Branch-site occlusion sign predicts the embolic origin of acute ischemic stroke: a meta-analysis

ObjectiveThe study aimed to investigate whether branch-site occlusion (BSO) sign could predict the etiology of acute intracranial large artery occlusion (ILVO) and the stentriever (SR) response.MethodsWe systematically reviewed studies that evaluated the predictive role of BSO for the etiology of ILVO-AIS or EVT outcome between 1 January 2000 and 31 August 2022 from PubMed, Embase, and Web of Science.ResultsThe sensitivity and specificity of BSO sign predicting etiology of ILVO-AIS were 0.87 (95% CI 0.81–0.91) and 0.64 (95% CI 0.33–0.87), respectively. The sensitivity and specificity of BSO sign predicting stentriever response were 0.84 (95% CI 0.63–0.94) and 0.61 (95% CI 0.18–0.92), respectively.ConclusionThe BSO sign could be a valid and precise imaging marker to predict embolism caused ILVO-AIS and recanalization success by SR without rescue therapy

Safety evaluation of employing temporal interference transcranial alternating current stimulation in human studies

Temporal interference transcranial alternating current stimulation (TI-tACS) is a new technique of noninvasive brain stimulation. Previous studies have shown the effectiveness of TI-tACS in stimulating brain areas in a selective manner. However, its safety in modulating human brain neurons is still untested. In this study, 38 healthy adults were recruited to undergo a series of neurological and neuropsychological measurements regarding safety concerns before and after active (2 mA, 20/70 Hz, 30 min) or sham (0 mA, 0 Hz, 30 min) TI-tACS. The neurological and neuropsychological measurements included electroencephalography (EEG), serum neuron-specific enolase (NSE), the Montreal Cognitive Assessment (MoCA), the Purdue Pegboard Test (PPT), an abbreviated version of the California Computerized Assessment Package (A-CalCAP), a revised version of the Visual Analog Mood Scale (VAMS-R), a self-assessment scale (SAS), and a questionnaire about adverse effects (AEs). We found no significant difference between the measurements of the active and sham TI-tACS groups. Meanwhile, no serious or intolerable adverse effects were reported or observed in the active stimulation group of 19 participants. These results support that TI-tACS is safe and tolerable in terms of neurological and neuropsychological functions and adverse effects for use in human brain stimulation studies under typical transcranial electric stimulation (TES) conditions (2 mA, 20/70 Hz, 30 min)

The Analysis of Precise Point Positioning of BeiDou Navigation Satellite System Application in Crustal Motion Monitoring

Based on more than two years BDS/GPS data observed by seven stations,we used precise point positioning (PPP) model of the PANDA software developed by Wuhan University,analyzed the positioning accuracy of single system and discussed the ability of BDS in crustal motion monitoring.The results showed that the BDS positioning accuracy in the horizontal direction was about 17 mm and the vertical direction was about 40 mm.The GPS positioning accuracy in the horizontal direction was better than 10 mm and the vertical direction was about 14 mm.The results of baseline statistics showed that BDS had lower ability to detect weak signals than GPS system,but it was still able to accurately reflect the characteristics of baseline length and rate between two sites.Comparing the velocity fields obtained from BDS and GPS,the results showed that the difference of the two sets of velocity field in horizontal directions was 1~2 mm/a,and there was no systematic difference.Although BDS PPP accuracy was lower than GPS,but it could still be used to monitor the crustal motion of the large deformation area

Surveying Colocated GNSS, VLBI, and SLR Stations in China

The local tie vectors between different space geodesy instruments in colocated sites, such as the global navigation satellite system (GNSS), very long baseline interferometry (VLBI), and satellite laser ranging (SLR), are essential for combination with the international terrestrial reference frame (ITRF). This paper introduces the surveying method and data processing model for determining the tie vectors in the seven colocated sites in Shanghai, Wuhan, Kunming, Beijing, Xian, Changchun, and Urumqi, and presents the values and full variance-covariance of these local ties. The surveying methodology and data processing method of the current work are rigorously determined to guarantee the relative positional precision of reference points (RPs) of different instruments in each colocation site to be a few millimeters. This paper compares the new tie vectors with those derived from ITRF 2008 products to consider the discrepancies at tie epoch. By comparing the new results to the previous results by other organizations, the new tie vector at the Wuhan site is in good agreement, but the vertical coordinate difference of the tie vector at the Shanghai site is as large as 2.24 cm. Therefore, the tie vector at the Shanghai site may have changed about 2 cm from 2003 to 2011

Pre-Earthquake and Coseismic Ionosphere Disturbances of the Mw 6.6 Lushan Earthquake on 20 April 2013 Monitored by CMONOC

In order to study the coupling relationship between large earthquakes and the ionosphere, the techniques of ionosphere data acquisition were refined by the Crustal Movement Observation Network of China (CMONOC) to detect the pre-earthquake ionospheric abnormal and coseismic ionospheric disturbances (CID) of the Mw 6.6 Lushan earthquake on 20 April 2013. Based on the regional ionosphere maps (RIMs) derived from the Global Positioning System (GPS) observations of CMONOC, the ionospheric local effects near the epicenter of the Lushan earthquake one month prior to the shock were analyzed. The results show that the total electron content (TEC) anomalies appeared 12–14 (6–8 April), 19 (1 April), and 25–27 (24–26 March) days prior to the Lushan earthquake, which are defined as periods 1, 2, and 3, respectively. Multi-indices including the ring current index (Dst), geomagnetic planetary (Kp) index, wind plasma speed (Vsw) index, F10.7, and solar flares were utilized to represent the solar–terrestrial environment in different scales and eliminate the effects of solar and geomagnetic activities on the ionosphere. After the interference of solar–terrestrial activity and the diurnal variation in the lower thermosphere were excluded, the TEC variations with obvious equatorial ionospheric anomaly (EIA) in period-1 were considered to be related to the Lushan earthquake. We further retrieved precise slant TECs (STECs) near the epicenter to study the coseismic ionospheric disturbance (CID). The results show that there was clear STEC disturbance occurring within half an hour after the Lushan earthquake, and the CID propagation distance was less than the impact radius of the Lushan earthquake (689 km). The shell models with different altitudes were adopted to analyze the propagation speed of the CID. It is found that at the F2-layer with the altitude of 277 km, which had a CID horizontal propagation velocity of 0.84 ± 0.03 km/s, was in accordance with the acoustic wave propagation velocity. The calculated velocity acoustic wave from the epicenter to the ionospheric pierce points of this shell model was about 0.53 ± 0.03 km/s, which was also consistent with its actual velocity within the altitude of 0–277 km. Affected by the geomagnetic field, the CID mainly propagated along the southeast direction at the azimuth of 190°, which was almost parallel to the local magnetic line