bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multi‐Source Perturbations in the Evolution of a Low‐Latitudinal Equatorial Plasma Bubble Event Occurred Over China
Authors: Sun Longchang , Xu Jiyao , Zhu Yajun , Yuan Wei , Gao Hong , Yan Chunxiao 
Published: March 2023

AbstractIn this paper, multi‐source perturbations during the evolution of an equatorial plasma bubble (EPB) event at low latitudes in China are studied by means of multi‐ground‐based instruments, including an all‐sky airglow imager, a very high frequency (VHF) radar and eight digisondes. We found that EPB event initially evolved from bottom perturbations (∼600 km scale) seeded by atmospheric gravity waves in a form of large‐scale wave‐like structure, accompanying smaller‐scale perturbations (∼150 km scale) mostly by collision‐shear instability (CSI); once formed, those seed perturbations further evolved into the ionospheric topside by the plasma instability. Observed and analyzed are two different instabilities: one is the Rayleigh‐Taylor instability (RTI) driven by a prereversal enhancement of the zonal electric field (PRE) occurred near sunset; the other is an equatorward wind‐induced secondary E × B gradient drift instability (GDI) around midnight. Accompanying the PRE‐induced RTI are freshly‐generated depletions with larger poleward (upward) velocities. The PRE‐driven RTI could elevate the bottom perturbations directly to form fast‐moving depletions/structures at the ionospheric topside. The E × B GDI was trigged by a vertical upward plasma jet caused by a seasonal equatorward wind in regions as far as 10°N (20°N) from the geomagnetic (geographic) equator. This equatorward wind‐induced E × B GDI continuously forced topside structures of those drifting‐type EPB depletions to extend poleward more slowly, resulting in active 3.2‐m irregularities around midnight. Besides, we present evidence that a westward polarization electric field generated in an adjacent trough region of the faster‐growing cluster‐type depletions inhibited the neighboring slower‐growing cluster‐type depletions.
Extreme Event Statistics in Dst, SYM‐H, and SMR Geomagnetic Indices
Authors: Bergin A. , Chapman S. C. , Watkins N. W. , Moloney N. R. , Gjerloev J. W. 
Published: March 2023

AbstractExtreme space weather events are rare, and quantifying their likelihood is challenging, often relying on geomagnetic indices obtained from ground‐based magnetometer observations that span multiple solar cycles. The Dst index ring‐current monitor, derived from an hourly average over four low‐latitude stations, is a benchmark for extreme space weather events, and has been extensively studied statistically. We apply extreme value theory (EVT) to two geomagnetic ring current indices: SYM‐H (derived from 6 stations) and SMR (derived from up to 120 stations). EVT analysis reveals a divergence between the return level found for Dst, and those for SYM‐H and SMR, that increases non‐linearly with return period. For return periods below 10 years, hourly averaged SYM‐H and SMR have return levels similar to Dst, but at return periods of 50 and 100 years, they respectively exceed that of Dst by about 10% and 15% (SYM‐H) and about 7% and 12% (SMR). One minute resolution SYM‐H and SMR return levels progressively exceed that of Dst; their 5, 10, 50, and 100 year return levels exceed that of Dst by about 10%, 12%, 20% and 25% respectively. Our results indicate that consideration should be given to the differences between the indices if selecting one to use as a bench mark in model validation or resilience planning for the wide range of space weather sensitive systems that underpin our society.
1ppm-detectable hydrogen gas sensors by using highly sensitive P+/N+ single-crystalline silicon thermopiles
Authors: Zhang Haozhi , Jia Hao , Ni Zao , Li Ming , Chen Ying , Xu Pengcheng , Li Xinxin 
Published: March 2023

