bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low angle estimation in MIMO radar based on unitary ESPRIT under spatial smoothing
Authors: Qin Cong , Zhang Qin , Zheng Guimei , Zheng Yu , Zhang Gangsheng 
Published: August 2024

AbstractAiming at the problem that the overlapping of multipath signals seriously affects the radar's performance of the elevation angle estimation for low‐altitude targets, the authors combine the unitary ESPRIT (UESPRIT) and the multi‐input and multi‐output (MIMO) radar system and propose an algorithm based on UESPRIT to estimate the direction of arrival for low‐altitude targets. Firstly, the virtual matrix after generalised matched filtering of MIMO radar multipath received signals is vectorised. Secondly, for the coherence of direct and reflected wave signals, which cannot be directly processed by the UESPRIT algorithm, the signal preprocessing is performed by spatial smoothing of the sampled data matrices. Finally, the low‐altitude target estimation is carried out by using the UESPRIT algorithm. The Cramer–Rao bound (CRB) for arbitrary unbiased estimation of angle estimation is derived. The relationship between the estimation performance of the algorithm and the signal‐to‐noise ratio, the number of snapshots and the number of elements is analysed by simulation and compared with CRB. The simulation results show that the algorithm can still effectively estimate the elevation angle of low‐altitude targets under the mutual weakening of direct and multipath reflection signals, and has better performance for low‐altitude targets than generalised MUSIC.
Short‐term load forecasting facilitated by edge data centres: A coordinated edge‐cloud approach
Authors: Li Junlong , Fang Lurui , Wei Xiangyu , Fang Mengqiu , Xiang Yue , You Peipei , Zhang Chao , Gu Chenghong 
Published: August 2024

AbstractCompared to load forecasting at the national level, two challenges arise in providing accurate forecasting for LV and MV networks: (1) customers within LV and MV networks are much less, implying greater volatility within those load profiles; (2) not all customers have smart metres. Particularly, the two challenges would exacerbate forecasting performance under unexpected events, such as extreme weather and COVID‐19 outbreaks. To secure accurate short‐term load forecasting for LV and MV networks, this paper customised a Spatio‐Temporal Edge‐Cloud‐coordinated (STEC) approach on a loop training structure—LV networks to MV networks to LV networks. For each LV network, this approach utilises XGboost to learn the relationship between weather data, substation‐side loads, and a few accessible customer‐side load data to deliver rough forecasting. Then, it adopts the rough forecasting results and accessible data for all LV networks within an MV network to train the convolutional neural networks and gated recurrent unit (CNN‐GRU) network. This step provides load forecasting for MV networks and simultaneously refines load forecasting for LV networks by generating the interacting relationship between LV substations of different locations. Case studies reveal that the STEC approach successfully extrapolates the demand‐varying information from long‐term datasets and improves short‐term forecasting performance under both normal scenarios and newly occurring unexpected scenarios for LV and MV networks. The loop training structure halves the forecasting error, compared to classic methodology by utilising the local data only for MV networks.
Application of the Eddington inversion method to constrain the dark matter halo of galaxies using only observed surface brightness profiles
Authors: Sánchez Almeida Jorge , Plastino Angel R. , Trujillo Ignacio 
Published: August 2024

