line regions. These new observational facts add further support to CP Pup as a magnetic cataclysmic variable (mCV). We compare the mCV and the non-mCV scenarios and, while we cannot conclude whether CP Pup is a long-period system, all pieces of observational evidence point at an intermediate polar-type CV.Fil: Mason, E.. Osservatorio Astronomico di Trieste; Italia; Space Telescope Science Institute, Estados Unidos de AmĂ©rica;Fil: Orio, M.. Osservatorio Astronomico di Padova; Italia;Fil: Mukai, K.. NASA Goddard Space Flight Center; Estados Unidos de AmĂ©rica;Fil: Bianchini, A.. Dipartimento di Astronomia; Italia;Fil: de Martino, D.. Osservatorio Astronomico di Capodimonte, Italia;Fil: Di Mille, F.. Australian Astronomical Observatory-Carnegie Observatories, Colina; Chile; Dipartimento di Astronomia; Italia;Fil: Williams, R. E.. Department of Astronomy, University of Wisconsin, Estados Unidos de AmĂ©rica;Fil: Abbot, T..Fil: de Propris, R..Fil: Luna, Gerardo Juan Manuel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa, Ciudad Universitaria. Instituto de AstronomĂa y FĂsica del Espacio (i)
Novel conopeptides of largely unexplored Indo Pacific <i>Conus</i> sp.
Cone snails are predatory creatures using venom as a weapon for prey capture and defense. Since this venom is neurotoxic, the venom gland is considered as an enormous collection of pharmacologically interesting compounds having a broad spectrum of targets. As such, cone snail peptides represent an interesting treasure for drug development. Here, we report five novel peptides isolated from the venom of Conus longurionis, Conus asiaticus and Conus australis. Lo6/7a and Lo6/7b were retrieved from C. longurionis and have a cysteine framework VI/VII. Lo6/7b has an exceptional amino acid sequence because no similar conopeptide has been described to date (similarity percentage C. asiaticus, has a typical framework III Cys arrangement, classifying the peptide in the M-superfamily. Asi14a, another peptide of C. asiaticus, belongs to framework XIV peptides and has a unique amino acid sequence. Finally, AusB is a novel conopeptide from C. australis. The peptide has only one disulfide bond, but is structurally very different as compared to other disulfide-poor peptides. The peptides were screened on nAChRs, NaV and KV channels depending on their cysteine framework and proposed classification. No targets could be attributed to the peptides, pointing to novel functionalities. Moreover, in the quest of identifying novel pharmacological targets, the peptides were tested for antagonistic activity against a broad panel of Gram-negative and Gram-positive bacteria, as well as two yeast strains
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) Spectrographs
We describe the design and performance of the near-infrared (1.51--1.70
micron), fiber-fed, multi-object (300 fibers), high resolution (R =
lambda/delta lambda ~ 22,500) spectrograph built for the Apache Point
Observatory Galactic Evolution Experiment (APOGEE). APOGEE is a survey of ~
10^5 red giant stars that systematically sampled all Milky Way populations
(bulge, disk, and halo) to study the Galaxy's chemical and kinematical history.
It was part of the Sloan Digital Sky Survey III (SDSS-III) from 2011 -- 2014
using the 2.5 m Sloan Foundation Telescope at Apache Point Observatory, New
Mexico. The APOGEE-2 survey is now using the spectrograph as part of SDSS-IV,
as well as a second spectrograph, a close copy of the first, operating at the
2.5 m du Pont Telescope at Las Campanas Observatory in Chile. Although several
fiber-fed, multi-object, high resolution spectrographs have been built for
visual wavelength spectroscopy, the APOGEE spectrograph is one of the first
such instruments built for observations in the near-infrared. The instrument's
successful development was enabled by several key innovations, including a
"gang connector" to allow simultaneous connections of 300 fibers; hermetically
sealed feedthroughs to allow fibers to pass through the cryostat wall
continuously; the first cryogenically deployed mosaic volume phase holographic
grating; and a large refractive camera that includes mono-crystalline silicon
and fused silica elements with diameters as large as ~ 400 mm. This paper
contains a comprehensive description of all aspects of the instrument including
the fiber system, optics and opto-mechanics, detector arrays, mechanics and
cryogenics, instrument control, calibration system, optical performance and
stability, lessons learned, and design changes for the second instrument.Comment: 81 pages, 67 figures, PASP, accepte
Dimers, Effective Interactions, and Pauli Blocking Effects in a Bilayer of Cold Fermionic Polar Molecules
We consider a bilayer setup with two parallel planes of cold fermionic polar
molecules when the dipole moments are oriented perpendicular to the planes. The
binding energy of two-body states with one polar molecule in each layer is
determined and compared to various analytic approximation schemes in both
coordinate- and momentum-space. The effective interaction of two bound dimers
is obtained by integrating out the internal dimer bound state wave function and
its robustness under analytical approximations is studied. Furthermore, we
consider the effect of the background of other fermions on the dimer state
through Pauli blocking, and discuss implications for the zero-temperature
many-body phase diagram of this experimentally realizable system.Comment: 18 pages, 10 figures, accepted versio
Periodic Emission from the Gamma-ray Binary 1FGL J1018.6-5856
Gamma-ray binaries are stellar systems containing a neutron star or black
hole with gamma-ray emission produced by an interaction between the components.
