bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optically steered time scale generation at OP and NPL and remote comparisons
Authors: Abgrall M , Chupin B , Uhrich P , Lorini L , Le Targat R , Pointard B , Lodewyck J , Tunesi J , Tran D B A , Parsons A O , Tofful A , Robertson B I , Johnson M Y H , Feng C-H , Schioppo M , Curtis E A , Hill I R , Godun R M , Margolis H S 
Published: November 2024

AbstractIn this paper, we present real-time optically steered time scales generated simultaneously at the Observatoire de Paris (OP) and the National Physical Laboratory (NPL). Throughout one month, experimental UTCx(k) time scales were generated concurrently in the two laboratories alongside the local operational UTC(k) time scales. The UTCx(k) time scales were based on hydrogen masers whose frequencies were calibrated by local optical frequency standards using optical frequency combs, with algorithms being developed for outlier filtering and frequency steering estimations in the two laboratories. The performance of the experimental time scales was assessed through local comparisons against the corresponding UTC(k) time scales, and also through remote comparisons performed both via Coordinated Universal Time (UTC) and by using the GPS Precise Point Positioning (PPP) technique. The two optically steered time scales remained within 4 ns of each other, outperforming the corresponding UTC(k) over the same period. To our knowledge, this is the first reported comparison of two independent “optical time scale” prototypes, and the results demonstrate the capability of optical clocks to produce operational time scales.
Highly charged ion optical clocks
Authors: Schmidt Piet O. , Spieß Lukas J. , Wilzewski Alexander , Wehrheim Malte , Chen Shuying , King Steven A. , Micke Peter , Leopold Tobias , Khan Nadir , Crespo López-Urrutia José R. 
Published: November 2024

Abstract
Optical atomic clocks are the most precise and accurate measurement devices, reaching fractional systematic uncertainties below one part in 10−18. Their exceptional performance opens up a wide range of applications in fundamental science and technology. The extreme electronic properties of highly charged ions (HCI) make them highly sensitive probes for tests of fundamental physical theories and significantly lower sensitivity to some of the leading systematic perturbations that affect state-of-the-art optical clocks. This makes them exciting candidates for next-generation clocks. In this contribution, we will briefly review the history of optical spectroscopy of HCI and how scientific advances enabled the first coherent spectroscopy of HCI using quantum logic techniques. A first generation of optical clocks based on HCI with atom-related systematic uncertainties at the 10−18 level and below is demonstrated. Comparisons of the isotope shift between 40Ar13+ and 36Ar13+ as well as g-factor measurements with theory are interpreted as a test of quantum electrodynamic (QED) theory. This demonstrates the suitability of HCI as references for high-accuracy optical clocks and to probe for physics beyond the standard model.
Development of a laser stabilized on an ultra-stable silicon cryogenic Fabry-Perot cavity for dark matter detection
Authors: Hariri Yara , Millo Jacques , Lacroûte Clément , Barbarat Joannès , Kersalé Yann , Gillot Jonathan 
Published: November 2024

Abstract
Astrophysical observations suggest the existence of an unknown kind of matter in the Universe, in the frame of the ΛCDM model. The research field of dark matter covers an energy scale going from massive objects to ultra-light scalar fields, which are the focus of the present work. It is supposed that ultra-light scalar fields affect the length of objects, whereas the speed of light stays unchanged. It follows that Fabry-Perot cavities are ideal tools for ultra-light dark matter detection since the fluctuations in the length of a cavity can be detected on the frequency of the laser stabilized to it. At FEMTO-ST, we have set up an ultra-stable silicon cavity suitable for a test of detection of ultra-light dark matter in an energy range close to 10−10 eV. Our 14 cm cavity is composed of two mirrors optically bonded to an ultra-rigid spacer, with each element made in single-crystal of silicon, and cooled at 17 K in order to cancel the first order thermal expansion coefficient of the silicon spacer. The projected fractional frequency stability of the laser is 3 × 10−17, mainly limited by the thermal noise of the amorphous dielectric reflective coatings. To reach this remarkable stability, several effects have to be reduced below the thermal noise limit. While the contribution of the residual amplitude modulation is now acceptable, we are currently implementing a laser power lock with residual fluctuations lower than 3 nW and a piezoelectric-based servo loop to actively reduce the vibration noise that has to be inferior to -110 dB(m s−2)2/Hz at 1 Hz. Here, we present both the status of the development of our ultra-stable laser and the mechanical response of the cavity in the presence of ultra-light dark matter.
Turbulent cascades in the Atmospheric Boundary Layers
Authors: Wacławczyk M , Nowak J L , Vassilicos J C , Król S , Malinowski S P 
Published: November 2024