Context. The halos of low-mass galaxies may allow us to constrain the nature of dark matter (DM), but the kinematic measurements needed to diagnose the required properties are technically extremely challenging. However, the photometry of these systems is doable.
Aims. Using only stellar photometry, we wanted to constrain key properties of the DM halos in low-mass galaxies.
Methods. Unphysical pairs of DM gravitational potentials and starlight distributions can be identified if the pair requires a distribution function, f, that is negative somewhere in the phase space. We used the classical Eddington inversion method (EIM) to compute f for a battery of DM gravitational potentials and ∼100 observed low-mass galaxies with M⋆ between 106 and 108 M⊙. The battery includes Navarro, Frenk, and White (NFW) potentials (expected from cold DM) and potentials stemming from cored mass distributions (expected in many alternatives to cold DM). The method assumes spherical symmetry and an isotropic velocity distribution and requires fitting the observed profiles with analytic functions, for which we used polytropes (with zero inner slope, also known as core) and profiles with variable inner and outer slopes. The validity of all these assumptions is analyzed.
Results. In general, the polytropes fit the observed starlight profiles well. If they are the correct fits (which could be the case), then all galaxies are inconsistent with NFW-like potentials. Alternatively, when the inner slope is allowed to vary for fitting, between 40% and 70% of the galaxies are consistent with cores in the stellar mass distribution and thus inconsistent with NFW-like potentials.
Conclusions. Even though the stellar mass of the observed galaxies is still not low enough to constrain the nature of DM, this work shows the practical feasibility of using the EIM technique to infer DM properties only from photometry.
X-Shooting ULLYSES: Massive stars at low metallicity
Authors: Sander A. A. C. , Bouret J.-C. , Bernini-Peron M. , Puls J. , Backs F. , Berlanas S. R. , Bestenlehner J. M. , Brands S. A. , Herrero A. , Martins F. , Maryeva O. , Pauli D. , Ramachandran V. , Crowther P. A. , Gómez-González V. M. A. , Gormaz-Matamala A. C. , Hamann W.-R. , Hillier D. J. , Kuiper R. , Larkin C. J. K. , Lefever R. R. , Mehner A. , Najarro F. , Oskinova L. M. , Schösser E. C. , Shenar T. , Todt H. , ud-Doula A. , Vink J. S. 
Published: August 2024

Context.The spectral analysis of hot, massive stars is a fundamental astrophysical method of determining their intrinsic properties and feedback. With their inherent, radiation-driven winds, the quantitative spectroscopy for hot, massive stars requires detailed numerical modeling of the atmosphere and an iterative treatment in order to obtain the best solution within a given framework.Aims.We present an overview of different techniques for the quantitative spectroscopy of hot stars employed within the X-Shooting ULLYSES collaboration, ranging from grid-based approaches to tailored spectral fits. By performing a blind test for selected targets, we gain an overview of the similarities and differences between the resulting stellar and wind parameters. Our study is not a systematic benchmark between different codes or methods; our aim is to provide an overview of the parameter spread caused by different approaches.Methods.For three different stars from the XShooting ULLYSES sample (SMC O5 star AzV 377, LMC O7 star Sk -69° 50, and LMC O9 star Sk-66° 171), we employ different stellar atmosphere codes (CMFGEN,Fastwind, PoWR) and different strategies to determine their best-fitting model solutions. For our analyses, UV and optical spectroscopy are used to derive the stellar and wind properties with some methods relying purely on optical data for comparison. To determine the overall spectral energy distribution, we further employ additional photometry from the literature.Results.The effective temperatures found for each of the three different sample stars agree within 3 kK, while the differences in loggcan be up to 0.2 dex. Luminosity differences of up to 0.1 dex result from different reddening assumptions, which seem to be systematically larger for the methods employing a genetic algorithm. All sample stars are found to be enriched in nitrogen. The terminal wind velocities are surprisingly similar and do not strictly follow theu∞−Teffrelation.Conclusions.We find reasonable agreement in terms of the derived stellar and wind parameters between the different methods. Tailored fitting methods tend to be able to minimize or avoid discrepancies obtained with coarser or increasingly automatized treatments. The inclusion of UV spectral data is essential for the determination of realistic wind parameters. For one target (Sk -69° 50), we find clear indications of an evolved status.
Surgical Management of Ipsilateral Internal Carotid Artery Stenosis and Unruptured Intracranial Aneurysm: Case Review and Treatment Considerations
Authors: Gautam Diwas , Findlay Matthew C. , Cole Kyril L. , Couldwell William T. , Rennert Robert C. 
Published: August 2024