AbstractHydrogen (H2) is currently of strategic importance in the pursuit of a decarbonized, environmentally benign, sustainable global energy system; however, the explosive nature of H2requires leakage monitoring to ensure safe application in industry. Therefore, H2gas sensors with a high sensitivity and fast response across a wide concentration range are crucial yet technically challenging. In this work, we demonstrate a new type of MEMS differential thermopile gas sensor for the highly sensitive, rapid detection of trace H2gas in air. Facilitated by a unique MIS fabrication technique, pairs of single-crystalline silicon thermopiles (i.e., sensing and reference thermopiles) are batch fabricated with high-density single-crystalline silicon thermocouples, yielding an outstanding temperature sensitivity at the sub-mK level. Such devices ensure the detection of miniscule temperature changes due to the catalytic reaction of H2with a detection limit as low as ~1 ppm at an operating temperature of 120 °C. The MEMS differential thermopiles also exhibit a wide linear detection range (1 ppm-2%, more than four orders of magnitude) and fast response and recovery times of 1.9 s and 1.4 s, respectively, when detecting 0.1% H2in air. Moreover, the sensors show good selectivity against common combustible gases and volatile organics, good repeatability, and long-term stability. The proposed MEMS thermopile H2sensors hold promise for the trace detection and early warning of H2leakage in a wide range of applications.
Application of quantitative T1, T2 and T2* mapping magnetic resonance imaging in cartilage degeneration of the shoulder joint
Authors: Cao Guijuan , Gao Shubo , Xiong Bin 
Published: March 2023

AbstractTo investigate and compare the values of 3.0 T MRI T1, T2 and T2* mapping quantification techniques in evaluating cartilage degeneration of the shoulder joint. This study included 123 shoulder joints of 119 patients, which were scanned in 3.0 T MRI with axial Fat Suppression Proton Density Weighted Image (FS-PDWI), sagittal fat suppression T2 Weighted Image (FS-T2WI), coronal T1Weighted Image (T1WI), FS-PDWI, cartilage-specific T1, T2 and T2* mapping sequences. Basing on MRI images, the shoulder cartilage was classified into grades 0 1, 2, 3 and 4 according to the International Cartilage Regeneration & Joint Preservation Society (ICRS). The grading of shoulder cartilage was based on MRI images with ICRS as reference, and did not involve arthroscopy or histology.The T1, T2 and T2* relaxation values in the superior, middle and inferior bands of shoulder articular cartilage were measured at all grades, and the differences in various indicators between groups were analyzed and compared using a single-factor ANOVA test. The correlation between T1, T2 and T2* relaxation values and MRI-based grading was analyzed by SPSS software. There were 46 shoulder joints with MRI-based grade 0 in healthy control group (n = 46), while 49 and 28 shoulder joints with grade 1–2 (mild degeneration subgroup) and grade 3–4 (severe degeneration subgroup) in patient group (n = 73), accounting for 63.6% and 36.4%, respectively. The T1, T2 and T2* relaxation values of the superior, middle and inferior bands of shoulder articular cartilage were significantly and positively correlated with the MRI-based grading (P < 0.01). MRI-basedgrading of shoulder cartilage was markedly associated with age (r = 0.766, P < 0.01). With the aggravation of cartilage degeneration, T1, T2 and T2* relaxation values showed an upward trend (all P < 0.01), and T1, T2 and T2* mapping could distinguish cartilage degeneration at all levels (all P < 0.01). The T1, T2 and T2* relaxation values were significantly different between normal group and mild degeneration subgroup, normal group and severe degeneration subgroup, mild degeneration subgroup and severe degeneration subgroup (all P < 0.05). Quantitative T1, T2 and T2* mapping can quantify the degree of shoulder cartilage degeneration. All these MRI mapping quantification techniques can be used as critical supplementary sequences to assess shoulder cartilage degeneration, among which T2 mapping has the highest value.
Seasonal sea-ice in the Arctic’s last ice area during the Early Holocene
Authors: Detlef Henrieka , O’Regan Matt , Stranne Christian , Jensen Mads Mørk , Glasius Marianne , Cronin Thomas M. , Jakobsson Martin , Pearce Christof 
Published: March 2023

