The Position of High Frequency Waves with Respect to the Granulation Pattern

High frequency velocity oscillations were observed in the spectral lines Fe I 543.45nm and 543.29nm, using 2D spectroscopy with a Fabry- Perot and speckle reconstruction, at the VTT in Tenerife. We investigate the radial component of waves with frequencies in the range 8 - 22mHz in the internetwork, network and a pore. We find that the occurrence of waves do not show any preference on location and are equally distributed over down-flows and up-flows, regardless of the activity of the observed area in the line of Fe I 543.45nm. The waves observed in the lower formed line of Fe I 543.29nm seem to appear preferentially over down-flows.Comment: Article has 12 pages and 7 images. It is accepted in Solar Physics Journa

Automated and Interpretable Detection of Hippocampal Sclerosis in Temporal Lobe Epilepsy: AID-HS

\ua9 2024 The Author(s). Annals of Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.Objective: Hippocampal sclerosis (HS), the most common pathology associated with temporal lobe epilepsy (TLE), is not always visible on magnetic resonance imaging (MRI), causing surgical delays and reduced postsurgical seizure-freedom. We developed an open-source software to characterize and localize HS to aid the presurgical evaluation of children and adults with suspected TLE. Methods: We included a multicenter cohort of 365 participants (154 HS; 90 disease controls; 121 healthy controls). HippUnfold was used to extract morphological surface-based features and volumes of the hippocampus from T1-weighted MRI scans. We characterized pathological hippocampi in patients by comparing them to normative growth charts and analyzing within-subject feature asymmetries. Feature asymmetry scores were used to train a logistic regression classifier to detect and lateralize HS. The classifier was validated on an independent multicenter cohort of 275 patients with HS and 161 healthy and disease controls. Results: HS was characterized by decreased volume, thickness, and gyrification alongside increased mean and intrinsic curvature. The classifier detected 90.1% of unilateral HS patients and lateralized lesions in 97.4%. In patients with MRI-negative histopathologically-confirmed HS, the classifier detected 79.2% (19/24) and lateralized 91.7% (22/24). The model achieved similar performances on the independent cohort, demonstrating its ability to generalize to new data. Individual patient reports contextualize a patient\u27s hippocampal features in relation to normative growth trajectories, visualise feature asymmetries, and report classifier predictions. Interpretation: Automated and Interpretable Detection of Hippocampal Sclerosis (AID-HS) is an open-source pipeline for detecting and lateralizing HS and outputting clinically-relevant reports. ANN NEUROL 2024

Cerebral Venous Thrombosis. A Challenging Diagnosis; A New Nonenhanced Computed Tomography Standardized Semi-Quantitative Method

Cerebral venous sinus thrombosis (CVST) on non-contrast CT (NCCT) is often challenging to detect. We retrospectively selected 41 children and 36 adults with confirmed CVST and two age-matched control groups with comparable initial symptoms. We evaluated NCCT placing four small circular ROIs in standardized regions of the cerebral dural venous system. The mean and maximum HU values were considered from each ROI, and the relative percentage variations were calculated (mean % variation and maximum % variation). We compared the highest measured value to the remaining three HU values through an ad-hoc formula based on the assumption that the thrombosed sinus has higher attenuation compared with the healthy sinuses. Percentage variations were employed to reflect how the attenuation of the thrombosed sinus deviates from the unaffected counterparts. The attenuation of the affected sinus was increased in patients with CVST, and consequently both the mean % and maximum % variations were increased. A mean % variation value of 12.97 and a maximum % variation value of 10.14 were found to be useful to distinguish patients with CVST from healthy subjects, with high sensitivity and specificity. Increased densitometric values were present in the site of venous thrombosis. A systematic, blind evaluation of the brain venous system can assist radiologists in identifying patients who need or do not need further imaging

Pollux: A weak dynamo-driven dipolar magnetic field and implications for its probable planet

