Context. The γ-ray BL Lac object OJ 287 is known to exhibit inner-parsec "jet-wobbling", high degrees of variability at all wavelengths and quasi-stationary features including an apparent (≈ 100 • ) position angle change in projection on the sky plane. Aims. Sub-50 micro-arcsecond resolution 86 GHz observations with the global mm-VLBI array (GMVA) supplement ongoing multifrequency VLBI blazar monitoring at lower frequencies. Using these maps together with cm/mm total intensity and γ-ray observations from Fermi/LAT from 2008-2014, we aimed to determine the location of γ-ray emission and to explain the inner-mas structural changes. Methods. Observations with the GMVA offer approximately double the angular resolution compared with 43 GHz VLBA observations and allow us to observe above the synchrotron self-absorption peak frequency. Fermi-LAT γ-ray data were reduced and analysed. The jet was spectrally decomposed at multiple locations along the jet. From this we could derive estimates of the magnetic field using equipartition and synchrotron self-absorption arguments. How the field decreases down the jet allowed an estimate of the distance to the jet apex and an estimate of the magnetic field strength at the jet apex and in the broad line region. Combined with accurate kinematics we attempt to locate the site of γ-ray activity, radio flares and spectral changes. Results. Strong γ-ray flares appeared to originate from either the "core" region, a downstream stationary feature, or both, with γ-ray activity significantly correlated with radio flaring in the downstream quasi-stationary feature. Magnetic field estimates were determined at multiple locations along the jet, with the magnetic field found to be ≥ 1.6 G in the "core" and ≤ 0.4 G in the downstream quasi-stationary feature. We therefore found upper limits on the location of the VLBI "core" as 6.0 pc from the jet apex and determined an upper limit on the magnetic field near the jet base of the order of thousands of Gauss.

Context. Investigating the magnetic field structure in the innermost regions of relativistic jets is fundamental to understanding the crucial physical processes giving rise to jet formation, as well as to their extraordinary radiation output up to γ-ray energies. Aims. We study the magnetic field structure of the quasar CTA 102 with 3 and 7 mm VLBI polarimetric observations, reaching an unprecedented resolution (∼50 µas). We also investigate the variability and physical processes occurring in the source during the observing period, which coincides with a very active state of the source over the entire electromagnetic spectrum. Methods. We perform the Faraday rotation analysis using 3 and 7 mm data and we compare the obtained rotation measure (RM) map with the polarization evolution in 7 mm VLBA images. We study the kinematics and variability at 7 mm and infer the physical parameters associated with variability. From the analysis of γ-ray and X-ray data, we compute a minimum Doppler factor value required to explain the observed high-energy emission.Results. Faraday rotation analysis shows a gradient in RM with a maximum value of ∼6×10 4 rad/m 2 and intrinsic electric vector position angles (EVPAs) oriented around the centroid of the core, suggesting the presence of large-scale helical magnetic fields. Such a magnetic field structure is also visible in 7 mm images when a new superluminal component is crossing the core region. The 7 mm EVPA orientation is different when the component is exiting the core or crossing a stationary feature at ∼0.1 mas. The interaction between the superluminal component and a recollimation shock at ∼0.1 mas could have triggered the multi-wavelength flares. The variability Doppler factor associated with such an interaction is large enough to explain the high-energy emission and the remarkable optical flare occurred very close in time.

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This study examines the role of an individual auditor's cognitive ability in delivering high‐quality audits. Our results from analyzing archival data from Sweden show that audit partners' IQ scores obtained from psychological tests are positively associated with going‐concern audit reporting accuracy and audit fee premiums. We also find some, albeit weak, evidence that audit partners' IQ scores are negatively associated with the income‐increasing abnormal accruals of the client. These results suggest that, although audit services are standardized through various control mechanisms and audits are conducted by teams rather than by individual auditors, the cognitive ability of audit partners responsible for an audit remains important in delivering high‐quality audit services.