Differential Imaging Research Articles

Glycyrrhizinate Monoammonium Cysteine-Loaded Lipid Nanoparticles Allow for Improved Acute Liver Injury Therapy

Background: Acute liver injury (ALI) is a prevalent and potentially lethal condition globally, where pharmacotherapy plays a vital role. However, challenges such as rapid drug excretion and insufficient concentration at hepatic lesions often impede the treatment’s effectiveness. Methods: We successfully prepared glycyrrhizinate monoammonium cysteine (GMC)-loaded lipid nanoparticles (LNPs) using high-pressure homogenization. The characterization and safety of the LNPs were measured using electrophoretic light scattering (ELS), transmission electron microscopy (TEM), dynamic light scattering (DLS), cytotoxicity assays, and hemolysis tests. The distribution of LNPs in mice was explored using fluorescence labeling methods. The encapsulation efficiency of LNP-GMC was detected using High-Performance Liquid Chromatography (HPLC), and its slow-release effect on GMC was assessed through dialysis. The therapeutic effects of LNP-GMC and pure GMC on the ALI model were evaluated using fibroblast activation protein inhibitor (FAPI) PET imaging, blood biochemical indicators, and liver pathology slices. Results: The encapsulation of GMC in LNPs enhances drug stability and prolongs its hepatic retention, significantly improving its bioavailability and sustained release within the liver. This study also explores the expression of fibroblast activation protein (FAP) in ALI, employing 68Ga-FAPI PET/CT imaging for effective differentiation and assessment of liver injury. Conclusions: Our results suggest that LNPs offer an enhanced therapeutic approach for ALI treatment, reducing the required drug dosage, and 68Ga-FAPI PET/CT imaging provides a novel method for diagnosis and treatment assessment. This study contributes valuable insights into the utilization of LNPs in liver disease treatment, presenting a promising direction for future clinical applications.

On the origin of MTF reduction in grating-based x-ray differential phase contrast CT imaging.

The complementary absorption contrast CT (ACT) and differential phase contrast CT (DPCT) can be generated simultaneously from an x-ray computed tomography (CT) imaging system incorporated with grating interferometer. However, it has been reported that ACT images exhibit better spatial resolution than DPCT images. By far, the primary cause of such discrepancy remainsunclear. The purpose of this study is to investigate the underlying cause of the resolution discrepancy between ACT and DPCT in a grating interferometer CT imagingsystem. In this study, theoretical derivations were performed with a -phase Talbot-Lau grating interferometer system to model the signal formation mechanism of absorption imaging and phase imaging, respectively. In addition, physical, and numerical experiments were conducted to verify the theoretical findings and assess the resolution discrepancy between ACT and DPCT under various conditions. Herein, the ACT and DPCT images were reconstructed from the filtered-back-projection algorithm using a standard Ramp filter and a standard Hilbert filter,respectively. Experiments demonstrated that the spatial resolution of ACT and DPCT images are primarily impacted by the beam diffraction induced signal splitting. In particular, lower modulation transfer function (MTF) was observed for DPCT than ACT due to the opposite-superposition of phase signals. In addition, factors such as focal spot size, beam spectra, object composition, sample size, and detector pixel size were found to have minor impacts on the MTFs of both ACT and DPCT. In conclusion, this study reveals that the opposite-superposition of split phase signals causes the spatial resolution reduction in DPCTimaging.

Measurement of Atmospheric Coherence Length from a Shack–Hartmann Wavefront Sensor with Extended Sources

Free Space Optical Communication (FSOC) is a wireless communication method that utilizes laser beams for high speed and secure data transmission. Its performance is affected by various factors, among which atmospheric turbulence causes random fluctuations in the atmospheric refractive index, significantly impacting the reliability of communication links. The atmospheric coherence length is a key parameter describing the coherence properties of a laser signal as it propagates through the atmosphere, and accurately measuring it is crucial for assessing the quality of FSOC links. This paper proposes a novel strategy that utilizes extended sources directly as the information sources, combining the wavefront phase variance method with the extended source offset algorithm based on Shack–Hartmann wavefront sensors to directly measure atmospheric coherence length. Existing methods in extended scenarios typically rely on deploying laser beacons to aid in the calibration of atmospheric coherence length but setting up suitable beacons on horizontal communication links is challenging. Additionally, these approaches can be costly in terms of equipment and measurement expenses. Compared to traditional measurement methods, the algorithm proposed in this paper can measure directly based on extended scenarios in horizontal links, thereby effectively reducing system complexity and equipment costs. To verify the feasibility and effectiveness of this method, targeted simulations and experiments were conducted, and the results show that the coherence length measured by the algorithm is highly consistent with that measured by the Differential Image Motion Monitor (DIMM), with a deviation of less than 2% from actual values, effectively demonstrating the algorithm’s feasibility in coherence length assessment.