Context.Pollux is considered as an archetype of a giant star hosting a planet since its radial velocity (RV) presents very stable sinusoidal variations with a period of about 590 d. We then discovered a weak magnetic field at its surface using spectropolarimetry, questioning the planetary hypothesis.Aims.We followed up our investigations on Pollux to characterize its magnetic field and to infer the effects of magnetic activity on the RV variations.Methods.We first used ESPaDOnS at CFHT and then Narval at TBL to obtain StokesIand StokesVspectra of Pollux to study their variations for a duration of 4.25 years, that is, for more than two periods of the RV variations. We used the least-squares deconvolution profiles to measure the longitudinal magnetic field and to perform a Zeeman Doppler imaging (ZDI) investigation.Results.The longitudinal magnetic field of Pollux is found to vary with a sinusoidal behavior and a period similar to that of the RV variations. From the ZDI investigation a rotation period of Pollux is determined to be equal to 660 ± 15 days and possibly different than the period of variations of the RV. As to the magnetic topology, the poloidal component is dominant and almost purely dipolar with an inclination of 10.5° of the dipole with respect to the rotation axis. The mean strength of the surface magnetic field is 0.44 G. Pollux is found approximately as active as the Sun observed as a star and this activity could induce moderate RV variations.Conclusions.As to the origin of the magnetic field of Pollux, we favor the hypothesis that it is maintained through contemporaneous dynamo action. Pollux appears as the representative of a class of slowly rotating and weakly magnetic G-K red giants. To explain the sinusoidal RV variations of Pollux, two scenarios are proposed. If the RV period is different from the rotation period, the observed periodic RV variations are due to the hosted planet and the contribution of Pollux magnetic activity is not significantly detected. In the peculiar case in which the two periods are equal, we cannot discard the possibility that the activity of Pollux could explain the total RV variations and that the planet hypothesis would appear unnecessary. In any case magnetic activity could contribute significantly to RV variations in some intermediate mass G-K red giants hosting planets, particularly those with small amplitude RV variations.</jats:p

Pollux: A weak dynamo-driven dipolar magnetic field and implications for its probable planet

International audienceContext. Pollux is considered as an archetype of a giant star hosting a planet since its radial velocity (RV) presents very stable sinusoidal variations with a period of about 590 d. We then discovered a weak magnetic field at its surface using spectropolarimetry, questioning the planetary hypothesis.Aims. We followed up our investigations on Pollux to characterize its magnetic field and to infer the effects of magnetic activity on the RV variations.Methods. We first used ESPaDOnS at CFHT and then Narval at TBL to obtain Stokes I and Stokes V spectra of Pollux to study their variations for a duration of 4.25 years, that is, for more than two periods of the RV variations. We used the least-squares deconvolution profiles to measure the longitudinal magnetic field and to perform a Zeeman Doppler imaging (ZDI) investigation.Results. The longitudinal magnetic field of Pollux is found to vary with a sinusoidal behavior and a period similar to that of the RV variations. From the ZDI investigation a rotation period of Pollux is determined to be equal to 660 ± 15 days and possibly different than the period of variations of the RV. As to the magnetic topology, the poloidal component is dominant and almost purely dipolar with an inclination of 10.5° of the dipole with respect to the rotation axis. The mean strength of the surface magnetic field is 0.44 G. Pollux is found approximately as active as the Sun observed as a star and this activity could induce moderate RV variations.Conclusions. As to the origin of the magnetic field of Pollux, we favor the hypothesis that it is maintained through contemporaneous dynamo action. Pollux appears as the representative of a class of slowly rotating and weakly magnetic G-K red giants. To explain the sinusoidal RV variations of Pollux, two scenarios are proposed. If the RV period is different from the rotation period, the observed periodic RV variations are due to the hosted planet and the contribution of Pollux magnetic activity is not significantly detected. In the peculiar case in which the two periods are equal, we cannot discard the possibility that the activity of Pollux could explain the total RV variations and that the planet hypothesis would appear unnecessary. In any case magnetic activity could contribute significantly to RV variations in some intermediate mass G-K red giants hosting planets, particularly those with small amplitude RV variations

Venous pathologies in paediatric neuroradiology: from foetal to adolescent life

The interpretation of cerebral venous pathologies in paediatric practice is challenging as there are several normal anatomical variants, and the pathologies are diverse, involving the venous system through direct and indirect mechanisms. This paper aims to provide a comprehensive review of these entities, as their awareness can avoid potential diagnostic pitfalls. We also propose a practical classification system of paediatric cerebral venous pathologies, which will enable more accurate reporting of the neuroimaging findings, as relevant to the underlying pathogenesis of these conditions. The proposed classification system comprises of the following main groups: arterio-venous shunting–related disorders, primary venous malformations and veno-occlusive disorders. A multimodal imaging approach has been included in the relevant subsections, with a brief overview of the modality-specific pitfalls that can also limit interpretation of the neuroimaging. The article also summarises the current literature and international practices in terms of management options and outcomes in specific disease entities

Multiparametric Imaging for Presurgical Planning of Craniopagus Twins: The Experience of Two Tertiary Pediatric Hospitals with Six Sets of Twins

Conjoined twins are rare and pose a challenge to radiologists and surgeons. Craniopagus twins, where conjunction involves the cranium, are especially rare. Even in large pediatric centers, radiologists are unlikely to encounter more than one such event in their medical careers. This rarity makes it daunting to select a CT and MRI protocol for these infants. Using the experience of two tertiary pediatric hospitals with six sets of craniopagus twins, this multidisciplinary and multimodal integrated imaging approach highlights the key questions that need addressing in the decision-making process for possible surgical intervention