Astrometric Reduction of Saturnian Satellites with Cassini-ISS Images Degraded by Trailed Stars

The Imaging Science Subsystem(ISS)mounted on the Cassini spacecraft has taken a lot of images,which provides an important source of high-precision astrometry of some planets and satellites.However,some of these images are degraded by trailed stars.Previously,these degraded images cannot be used for astrometry.In this paper,a new method is proposed to detect and compute the centers of these trailed stars automatically.The method is then performed on the astrometry of ISS images with trailed stars.Finally,we provided 658 astrometric positions between 2004 and 2017 of several satellites that include Enceladus,Dione,Tethys,Mimas and Rhea.Compared with the JPL ephemeris SAT427,the mean residuals of these measurements are 0.11 km and 0.26 km in R.A.and decl.,respectively.Their standard deviations are 1.08 km and 1.37 km,respectively.The results show that the proposed method performs astrometric measurements of Cassini ISS images with trailed stars effectively.

Regional volume changes of the brain in migraine chronification

The pathophysiology of migraine is complex.Neuroimaging studies reveal functional and structural changes in the brains of migraine patients.We sought to explore regional volume differences in intracranial structures in patients with episodic and chronic migraine.Sixteen episodic migraine patients,16 chronic migraine patients,and 24 normal controls were recruited and underwent 3.0 T MRI scanning.The volumes of 142 brain regions were calculated by an automatic volumetric algorithm and compared with clinical variables.Results demonstrated that the volumes of specific regions in the frontal and occipital lobes,and the right putamen,were increased and the volume of the fourth ventricle was decreased in the episodic migraine patients compared with controls.The volumes of the left basal forebrain,optic chiasm,and,the fourth ventricle were decreased in the chronic migraine patients,while the occipital cortex and the right putamen were larger.Compared to episodic migraine patiants,chronic migraine patients displayed larger left thalamus and smaller frontal regions.Correlation analysis showed that headache frequency was negatively correlated with the volume of the right frontal pole,right lateral orbital gyrus,and medial frontal lobes and positively correlated with the volume of the left thalamus.The sleep disturbance score was negatively correlated with the volume of the left basal forebrain.This suggests that migraine patients have structural changes in regions associated with pain processing and modulation,affective and cognitive processing,and visual perception.The remodeling of selective intracranial structures may be involved in migraine attacks.This study was approved by the Ethics Committee of Chinese PLA General Hospital(approval No.S2018-027-02)on May 31,2018.

MRI Evaluation of Lateral Geniculate Body in Normal Aging Brain Using Quantitative Susceptibility Mapping

Objective To investigate the changes of lateral geniculate body(LGB) in the normal aging brain using quantitative susceptibility mapping(QSM) technique. Methods Magnetic resonance(MR) phase and magnitude images were acquired from enhanced gradient echo T2 star weighted angiography sequence with 16 echoes on 3.0T MR system using the head coil with 32 channels. Morphology Enabled Dipole Inversion(MEDI) method was applied for QSM, and the susceptibility value of LGB was measured by region of interest(ROI) drawn manually on three orthogonal planes. Results LGB of the middle-aged group had a higher susceptibility value(0.16±0.05 ppm) than that of the youth group(0.12±0.05 ppm) and elderly group(0.13±0.03 ppm)(all P<0.05). Partial correlation analysis demonstrated that there was significantly positive correlation between susceptibility value and age in the youth group(r=0.71, P<0.05). Conclusion LGB could clearly be identified on QSM in the brain in vivo.

Functional changes of the lateral pterygoid muscle in patients with temporomandibular disorders:a pilot magnetic resonance images texture study