Three Years of High-contrast Imaging of the PDS 70 b and c Exoplanets at Hα with MagAO-X: Evidence of Strong Protoplanet Hα Variability and Circumplanetary Dust

We present 3 yr of high-contrast imaging of the PDS 70 b and c accreting protoplanets with the new extreme AO system MagAO-X as part of the MaxProtoPlanetS survey of Hα protoplanets. In 2023 and 2024, our sharp (25–27 mas FWHM), well-AO-corrected (20%–26% Strehl), deep (2–3.6 hr) images detected compact (r ∼ 30 mas; r ∼ 3 au) circumplanetary disks (CPDs) surrounding both protoplanets. Starlight scattering off the front edge of these dusty CPDs is the likely source of the bright compact continuum light detected within ∼30 mas of both planets in our simultaneously obtained continuum 668 nm filter images. After subtraction of contaminating continuum and point-spread function residuals with pyKLIP angular differential imaging and spectral differential imaging, we obtained high-contrast ASDI Hα images of both planets in 2022, 2023, and 2024. We find the Hα line flux of planet b fell by (8.1 ± 1.6) × 10−16 erg s−1 cm−2, a factor of 4.6 drop in flux from 2022 to 2023. In 2024 March, planet b continued to be faint with just a slight 1.6× rise to an Hα line flux of (3.64 ± 0.87) × 10−16 erg s−1 cm−2. For c, we measure a significant increase of (2.74 ± 0.51) × 10−16 erg s−1 cm−2 from 2023 to 2024, which is a factor of 2.3 increase. So both protoplanets have recently experienced significant Hα variability with ∼1 yr sampling. In 2024, planet c is brighter than b: as c is brightening and b generally fading. We also tentatively detect one new point source “CC3” inside the inner disk (∼49 mas; at PA ∼ 295°; 2024) with orbital motion roughly consistent with a ∼5.6 au orbit.

Transient global amnesia – current state of knowledge

Introduction and purpose Transient global amnesia (TGA) is a sudden, short-lasting episode of anterograde and retrograde memory loss not caused by stroke or epileptic seizure. It affects 3.4-10.4 per 100,000 people per year, especially those in their 70s. There are several hypotheses regarding the etiopathology of this disorder, none of which have been unequivocally confirmed. This study aims to review the current knowledge about TGA, and to show its essence to the wider community. Description TGA is mainly manifested by a sudden, up to 24-hour loss of anterograde and retrograde memory, which may be accompanied by mild neuropsychological deficits. Diagnosis is based on a neurological examination and exclusion of numerous possible differential diagnoses, including laboratory and imaging tests. There is no specific treatment for this condition, and patient care is based primarily on patient education and risk factor control. They rarely recur and do not cause long-term complications. Summary Although TGA is considered a benign condition, its sudden onset and the temporary nature of memory loss can cause significant anxiety for both patients and their families. Increased awareness and prompt diagnosis are essential to provide reassurance and to rule out more serious conditions such as stroke or epilepsy. Expanding research on TGA is crucial to uncover potential preventive strategies and enhance our understanding of transient memory dysfunctions.

New geometrid moths from Iraqi Kurdistan (Lepidoptera, Geometridae: Sterrhinae, Larentiinae).

A large number of geometrid moths was collected by the first author in Iraqi Kurdistan including several undescribed species and subspecies. In this paper we describe three new geometrid taxa: Idaea medianocturna walaila ssp. nov., Lulavia mahwii sp. nov. and Protorhoe drechseli nebuloides ssp. nov. We present differential diagnoses and images of adult moths and genitalia.

Phase-contrast visualization of human tissues using superimposed wavefront imaging of diffraction-enhanced x-rays.

