Large Baseline Research Articles

Understanding Black Hole Imaging Based on Very Large Baseline Interferometry (VLBI)

In 2019, the Event Horizon Telescope made history when it captured the first known image of a blackhole. The black hole, situated in the center of the Messier 87 galaxy, is more than 55 million light-years away from earth, and was only able to be captured using Very Large Baseline Interferometry (VLBI) technology and the computational imaging technologies integrated into the Event Horizon Telescope array (The Event Horizon Telescope Collaboration, 2019). Astronomical image processing and interferometry requires the collection of radio waves using a radio telescope and analyzing that data with software. VLBI collects signals with multiple telescopes simultaneously, and the resulting data can be reduced and analyzed as data collected by a telescope with the diameter equal to the largest distance between the telescopes, thus is capable of producing an image with higher angular resolution and capturing objects further away from earth. However, due to the distance between the VLBI telescopes, algorithms are needed to fill in the hole within the collected data and reduce atmospheric noise and delays in signals (Very Long Baseline Array (VLBA)). We conduct an in depth review of the algorithm and VLBI as a whole in this paper, and hope to use our findings to further push the development of this great technology.

Outcomes and CT Perfusion Thresholds of Mechanical Thrombectomy for Patients With Large Ischemic Core Lesions.

ObjectiveTo explore the clinical prognosis and factors after mechanical thrombectomy (MT) in patients with large cerebral infarction assessed by computed tomographic perfusion (CTP)and the optimal threshold of cerebral blood flow (CBF) for estimating ischemic core.MethodsWe analyzed data from the anterior circulation database of our hospital (August 2018–June 2021). Multivariate logistic regression analyses identified the predictors of clinical outcomes for patients with large baseline infarcts (>50 ml) assessed by the MIStar software. The receiver operating characteristic (ROC) analysis was used to explore the cutoff value of factors.ResultsThe present study included one hundred thirty-seven patients with large baseline infarcts. Moreover, 23 (16.8%) patients achieved functionally independent outcomes, and 50 (36.5%) patients died at 90 days. A total of 20 (14.7%) patients had symptomatic intracranial hemorrhage (sICH). The multivariable analysis showed that higher age and larger core volume were independent of poor outcomes. The cutoff value of core volume was 90 ml, and the age was 76 years. Hypertension and rt-PA treatment were independent factors of sICH. Higher age and larger ischemic volume were independent risk factors of mortality.ConclusionsMechanical thrombectomy can be applied in patients with large ischemic core volumes. Patients older than 76 years with large cores (>90 ml) are unlikely to benefit from MT. These findings may be helpful in selecting patients with large baseline infarcts to be treated by MT. The threshold of CBF < 30% is the independent factor, and this is worth evaluating in future studies to find the optimal threshold of CBF.

Prevalence of Wormian (Sutural) Bones in the Paris Catacombs Ossuary

Wormian, or sutural bones, vary in number, size, and arrangement in humans and other vertebrates. While their occurrence has been noted in some genetic bone development disorders, Wormian bones are also found in the general population. Currently, there are not reliable data to estimate the frequency at which they are found in humans with no underlying disorder. Some anthropologists have attempted to assess Wormian bone frequency in different human populations hoping to find whether there are differences among peoples of different genetic lineage. However, the sample sizes in these studies are too small to be able to compare such highly variable structures. The data presented here examining 500 skulls in the ossuary within les catacombes de Paris has revealed that Wormian bone occur in about 85% of skulls examined. This contrasts with most published studies that report incidences in the 10‐20% range. Les catacombes de Parisare believed to contain remains mostly from the late 18th and early 19th centuries. While there may be bones from earlier times, it is likely that these are fragile and fragmentary, and thus almost certainly do not contribute to the accessible visible walls of bones. These results are compared to surveys of skulls in three Italian collections: Museo di Anatomia umanaat Luigi Rolando dell'Università di Torino, Museo di Antropologiaat Università degli Studi di Padova,and Museo di Storia Naturale Sezione di Antropologia e Etnologia di Firenze, and in the only two known medieval English church ossuaries, in Hythe and Rothwell. The Italian collections represent Europeans, most if not all from late 19th and early 20th centuries, and the English skulls are presumed to be from the 13th and14th centuries. Wormian bones were found slightly more frequently in les catacombes de Paris than the other sites, but in each as well as all taken together, the incidence is significantly higher than is commonly reported for skulls from other parts of the world. The sample size of each of these studies individually, as well as in composite, is a very large. This large sample size further increases the credibility of these data. These findings expand the data set for comparison of Wormian bones from different parts of Europe and to peoples from other regions of the world, thus serving the greater community by providing a large baseline against which smaller sample groups may be compared. Additionally, the photographic evidence collected in this project may be used to support further research in human anatomical variation.

