491 research outputs found
What are the indications for tonsillectomy in children?
Tonsillectomy with or without adenoidectomy is minimally effective when combined with tympanostomy tube placement in preventing recurrent otitis media in the 3 years following surgery. The risks of surgery must be weighed against potential benefit. (Grade of recommendation: B, based on low-quality randomized controlled trials [RCTs]). The evidence supporting tonsillectomy for recurrence of sore throat is controversial. There is insufficient evidence to recommend other potential indications. (Grade of recommendation: C, based on case series.
Biotechnological synthesis of Pd/Ag and Pd/Au nanoparticles for enhanced SuzukiâMiyaura crossâcoupling activity
A New Class of Changing-Look LINERs
We report the discovery of six active galactic nuclei (AGN) caught "turning
on" during the first nine months of the Zwicky Transient Facility (ZTF) survey.
The host galaxies were classified as LINERs by weak narrow forbidden line
emission in their archival SDSS spectra, and detected by ZTF as nuclear
transients. In five of the cases, we found via follow-up spectroscopy that they
had transformed into broad-line AGN, reminiscent of the changing-look LINER
iPTF 16bco. In one case, ZTF18aajupnt/AT2018dyk, follow-up HST UV and
ground-based optical spectra revealed the transformation into a narrow-line
Seyfert 1 (NLS1) with strong [Fe VII, X, XIV] and He II 4686 coronal lines.
Swift monitoring observations of this source reveal bright UV emission that
tracks the optical flare, accompanied by a luminous soft X-ray flare that peaks
~60 days later. Spitzer follow-up observations also detect a luminous
mid-infrared flare implying a large covering fraction of dust. Archival light
curves of the entire sample from CRTS, ATLAS, and ASAS-SN constrain the onset
of the optical nuclear flaring from a prolonged quiescent state. Here we
present the systematic selection and follow-up of this new class of
changing-look LINERs, compare their properties to previously reported
changing-look Seyfert galaxies, and conclude that they are a unique class of
transients well-suited to test the uncertain physical processes associated with
the LINER accretion state.Comment: Submitted to ApJ, 31 pages, 17 Figures (excluding Appendix due to
file size constraints but will be available in electronic version
Cataclysmic Variables in the First Year of the Zwicky Transient Facility
Using selection criteria based on amplitude, time, and color, we have identified 329 objects as known or candidate cataclysmic variables (CVs) during the first year of testing and operation of the Zwicky Transient Facility. Of these, 90 are previously confirmed CVs, 218 are strong candidates based on the shape and color of their light curves obtained during 3â562 days of observation, and the remaining 21 are possible CVs but with too few data points to be listed as good candidates. Almost half of the strong candidates are within 10 deg of the galactic plane, in contrast to most other large surveys that have avoided crowded fields. The available Gaia parallaxes are consistent with sampling the low mass transfer CVs, as predicted by population models. Our follow-up spectra have confirmed Balmer/helium emission lines in 27 objects, with four showing high-excitation He ii emission, including candidates for an AM CVn, a polar, and an intermediate polar. Our results demonstrate that a complete survey of the Galactic plane is needed to accomplish an accurate determination of the number of CVs existing in the Milky Way
Near-IR search for lensed supernovae behind galaxy clusters: I. Observations and transient detection efficiency
Massive galaxy clusters at intermediate redshift can magnify the flux of
distant background sources by several magnitudes and we exploit this effect to
search for lensed distant supernovae that may otherwise be too faint to be
detected. A supernova search was conducted at near infrared wavelengths using
the ISAAC instrument at the VLT. The galaxy clusters Abell 1689, Abell 1835 and
AC114 were observed at multiple epochs of 2 hours of exposure time, separated
by a month. Image-subtraction techniques were used to search for transient
objects with light curve properties consistent with supernovae, both in our new
and archival ISAAC/VLT data. The limiting magnitude of the individual epochs
was estimated by adding artificial stars to the subtracted images. Most of the
epochs reach 90% detection efficiency at SZ(J) ~= 23.8-24.0 mag (Vega). Two
transient objects, both in archival images of Abell 1689 and AC114, were
detected. The transient in AC114 coincides - within the position uncertainty -
with an X-ray source and is likely to be a variable AGN at the cluster
redshift. The transient in Abell 1689 was found at SZ=23.24 mag, ~0.5 arcsec
away from a galaxy with photometric redshift z=0.6 +/-0.15. The light curves
and the colors of the transient are consistent with a reddened Type IIP
supernova at redshift z=0.59 +/- 0.05. The lensing model of Abell 1689 predicts
~1.4 mag of magnification at the position of the transient, making it the most
magnified supernova ever found and only the second supernova found behind a
galaxy cluster. Our pilot survey has demonstrated the feasibility to find
distant gravitationally magnified supernovae behind massive galaxy clusters.
One likely supernova was found behind Abell 1689, in accordance with the
expectations for this survey, as shown in an accompanying analysis paper.Comment: Language-edited version, 9 pages, 6 figures, accepted by A&
Novel mutations in TARDBP (TDP-43) in patients with familial amyotrophic lateral sclerosis.