Phase-contrast computed tomography (CT) using high-brilliance, synchrotron-generated x-rays enable three-dimensional (3D) visualization of microanatomical structures within biological specimens, offering exceptionally high-contrast images of soft tissues. Traditional methods for phase-contrast CT; however, necessitate a gap between the subject and the x-ray camera, compromising spatial resolution due to penumbral blurring. Our newly developed technique, Superimposed Wavefront Imaging of Diffraction-enhanced x-rays (SWIDeX), leverages a Laue-case Si angle analyzer affixed to a scintillator to convert x-rays to visible light, capturing second-order differential phase contrast images and effectively eliminating the distance to the x-ray camera. This innovation achieves superior spatial resolution over conventional methods. In this paper, the imaging principle and CT reconstruction algorithm based on SWIDeX are presented in detail and compared with conventional analyzer-based imaging (ABI). It also shows the physical setup of SWIDeX that provides the resolution preserving second-order differential images for reconstruction. We compare the spatial resolution and the sensitivity of SWIDeX to conventional ABI. To demonstrate high-spatial resolution achievable by SWIDeX, the internal structures of four human tissues-ductal carcinoma in situ, normal stomach, normal pancreas, and intraductal papillary mucinous neoplasm of the pancreas-were visualized using an imaging system configured at the Photon Factory's BL14B beamline under the High Energy Accelerator Research Organization (KEK). Each tissue was thinly sliced after imaging, stained with hematoxylin and eosin (H&E) for conventional microscope-based pathology. A comparison of SWIDeX-CT and pathological images visually demonstrates the effectiveness of SWIDeX-CT for biological tissue imaging. SWIDeX could generate clearer 3D images than existing analyzer-based phase-contrast methods and accurately delineate tissue structures, as validated against histopathological images. SWIDeX can visualize important 3D structures in biological soft tissue with high spatial resolution and can be an important tool for providing information between the disparate scales of clinical and pathological imaging.

High strehl and high contrast for the ELT instrument METIS

The Mid-infrared ELT Imager and Spectrograph (METIS) is a first-generation instrument for the Extremely Large Telescope (ELT), Europe’s next-generation 39 m ground-based telescope for optical and infrared wavelengths, which is currently under construction at the European Southern Observatory (ESO) site at Cerro Armazones in Chile. METIS will offer diffraction-limited imaging, low- and medium-resolution slit spectroscopy, and coronagraphy for high-contrast imaging between 3 and 13 microns, as well as high-resolution integral field spectroscopy between 3 and 5 microns. The main METIS science goals are the detection and characterisation of exoplanets, the investigation of proto-planetary disks, and the formation of planets. The Single-Conjugate Adaptive Optics (SCAO) system corrects atmospheric distortions and is thus essential for diffraction-limited observations with METIS. SCAO will be used for all observing modes, with high-contrast imaging imposing the most demanding requirements on its performance. The Final Design Review (FDR) of METIS took place in the fall of 2022; the development of the instrument, including its SCAO system, has since entered the Manufacturing, Assembly, Integration and Testing (MAIT) phase. Numerous challenging aspects of an ELT Adaptive Optics (AO) system are addressed in the mature designs for the SCAO control system and the SCAO hardware module: the complex interaction with the telescope entities that participate in the AO control, wavefront reconstruction with a fragmented and moving pupil, secondary control tasks to deal with differential image motion, non-common path aberrations and mis-registration. A K-band pyramid wavefront sensor and a GPU-based Real-Time Computer (RTC), tailored to the needs of METIS at the ELT, are core components. This current paper serves as a natural sequel to our previous work presented in Hippler et al. (2018). It reflects all the updates that were implemented between the Preliminary Design Review (PDR) and FDR, and includes updated performance estimations in terms of several key performance indicators, including achieved contrast curves. We outline all important design decisions that were taken, and present the major challenges we faced and the main analyses carried out to arrive at these decisions and eventually the final design. We also elaborate on our testing and verification strategy, and, last not least, comprehensively present the full design, hardware and software in this paper to provide a single source of reference which will remain valid at least until commissioning.

Evaluating the reproducibility of a deep learning algorithm for the prediction of retinal age.

