Obscuration-dependent evolution of Active Galactic Nuclei

We aim to constrain the evolution of AGN as a function of obscuration using an X-ray selected sample of $\sim2000$ AGN from a multi-tiered survey including the CDFS, AEGIS-XD, COSMOS and XMM-XXL fields. The spectra of individual X-ray sources are analysed using a Bayesian methodology with a physically realistic model to infer the posterior distribution of the hydrogen column density and intrinsic X-ray luminosity. We develop a novel non-parametric method which allows us to robustly infer the distribution of the AGN population in X-ray luminosity, redshift and obscuring column density, relying only on minimal smoothness assumptions. Our analysis properly incorporates uncertainties from low count spectra, photometric redshift measurements, association incompleteness and the limited sample size. We find that obscured AGN with $N_{H}>{\rm 10^{22}\, cm^{-2}}$ account for ${77}^{+4}_{-5}\%$ of the number density and luminosity density of the accretion SMBH population with $L_{{\rm X}}>10^{43}\text{ erg/s}$, averaged over cosmic time. Compton-thick AGN account for approximately half the number and luminosity density of the obscured population, and ${38}^{+8}_{-7}\%$ of the total. We also find evidence that the evolution is obscuration-dependent, with the strongest evolution around $N_{H}\thickapprox10^{23}\text{ cm}^{-2}$. We highlight this by measuring the obscured fraction in Compton-thin AGN, which increases towards $z\sim3$, where it is $25\%$ higher than the local value. In contrast the fraction of Compton-thick AGN is consistent with being constant at $\approx35\%$, independent of redshift and accretion luminosity. We discuss our findings in the context of existing models and conclude that the observed evolution is to first order a side-effect of anti-hierarchical growth.Comment: Published in Ap

Generating Controlled Image Sets in Cognitive Neuroscience Research

The investigation of perceptual and cognitive functions with non-invasive brain imaging methods critically depends on the careful selection of stimuli for use in experiments. For example, it must be verified that any observed effects follow from the parameter of interest (e.g. semantic category) rather than other low-level physical features (e.g. luminance, or spectral properties). Otherwise, interpretation of results is confounded. Often, researchers circumvent this issue by including additional control conditions or tasks, both of which are flawed and also prolong experiments. Here, we present some new approaches for controlling classes of stimuli intended for use in cognitive neuroscience, however these methods can be readily extrapolated to other applications and stimulus modalities. Our approach is comprised of two levels. The first level aims at equalizing individual stimuli in terms of their mean luminance. Each data point in the stimulus is adjusted to a standardized value based on a standard value across the stimulus battery. The second level analyzes two populations of stimuli along their spectral properties (i.e. spatial frequency) using a dissimilarity metric that equals the root mean square of the distance between two populations of objects as a function of spatial frequency along x- and y-dimensions of the image. Randomized permutations are used to obtain a minimal value between the populations to minimize, in a completely data-driven manner, the spectral differences between image sets. While another paper in this issue applies these methods in the case of acoustic stimuli (Aeschlimann etal., Brain Topogr 2008), we illustrate this approach here in detail for complex visual stimul

An Empirical Validation of Cognitive Complexity as a Measure of Source Code Understandability

Background: Developers spend a lot of their time on understanding source code. Static code analysis tools can draw attention to code that is difficult for developers to understand. However, most of the findings are based on non-validated metrics, which can lead to confusion and code, that is hard to understand, not being identified. Aims: In this work, we validate a metric called Cognitive Complexity which was explicitly designed to measure code understandability and which is already widely used due to its integration in well-known static code analysis tools. Method: We conducted a systematic literature search to obtain data sets from studies which measured code understandability. This way we obtained about 24,000 understandability evaluations of 427 code snippets. We calculated the correlations of these measurements with the corresponding metric values and statistically summarized the correlation coefficients through a meta-analysis. Results: Cognitive Complexity positively correlates with comprehension time and subjective ratings of understandability. The metric showed mixed results for the correlation with the correctness of comprehension tasks and with physiological measures. Conclusions: It is the first validated and solely code-based metric which is able to reflect at least some aspects of code understandability. Moreover, due to its methodology, this work shows that code understanding is currently measured in many different ways, which we also do not know how they are related. This makes it difficult to compare the results of individual studies as well as to develop a metric that measures code understanding in all its facets.Comment: 12 pages. To be published at ESEM '20: ACM / IEEE International Symposium on Empirical Software Engineering and Measuremen