Chemical shift assignments of calmodulin under standard conditions at neutral pH

The Ca2+ sensor protein, calmodulin (CaM) is ubiquitously expressed in all cells where it binds to hundreds of different target proteins, including dozens of enzymes, receptors, ion channels and numerous Ca2+ transporters. The only published NMR chemical shift assignments for Ca2+-bound CaM (in the absence of a target) have been determined under acidic conditions: at pH 6.5/310 K (BMRB 6541) and pH 6.3/320 K (BMRB 547). However, some CaM/target complexes are not soluble under these conditions. Also, amide chemical shifts are very sensitive to pH and temperature, which can cause large baseline errors when using the existing chemical shift assignments of free CaM to calculate chemical shift perturbations caused by target binding at neutral pH and physiological temperature. We report complete NMR chemical shift assignments of Ca2+-saturated CaM under a set of standard conditions at neutral pH and 308 K that will enable more accurate chemical shift comparison between free CaM and CaM/target complexes (BMRB 51289).

Longitudinal associations between energy utilization and brain volumes in cognitively normal middle aged and older adults

Peak energy capacity of the whole person is associated with neurodegeneration. However, change in ability to utilize energy manifests as combination of declining peak energy capacity and rising energetic costs of mobility in mid-to-late life. We examined longitudinal associations between change in energy utilization and brain volumes. Cognitively normal participants from the Baltimore Longitudinal Study of Aging (N = 703, age = 70.4 ± 12.1 years, 54.1% women, 30% black) had concurrent data on brain volumes and energy utilization (defined as ratio of energetic cost of walking to peak energy capacity (“cost-to-capacity ratio”) at ≥ 1 visit between 2008 and 2018. We performed linear mixed-effect models, adjusting for demographics, medical history and walking engagement. Average baseline cost-to-capacity ratio was 0.55 ± 0.16, with average annual increase of 0.04 ± 0.13 over 3.9 follow-up years. A 10% higher baseline cost-to-capacity ratio was associated with 2.00 cm3 (SE = 0.44) larger baseline ventricular volume (p < 0.001), and 0.10 cm3 (SE = 0.03) greater annual increase in ventricular volume (p = 0.004) after adjustment. Longitudinal change in cost-to-capacity ratio was not associated with brain volumes. These findings highlight, among cognitive-normal adults, poorer baseline energy utilization is associated with subsequent ventricular enlargement, an indirect measure of central brain atrophy. Future studies should explore whether early detection of worsening energy utilization may act as a marker of underlying brain atrophy.

A quantitative comparison of amplitude versus intensity interferometry for astronomy

Astronomical imaging can be broadly classified into two types. The first type is amplitude interferometry, which includes conventional optical telescopes and very large baseline interferometry (VLBI). The second type is intensity interferometry, which relies on Hanbury Brown and Twiss-type measurements. At optical frequencies, where direct phase measurements are impossible, amplitude interferometry has an effective numerical aperture that is limited by the distance from which photons can coherently interfere. Intensity interferometry, on the other hand, correlates only photon fluxes and can thus support much larger numerical apertures, but suffers from a reduced signal due to the low average photon number per mode in thermal light. It has hitherto not been clear which method is superior under realistic conditions. Here, we give a comparative analysis of the performance of amplitude and intensity interferometry, and we relate this to the fundamental resolution limit that can be achieved in any physical measurement. Using the benchmark problem of determining the separation between two distant thermal point sources, e.g., two adjacent stars, we give a short tutorial on optimal estimation theory and apply it to stellar interferometry. We find that for very small angular separations the large baseline achievable in intensity interferometry can more than compensate for the reduced signal strength. We also explore options for practical implementations of very large baseline intensity interferometry (VLBII).