Recently, a deep learning algorithm (DLA) has been developed to predict the chronological age from retinal images. The Retinal Age Gap (RAG), a deviation between predicted age from retinal images (Retinal Age, RA) and chronological age, correlates with mortality and age-related diseases. This study evaluated the reliability and accuracy of RA predictions and analyzed various factors that may influence them. We analyzed two groups of participants: Intravisit and Intervisit, both imaged by color fundus photography. RA was predicted using an established algorithm. The Intervisit group comprised 26 subjects, imaged in two sessions. The Intravisit group had 41 subjects, of whom each eye was photographed twice in one session. The mean absolute test-retest difference in predicted RA was 2.39years for Intervisit and 2.13years for Intravisit, with the latter showing higher prediction variability. The chronological age was predicted accurately from fundus photographs. Subsetting image pairs based on differential image quality reduced test-retest discrepancies by up to 50%, but mean image quality was not correlated with retest outcomes. Marked diurnal oscillations in RA predictions were observed, with a significant overestimation in the afternoon compared to the morning in the Intravisit cohort. The order of image acquisition across imaging sessions did not influence RA prediction and subjective age perception did not predict RAG. Inter-eye consistency exceeded 3years. Our study is the first to explore the reliability of RA predictions. Consistent image quality enhances retest outcomes. The observed diurnal variations in RA predictions highlight the need for standardized imaging protocols, but RAG could soon be a reliable metric in clinical investigations.

SURGICAL RESECTION OF A COMPLEX TUBERCULUM SELLAE MENINGIOMA ENCASING MAJOR ARTERIES

Introduction Though constituting only a minor proportion (1%) of sellar masses, suprasellar meningiomas pose a significant diagnostic challenge within the region of sellar and suprasellar tumors. Pituitary adenomas, at nearly 90% prevalence, dominate this anatomical region. Distinguishing these two entities is paramount, as both clinical presentation and, to some extent, biochemical profiles exhibit notable overlap. Accurate preoperative differentiation is critical due to the contrasting behaviors of these tumors. Meningiomas, with their robust vascularity supplied by dural and osseous arteries, present a heightened risk of intraoperative hemorrhage. Clinical Case A 53-year-old woman presented with a two-month history of worsening headaches and gradual vision loss. Neurological examination revealed only visual acuity decline. Her hormone profile showed elevated prolactin but lacked clinical features of prolactin excess, suggesting a possible prolactin-secreting pituitary macroadenoma. A contrast-enhanced MRI confirmed a significant sellar and suprasellar mass with homogeneous enhancement, extending to the right paramedian region and encasing the right internal carotid artery (ICA) at its critical segment involving the cavernous and supraclinoid portions. Furthermore, the right middle meningeal artery (M1) and anterior cerebral artery (A1) originated from this same location, highlighting the high surgical risk. Surgical resection was deemed necessary. The patient underwent a right pterional craniotomy, revealing a grayish, extradural soft mass lesion encasing the ICA bifurcation. Careful microsurgical dissection with basal devascularization was performed, followed by near-complete tumor removal using an ultrasonic aspirator to minimize damage to the encased arteries. Postoperative follow-up CT scan confirmed successful near-total tumor ablation. Conclusion This case underscores the critical role of meticulous preoperative diagnosis in managing complex sellar tumors. While pituitary adenomas dominate this region, suprasellar meningiomas, despite their rarity, demand a high index of suspicion. Overlapping clinical and biochemical presentations highlight the reliance on advanced imaging for accurate differentiation. The intricate vascularity of meningiomas, as exemplified by the encasement of critical arteries in this case, necessitates meticulous surgical technique with devascularization strategies. This successful near-complete tumor removal emphasizes the importance of such surgical expertise in navigating these diagnostically challenging sellar lesions.

Single-shot quantitative differential phase contrast microscope using a single calcite beam displacer

This paper presents the development of a single-shot, partially spatially coherent quantitative differential phase contrast microscopy (Q-DPCM) system. The optical scheme comprises a polarizer, lenses, calcite beam displacer, and analyzer, which can be seamlessly integrated to an existing bright-field microscopy system, transforming it into a Q-DPCM system. It utilizes a partially spatially coherent light source, enabling single-shot quantitative differential phase recovery of the specimens with high spatial phase sensitivity. It generates highly sensitive quantitative differential phase images of the specimens along one direction, like a gradient light interference microscopy (GLIM) system, using only a single interferogram. First, we validated the differential phase measurement capability of the system through experiments on polystyrene spheres (diameter 5.2 µm) and HeLa cells. Next, the system is utilized to generate quantitative phase maps of human red blood cells using two orthogonal differential interferograms recorded at two orientations of the calcite beam displacer. Further, the Q-DPCM system is implemented for 1-h time-lapse live cell monitoring, revealing the dynamics of intracellular granules such as nucleolus and lipids in U2OS cells.