Abstract
Introduction The coexistence of carotid artery stenosis and a concomitant downstream ipsilateral unruptured intracranial aneurysm requires unique treatment considerations to balance the risk of thromboembolic complications from carotid artery stenosis and the risk of subarachnoid hemorrhage from intracranial aneurysm rupture. These considerations include the selection of optimal treatment modalities, the order and timing of interventions, and potential management of antiplatelet agents with endovascular approaches. We present strategies to optimize treatment in such a case.
Case Report We discuss the case of a 69-year-old woman with 90% stenosis of the right internal carotid artery and an ipsilateral, wide-necked, 4.8-mm, irregular-appearing right A1–2 junction aneurysm with an associated daughter sac. Open, endovascular, and mixed treatment strategies were considered. The patient selected and underwent a staged, open treatment approach with a carotid endarterectomy followed by a right craniotomy for microsurgical clipping of the aneurysm 5 days later. Both procedures were performed on daily full-dose aspirin without complications. On follow-up, the right carotid artery was widely patent, the aneurysm was secured, and the patient remained at her neurologic baseline.
Discussion The presented strategy for ipsilateral carotid artery stenosis and an unruptured intracranial aneurysm initially optimized cerebral perfusion to mitigate ischemic risks while permitting timely aneurysm intervention without a need for dual antiplatelet therapy or to traverse an earlier procedure site.
Reaction under Ball-Milling: Solvent- and Metal-Free One-Pot Diastereoselective Synthesis of Tetrahydroquinoline Derivatives as Potential Antibacterial and Anticancer Agents
Authors: Adak Laksmikanta , Roy Keya , Saha Anay , Sahoo Suprakash , Banerjee Subhrajyoti , Mukhopadhyay Chitrangada Das , Banerjee Subhash 
Published: August 2024

AbstractA mild and efficient one-pot, three-component ball-mill-assisted reaction of aldehydes, anilines, and dihydrofuran (or dihydropyran and cyclohexenone) has been described for the first time in the presence of the catalytic amount of aqueous perchloric acid (8 mol%) at room temperature under organic solvent- and metal-free conditions. The reactions are fast (1 h), providing the products with excellent yields and high diastereoselectivity. This procedure endows a simple, efficient, and cost-effective method for the diastereoselective synthesis of furano- and pyrano-tetrahydroquinolines and phenanthridinone derivatives, which are important biological compounds. The diastereomers with cis configuration were isolated as major products. The H–H COSY, NOESY experiments and X-ray crystallographic analysis of selected compounds were performed to confirm the cis isomer. The synthesized tetrahydroquinolines have been evaluated in vitro for their antibacterial and anticancer activities, and it was found that both the prepared compounds showed significant antibacterial and anticancer properties.
Solvent-Controlled Divergent Synthesis of Thiocyanated Carbazoles and Di/Triphenylamines
Authors: Tang You-Hui , Chen Peng , Jiang Yi-Jun , Yin Jin , Shi Jianghuan 
Published: August 2024

AbstractA solvent-controlled divergent thiocyanation of carbazoles and di/triphenylamines has been developed. Using either CH3CN/H2O (3:1) or DMSO as the solvent, a facile and efficient protocol for the solvent-controlled divergent synthesis of mono- and di-thiocyanation of carbazoles and di/triphenylamines was achieved. The salient features of this transformation include simple and mild reaction conditions, easily available substrates, and broad substrate scope.
Comparison of Full-Field Digital Mammography with Synthesized Mammography from Tomosynthesis in a Diagnostic population: Prospective Study
Authors: Dhamija Ekta , Mohan Supraja Laguduva , Anand Roshni , Khan Maroof Ahmad , Deo Sankaravamsam Venkata Suryanarayana , Hari Smriti 
Published: August 2024

Abstract
Background Synthesized mammography (SM) refers to two-dimensional (2D) images derived from the digital breast tomosynthesis (DBT) data. It can reduce the radiation dose and scan duration when compared with conventional full-field digital mammography (FFDM) plus tomosynthesis.
Purpose To compare the diagnostic performance of 2D FFDM with synthetic mammograms obtained from DBT in a diagnostic population.
Materials and Methods A total of 1,468 mammograms with both FFDM and SM + DBT images were obtained and analyzed over 2 years, after obtaining approval from the institute ethics committee. The images were reported and compared as per the 2013 American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) lexicon in terms of breast density, morphological features of mass, calcifications, and presence of asymmetry or architectural distortion followed by the BI-RADS category. The agreement between the two modalities was studied using the Kappa value, and the radiation exposure dose was recorded in both groups.
Results FFDM and SM + DBT showed strong agreement for breast density, mass characteristics, and detection of calcifications (kappa > 0.8). Downstaging of breast density and mass density were seen by SM + DBT without any statistically significant difference. The nipple–areola complex visualization was poor in SM (50.34 vs. 76.29% in FFDM), and there were SM-specific artifacts mainly related to the reconstruction algorithm. The radiation dose was higher with SM.
Conclusion FFDM has comparable performance to SM + DBT in diagnostic setup. The latter may be particularly helpful in patients with dense breasts.
Optimal Magnetic Resonance Sequence for Assessment of Central Cartilage Tumor Scalloping
Authors: Shirodkar Kapil K. , Jenko Nathan , Azzopardi Christine , Murphy Jennifer , Patel Anish , James Steven L. , Davies Arthur Mark , Botchu Rajesh 
Published: August 2024