Physically motivated X-ray obscurer models

The nuclear obscurer of Active Galactic Nuclei (AGN) is poorly understood in terms of its origin, geometry and dynamics. We investigate whether physically motivated geometries emerging from hydro-radiative simulations can be differentiated with X-ray reflection spectroscopy. For two new geometries, the radiative fountain model of Wada (2012) and a warped disk, we release spectral models produced with the ray tracing code XARS. We contrast these models with spectra of three nearby AGN taken by NuSTAR and Swift/BAT. Along heavily obscured sight-lines, the models present different 4-20keV continuum spectra. These can be differentiated by current observations. Spectral fits of the Circinus Galaxy favor the warped disk model over the radiative fountain, and clumpy or smooth torus models. The necessary reflector (NH>10^25/cm^2) suggests a hidden population of heavily Compton-thick AGN amongst local galaxies. X-ray reflection spectroscopy is a promising pathway to understand the nuclear obscurer in AGN.Comment: Accepted in A&A. X-ray spectral models can be downloaded from https://github.com/JohannesBuchner/xars/blob/master/doc/warpeddisk.rst (warped disk) and https://github.com/JohannesBuchner/xars/blob/master/doc/wada.rst (radiative fountain model). The XARS code is at https://github.com/JohannesBuchner/xars

The effects of mental health interventions on labour market outcomes in low-and-middle-income countries

Mental health conditions are prevalent but rarely treated in low- and middle-income countries (LMICs). Little is known about how these conditions affect economic participation. This paper shows that treating mental health conditions substantially improves recipients’ capacity to work in these contexts. First, we perform a systematic review and meta-analysis of all randomized controlled trials (RCTs) ever conducted that evaluate treatments for mental ill-health and measure economic outcomes in LMICs. On average, treating common mental disorders like depression with psychotherapy improves an aggregate of labor market outcomes made up of employment, time spent working, capacity to work and job search by 0.16 standard deviations. Treating severe mental disorders, like schizophrenia, improves the aggregate by 0.30 standard deviations, but effects are noisily estimated. Second, we build a new dataset, pooling all available microdata from RCTs using the most common trial design: studies of psychotherapy in LMICs that treated depression and measured days participants were unable to work in the past month. We observe comparable treatment effects on mental health and work outcomes in this sub-sample of highly similar studies. We also show evidence consistent with mental health being the mechanism through which psychotherapy improves work outcomes

Compact corrugated feedhorns with high Gaussian coupling efficiency and -60 dB sidelobes

We demonstrate that very high performance, extremely compact, scalar corrugated feedhorns can be designed and constructed by optimizing the excitation and phasing of the HE11, HE12 and HE13 modes near the throat of the horn whilst limiting excitation of higher order modes. We present the design and measurement of two families of dual-profiled horn, both with a directivity of 20 dBi that couple with very high efficiency to a fundamental Gaussian mode. The first was optimized for sidelobe performance and features sidelobes approaching -60 dB for a horn length of only 15.6λ. The second was designed to minimize horn length and achieves sidelobe levels below -35 dB for a horn which is only 4.8λ long. The horns exhibit excellent coupling to the fundamental free-space Gaussian mode, with LG00 power coupling of 99.92% and 99.75% respectively. We demonstrate excellent agreement between simulation and experiment at 94 GHz and simulate the performance over a 20% bandwidth. High performance compact scalar horns are of interest because they reduce manufacturing risk at high frequencies, and reduce size and weight at lower frequencies, which can be important in horn arrays and space applications, where horn arrays often have serious weight and size restrictions.PostprintPeer reviewe