Impact of non-thermal particles on the spectral and structural properties of M87

Context. The recent 230 GHz observations of the Event Horizon Telescope are able to image the innermost structure of M 87 and show a ring-like structure that agrees with thermal synchrotron emission generated in a torus surrounding a supermassive black hole. However, at lower frequencies, M 87 is characterised by a large-scale and edge-brightened jet with clear signatures of non-thermal emission. In order to bridge the gap between these scales and to provide a theoretical interpretation of these observations, we perform general relativistic magnetohydrodynamic simulations of accretion onto black holes and jet launching. Aims. M 87 has been the target for multiple observations across the entire electromagnetic spectrum. Among these, very large baseline interferometry (VLBI) observations provide unique details of the collimation profile of the jet down to several gravitational radii. We aim to model the observed broad-band spectrum of M 87 from the radio to the near-IR regime and at the same time, fit the jet structure as observed with global millimeter-VLBI at 86 GHz. Methods. We used general relativistic magnetohydrodynamics and simulated the accretion of the magnetised plasma onto Kerr black holes in 3D. The radiative signatures of these simulations were computed taking different electron distribution functions into account, and a detailed parameter survey was performed in order to match the observations. Results. The results of our simulations show that magnetically arrested disks around fast-spinning black holes (a⋆ ≥ 0.5) together with a mixture of thermal and non-thermal particle distributions are able to simultaneously model the broad-band spectrum and the innermost jet structure of M 87.

Incidence and risk of advanced age-related macular degeneration in eyes with drusenoid pigment epithelial detachment

To investigate the incidence and risk of advanced age-related macular degeneration (AMD), including geographic atrophy (GA) and macular neovascularization (MNV), in eyes with drusenoid pigment epithelial detachment (PED). Eighty-five eyes with drusenoid PED from 85 patients (77.2 ± 7.0 years, male/female: 44/41) were included in this study. Patients were followed up every 1–3 months via spectral-domain optical coherence tomography (SD-OCT) and color fundus photography. If exudation was observed on SD-OCT, fluorescein and indocyanine green angiography were performed to confirm the MNV subtype accordingly. The maximum follow-up period was 60 months. During the study period, GA developed in 8 eyes while MNV also developed in 8 eyes. The Kaplan–Meier estimator revealed that the cumulative incidence for 60 months was 17.9% and 12.2% for GA and MNV, respectively. In eyes developing MNV, retinal angiomatous proliferation was the most common. Cox regression analysis revealed that baseline PED width was the only factor associated with advanced AMD. (p = 0.0026, Cox regression analysis). The 5-year cumulative incidence of advanced AMD, including GA and MNV, was approximately 30% in eyes with drusenoid PED among the Japanese elderly. A larger baseline PED width was the only risk factor for advanced AMD.

Flexible Light Field Angular Superresolution via a Deep Coarse-to-Fine Framework

Acquisition of densely-sampled light fields (LFs) is challenging. In this paper, we develop a coarse-to-fine light field angular superresolution that reconstructs densely-sampled LFs from sparsely-sampled ones. Unlike most of other methods, which are limited by the regularity of sampling patterns, our method can flexibly deal with different scale factors with one model. Specifically, a coarse restoration on epipolar plane images (EPIs) with arbitrary angular resolution is performed and then a refinement with 3D convolutional neural networks (CNNs) on stacked EPIs. The subaperture images in LFs are synthesized first horizontally, then vertically, forming a pseudo 4DCNN. In addition, our method can handle large baseline light field without using geometry information, which means it is not constrained by Lambertian assumption. Experimental results over various light field datasets including large baseline LFs demonstrate the significant superiority of our method when compared with state-of-the-art ones.