Abstract
Background Magnetic resonance imaging (MRI) is key in evaluating central cartilage tumors. The BACTIP (Birmingham Atypical Cartilaginous Tumour Imaging Protocol) protocol assesses central cartilage tumor risk based on the tumor size and degree of endosteal scalloping on MRI. It provides a management protocol for assessment, follow-up, or referral of central cartilage tumors.
Objectives Our study compared four MRI sequences: T1-weighted (T1-w), fluid sensitive (Short Tau Inversion Recovery (STIR)- weighted, STIR-w), and grayscale inversions (T1-w GSI and short tau inversion recovery [STIR] GSI) to see how reliably endosteal scalloping was detected.
Materials and Methods Two senior consultant musculoskeletal radiologists with experience reviewed randomly selected 60 representative central cartilage tumor cases with varying degree of endosteal scalloping to reflect a spectrum of BACTIP pathologies. The endosteal scalloping was graded as per the definition of BACTIP A, B, and C. They agreed on a consensus BACTIP grade for each of the 240 key images (60 cases × 4 sequences), which was considered the final “consensus” BACTIP grade. These 240 images were then randomized into a test set and given to two fellowship-trained consultant musculoskeletal radiologists for analysis. They assigned a BACTIP grade to each of the 240 selected images while being blinded to the final “consensus” BACTIP grade. The training set was further subdivided into three groups based on the MR image quality (good quality, average quality, and poor quality) to ascertain if the quality of the acquired images influenced intraobserver and interobserver agreements on the BACTIP grading. The two observers were blinded to the grade assigned to the image quality.
Results Linearly weighted kappa analysis was performed to measure the agreement between the BACTIP grading answers by two observers and the “consensus” BACTIP grading answers, as well as the BACTIP grading agreement between the two observers themselves. The analysis revealed that T1-w and STIR-w sequences demonstrated more consistent and higher agreement across different image qualities. However, the T1-w GSI and STIR-w GSI sequences exhibited lower agreement, particularly for poor-quality images. T1-w imaging demonstrated substantial agreement between BACTIP gradings for poor-quality images, suggesting potential resilience of T1-w sequence in challenging imaging conditions.
Conclusion T1-w imaging is the best sequence for BACTIP grading of endosteal scalloping, followed by fluid-sensitive STIR sequences.
Evaluation of the Articular Disc Using the Magnetic Resonance Cartigram in Asymptomatic and Symptomatic Temporomandibular Disorders
Authors: Sivakumar Aparna , Ganesan Anuradha , Lakshmi Krithika Chandrasekar , Aniyan Yesoda , Kannan Saravanan 
Published: August 2024

Abstract
Objectives The study is aimed to perform magnetic resonance (MR) cartigram of the articular disc in patients with asymptomatic and symptomatic temporomandibular disorders (TMD).
Materials and Methods Thirty-nine volunteers were divided into three groups: 16 symptomatic TMD, 16 asymptomatic TMD, and 7 controls. The articular disc was divided into three segments (anterior, middle, and posterior) and analyzed using morphological magnetic resonance imaging (MRI) and T2 mapping sequences. T2 relaxation values were measured and assessed by an experienced radiologist and two observers. The T2 values in the discs were compared between the control, asymptomatic, and symptomatic groups using the Kruskal–Wallis test. The right and left discs were compared using the Wilcoxon signed rank test. Inter-examiner reliability among different examiners was evaluated.
Results The controls had the highest T2 values compared with the other groups. The comparison among the right and left sides of all the groups revealed statistically significant results in the anterior portion in the asymptomatic group and the middle portion in the symptomatic group (p < 0.05). The inter-examiner reliability coefficients among the three examiners were consistently high, with values of 0.921, 0.920, and 0.930.
Conclusion Our study found the T2 relaxation time span was shorter than that reported in previous studies, which could be attributed to the early stage of cartilage deterioration in the individuals with TMD inferring treatment at this phase may be eventually effective with a good prognosis.
Granular Cell Tumor of the Anal Canal: Case Report and Literature Review
Authors: Prats Jorge Arche , Prado Diego García , Villegas Gonzalo Campaña , Mardónez Mónica Martínez 
Published: August 2024