Deep Search for a Scattered Light Dust Halo Around Vega with the Hubble Space Telescope

We present a provisory scattered-light detection of the Vega debris disk using deep Hubble Space Telescope (HST) coronagraphy (PID 16666). At only 7.7 pc, Vega is immensely important in debris disk studies both for its prominence and also because it allows the highest physical resolution among all debris systems relative to temperature zones around the star. We employ the STIS coronagraph’s widest wedge position and classical reference differential imaging to achieve among the lowest surface-brightness sensitivities to date ( ∼4μJyarcsec−2 ) at wide separations using 32 orbits in Cycle 29. We detect a halo extending from the inner edge of our effective inner working angle at 10.″5 out to the photon noise floor at 30″ (80–230 au). The face-on orientation of the system and the lack of a perfectly color-matched point-spread function star have posed significant challenges to the reductions, particularly regarding artifacts from the imperfect color matching. However, we find that a halo of small dust grains provides the best explanation for the observed signal. Unlike Fomalhaut (a close twin to Vega in luminosity, distance, and age), there is no clear distinction in scattered light between the parent planetesimal belt observed with the Atacama Large Millimeter/submillimeter Array and the extended dust halo. These HST observations complement JWST GTO Cycle 1 observations of the system with NIRCam and MIRI.

Radiomics analysis in differentiating osteosarcoma and chondrosarcoma based on T2-weighted imaging and contrast-enhanced T1-weighted imaging

This study was performed to investigate the diagnostic value of radiomics models constructed by fat suppressed T2-weighted imaging (T2WI-FS) and contrast-enhanced T1-weighted imaging (CET1) based on magnetic resonance imaging (MRI) for differentiation of osteosarcoma (OS) and chondrosarcoma (CS). In this retrospective cohort study, we included all inpatients with pathologically confirmed OS or CS from Second Xiangya Hospital of Central South University (Hunan, China) as of October 2020. Demographic and imaging variables were extracted from electronic medical records and compared between OS and CS group. Totals of 530 radiomics features were extracted from CET1 and T2WI-FS sequences based on MRI. The least absolute shrinkage and selection operator (LASSO) method was used for screening and dimensionality reduction of the radiomics model. Multivariate logistic regression analysis was performed to construct the radiomics model, and receiver operating characteristic curve (ROC) was generated to evaluate the diagnostic accuracy of the radiomics model. The training cohort and validation cohort included 87 and 29 patients, respectively. 8 CET1 features and 15 T2WI-FS features were screened based on the radiomics features. In the training group, the area under the receiver-operator characteristic curve (AUC) value for CET1 and T2WI-FS sequences in the radiomics model was 0.894 (95% CI 0.817–0.970) and 0.970 (95% CI 0.940–0.999), respectively. In the validation group, the AUC value for CET1 and T2WI-FS sequences in the radiomics model was 0.821 (95% CI 0.642–1.000) and 0.899 (95% CI 0.785–1.000), respectively. In this study, we developed a radiomics model based on T2WI-FS and CET1 sequences to differentiate between OS and CS. This model exhibits good performance and can help clinicians make decisions and optimize the use of healthcare resources.

Unveiling sulfur vacancy pairs as bright and stable color centers in monolayer WS2

Color centers, arising from zero-dimensional defects, exploit quantum confinement to access internal electron quantum degrees of freedom, holding potential for quantum technologies. Despite intensive research, the structural origin of many color centers remains elusive. In this study, we employ in-situ cathodoluminescence scanning transmission electron microscopy combined with integrated differential phase contrast imaging to examine how defect configuration in tungsten sulfide determines color-center emission. Using an 80-kV accelerated electron beam, defects were deliberately produced, visualized, excited in situ and characterized in real time in monolayer WS2 within hBN|WS2 | hBN heterostructures at 100 K. These color centers were simultaneously measured by cathodoluminescence microscopy and differentiated by machine learning. Supported by DFT calculations, our results identified a crucial sulfur vacancy configuration organized into featured vacancy pairs, generating stable and bright luminescence at 660 nm. These findings elucidate the atomic-level structure-exciton relationship of color centers, advancing our understanding and quantum applications of defects in 2D materials.