How to measure person-centred practice – an analysis of reviews of the literature

BACKGROUND: Facilitation and collaboration differentiates person-centred practice (PcP) from biomedical practice. In PcP, a person-centred consultation requires clinicians to juggle three processes: facilitation, clinical reasoning and collaboration. How best to measure PcP in these processes remains a challenge. AIM: To assess the measurement of facilitation and collaboration in selected reviews of PcP instruments. METHODS: Ovid Medline and Google Scholar were searched for review articles evaluating measurement instruments of patient-centredness or person-centredness in the medical consultation. RESULTS: Six of the nine review articles were selected for analysis. Those articles considered the psychometric properties and rigour of evaluation of reviewed instruments. Mostly, the articles did not find instruments with good evidence of reliability and validity. Evaluations in South Africa rendered poor psychometric properties. Tools were often not transferable to other sociocultural-linguistic contexts, both with and without adaptation. CONCLUSION: The multiplicity of measurement tools is a product of many dimensions of personcentredness, which can be approached from many perspectives and in many service scenarios inside and outside the medical consultation. Extensive research into the myriad instruments found no single valid and reliable measurement tool that can be recommended for general use. The best hope for developing one is to focus on a specific scenario, conduct a systematic literature review, combine the best items from existing tools, involve multiple disciplines and test the tool in real-life situations.http://www.phcfm.orgpm2020Family Medicin

An output coupler for a W-band high power wideband gyro-amplifier

This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) U.K. under Research Grant EP/K029746/1, and Science and Technology Facilities Council (STFC) U.K. under Research Grants ST/K006673/1 & ST/K006703/1, ST/N002326/1 & ST/N002318/1.An output coupler for a W-band high power wideband gyro-amplifier has been designed, manufactured and experimentally measured. It consists of a high performance sin2-parallel corrugated horn integrated with a broadband multi-layer window. The major design requirements are that the horn/window combination must have an input return loss lower than -30 dB over a 10 GHz bandwidth, provide a high quality output beam pattern, and operate under ultra-high vacuum conditions. The coupler converts a circular wave guide TE11 mode into the free space Laguerre Gaussian LG00 mode over the frequency band of 90–100 GHz with a measured return loss of between -30 and -40 dB and a simulated Gaussian coupling efficiency of over 99% at 94 GHz.PostprintPeer reviewe

Methyl-CpG-binding domain sequencing reveals a prognostic methylation signature in neuroblastoma

Accurate assessment of neuroblastoma outcome prediction remains challenging. Therefore, this study aims at establishing novel prognostic tumor DNA methylation biomarkers. In total, 396 low- and high-risk primary tumors were analyzed, of which 87 were profiled using methyl-CpG-binding domain (MBD) sequencing for differential methylation analysis between prognostic patient groups. Subsequently, methylation-specific PCR (MSP) assays were developed for 78 top-ranking differentially methylated regions and tested on two independent cohorts of 132 and 177 samples, respectively. Further, a new statistical framework was used to identify a robust set of MSP assays of which the methylation score (i.e. the percentage of methylated assays) allows accurate outcome prediction. Survival analyses were performed on the individual target level, as well as on the combined multimarker signature. As a result of the differential DNA methylation assessment by MBD sequencing, 58 of the 78 MSP assays were designed in regions previously unexplored in neuroblastoma, and 36 are located in non-promoter or non-coding regions. In total, 5 individual MSP assays (located in CCDC177, NXPH1, lnc-MRPL3-2, lnc-TREX1-1 and one on a region from chromosome 8 with no further annotation) predict event-free survival and 4 additional assays (located in SPRED3, TNFAIP2, NPM2 and CYYR1) also predict overall survival. Furthermore, a robust 58-marker methylation signature predicting overall and event-free survival was established. In conclusion, this study encompasses the largest DNA methylation biomarker study in neuroblastoma so far. We identified and independently validated several novel prognostic biomarkers, as well as a prognostic 58-marker methylation signature