Background:Texture features were the intrinsic properties of the human tissues and could efficiently detect the subtle functional changes of involved tissue.The pathologic changes of the lateral pterygoid muscle(LPM)were significantly correlated with the temporomandibular disc displacement.However,the occult functional changes of LPM could not be detected by the naked eye on the medical images.The current study was aimed to evaluate the functional changes of the LPM in the patients with temporomandibular disorders(TMDs)using texture analysis.Methods:Twenty-nine patients with TMD were performed with magnetic resonance(MR)imaging on a 3.0T MR scanner,who were consecutively recruited from the TMD clinic of Hainan Hospital of Chinese People’s Liberation Army General Hospital from February 2019 to September 2019.The patients were classified into three groups according to the disc displacement:disc without displacement(DWoD),disc displacement with reduction(DDWR)and disc displacement without reduction(DDWoR).The graylevel co-occurrence matrix method was applied with the texture analysis of LPM on the axial T2-weighted imaging.The texture features included angular second moment,contrast,correlation,inverse different moment,and entropy.One-way analysis of variance was used for grouped comparisons and receiver operating characteristics(ROC)curve analysis was applied to evaluate the diagnostic efficacy of the texture parameters.Results:Texture contrast of LPM presented significantly lower in DDWoR(46.30[35.03,94.48])than that in DWoD(123.85[105.06,143.23];test statistic=23.05;P<0.001).Texture entropy of LPM showed significant differences among DWoD(7.62±0.33),DDWR(6.76±0.35),and DDWoR(6.46±0.39)(PDWoD-DDWR<0.001,PDWoD-DDWoR<0.001,and PDDWR-DDWoR=0.014).Area under the ROC curve(AUC)demonstrated that texture entropy had an excellent diagnostic accuracy for DWoD-DDWR(AUC=0.96)and DWoD-DDWoR(AUC=0.98).Conclusion:The texture contrast and entropy could identify the altered functional status of LPM in patients withTMDand could be considered as the effective imaging biomarker to evaluate the functional changes of LPM in TMD.

Volume Gain of Brainstem on Medication-Overuse Headache Using Voxel-Based Morphometry

Background： Histopathology identified the anatomical and molecular abnormalities ofbrainstem nuclei in migraine patients. However, the exact whole brainstem structural changes in vivo have not yet been identified in medication-overuse headache （MOH） transformed from migraine. The aim of this study was to investigate the regional volume changes over the whole brainstem in the MOH patients using voxel-based morphometry （VBM） in vivo.Methods： High-resolution three-dimensional structural images were obtained using a 3.0-Tesla magnetic resonance system from 36 MOH patients and 32 normal controls （NCs） who were consecutively recruited from the International Headache Center, Chinese People＇s Liberation Army General Hospital, from March 2013 to June 2016. VBM was used to assess the brainstem structural alteration in the MOH patients, and voxel-wise correlation was performed to evaluate the relationship with the clinical characteristics.Results： The brainstem region with increased volume located in the left ventrolateral periaqueductal gray （MNI coordinate： -1, -33, -8）, ventral tegmental area （MNI coordinate： 0, -22, - 12）, bilateral substantia nigra （MNI coordinate： -8, - 16, - 12, 9, - 16, - 12）, and trigeminal root entry zone （MNI coordinate： -19, -29, -31; 19, -32, -29） in MOH patients compared with NCs. The headache visual analog scale score was positively related with the left rostral ventromedial medulla （RVM） （MNI coordinate： -1, -37, -56; cluster size： 20; r = 0.602） in the MOH patients.Conclusions： The regional volume gain ofbrainstem could underlie the neuromechanism of impaired ascending and descending pathway in the MOH patients, and the left RVM volume alteration could imply the impaired tolerance ofnociceptive pain input and could be used to assess the headache disability in the MOH patients.

A new hierarchical software architecture towards safety-critical aspects of a drone system

A new hierarchical software architecture is proposed to improve the safety and reliability of a safetycritical drone system from the perspective of its source code. The proposed architecture uses formal verification methods to ensure that the implementation of each module satisfies its expected design specification, so that it prevents a drone from crashing due to unexpected software failures. This study builds on top of a formally verified operating system kernel, certified kit operating system(CertiKOS). Since device drivers are considered the most important parts affecting the safety of the drone system, we focus mainly on verifying bus drivers such as the serial peripheral interface and the inter-integrated circuit drivers in a drone system using a rigorous formal verification method. Experiments have been carried out to demonstrate the improvement in reliability in case of device anomalies.

Multimodal Magnetic Resonance Imaging Studies of Migraines Related to Increasing Risk Factors for Brain Lesions Would Be an Optimal Research Focus： A Pilot Literature Citation Analysis

To the Editor： Migraine is the third most prevalent headache disorder and the seventh leading cause of disability worldwide.The first magnetic resonance imaging （MRI） migraine study was reported in 1995, with many subsequent MRI migraine studies appearing after the development of structural brain and functional MRIs. Advanced MRI techniques such as voxel-based morphometry, advanced brain structure segment.