Deep View Synthesis via Self-Consistent Generative Network

View synthesis aims to produce unseen views from a set of views captured by two or more cameras at different positions. This task is non-trivial since it is hard to conduct pixel-level matching among different views. To address this issue, most existing methods seek to exploit the geometric information to match pixels. However, when the distinct cameras have a large baseline (i.e., far away from each other), severe geometry distortion issues would occur and the geometric information may fail to provide useful guidance, resulting in very blurry synthesized images. To address the above issues, in this paper, we propose a novel deep generative model, called Self-Consistent Generative Network (SCGN), which synthesizes novel views from the given input views without explicitly exploiting the geometric information. The proposed SCGN model consists of two main components, i.e., a View Synthesis Network (VSN) and a View Decomposition Network (VDN), both employing an Encoder-Decoder structure. Here, the VDN seeks to reconstruct input views from the synthesized novel view to preserve the consistency of view synthesis. Thanks to VDN, SCGN is able to synthesize novel views without using any geometric rectification before encoding, making it easier for both training and applications. Finally, adversarial loss is introduced to improve the photo-realism of novel views. Both qualitative and quantitative comparisons against several state-of-the-art methods on two benchmark tasks demonstrated the superiority of our approach.

Light Field Reconstruction Using Efficient Pseudo 4D Epipolar-Aware Structure

Limited by sensor resolution, Light Field (LF) images often suffer from an inherent trade-off between angular resolution and spatial resolution. LF reconstruction, including Spatial Super-Resolution (LFSSR) and Angular Super-Resolution (LFASR), upsamples LF in spatial and angular domain based on the complementary information in different views. In this paper, we propose efficient pseudo-4D end-to-end frameworks for LFSSR and LFASR, respectively. Since the epipolar information and spatial-angular information reflect the relationship between views, we propose to fully consider both of them to exploit complementary information thoroughly. Specifically, we first extract epipolar information from horizontally and vertically stacked views separately. Then an Epipolar-Aware Grid (EAG) network composed of Dual Interactive Blocks (DIBs) fully interacts the epipolar information, characterizing the grid-like LF parallax structure. In order to effectively achieve dense interaction between the spatial and angular domain to extract complementary information, several Parallel Spatial-Angular Integration Blocks (PSAIBs) are further introduced. For LFs with large baselines, we also propose a generic shear attention network, which generalizes the model designed for small baselines to large baselines without depth estimation. As compared to the state-of-the-art methods, extensive experiments conducted on both synthetic and real-world datasets demonstrate our superiority in LFSSR tasks and LFASR tasks.

Extraction of Absolute Water Level Using TanDEM-X Bistatic Observations With a Large Perpendicular Baseline

The application of Wetland synthetic aperture radar interferometry (InSAR) has often been restricted in practical hydrological monitoring because it is based on relative estimates of water level changes between two synthetic aperture radar acquisitions, as opposed to absolute water levels obtained by ground measurements. TanDEM-X bistatic observations can provide absolute water level estimates using simultaneous phase measurements by a two-satellite constellation with TerraSAR-X. We evaluated two datasets of TanDEM-X bistatic observations acquired during an experimental science phase on August 26 and 31, 2015, with a very large baseline configuration to extract absolute water levels of Everglades wetland in southern Florida, USA. The perpendicular baselines are 1.43 and 1.36 km, and the ambiguities of height were calculated as 3.61 and 3.90 m in each interferometric pair, respectively. Hourly water level measurements provided by the Everglades depth estimation network (EDEN) were used to verify the estimated absolute water levels. Several stage stations located in densely vegetated areas that showed incoherence were excluded from the verification as outliers. The verification results show an excellent agreement (degree of determination > 0.95) between the InSAR derived absolute water levels and the stage station measurements. The root mean square error (RMSE) between the TanDEM-X results and stage records was 0.77 and 0.66 m, respectively. Severe volume decorrelations over the vegetated area, owing to the large perpendicular baselines, were detected, despite near zero temporal baseline of the bistatic observations. The absolute water levels can be used as excellent constraints for wetland surface flow models.