Abstract
We investigate the scale-by-scale budget of the turbulence kinetic energy in the Atmospheric Boundary Layer (ABL) using airborne measurements performed by the helicopter-borne measurement system HELiPOD over the Baltic sea. The available, long time series of the turbulent wind velocity, temperature and humidity allow for a detailed study of turbulence properties in the ABL over the Baltic sea. In particular, we calculate the buoyancy forcing term and the third-order velocity structure function. The buoyancy’s production of turbulence energy is only significant at the largest-scales, above L = 100m. Unlike the ABL over the Atlantic in the shallow trade-wind regime, the buoyancy is dominated by temperature variations with little contribution from water-vapour mixing ratio. At the altitudes of the order of 100m studied here, a clear Kolmogorov equilibrium is observed at scales below 100m because of the combined absence of buoyancy and apparent presence of homogeneity and stationarity at these scales.
Touch-down condition control for the bipedal spring-mass model in walking
Authors: Vejdani Hamid , Wu Albert , Geyer Hartmut , W Hurst Jonathan 
Published: November 2024

Abstract
Behaviors of animal bipedal locomotion can be described, in a simplified form, by the bipedal spring-mass model. The model provides predictive power, and helps us understand this complex dynamical behavior. In this paper, we analyzed a range of gaits generated by the bipedal spring-mass model during walking, and proposed a stabilizing touch-down condition for the swing leg. This policy is stabilizing against disturbances inside and outside the same energy level and requires only internal state information. In order to generalize the results to be independent of size and dimension of the system, we nondimensionalized the equations of motion for the bipedal spring-mass model. We presented the equilibrium gaits (a.k.a fixed point gaits) as a continuum on the walking state space showing how the different types of these gaits evolve and where they are located in the state space. Then, we showed the stability analysis of the proposed touch-down control policy for different energy levels and leg stiffness values. The results showed that the proposed touch-down control policy can stabilize towards all types of the symmetric equilibrium gaits. Moreover, we presented how the peak leg force changes within an energy level and as it varies due to the type of the gait since peak force is important as a measurement of injury or damage risk on a robot or animal. Finally, we presented simulations of the bipedal spring-mass model walking on level ground and rough terrain transitioning between different equilibrium gaits as the energy level of the system changes with respect to the ground height. The analysis in this paper is theoretical, and thus applicable to further our understanding of animal bipedal locomotion and the design and control of robotic systems like ATRIAS, Cassie, and Digit.
Empowering multi-source SAR Flood mapping with unsupervised learning
Authors: Jiang Xin , Zeng Zhenzhong 
Published: November 2024

Abstract
Flood mapping plays a crucial role in effective disaster management, risk assessment, and mitigation planning, given the widespread and destructive nature of floods. However, current synthetic aperture radar (SAR)-based methods face challenges related to extensive labeled training data, compromised classification accuracy, and limited applicability across different satellite systems and resolutions. In response to these challenges, our research introduces a pioneering unsupervised SAR-based flood mapping algorithm, inspired by artificial general intelligence principles. Notably, the innovative method demonstrates flexibility, performing effectively across various SAR satellites with differing resolutions and sensors, eliminating the need for satellite-specific algorithms. Our algorithm enhances processing speed and scalability by eliminating labor-intensive labeling of training data and manual intervention. To validate its performance, we conducted tests in three distinct regions using meter-level imagery from HISEA-1, Gaofen-3, and Sentinel-1 satellites. Consistently outperformed prevalent unsupervised techniques like Kmeans and Otsu, and even a Supervised-convolutional neural network segmentation algorithm by AI-Earth, with F1-scores exceeding 0.91. This outstanding performance showcases its accuracy, irrespective of the satellite systems or regions utilized. Furthermore, the seamless integration of our algorithm with high-performance cloud computing platforms such as Google Earth Engine enhances its adaptability and scalability, enabling continuous monitoring of global floods. This is crucial in understanding flood trends, assessing their impacts, and formulating effective disaster mitigation strategies.
Soil moisture–atmosphere coupling amplifies the change in extreme heat in inner East Asia under rapid summer warming
Authors: Yin Zejiang , Dong Buwen , Yang Song , Wei Wei 
Published: November 2024

