641 research outputs found
Blind correction of the EB-leakage in the pixel domain
We study the problem of EB-leakage that is associated with incomplete
polarized CMB sky. In the blind case that assumes no additional information
about the statistical properties and amplitudes of the signal from the missing
sky region, we prove that the recycling method (Liu et al.~2018) gives the
unique best estimate of the EB-leakage. Compared to the previous method, this
method reduces the uncertainties in the BB power spectrum due to EB-leakage by
more than one order of magnitude in the most interesting domain of multipoles,
where is between and . This work also provides a useful
guideline for observational design of future CMB experiments.Comment: Minor modification
From top-hat masking to smooth transitions: P-filter and its application to polarized microwave sky maps
In CMB science, the simplest idea to remove a contaminated sky region is to
multiply the sky map with a mask that is 0 for the contaminated region and 1
elsewhere, which is also called a top-hat masking. Although it is easy to use,
such top-hat masking is known to suffer from various leakage problems.
Therefore, we want to extend the top-hat masking to a series of semi-analytic
functions called the P-filters. Most importantly, the P-filters can seamlessly
realize the core idea of masking in CMB science, and, meanwhile, guarantee
continuity up to the first derivative everywhere. The P-filters can
significantly reduce many leakage problems without additional cost, including
the leakages due to low-, high-, and band-pass filtering, and the E-to-E,
B-to-B, B-to-E, and E-to-B leakages. The workings of the P-filter are
illustrated by using the WMAP and Planck polarization sky maps. By comparison
to the corresponding WMAP/Planck masks, we show that the P-filter performs much
better than top-hat masking, and meanwhile, has the potential to supersede the
principal idea of masking in CMB science. Compared to mask apodization, the
P-filter is ``outward'', that tends to make proper use of the region that was
marked as 0; whereas apodization is ``inward'', that always kills more signal
in the region marked as 1.Comment: 19 pages and 11 figure
On the time lags of the LIGO signals
To date, the LIGO collaboration has detected three gravitational wave (GW)
events appearing in both its Hanford and Livingston detectors. In this article
we reexamine the LIGO data with regard to correlations between the two
detectors. With special focus on GW150914, we report correlations in the
detector noise which, at the time of the event, happen to be maximized for the
same time lag as that found for the event itself. Specifically, we analyze
correlations in the calibration lines in the vicinity of 35\,Hz as well as the
residual noise in the data after subtraction of the best-fit theoretical
templates. The residual noise for the other two events, GW151226 and GW170104,
exhibits similar behavior. A clear distinction between signal and noise
therefore remains to be established in order to determine the contribution of
gravitational waves to the detected signals.Comment: The body of the current version is essentially identical to the
previous one submitted to arxiv and JCAP. In order to meet the various
suggestions of the referees, we have included an extended and detailed
Appendix. This Appendix also contains significant new results that provide
additional support for our conclusions. This version of our manuscript has
been accepted for publication by JCA
Degeneracy of gravitational waveforms in the context of GW150914
We study the degeneracy of theoretical gravitational waveforms for binary
black hole mergers using an aligned-spin effective-one-body model. After
appropriate truncation, bandpassing, and matching, we identify regions in the
mass--spin parameter space containing waveforms similar to the template
proposed for GW150914, with masses and , using the cross-correlation coefficient as a measure of
the similarity between waveforms. Remarkably high cross-correlations are found
across broad regions of parameter space. The associated uncertanties exceed
these from LIGO's Bayesian analysis considerably. We have shown that waveforms
with greatly increased masses, such as and , and strong anti-aligned spins ( and )
yield almost the same signal-to-noise ratio in the strain data for GW150914.Comment: Accepted for publication in JCA
Statistics of non-polarized points in the CMB polarization maps
The non-polarized points (NPP) of the and Stokes parameters of the
CMB can be classified according to the geometry of the polarization field. We
describe a procedure to identify these points in the pixelized sky and present
the shape of the polarization angles in the vicinity of NPPs. We design a test
of Gaussianity using the Kullback-Leibler divergence. We show that the total
number density of non-polarized points of the E- and B-families is closely
related to the presence of lensing and the tensor-to-scalar ratio . We
further show that in the absence of lensing, the total number of NPPs of all
types does not depend on , while the lensing effect removes this degeneracy.