These systems are rare, even though binary evolution models predict dozens in
our Galaxy. A search for gamma-ray binaries with the Fermi Large Area Telescope
(LAT) shows that 1FGL J1018.6-5856 exhibits intensity and spectral modulation
with a 16.6 day period. We identified a variable X-ray counterpart, which shows
a sharp maximum coinciding with maximum gamma-ray emission, as well as an
O6V((f)) star optical counterpart and a radio counterpart that is also
apparently modulated on the orbital period. 1FGL J1018.6-5856 is thus a
gamma-ray binary, and its detection suggests the presence of other fainter
binaries in the Galaxy.Comment: Contact authors: R.H.D. Corbet, M. Kerr, C.C. Cheun
On the Spectroscopic Classes of Novae in M33
We report the initial results from an ongoing multi-year spectroscopic survey
of novae in M33. The survey resulted in the spectroscopic classification of six
novae (M33N 2006-09a, 2007-09a, 2009-01a, 2010-10a, 2010-11a, and 2011-12a) and
a determination of rates of decline (t_2 times) for four of them (2006-09a,
2007-09a, 2009-01a, and 2010-10a). When these data are combined with existing
spectroscopic data for two additional M33 novae (2003-09a and 2008-02a) we find
that 5 of the 8 novae with available spectroscopic class appear to be members
of either the He/N or Fe IIb (hybrid) classes, with only two clear members of
the Fe II spectroscopic class. This initial finding is very different from what
would be expected based on the results for M31 and the Galaxy where Fe II novae
dominate, and the He/N and Fe IIb classes together make up only ~20% of the
total. It is plausible that the increased fraction of He/N and Fe IIb novae
observed in M33 thus far may be the result of the younger stellar population
that dominates this galaxy, which is expected to produce novae that harbor
generally more massive white dwarfs than those typically associated with novae
in M31 or the Milky Way.Comment: 30 pages; 5 figures; accepted for publication in the Astrophysical
Journal; second version corrects some references to Table 3, and a few typo
Making effective use of healthcare data using data-to-text technology
Healthcare organizations are in a continuous effort to improve health
outcomes, reduce costs and enhance patient experience of care. Data is
essential to measure and help achieving these improvements in healthcare
delivery. Consequently, a data influx from various clinical, financial and
operational sources is now overtaking healthcare organizations and their
patients. The effective use of this data, however, is a major challenge.
Clearly, text is an important medium to make data accessible. Financial reports
are produced to assess healthcare organizations on some key performance
indicators to steer their healthcare delivery. Similarly, at a clinical level,
data on patient status is conveyed by means of textual descriptions to
facilitate patient review, shift handover and care transitions. Likewise,
patients are informed about data on their health status and treatments via
text, in the form of reports or via ehealth platforms by their doctors.
Unfortunately, such text is the outcome of a highly labour-intensive process if
it is done by healthcare professionals. It is also prone to incompleteness,
subjectivity and hard to scale up to different domains, wider audiences and
varying communication purposes. Data-to-text is a recent breakthrough
technology in artificial intelligence which automatically generates natural
language in the form of text or speech from data. This chapter provides a
survey of data-to-text technology, with a focus on how it can be deployed in a
healthcare setting. It will (1) give an up-to-date synthesis of data-to-text
approaches, (2) give a categorized overview of use cases in healthcare, (3)
seek to make a strong case for evaluating and implementing data-to-text in a
healthcare setting, and (4) highlight recent research challenges.Comment: 27 pages, 2 figures, book chapte
SN 2005cs in M51 II. Complete Evolution in the Optical and the Near-Infrared
We present the results of the one year long observational campaign of the
type II-plateau SN 2005cs, which exploded in the nearby spiral galaxy M51 (the
Whirlpool Galaxy). This extensive dataset makes SN 2005cs the best observed
low-luminosity, 56Ni-poor type II-plateau event so far and one of the best
core-collapse supernovae ever. The optical and near-infrared spectra show
narrow P-Cygni lines characteristic of this SN family, which are indicative of
a very low expansion velocity (about 1000 km/s) of the ejected material. The
optical light curves cover both the plateau phase and the late-time radioactive
tail, until about 380 days after core-collapse. Numerous unfiltered
observations obtained by amateur astronomers give us the rare opportunity to
monitor the fast rise to maximum light, lasting about 2 days. In addition to
optical observations, we also present near-infrared light curves that (together
with already published UV observations) allow us to construct for the first
time a reliable bolometric light curve for an object of this class. Finally,
comparing the observed data with those derived from a semi-analytic model, we
infer for SN 2005cs a 56Ni mass of about 0.003 solar masses, a total ejected
mass of 8-13 solar masses and an explosion energy of about 3 x 10^50 erg.Comment: 18 pages, 18 figures, accepted for publication in MNRA
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