The TAR DNA-binding protein 43 (TDP-43) has been identified as the major disease protein in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitin inclusions (FTLD-U), defining a novel class of neurodegenerative conditions: the TDP-43 proteinopathies. The first pathogenic mutations in the gene encoding TDP-43 (TARDBP) were recently reported in familial and sporadic ALS patients, supporting a direct role for TDP-43 in neurodegeneration. In this study, we report the identification and functional analyses of two novel and one known mutation in TARDBP that we identified as a result of extensive mutation analyses in a cohort of 296 patients with variable neurodegenerative diseases associated with TDP-43 histopathology. Three different heterozygous missense mutations in exon 6 of TARDBP (p.M337V, p.N345K, and p.I383V) were identified in the analysis of 92 familial ALS patients (3.3%), while no mutations were detected in 24 patients with sporadic ALS or 180 patients with other TDP-43-positive neurodegenerative diseases. The presence of p.M337V, p.N345K, and p.I383V was excluded in 825 controls and 652 additional sporadic ALS patients. All three mutations affect highly conserved amino acid residues in the C-terminal part of TDP-43 known to be involved in protein-protein interactions. Biochemical analysis of TDP-43 in ALS patient cell lines revealed a substantial increase in caspase cleaved fragments, including the approximately 25 kDa fragment, compared to control cell lines. Our findings support TARDBP mutations as a cause of ALS. Based on the specific C-terminal location of the mutations and the accumulation of a smaller C-terminal fragment, we speculate that TARDBP mutations may cause a toxic gain of function through novel protein interactions or intracellular accumulation of TDP-43 fragments leading to apoptosis
Cosmic Flows on 100 Mpc/h Scales: Standardized Minimum Variance Bulk Flow, Shear and Octupole Moments
The low order moments, such as the bulk flow and shear, of the large scale
peculiar velocity field are sensitive probes of the matter density fluctuations
on very large scales. In practice, however, peculiar velocity surveys are
usually sparse and noisy, which can lead to the aliasing of small scale power
into what is meant to be a probe of the largest scales. Previously, we
developed an optimal ``minimum variance'' (MV) weighting scheme, designed to
overcome this problem by minimizing the difference between the measured bulk
flow (BF) and that which would be measured by an ideal survey. Here we extend
this MV analysis to include the shear and octupole moments, which are designed
to have almost no correlations between them so that they are virtually
orthogonal. We apply this MV analysis to a compilation of all major peculiar
velocity surveys, consisting of 4536 measurements. Our estimate of the BF on
scales of ~ 100 Mpc/h has a magnitude of |v|= 416 +/- 78 km/s towards Galactic
l = 282 degree +/- 11 degree and b = 6 degree +/- 6 degree. This result is in
disagreement with LCDM with WMAP5 cosmological parameters at a high confidence
level, but is in good agreement with our previous MV result without an
orthogonality constraint, showing that the shear and octupole moments did not
contaminate the previous BF measurement. The shear and octupole moments are
consistent with WMAP5 power spectrum, although the measurement noise is larger
for these moments than for the BF. The relatively low shear moments suggest
that the sources responsible for the BF are at large distances.Comment: 13 Pages, 7 figures, 4 tables. Some changes to reflect the published
versio
Near-IR Search for Lensed Supernovae Behind Galaxy Clusters - II. First Detection and Future Prospects
Powerful gravitational telescopes in the form of massive galaxy clusters can
be used to enhance the light collecting power over a limited field of view by
about an order of magnitude in flux. This effect is exploited here to increase
the depth of a survey for lensed supernovae at near-IR wavelengths. A pilot SN
search program conducted with the ISAAC camera at VLT is presented. Lensed
galaxies behind the massive clusters A1689, A1835 and AC114 were observed for a
total of 20 hours split into 2, 3 and 4 epochs respectively, separated by
approximately one month to a limiting magnitude J<24 (Vega). Image subtractions
including another 20 hours worth of archival ISAAC/VLT data were used to search
for transients with lightcurve properties consistent with redshifted
supernovae, both in the new and reference data. The feasibility of finding
lensed supernovae in our survey was investigated using synthetic lightcurves of
supernovae and several models of the volumetric Type Ia and core-collapse
supernova rates as a function of redshift. We also estimate the number of
supernova discoveries expected from the inferred star formation rate in the
observed galaxies. The methods consistently predict a Poisson mean value for
the expected number of SNe in the survey between N_SN=0.8 and 1.6 for all
supernova types, evenly distributed between core collapse and Type Ia SN. One
transient object was found behind A1689, 0.5" from a galaxy with photometric
redshift z_gal=0.6 +- 0.15. The lightcurve and colors of the transient are
consistent with being a reddened Type IIP SN at z_SN=0.59. The lensing model
predicts 1.4 magnitudes of magnification at the location of the transient,
without which this object would not have been detected in the near-IR ground
based search described in this paper (unlensed magnitude J~25). (abridged)Comment: Accepted by AA, matches journal versio
The USNO-B Catalog
USNO-B is an all-sky catalog that presents positions, proper motions,
magnitudes in various optical passbands, and star/galaxy estimators for
1,042,618,261 objects derived from 3,643,201,733 separate observations. The
data were obtained from scans of 7,435 Schmidt plates taken for the various sky
surveys during the last 50 years. USNO-B1.0 is believed to provide all-sky
coverage, completeness down to V = 21, 0.2 arcsecond astrometric accuracy at
J2000, 0.3 magnitude photometric accuracy in up to five colors, and 85%
accuracy for distinguishing stars from non-stellar objects. A brief discussion
of various issues is given here, but the actual data are available from
http://www.nofs.navy.mil and other sites.Comment: Accepted by Astronomical Journa
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