AbstractAccording to climate models, the Lincoln Sea, bordering northern Greenland and Canada, will be the final stronghold of perennial Arctic sea-ice in a warming climate. However, recent observations of prolonged periods of open water raise concerns regarding its long-term stability. Modelling studies suggest a transition from perennial to seasonal sea-ice during the Early Holocene, a period of elevated global temperatures around 10,000 years ago. Here we show marine proxy evidence for the disappearance of perennial sea-ice in the southern Lincoln Sea during the Early Holocene, which suggests a widespread transition to seasonal sea-ice in the Arctic Ocean. Seasonal sea-ice conditions were tightly coupled to regional atmospheric temperatures. In light of anthropogenic warming and Arctic amplification our results suggest an imminent transition to seasonal sea-ice in the southern Lincoln Sea, even if the global temperature rise is kept below a threshold of 2 °C compared to pre-industrial (1850–1900).
Multiscale feature cross‐layer fusion remote sensing target detection method
Authors: Lin Yuting , Zhang Jianxun , Huang Jiaming 
Published: March 2023

AbstractTarget detection based on remotely sensed images, which has recently attracted much attention, is a fundamental but challenging task. In remote sensing images, the problem of difficult recognition of small targets or targets with a large aspect ratio arises because the targets have the characteristics of small proportion, dense distribution, and multidirectionality. To address the above problems, this article proposes an improved multiscale feature cross‐layer fusion remote sensing target detector based on YOLOv5. First, this method introduces the circular smooth label technique, using YOLOv5 as a rotation detector to solve the angular boundary condition and angle prediction problem for large aspect ratio targets. Second, the explicit visual centre module is introduced to solve the problem of missed detection in target‐dense distribution tasks. Finally, a multiscale feature cross‐layer fusion structure (S‐160) is proposed based on YOLOv5, which improves the detection accuracy of each scale target by fusing shallow and deep feature information and introduces new large‐scale features for small target detection to solve the problem that ultrasmall targets in remote sensing images cannot be recognised. Our experiments were conducted on three public remote sensing datasets, DOTA, DIOR‐R, and HRSC2016, and the average accuracy (mAP) on the datasets was 76.50%, 70.34%, and 97.68%, respectively, demonstrating the substantial detection performance of the proposed method.
The adaptive constant false alarm rate for sonar target detection based on back propagation neural network access
Authors: Chen Zhou , Zhao Xianwen , Zhou Ziqi , Ma Xuefei , Cheng Qi , Cai Xuan , Jiang Bowang , Khan Rahim , Kumar Sharma Pradip , Alfarraj Osama , Tolba Amr 
Published: March 2023

AbstractWith oceanic reverberation and a large amount of data being the main sources of interference for underwater acoustic target detection, it is difficult to obtain a more robust detection performance by relying on the traditional constant false alarm rate (CFAR) detection method. An adaptive sonar CFAR detection method based on a back propagation (BP) neural network is proposed. The method combines the artificial intelligence algorithm and the traditional detection algorithm, and uses the classification ability of the algorithm to select the detection algorithm, which can effectively improve the adaptation ability of the algorithm and the environment and the false alarm control ability. The method combines the artificial intelligence algorithm and the traditional detection algorithm, and uses the classification ability of the algorithm to select the detection algorithm, which can effectively improve the adaptation ability of the algorithm and the environment and the false alarm control ability. This method uses a BP neural network to train the target echo signal to complete the clutter background classification and establish the clutter background recognition classification set. According to the output result of each classification, the best CFAR detector is selected from four CA/SO/GO/OS‐CFAR detectors to detect the target. The simulation results show the detection performance of the proposed method in a uniform environment, a multi‐target environment, and a clutter edge environment. The results show that the environment adaptability is strong for different clutter backgrounds, which further improves the control ability of false alarms under a non‐uniform background.
Polar particle flux distribution and its spatial extent
Authors: Yakovchuk Olesya , Wissing Jan Maik 
Published: March 2023

