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 $\ell$ is between $80$ and $200$. 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 $m_1 = 36^{+5}_{-4} M_\odot$ and $m_2 = 29^{+4}_{-4} M_\odot$, 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 $m_1 = 70 M_\odot$ and $m_2 = 35 M_\odot$, and strong anti-aligned spins ($\chi_1=0.95$ and $\chi_2=-0.95$) 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 $Q$ and $U$ 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 $r$. We further show that in the absence of lensing, the total number of NPPs of all types does not depend on $r$, 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 $p$-value $0.07$) and NILC ($p = 0.15$) maps.Comment: 12 pages, 9 figures, 2 table

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, "$EB$~leakage" refers to the artificial $B$-mode signal coming from the leakage of $E$-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 $B$-mode signal. In this work, we design two independent methods for correcting the $EB$~leakage directly in the pixel domain using standard definitions of the $E$- and $B$-modes. The two methods give consistent results, and both are fast and easy to implement. Tests on a CMB simulation containing zero initial $B$-mode show an efficient suppression of the $EB$ leakage. When combined with the MASTER method to reconstruct the full-sky $B$-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

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