Abstract
Inner East Asia (IEA) is an important component of the global grassland ecosystem and has experienced a more rapid increase in extreme surface air temperatures compared to the summer mean in recent decades (2001–2020, relative to 1971–1990). This excess hot-extreme warming (EHEW) is particularly pronounced in the southern IEA, where extremely hot temperatures have increased twice as quickly as the summer mean warming, which itself already exceeds global-land warming by more than threefold. A quantitative analysis based on a Lagrangian temperature-anomaly equation along air-parcel backward trajectories initiated on hot days across IEA reveals that the observed EHEW is primarily attributable to increased diabatic heating, which predominantly occurs from 2 days before to the hot days. Meanwhile, changes in heat-prone synoptic-scale circulation only exert a limited influence on the excess warming. Soil drying within IEA appears to be a critical factor contributing to increased diabatic heating through soil moisture–atmosphere coupling, as it limits evaporation and enhances sensitive heat flux, thereby triggering positive soil moisture-temperature feedback. Our analysis underscores the significant impact of local soil moisture deficits on the intensified extreme heat. Urgent implementation of grassland and livestock management strategies, coupled with drought mitigation measures, is essential for adaptation and ecosystem conservation.
Correlations between propofol concentration in exhaled breath and BIS in patients undergoing thyroid surgery
Authors: Li Xiaoxiao , Chang Pan , Liu Xing , Zhao Zhongjun , Duan Yixiang , Zhang Wensheng 
Published: November 2024

Abstract
Several clinical studies have reported promising correlations between propofol concentration in exhaled breath (Ce-pro) and the bispectral index (BIS) in patients, suggesting the potential of exhaled propofol measurement as a non-invasive method for adjusting anesthesia depth. However, these studies are still in the validation phase of instrument effectiveness, often limited by small sample sizes or inappropriate instrument selection, and thus lack convincing results regarding these correlations. In this study, one hundred patients aged 18–65, undergoing elective thyroid surgery under general anesthesia were included. The vacuum ultraviolet photoionization and time-of-flight mass spectrometry was employed to monitor Ce-pro at 20 s intervals, alongside continuous BIS measurement. The association between Ce-pro and BIS was analyzed using linear mixed-effects models, with marginal R
2 used to assess the correlation. The threshold of Ce-pro at awakening was also explored. Additionally, the univariate and multifactorial diagnostic model, including end-of-surgery Ce-pro, were employed to assess the accuracy of predicting delayed recovery. A weak correlation was observed between intraoperative Ce-pro and BIS (marginal R
2 = 0.348). Predictive models utilizing end-of-surgery Ce-pro levels showed good accuracy (area under the curve (AUC) = 0.75, 95% CI: 0.62–0.89, P = 0.003) in predicting delayed recovery, while the model using end-of-surgery Ce-pro combined with gender, sufentanil dosage, the time from the last administration of sufentanil to the end of surgery, and anesthesia duration demonstrated stronger predicting accuracy (AUC = 0.91, 95% CI: 0.85–0.98, P < 0.001). This study suggests that Ce-pro alone may not reliably predict the depth of anesthesia in clinical practice, but shows promising accuracy in predicting delayed recovery from anesthesia.
Enhancing vaginal reconstruction through 3D bioprinted scaffolds using a novel vECM-GelMA-SF bioink
Authors: Zheng Jiahua , Zhang Xuemei , Guo Kaixuan , Yan Liman , Xu Xiaotong , Shi Wenxin , Zhang Jingkun , Du Yanfang , Zhang Mingle , Huang Xianghua 
Published: November 2024