Context: The main challenge in atmospheric ionisation modelling is that sparse measurements are used to derive a global precipitation pattern. Typically this requires intense interpolation or scaling of long-term average maps. In some regions however, the particle flux might be similar and a combination of these regions would not limit the results even though it would dramatically improve the spatial and temporal data coverage.
Aims: The paper intends to statistically analyse the particle flux distribution close to the geomagnetic poles labelled as Polar Particle Flux Distribution (PPFD) and identify similar distributions in neighbouring bins. Those bins are grouped and the size of the PPFD area is estimated. The benefit is that single measurements within the PPFD area should be able to represent the particle flux for the whole area at a given time.
Methods: We use spatially binned energetic particle flux distributions measured by POES and Metop spacecraft during 2001–2018 to identify a Kp-dependent area with a similar flux distribution as the one found close to the geomagnetic poles (|magn.lat| > 86°). First, the particle flux is mapped on a magnetic local time (MLT) vs. magnetic latitude grid. In the second step, the gridded data is split up according to Kp levels (forming the final bins). Third, the particle flux in every bin has been recalculated in order to replace zero-count rates with rates based on longer measurement periods which results in a more realistic low flux end of the particle distribution. Then the binned flux distributions are compared to the PPFD. A “Δ-test” indicates the similarity. A threshold for the Δ-test is defined using the standard deviation of Δ-test values inside the (|magn.lat| > 86°) area. Bins that meet the threshold are attributed as PPFD area.
Results: PPFDs and the corresponding PPFD areas have been determined for all investigated particle channels, covering an energy range of 154 eV–300 keV for electrons and 154 eV–2.5 MeV for protons. Concerning low energy channels a gradual flux increase with rising Kp has been identified. High energy channels show a combination of background population and solar particle event (SPE) population that adds up with increasing Kp. The size of the PPFD area depends on particle species, energy and geomagnetic disturbance, as well as MLT. The main findings are: a) There are small but characteristic hemispheric differences. b) Only above a certain energy threshold do the PPFD areas increase with particle energy. c) A clear enlargement with rising Kp is identified – with exceptions for very low Kp. d) The centre of the PPFD area is shifted towards midnight and moves with Kp. Asymmetries of the boundaries could be explained by auroral intensity. e) For low-energy particles the main restriction of the PPFD area seems to be the auroral precipitation.
Laboratory Evaluation of Antithrombin, Protein C, and Protein S
Authors: Marlar Richard A. 
Published: March 2023

AbstractThrombophilia is a complex disease process, clinically manifesting in various forms of venous thromboembolism. Although both genetic and acquired (or environmental) risks factors have been reported, the presence of a genetic defect (antithrombin [AT], protein C [PC], protein S [PS]) is considered three of the major contributing factors of thrombophilia. The presence of each of these risk factors can be established by clinical laboratory analysis; however, the clinical provider and laboratory personnel must understand the testing limitations and shortcomings associated with the assays for these factors to be able to ensure an accurate diagnosis. This article will describe the major pre-analytical, analytical, and post-analytical issues associated with the various types of assays and discuss evidence-based algorithms for analyzing AT, PC, and PS in plasma.
A Brief History of Hemostasis and Thrombosis at the Mayo Clinic
Authors: Chen Dong , Pruthi Rajiv 
Published: March 2023

AbstractCoagulation is a crucial biological mechanism in human bodies to prevent blood loss. Abnormal coagulation can cause bleeding diathesis or thrombosis, common pathologic conditions in our clinical practice. Many individuals and organizations have dedicated their efforts in the past decades to understanding the biological and pathological mechanisms of coagulation and developing laboratory testing tools and treatment options to help patients with bleeding or thrombotic conditions. Since 1926, the Mayo Clinic coagulation group has made significant contributions to the clinical and laboratory practice, basic and translational research on various hemostatic and thrombotic disorders, and the education and collaboration to share and advance our knowledge in coagulation through a highly integrated team and practice model. We would like to use this review to share our history and inspire medical professionals and trainees to join the efforts to advance our understanding of coagulation pathophysiology and improve our care for patients with coagulation disorders.
A pre-time-zero spatiotemporal microscopy technique for the ultrasensitive determination of the thermal diffusivity of thin films
Authors: Varghese Sebin , Mehew Jake Dudley , Block Alexander , Reig David Saleta , Woźniak Paweł , Farris Roberta , Zanolli Zeila , Ordejón Pablo , Verstraete Matthieu J. , van Hulst Niek F. , Tielrooij Klaas-Jan 
Published: March 2023

