bluuebunny/crossref_metadata_2025_split huggingface dataset:
Developments to improve the stability of optical lattice clocks
Authors: Bize S. , Fang B. , Le Coq Y. , Le Targat R. , Lodewyck J. , Pottie P.-E. , Shang H. , Zyskind C. 
Published: November 2024

Abstract
We present several developments aimed at improving the stability of optical lattice clocks. First, we present our developments of an optical lattice clock using neutral mercury. We mention recent advances made with the fermionic isotope 199Hg. We also mention our work aimed at using bosonic isotopes, which offer the possibility to circumvent the relatively short lifetime of the upper clock state in 199Hg. Second, we present our work on a non-destructive detection in a Sr optical lattice clock. We describe developments that brought the detection scheme from the classical non-destructive regime to the quantum non-destructive regime. Our detection scheme is practical and has the capability to the used beyond proving the principle. Finally, we present our work on laser stabilization using spectral hole burning in a Eu3+:Y2SiO5 crystal at cryogenic temperatures. We describe our development of low noise interrogation based on digital IQ modulation and detection that can probe multiple spectral features simultaneously, as well as several investigations towards fluctuating environmental factors. These advances, individually or combined for example with spectral purity transfer with combs and composite clock approaches, shall bring significant progress in clock stability and accuracy.
Pure frequency-based dispersive spectroscopy
Authors: Cygan A. , Bielska K. , Charczun D. , Kowzan G. , Nishiyama A. , Wcisło P. , Wójtewicz S. , Zaborowski M. , Masłowski P. , Lisak D. , Ciuryło R. , Fleisher A. J. , Gillis K. A. , Hodges J. T. , Voumard T. , Wilidi T. , Herr T. , Brasch V. 
Published: November 2024

Abstract
Dispersion spectroscopy based on frequency measurement of the high finesse optical cavity mode shifts induced by the presence of a gas medium with absorption resonances is an attractive alternative to standard absorptive spectroscopy. The main advantage of such pure frequency-based dispersive spectroscopy technique is the unique combination of sensitivity and accuracy. High sensitivity is ensured by high finesse optical cavities providing extremely long effective optical paths. On the other hand, high accuracy is provided by frequency measurement cavity mode shift. This makes this technique free from systematic errors coming from the non-linearity of light intensity measurements, which is one of the limiting factors in typical absorptive spectroscopy. We review several realizations of dispersive spectroscopy in high finesse optical cavities from Doppler-free to broadband. These techniques are especially useful for studying weak molecular transitions applicable in testing fundamental physics, gas metrology, spectroscopic thermometry, and a new generation of spectroscopic databases.
Computational assessment of mass-diffusive compressible fluids flows models
Authors: Bodnár Tomáš , Fraunié Philippe 
Published: November 2024

Abstract
This paper deals with the numerical simulations using novel, non-standard models applicable to flow of compressible viscous fluid. Instead of the classical compressible Navier-Stokes-Fourier system, two other variants and approximations are used. Models are solved numerically by high resolution finite-difference scheme in two-dimensional test cases, trying to point out and document the mutual differences in the predictions of different models. The numerical simulations performed for the Kelvin-Helmhotz instability and the double-periodic shear layer presented and discussed. The comparison shows a very good agreement of the model predictions, with only minor discrepancies in the divergence of velocity field in the proximity of high solution gradients.
Mapping spatiotemporal patterns of avocado expansion and land-use intensity in central Mexico and their effects on landscape connectivity
Authors: Ramírez-Mejía Diana , Levers Christian , Kolb Melanie , Ghilardi Adrian , Godínez-Gomez Oscar , Mas Jean-François 
Published: November 2024

Abstract
Agricultural expansion and intensification are major drivers of global biodiversity loss, endangering natural habitats and ecosystem functions, such as pollination. In this study, we analyze the spatiotemporal dynamics of avocado frontier expansion and intensification from 2011 to 2019 and assess their effects on landscape connectivity, focusing on Michoacán, Mexico, the world’s leading avocado exporter. Using high-resolution satellite imagery combined with deep learning based on convolutional neural networks, we delineated avocado orchards and other land use/cover classes, mapped individual avocado tree crowns and irrigation ponds, and identified hotspots of expanding and intensifying avocado production. We used a circuit theory approach to evaluate the effects of avocado expansion and intensification on the connectivity of natural and semi-natural habitats. Our results reveal a rapid increase in avocado orchards, which expanded by 4175 ha—a growth from 27.9% to 37% in area—over the eight-year period. There was also a decline in rainfed agriculture by 3252 ha, and oak-pine forests by 1343 ha. We observed not only the expansion of the avocado frontier into forests but also an intensification of avocado production via increases in high-density plantations, irrigation ponds, and orchards prone to intensive pruning. Moreover, lower-intensity land-use classes, such as rainfed crops, were rapidly converted to avocado orchards. This expansion and intensification have led to increasing isolation of forest fragments. Although we identified routes that could facilitate the movement of species, the dense avocado monocultures continue to threaten the connectivity of natural and semi-natural habitats, causing notable losses of old-growth oak-pine forests and disrupting crucial ecological corridors. Our research underscores the adverse effects of avocado production on land use and landscape connectivity, emphasizing the need for sustainable management practices to ensure the long-term viability of avocado production systems and overall ecosystem functioning.
The impact of human disturbances on the regeneration layer of tropical rainforests
Authors: Arasa-Gisbert Ricard , Arroyo-Rodríguez Víctor , Meave Jorge A 
Published: November 2024