This analysis is applied to the CMB maps from the 2018 Planck release. We show
that there is general consistency of SMICA and NILC maps compared to a
reference set of Gaussian simulations. The strongest discrepancies are found in
the Commander (with corresponding -value ) and NILC () maps.Comment: 12 pages, 9 figures, 2 table
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Anxiety disorders in children and adolescents
Anxiety disorders are among the most common psychiatric disorders in children and adolescents. They commonly interfere with peer relationships, schooling and family life, and persist into adulthood if left untreated. This paper gives an overview of the identification, assessment and treatment of anxiety disorders in children and young people. Identification of anxiety disorders is often poor and many young people with anxiety disorders go untreated. We present a brief review of the evidence base for pharmacological and psychological treatment approaches to the management of anxiety disorders in youth. Both have been found to be effective in the treatment of anxiety disorders, although psychological treatments such as Cognitive Behavioural Therapy (CBT) are considered the first-line treatment due to relative benefits in terms of patient safety and parental preference. Low intensity CBT approaches such as bibliotherapy and online therapies are effective and have the potential to improve access to evidence-based interventions. CBT approaches have also been found to be effective with particular patient groups, such as those with long-term physical health conditions and autism spectrum disorders, who are at an increased risk of anxiety disorders
Methods for pixel domain correction of EB leakage
In observation of the cosmic microwave background (CMB) polarization,
"~leakage" refers to the artificial -mode signal coming from the leakage
of -mode signal when part of the sky is unavailable or excluded. Correction
of such leakage is one of the preconditions for detecting primordial
gravitational waves via the CMB -mode signal. In this work, we design two
independent methods for correcting the ~leakage directly in the pixel
domain using standard definitions of the - and -modes. The two methods
give consistent results, and both are fast and easy to implement. Tests on a
CMB simulation containing zero initial -mode show an efficient suppression
of the leakage. When combined with the MASTER method to reconstruct the
full-sky -mode spectrum in simulations with a relatively simple mask, the
error from EB-leakage is suppressed further by more than one order of magnitude
at the recombination bump, and up to three orders of magnitude at higher
multipoles, compared to a "pure" MASTER scheme under the same conditions.
Meanwhile, although the final power spectrum estimation benefits from
apodization, the pixel domain correction itself is done without apodization,
and thus the methods offer more freedom in choosing an apodization based on
specific requirements.Comment: Add noises to simulations, move some technical descriptions to
appendix. Accepted for publication in PR
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The treatment of child anxiety disorders via guided parent-delivered cognitive-behavioural therapy: a randomised controlled trial
Background
Promising evidence has emerged of clinical gains using guided self-help cognitive-behavioural therapy (CBT) for child anxiety and by involving parents in treatment; however, the efficacy of guided parent-delivered CBT has not been systematically evaluated in UK primary and secondary settings.
Aims
To evaluate the efficacy of low-intensity guided parent-delivered CBT treatments for children with anxiety disorders.
Method
A total of 194 children presenting with a current anxiety disorder, whose primary carer did not meet criteria for a current anxiety disorder, were randomly allocated to full guided parent-delivered CBT (four face-to-face and four telephone sessions) or brief guided parent-delivered CBT (two face-to-face and two telephone sessions), or a wait-list control group (trial registration: ISRCTN92977593). Presence and severity of child primary anxiety disorder (Anxiety Disorders Interview Schedule for DSM-IV, child/parent versions), improvement in child presentation of anxiety (Clinical Global Impression-Improvement scale), and change in child anxiety symptoms (Spence Children’s Anxiety Scale, child/parent version and Child Anxiety Impact scale, parent version) were assessed at post-treatment and for those in the two active treatment groups, 6 months post-treatment.
Results
Full guided parent-delivered CBT produced superior diagnostic outcomes compared with wait-list at post-treatment, whereas brief guided parent-delivered CBT did not: at post-treatment, 25 (50%) of those in the full guided CBT group had recovered from their primary diagnosis, compared with 16 (25%) of those on the wait-list (relative risk (RR) 1.85, 95% CI 1.14-2.99); and in the brief guided CBT group, 18 participants (39%) had recovered from their primary diagnosis post-treatment (RR = 1.56, 95% CI 0.89-2.74). Level of therapist training and experience was unrelated to child outcome.
Conclusions
Full guided parent-delivered CBT is an effective and inexpensive first-lin
A blind search for a common signal in gravitational wave detectors
We propose a blind, template-free method for the extraction of a common
signal between the Hanford and Livingston detectors and apply it especially to
the GW150914 event. We construct a log-likelihood method that maximizes the
cross-correlation between each detector and the common signal and minimizes the
cross-correlation between the residuals. The reliability of this method is
tested using simulations with an injected common signal. Finally, our method is
used to assess the quality of theoretical gravitational wave templates for
GW150914.Comment: Accepted for publication in JCA
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