RTSfM: Real-Time Structure From Motion for Mosaicing and DSM Mapping of Sequential Aerial Images With Low Overlap

Inspired by simultaneous localization and mapping (SLAM) style workflow, this article presented an online sequential structure from motion (SfM) solution for high-frequency video and large baseline high-resolution aerial images with high efficiency and novel precision. First, as traditional SLAM systems are not good in processing low overlap images, based on our novel hierarchical feature matching paradigm with multihomography and BoW, we proposed a robust tracking method where the relative pose and its scale are estimated separately followed by a joint optimization by considering both perspective-n-point (PnP) and epipolar constraints. Second, to further optimize the camera poses for the sparse map and dense pointcloud reconstruction, we provided a graph-based optimization with reprojection and GPS constraints, which make the camera trajectory and map georeferenced. We also incrementally generated the dense point cloud in real time from keyframes after local mapping optimization. Finally, we use a publicly available aerial image dataset with sequences of different environments, to evaluate the effectiveness of the proposed method, meanwhile, the robust performance of our solution is demonstrated with applications of high-quality aerial images mosaic and digital surface model (DSM) reconstruction in real time. Compared with the state-of-the-art SLAM and traditional SfM methods, the presented system can output large-scale high-quality ortho-mosaic and DSM in real time with the low computational cost.

Detecting Rock Glacier Displacement in the Central Himalayas Using Multi-Temporal InSAR

Rock glaciers represent typical periglacial landscapes and are distributed widely in alpine mountain environments. Rock glacier activity represents a critical indicator of water reserves state, permafrost distribution, and landslide disaster susceptibility. The dynamics of rock glacier activity in alpine periglacial environments are poorly quantified, especially in the central Himalayas. Multi-temporal Interferometric Synthetic Aperture Radar (MT-InSAR) has been shown to be a useful technique for rock glacier deformation detection. In this study, we developed a multi-baseline persistent scatterer (PS) and distributed scatterer (DS) combined MT-InSAR method to monitor the activity of rock glaciers in the central Himalayas. In periglacial landforms, the application of the PS interferometry (PSI) method is restricted by insufficient PS due to large temporal baseline intervals and temporal decorrelation, which hinder comprehensive measurements of rock glaciers. Thus, we first evaluated the rock glacier interferometric coherence of all possible interferometric combinations and determined a multi-baseline network based on rock glacier coherence; then, we constructed a Delaunay triangulation network (DTN) by exploiting both PS and DS points. To improve the robustness of deformation parameters estimation in the DTN, we combined the Nelder–Mead algorithm with the M-estimator method to estimate the deformation rate variation at the arcs of the DTN and introduced a ridge-estimator-based weighted least square (WLR) method for the inversion of the deformation rate from the deformation rate variation. We applied our method to Sentinel-1A ascending and descending geometry data (May 2018 to January 2019) and obtained measurements of rock glacier deformation for 4327 rock glaciers over the central Himalayas, at least more than 15% detecting with single geometry data. The line-of-sight (LOS) deformation of rock glaciers in the central Himalayas ranged from −150 mm to 150 mm. We classified the active deformation area (ADA) of all individual rock glaciers with the threshold determined by the standard deviation of the deformation map. The results show that 49% of the detected rock glaciers (monitoring rate greater than 30%) are highly active, with an ADA ratio greater than 10%. After projecting the LOS deformation to the steep slope direction and classifying the rock glacier activity following the IPA Action Group guideline, 12% of the identified rock glaciers were classified as active and 86% were classified as transitional. This research is the first multi-baseline, PS, and DS network-based MT-InSAR method applied to detecting large-scale rock glaciers activity.