Diffusion is one of the most ubiquitous transport phenomena in nature. Experimentally, it can be tracked by following point spreading in space and time. Here, we introduce a spatiotemporal pump–probe microscopy technique that exploits the residual spatial temperature profile obtained through the transient reflectivity when probe pulses arrive before pump pulses. This corresponds to an effective pump–probe time delay of 13 ns, determined by the repetition rate of our laser system (76 MHz). This pre-time-zero technique enables probing the diffusion of long-lived excitations created by previous pump pulses with nanometer accuracy and is particularly powerful for following in-plane heat diffusion in thin films. The particular advantage of this technique is that it enables quantifying thermal transport without requiring any material input parameters or strong heating. We demonstrate the direct determination of the thermal diffusivities of films with a thickness of around 15 nm, consisting of the layered materials MoSe2 (0.18 cm2/s), WSe2 (0.20 cm2/s), MoS2 (0.35 cm2/s), and WS2 (0.59 cm2/s). This technique paves the way for observing nanoscale thermal transport phenomena and tracking diffusion of a broad range of species.
Geometric part error and material property profile separation technique of the additively manufactured and post-processed rods
Authors: Kim Jungsub , Chun Heebum , Nguyen Phuc , Li-Jung Tai Bruce , Lee Chabum 
Published: March 2023

This paper presents novel surface profilometry for both geometric part error and metallurgical material property distribution measurements of the additively manufactured and post-processed rods. The measurement system, the so-called fiber optic-eddy current sensor, consists of a fiber optic displacement sensor and an eddy current sensor. The electromagnetic coil was wrapped around the probe of the fiber optic displacement sensor. The fiber optic displacement sensor was used to measure the surface profile, and the eddy current sensor was used to measure the change in permeability of the rod under varying electromagnetic excitation conditions. The permeability of the material changes upon exposure to mechanical forces, such as compression or extension and high temperatures. The geometric part error and material property profiles of the rods were successfully extracted by using a reversal method that is conventionally used for spindle error separation. The fiber optic displacement sensor and the eddy current sensor developed in this study have a resolution of 0.286 µm and 0.00359 μr, respectively. The proposed method was applied not only to characterize the rods but also to characterize composite rods.
A gravitationally induced decoherence model using Ashtekar variables
Authors: Fahn Max Joseph , Giesel Kristina , Kobler Michael 
Published: March 2023

Abstract
We consider the coupling of a scalar field to linearised gravity and derive a relativistic gravitationally induced decoherence model using Ashtekar variables. The model is formulated at the gauge invariant level using suitable geometrical clocks in the relational formalism, broadening existing gauge invariant formulations of decoherence models. For the construction of the Dirac observables we extend the known observable map by a kind of dual map where the role of clocks and constraints is interchanged. We also discuss a second choice of geometrical clocks existing in the ADM literature. Then we apply a reduced phase space quantisation on Fock space and derive the final master equation choosing a Gibbs state for the gravitational environment and using the projection operator technique. The resulting master equation is not automatically of Lindblad type, a starting point sometimes assumed for phenomenological models, but still involves a residual time dependence at the level of the effective operators in the master equation due to the form of the correlation functions that we express in terms of thermal Wightman functions. Furthermore, we discuss why in the model analysed here the application of a second Markov approximation in order to obtain a set of time independent effective system operators is less straightforward than in some of the quantum mechanical models.
Lorentzian wormholes in an emergent universe
Authors: Sengupta Rikpratik , Ghosh Shounak , Paul B C , Kalam M 
Published: March 2023

Abstract
A non-singular emergent universe (EU) scenario within the realm of standard Relativistic physics requires a generalization of the equation of state (EoS) connecting the pressure and energy density. This generalized EoS is capable of describing a composition of exotic matter, dark energy and cosmological dust matter. Since the EU scenario is known to violate the null energy condition (NEC), we investigate the possibility of presence of static, spherically symmetric and traversable Lorentzian wormholes in an EU. The obtained shape function is found to satisfy the criteria for wormhole formation, besides the violation of the NEC at the wormhole throat and ensuring traversability such that tidal forces are within desirable limits. Also, the wormhole is found to be stable through linear stability analysis. Most importantly, the numerical value of the EU parameter B as estimated by our wormhole model is in agreement with and lies within the range of values as constrained by observational data in a cosmological context. Also, the negative sign of the second EU parameter A as obtained from our wormhole model is in agreement with the one required for describing an EU, which further indicates on the existence of such wormholes in an EU without accounting for any additional exotic matter field or any modification to the gravitational sector.