Abstract
Overcoming the low cell survival rates and insufficient neovascularization associated with tissue engineering of the vagina is crucial for advancing the vaginal reconstruction. In this research, we have developed a unique bioink composed of porcine vaginal extracellular matrix (vECM), gelatin methacrylamide (GelMA), and silk fibroin (SF) to facilitate the bioprinting of a vaginal scaffold. The vECM-GelMA-SF bioink effectively replicates the in vivo microenvironment, supporting the in vitro cultivation of 3D bioprinted vaginal scaffolds. It promotes stem cell viability and enhances neovascularization by harnessing the mechanical properties of GelMA/SF and the tissue specificity of vECM. In vivo orthotopic studies have demonstrated that the use of 3D bioprinted vaginal scaffolds significantly improves the functionality of reconstructed vaginas, promoting angiogenesis, rapid epithelialization, muscle regeneration, glycogen secretion, and nerve repair. The reconstructed vaginal tissues in the 3D cell-loaded scaffold group closely resemble natural vaginal tissues. Differential proteomics analysis has provided insights into the genetic functions and biological pathways involved in vaginal reconstruction. Our study successfully optimized the composition of the vECM-GelMA-SF bioink, achieving a balance between biocompatibility and printability. This bioink is suitable for constructing 3D bioprinted vaginal scaffolds of various dimensions, transplantable in situ in animal models with different degrees of vaginal absence. The bioink may find applications in clinical settings, improving the overall effectiveness and safety of in vivo vaginal reconstruction procedures.
Harmonic achromatic metalens with a wide field of view for AR/VR applications
Authors: Nasir Badar , Javed Isma , Naveed Muhammad Ashar , Aljaloud Khaled A , Alhuwimel Saad , Hussain Rifaqat , Mehmood Muhammad Qasim 
Published: November 2024

Abstract
Metalens is a cutting-edge optical marvel, revolutionizes a plethora of applications like cameras, telescope, augmented reality (AR) and virtual reality (VR). Despite having ultrathin structure, lightweight nature, and multifunctionality, achievement of both achromatic imaging and wide field of view (WFOV) remains a persistent challenge. To address these concerns, here we present a novel approach using a harmonic metalens featuring a quadratic phase profile to achieve achromatic behavior and WFOV simultaneously. This innovation enables WFOV imaging using the Fourier transform of quadratic phase profile and achromatic behavior at RGB wavelengths (blue λ = 488 nm, green λ = 532 nm and red λ = 633 nm) with a WFOV of up to

±

45
∘

. The designed harmonic metalens is polarization-insensitive, with a numerical aperture of 0.79, and it achieves a maximum focusing efficiency of ∼50% at a wavelength of 633 nm under normal incidence. Being polarization insensitive and achromatic, proposed scheme will certainly broaden the utilization of metalenses in AR/VR, displays and applications in imaging. © 2024 Optical Society of America.
Effect of Sn on the microstructure and properties of biodegradable Mg-1.0Zn-0.3Zr magnesium alloy
Authors: Zhao Fei , Li Huan , Yan Chengqi , Song Beibei , Mao Xiangshan 
Published: November 2024

Abstract
In order to prepare a new biodegradable magnesium alloy with high biosafety, better mechanical properties, and lower degradation rate, in this paper, the effect of the non-toxic element Sn (0%∼2%, mass%) on the microstructure, mechanical properties, and corrosion resistance of the Mg-1.0Zn-0.3Zr alloy was investigated using optical microscopy, scanning electron microscopy, x-ray diffraction, tensile testing, and corrosion experiments. The results indicated that the addition of Sn to the alloy resulted in the formation of the Mg2Sn phase, which improved the mechanical properties of the alloy. However, a higher concentration of this phase and its continuous distribution along the grain boundaries decreased the alloy’s corrosion resistance. The mechanical properties and corrosion resistance of the alloy exhibited an increasing trend with the increase of Sn content, followed by a decreasing trend. At an Sn content of 1%, the alloy demonstrated better mechanical properties and corrosion resistance simultaneously. The yield strength, tensile strength, and elongation of the alloy were 114 ± 2 MPa, 164 ± 5 MPa, and 13.3 ± 0.1%, respectively. Additionally, the corrosion rate of the alloy was only 0.61 mm y−1 after being immersed in simulated body fluids for 120 h. These properties represent a significant improvement over those of the Mg-1.0Zn-0.3Zr alloy. Our results indicate that the addition of an appropriate amount of Sn element can improve both the mechanical properties and corrosion resistance of the alloy, supporting the development of new biodegradable magnesium alloys.
Synergistic effects of boron carbide and niobium reinforcements on the mechanical performance of Al-8090 alloys
Authors: Meenuga Shanthi Raju , Birru Anil Kumar , Pulisheru Kumara Swamy , Apparao K Ch , Sridatha Bommidi , Rao Gadudasu Babu , Bannaravuri Praveen Kumar 
Published: November 2024