Retrieval of Boreal Forest Heights Using an Improved Random Volume over Ground (RVoG) Model Based on Repeat-Pass Spaceborne Polarimetric SAR Interferometry: The Case Study of Saihanba, China

Spaceborne polarimetric synthetic aperture radar interferometry (PolInSAR) has the potential to deal with large-scale forest height inversion. However, the inversion is influenced by strong temporal decorrelation interference resulting from a large temporal baseline. Additionally, the forest canopy induces phase errors, while the smaller vertical wavenumber (kz) enhances the sensitivity of the inversion to temporal decorrelation, which limits the efficiency in forest height inversion. This research is based on the random volume over ground (RVoG) model and follows the assumptions of the three-stage inversion method, to quantify the impact of repeat-pass spaceborne PolInSAR temporal decorrelation on the relative error of retrieval height, and develop a semi-empirical improved inversion model, using ground data to eliminate the interference of coherence and phase error caused by temporal decorrelation. Forest height inversion for temperate forest in northern China was conducted using repeat-pass spaceborne L-band ALOS2 PALSAR data, and was further verified using ground measurement data. The correction of temporal decorrelation using the improved model provided robust inversion for mixed conifer-broad forest height retrieval as it addressed the over-sensitivity to temporal decorrelation resulting from the inappropriate kz value. The method performed height inversion using interferometric data with temporal baselines ranging from 14 to 70 days and vertical wavenumbers ranging from 0.015 to 0.021 rad/m. The R2 and RMSE reached 0.8126 and 2.3125 m, respectively.

Optical intensity interferometry lab tests in preparation of stellar diameter measurements at IACTs at GHz photon rates

ABSTRACTAstronomical intensity interferometry enables quantitative measurements of the source geometry by measuring the photon fluxes in individual telescopes and correlating them, rather than correlating the electromagnetic waves’ amplitudes. This simplifies the realization of large telescope baselines and high angular resolutions. Imaging Atmospheric Cherenkov Telescopes (IACTs), intended to detect the optical emission of γ-ray-induced air showers, are excellent candidates to perform intensity correlations in the optical at reasonable signal-to-noise ratios. The detected coherence time is on the scale of (10−12)–(10−15) s – depending on the optical bandwidth of the measurement – which challenges the detection system to work in a stable and accurate way. We developed an intensity interferometry set-up applicable to IACTs, which measures the photocurrents from photomultipliers and correlates them offline, and as such is designed to handle the very large photon rates provided by the telescopes. We present measurements in the lab simulating starlight using a xenon lamp and measured at different degrees of temporal and spatial coherence. Necessary calibration procedures are described with the goal of understanding the measurements quantitatively. Measured coherence times between $5\,$femtoseconds (corresponding signal-to-background ratio 5 × 10−7) and $110\,$femtoseconds (signal-to-background ratio 10−5) are in good agreement with expectations, and so are the noise levels in the correlations, reaching down to 6 × 10−8, after measurements between $30\,$min and $1\,$h.

Uncued Detection and Initial Orbit Determination From Short Observations With the Murchison Widefield Array

This article details the latest developments in the use of the Murchison Widefield Array as a passive radar receiver for the surveillance of space. We cover methods developed to incorporate orbital parameters into matched-filter processing to achieve uncued detection without a prior track, and generate accurate detection-level initial orbit estimates. We present the results from a short collection campaign conducting broad surveillance stares, using FM transmitters as an illuminator with a significantly large bistatic baseline length of 600 km. Initial results demonstrate improved performance in the Murchison Widefield Array's detection of objects in typical low Earth orbital regimes, detecting objects with radar cross section of 1 m2 as well as the generation of accurate initial orbital estimates using very short arc detections spanning less than half a degree.