Multiple reference star differential imaging with VLT/SPHERE

Context. High-contrast imaging observations mostly rely on angular differential imaging, a successful technique for detecting point-sources, such as planets. However, in the vicinity of the star (typically below 300 mas), this technique suffers from signal self-subtraction when there is not enough field rotation. Building large libraries of reference stars from archival data later used to optimally subtract the stellar halo is a powerful technique known as reference star differential imaging (RSDI) that can overcome this limitation. Aims. We aim at investigating new methods for creating reference libraries composed of multiple stars when applying reference star differential imaging to VLT/SPHERE data. We used for that purpose a data set from the SPHERE High Angular Resolution Debris Disk Survey (SHARDDS), composed of 55 targets observed in broad-band H with the InfraRed Dual-band Imager and Spectrograph (IRDIS) during 2015-2016, with a total of ~20 000 frames. We consider HD 206893, known to host a close-in bound substellar companion HD 206893 B, as a benchmark science target to demonstrate the improved sensitivity provided by this method. Methods. We created libraries of reference frames based on different image similarity metrics: the cosine distance between descriptors created by a convolutional neural network, the Pearson correlation coefficient, the Structural Similarity Index, the Strehl ratio, and raw contrast criteria. We used principal component analysis (PCA) to subtract the stellar halo and tested various normalization options. Results. We obtained the best signal-to-noise ratio (S/N) on HD 206893 B by using the Pearson correlation coefficient (PCC) applied to an annulus between 245 and 612 mas to select reference frames. The ten reference libraries with the highest S/N on the substellar companion HD 206893 B were all based on the PCC method, outperforming other similarity metrics. While the Strehl ratio is the environment variable most correlated to the contrast, it is insufficient to select similar images. We also show that having multiple reference stars in the reference library produces better results than using a single well-chosen reference star. Conclusions. Using the Pearson correlation computed on a specific area of interest to select reference frames is a promising alternative to improve the detectability of faint point-sources when applying reference star differential imaging. In the future, reducing all the data available in the SPHERE archive using this technique might offer interesting results in the search for previously undetected planets.

Transport-of-intensity differential phase contrast imaging: defying weak object approximation and matched-illumination condition

Quantitative phase imaging (QPI) has emerged as a promising label-free imaging technique with growing importance in biomedical research, optical metrology, materials science, and other fields. Partially coherent illumination provides resolution twice that of the coherent diffraction limit, along with improved robustness and signal-to-noise ratio, making it an increasingly significant area of study in QPI. Partially coherent QPI, represented by differential phase contrast (DPC), linearizes the phase-to-intensity transfer process under the weak object approximation (WOA). However, the nonlinear errors caused by WOA in DPC can lead to phase underestimation. Additionally, DPC requires strict matching of the illumination numerical aperture (NA) to ensure the complete transmission of low-frequency information. This necessitates precise alignment of the optical system and limits the flexible use of objective and illumination. In this study, the applicability of the WOA under different coherence parameters is explored, and a method to defy WOA by reducing the illumination NA is proposed. The proposed method uses the transport-of-intensity equation through an additional defocused intensity image to recover the lost low-frequency information due to illumination mismatch, without requiring any iterative procedure. This method overcomes the limitations of DPC being unable to recover large phase objects and does not require the strict illumination matching conditions. The accurate quantitative morphological characterization of customized artifact and microlens arrays that do not satisfy WOA under non-matched-illumination conditions demonstrated the precise quantitative capability of the proposed method and its excellent performance in the field of measurement. Meanwhile, the phase retrieval of tongue slices and oral epithelial cells demonstrated its application potential in the biomedical field. The ability to accurately recover phase under a concise and implementable optical setup makes it a promising solution for widespread application in various label-free imaging domains.

MTCSNet: One-Stage Learning and Two-Point Labeling are Sufficient for Cell Segmentation.