Abstract
This experimental study investigates the impact of boron carbide (B4C) and Niobium (Nb) reinforcement particles on the microstructural, mechanical and surface properties of Al-8090 base alloy. The inclusion of B4C and Nb particles significantly refines the structure which enhances the properties via nucleation and dispersion strengthening effects. Optical microstructures and Scanning Electron Microscopy images show that an increase in reinforcement percentages precedes finer grains and uniform particle distribution. Energy Dispersive x-ray Spectroscopy analysis highlights a predominant aluminium (Al) peak in the Al-8B4C-5 Nb sample and Nb and Fe minor peaks indicate potential diffusion interaction. Mechanical tests reveal substantial improvements in hardness, tensile strength, and density of the Al-7B4C-3 Nb sample obtained the highest values. However, increasing reinforcement content causes agglomeration which declines the hardness and increases porosity. The wear test demonstrates that the reinforced composites perform superior properties, with B4C providing surface layer protection and Nb refining the grain structure. Corrosion analysis reveals that inclusion reinforcements act as initiation sites for intergranular and localized corrosion due to the galvanic interaction effect. These findings recommend that an optimized reinforcement content in Al-8090 base alloy yields better mechanical performance and wear resistance for high-strength applications.
Design of insulation support system of 120 keV positive ion source accelerator
Authors: DENG 邓 Wen 文 , XIE 谢 Yahong 亚红 , GU 顾 Yuming 玉明 , JIANG 江 Yunfei 云飞 , LIU 刘 Longbin 龙斌 , WANG 王 Fang 昉 , WEI 韦 Jianglong 江龙 , HU 胡 Chundong 纯栋 
Published: November 2024

Abstract
In order to support the physical research on the EAST tokamak, a new positive ion source with designed beam energy of 120 keV was proposed to be developed. Accelerator structure is one of the key components of the ion source. Through the finite element analysis method, the electrostatic analyses of insulators and grid plates were carried out, the material and structure parameters of insulators were determined. The maximum electric field around each insulator is about 4 kV/mm, and the maximum electric field between grids is about 14 kV/mm, which can meet the 120 keV withstand voltage holding. The insulation system for the positive ion source accelerator with 120 keV is designed, and the connection and basic parameters of insulators and support flanges are analyzed and determined.
Hydroeconomic insights for transboundary water challenges and potential collaboration in the Tigris-Euphrates river basin
Authors: Taheripour Farzad , Haqiqi Iman , Golub Alla A , Sajedinia Ehsanreza , Karami Omid 
Published: November 2024

Abstract
For countries sharing transboundary water resources, measuring changes in water availability and ensuing economic outcomes is challenging due to downstream impacts and interconnected agricultural markets. Using a coupled modeling approach that combines a detailed multi-sector model of international trade with a gridded hydrological model, this paper quantifies the impacts of climate change and anthropogenic activities on water scarcity and its economy-wide consequences for the riparian countries in the Tigris-Euprates (TE) river basin and evaluates scenarios of collaboration in basin water management as an adaptation strategy. By mid-century climate change will significantly increase water scarcity in the basin: up to 30% in Iran, 27% in Türkiye, 17% in Iraq, and 14% in Syria. Depending on the climate change scenario, average annual GDP losses from water scarcity and changes in crop yields range from 12 to 84 billion USD for these economies. However, collaboration among the TE river basin riparian countries in water allocation and use could mitigate the adverse economic effects and, relative to the status quo, generate direct GDP gain in the 42–58 billion USD range for these countries and indirect gains for other countries in the Middle East region. The results suggest that collaboration in water management in the TE river basin is an effective option to tackle emerging challenges such as the impact of climate change on water availability.