Radio astronomy and Space science in Azores: Enhancing the Atlantic VLBI infrastructure cluster

Radio astronomy and Space Infrastructures in the Azores have a great scientific and industrial interest because they benefit from a unique geographical location in the middle of the North Atlantic allowing a vast improvement in the sky coverage. This fact obviously has a very high added value for: i) the establishment of space tracking and communications networks for the emergent global small satellite fleets ii) it is invaluable to connect the radio astronomy infrastructure networks in Africa, Europe and America continents using Very Large Baseline Interferometry (VLBI) techniques, iii) it allows excellent potential for monitoring space debris and Near Earth Objects (NEOs). There is in S. Miguel island a 32-metre SATCOM antenna that could be integrated in advanced VLBI networks and be capable of additional Deep Space Network ground support. This paper explores the space science opportunities offered by the upgrade of the S. Miguel 32-metre SATCOM antenna into a world-class infrastructure for radio astronomy and space exploration: it would enable a Deep Space Network mode and would constitute a key space facility for data production, promoting local digital infrastructure investments and the testing of cutting-edge information technologies. Its Atlantic location also enables improvements in angular resolution, provides many baselines in East–West and North–South directions connecting the emergent VLBI stations in America to Europe and Africa VLBI arrays therefore contributing for greater array imaging capabilities especially for sources or well studied fields close to or below the celestial equator, where ESO facilities, ALMA, SKA and its precursors do or will operate and observe in the coming decades.

Predictors of hemorrhagic complications after intravenous thrombolysis in acute cerebral infarction patients: A single-center study of 391 cases.

For patients with ischemic stroke, intravenous (IV) thrombolysis with Urokinase within 6 hours has been accepted as beneficial, but its application is limited by high risk of hemorrhagic complications after thrombolysis. This study aimed to analyze the risk factors of hemorrhagic complications after intravenous thrombolysis using Urokinase in acute cerebral infarction (ACI) patients.Total 391 consecutive ACI patients were enrolled and divided into 2 groups: the hemorrhagic complications group and the non-hemorrhagic complications group. The related data were collected and analyzed.Univariate analysis showed significant differences in prothrombin time, atrial fibrillation (AF), Mean platelet volume, large platelet ratio (L-PLR), triglyceride (TG), Lactate dehydrogenase, alanine aminotransferase (ALT), high-density lipoprotein, and baseline National Institute of Health Stroke Scale score between the hemorrhagic complications and the non-hemorrhagic complications group (P < .1). Multivariate logistic regression analysis indicated that AF (odds ratio [OR] = 2.91, 95% confidence interval [CI] = 1.06–7.99 P = .039) was the risk factor of hemorrhagic complications, while ALT (OR = 0.27, 95% CI = 0.10–0.72 P = .009) and TG (OR = 0.16, 95% CI = 0.06–0.45 P = .000) were protective factors of hemorrhagic complications.For patients with AF and lower levels of ALT or TG, the risk of hemorrhagic complications might increase after ACI.

Efficient global stereo-matching method of general images under a long baseline based on baseline estimation.

For three-dimensional (3D) measurement of a large object, stereo matching needs to be done under a relatively long baseline in order to reduce the accumulated errors caused by the splicing process, but this brings new challenges to matching efficiency. The images under a short baseline have an advantage avoiding a very large disparity level that is usually presented in a large baseline to improve efficiency, whether the image pairs to be matched are of translation or rotation configuration. This paper mainly focuses on the general case existing for both, and the purpose is to efficiently execute a stereo matching in this scene based on short baseline estimation. A rectification method of three images used for baseline estimation is first studied to make the image planes become coplanar, which removes the vertical disparity. The three rectified images can form a stereo pair with a short baseline and the other one has a long baseline. Then the relationship that exists between disparities of a pixel on rectified stereo pairs with different baselines is deduced by considering the quantization error introduced in the projection and rectification. In this way, the disparity search range of a pixel on the rectified stereo pair with the long baseline is reduced from the usual hundreds of pixels to a few pixels predicted by its disparity with the short baseline, which greatly improves the calculation efficiency and makes it especially suitable for the 3D measurement of large objects. Experimental results are presented to demonstrate the efficiency and accuracy of the method.