AbstractGranular cell tumors (GCTs) are rare benign neoplasms that can occur anywhere in the body but are most commonly found in the head and neck region. These tumors are often asymptomatic and are incidentally discovered during routine rectal examination. In some cases, symptoms may include bleeding, pain, and a palpable mass. Imaging studies such as colonoscopy, ultrasound, magnetic resonance imaging (MRI), or computed tomography can be used to characterize and measure the tumor. Treatment typically involves local resection, with or without adjuvant radiotherapy, depending on the size, location, and pathological characteristics of the tumor. The prognosis for GCTs of the anal canal is generally good, with few cases of recurrence or metastasis reported, but long-term follow-up is recommended due to the potential for late recurrence or malignant transformation. The present study reports a 39-year-old female patient who presented with anal itching associated with protrusion of a perianal mass and who underwent treatment between November 2022 and December 2023. The MRI scan revealed a nodular image in its caudal aspect with involvement of the internal sphincter between 12 and 5 o'clock, which was successfully resected. Histopathology was compatible with GCT, and the patient had a satisfactory recovery and was discharged. In conclusion, GCTs of the anal canal are rare and extremely unusual tumors that can be difficult to diagnose and manage, requiring a multidisciplinary approach for optimal management.
5–13.5 μm broadband tunable long-wave infrared femtosecond laser
Authors: Liu Yunpeng , Qian Junyu , Feng Renyu , Li Wenkai , Li Yanyan , Peng Yujie , Leng Yuxin 
Published: August 2024

We introduce a broadband tunable femtosecond laser source in the long-wave infrared (LWIR) band, covering the range of 5–13.5 μm, based on the integration of optical parametric amplification and difference frequency generation techniques. We utilize a dual-stage tuning method, combined with the high nonlinear coefficient and broadband phase matching range of the BaGa4Se7 crystal, to facilitate significant improvements in spectral coverage and energy efficiency. The laser yields a peak output energy of 43 μJ and maintains energies above 10 μJ across the entire tuning range, with an average power output exceeding 10 mW. The pulse duration at the central wavelength of 8.3 μm is measured at 72 fs full width at half-maximum using the electro-optic sampling method. This LWIR femtosecond laser can be used in many applications, such as molecular fingerprint spectral analysis, ultrafast chemical reaction spectral analysis, materials science, and ultrafast physics research, providing an important research basis for the generation and application of mid-infrared ultrafast laser sources.
Investigation of vacuum arc ignition characteristics and erosion morphology microstructure characteristics of CuCr55 electrode contact materials
Authors: Liu Siyuan , Bo Xianglai , Liu Zhiyuan , Geng Yingsan 
Published: August 2024

Copper–chromium alloy material, as one of the most important electrode contact materials in the field of electrical contact, has been widely used in vacuum interrupters. To replace the SF6 circuit breakers at higher voltage levels and larger breaking capacities, there is an urgent need for new electrode contact materials to meet the comprehensive electrical performance requirements of high withstand voltage, high insulation, and erosion resistance. In this study, a novel electrode contact material, CuCr55, for a 252 kV single break vacuum interrupter was prepared by the arc melting method, and the microstructures of arc-cast CuCr25, melt-infiltrated CuCr50, and arc-melted CuCr55 materials were compared. The vacuum arc ignition and erosion characteristics of arc-melted CuCr55 contact materials were analyzed in detail. A high-speed camera was used to capture the arc ignition characteristics of short-circuit currents, and the critical currents for the formation of anode spots for different materials were obtained. The micro-morphology of the contact surface after erosion was observed using electron microscopy. The research results showed that the arc-melted CuCr55 contacts had a fine and uniform distribution of chromium particles with spherical and dispersed microstructures. After vacuum arc erosion, there was no material fracture or significant protrusion on the surface of CuCr55 contacts, and they exhibited a higher critical current for anode spot formation and good uniform erosion characteristics.