Deep convolution neural networks have been widely used in medical image analysis, such as lesion identification in whole-slide images, cancer detection, and cell segmentation, etc. However, it is often inevitable that researchers try their best to refine annotations so as to enhance the model performance, especially for cell segmentation task. Weakly supervised learning can greatly reduce the workload of annotations, while there is still a huge performance gap between the weakly and fully supervised learning approaches. In this work, we propose a weakly-supervised cell segmentation method, namely Multi-Task Cell Segmentation Network (MTCSNet), for multi-modal medical images, including pathological, brightfield, fluorescent, phase-contrast and differential interference contrast images. MTCSNet is learnt in a single-stage training manner, where only two annotated points for each cell provide supervision information, and the first one is the centroid, the second one is its boundary. Additionally, five auxiliary tasks are elaborately designed to train the network, including two pixel-level classifications, a pixel-level regression, a local temperature scaling and an instance-level distance regression task, which is proposed to regress the distances between the cell centroid and its boundaries in eight orientations. The experimental results indicate that our method outperforms all state-of-the-art weakly-supervised cell segmentation approaches on public multi-modal medical image datasets. The promising performance also shows that a single-stage learning with two-point labeling approach are sufficient for cell segmentation, instead of fine contour delineation. The codes are available at: https://github.com/binging512/MTCSNet.

Diagnostic Accuracy of Preoperative Imaging for Differentiation of Branch Duct Versus Mixed Duct Intraductal Papillary Mucinous Neoplasms: Erratum.

Diagnostic Accuracy of Preoperative Imaging for Differentiation of Branch Duct Versus Mixed Duct Intraductal Papillary Mucinous Neoplasms: Erratum.

Temporal and chromatic variation of polarized scattered light in the outer disk of PDS 70

Context. PDS 70 stands out as the only system hosting a protoplanetary disk and two confirmed planets undergoing formation. It is a unique target for characterizing the dust in this type of disk. Aims. We aim to accurately measure the reflected polarized intensity and quantify the variability and asymmetry for PDS 70 across multiple epochs and wavelengths in the optical and near-infrared. We present new high-contrast polarimetric differential imaging observations of PDS 70, with the N_R filter on SPHERE/ZIMPOL. Methods. We combined the new observation with archival data of the VLT/SPHERE instrument, spanning five wavelengths (N_R, VBB, J, H, and Ks) over seven epochs and eight years. For each observational epoch, we corrected the smearing effect due to finite instrument resolution, measured the azimuthal brightness profiles, and derived the intrinsic disk-integrated polarized reflectivity and the intrinsic brightness contrasts. Results. With our homogeneous analysis of all available optical and near-infrared data sets of the disk around PDS 70, we find significant temporal variability of the integrated polarized reflectivity as well as the azimuthal brightness profile. This indicates variable shadowing on the outer disk by inner disk structures beyond the resolution limit of current imaging instruments. Despite these variabilities, we observe a systematic wavelength-dependent contrast between the near side and the far side of the inclined disk. These results underline the importance of considering both the shadowing effect from the inner disk and the surface geometry of the observed reflecting disk in the analysis and interpretation of observational data.

VLT/MUSE Detection of Accretion/Ejection Associated with the Close Stellar Companion in the HT Lup System

The accretion/ejection processes in T Tauri stars are fundamental to their physical evolution, while also impacting the properties and evolution of the circumstellar material at a time when planet formation takes place. To date, the characterization of ongoing accretion processes in stellar pairs at 5–50 au scales has been challenging as high-angular resolution spectrographs are required to extract the spectral features of each component. We present the analysis of spectroscopic observations of the tight (160 mas, 25 au) T Tauri system HT Lup A/B, obtained with MUSE at the Very Large Telescope in 2021 March and July. We focus on constraining the accretion/ejection processes and variability of the secondary component HT Lup B by searching for accretion tracers by applying high-resolution spectral differential imaging techniques. We retrieve strong (signal-to-noise ratio > 5) Hα, Hβ, and [O i]λ6300 emission in both epochs. The Hα and Hβ line fluxes showcase high variability, with variations up to 200%–300% between epochs. The fluxes are consistent with accretion rates of 3× 10−9 M ⊙ yr−1 and 8 × 10−10 M ⊙ yr−1 for the first and second epochs, respectively. We attribute the increased accretion activity during the first night to a “burst-like” event, followed by a relaxation period more representative of the common accretion activity of the system. The [O i]λ6300 line profiles remain relatively similar between epochs and suggest ejection rates on the order of 10−9−10−10 M ⊙ yr−1, compatible with moderate disk wind emission. Our results also indicate that the accretion processes of HT Lup B are compatible with Classical T Tauri stars, unlike previous classifications.