Abstract
The global biodiversity crisis is driven by a complex set of human-caused disturbances across different spatial scales. Such disturbances not only cause species losses but also affect a myriad of ecological processes that are critical for forest recovery. Here, we present the most comprehensive meta-analysis to date (1976–2023) of human impacts on the regenerating tree community (i.e. seedlings, saplings, and juveniles) across tropical rainforests. We examined the response of woody plant (i.e. trees, shrubs and palms) community patterns (e.g. species diversity) and processes (e.g. individual growth and survival) to four major human disturbances: fire, defaunation, logging, and exotic/invasive species. We gathered 773 disturbed vs. non-disturbed comparisons from 99 studies. Exotic/invasive species and fire showed strong negative impacts on the regenerating plant community, causing a decrease in species richness, diversity and abundance in more disturbed areas. Such impacts were especially detrimental to old-growth forest species, which are usually rare and more prone to local extirpation. Time since the last fire had a negative impact on the early phases of the regenerating community recovery. Conversely, most response variables increased in defaunated and logged forests, as these disturbances (e.g. loss of herbivores) increased plant performance. Yet, the loss of seed dispersers seems to have weak effects on most responses. Interestingly, reduced-impact logging activities show effects similar to those of conventional and selective logging. Overall, our results revealed that human disturbances threaten the abundance and diversity of regenerating tropical trees, but tree performance and productivity variables may be favored by some human activities. Although further research is needed to fill persisting knowledge gaps, our findings have valuable ecological and applied implications that can guide urgently needed conservation and restoration strategies aimed at mitigating the impact of human disturbances on forest regeneration.
Changes in fire-season burned area in northeastern China regulated by tropical North Atlantic variability
Authors: Hua Wenjian , Zhou Lu , Jiang Yan , Zhou Liming , Xu Xiyan , Chen Haishan 
Published: November 2024

Abstract
Mapping and monitoring regional fire activity are essential to understand their responses to human activities and climate change. Here we use multiple sources of observations, reanalysis data, and model simulations to examine the responses of fire activity to climate change over northeastern China in the past two decades. We detected significant positive burned area (BA) trends in this region since 2003 during spring and much stronger interannual variations in BA in the last decade. We then separated the study region into cropland and natural vegetation and found that the increasing BA trends come mainly from agricultural burning. Our results also show that temperature is the dominant driver for BA variations in natural vegetation, whereas agricultural burning is influenced by precipitation, although human activities largely contribute to BA variations due to farming practices and land use and management. Our results further suggest that tropical North Atlantic (TNA) sea surface temperatures (SST) variability regulates the fire weather conditions (temperature and precipitation) in northeastern China through the Rossby wave train from the tropical Atlantic to the Eurasian continent. The cooling of TNA SST since 2010 could induce an anomalous anticyclonic circulation around Northeast Asia, leading to sinking motion and divergence in the region and resulting in reduced precipitation and warm temperatures. Thus, the co-occurrence of warm and dry anomalies has led to more frequent burning since the 2010s. Our study not only detects recent BA variations in northeastern China but also provides further evidence for the remote impact of TNA variability on recent BA and climate variations over the region.
Spectral properties of radiation for the Helmholtz equation with a random coefficient
Authors: Karamehmedović Mirza , Linder-Steinlein Kristoffer 
Published: November 2024

Abstract
We consider the Helmholtz equation

[
Δ
+

k
0
2

(
1
+
q
(
x
,
ω
)
)
]
u
=
−
f

in

R

R

2

and

R

R

3

, where the coefficient

q
(
x
,
ω
)

is a Gaussian random field. For any open ball B that includes the support of

x
↦
q
(
x
,
ω
)

, we approximate and characterize spectrally the source-to-measurement map

f
↦
u

|

∂
B

in the weak scattering/low-frequency setting. To this end, we first analyze the case with a deterministic coefficient q(x), and here we discover and quantify a ‘spectral leakage’ effect caused by the presence of the medium. Furthermore, we compare numerically our first-order asymptotic expansion of the source-to-measurement map with the map achieved by a Finite Element Method implementation of an example radiation problem. Our results are applicable in the analysis of the robustness of the solution of inverse source problems in the presence of deterministic and random media.
Enhanced dielectric properties and band gap expansion in NiO submicron powders via substitutional be doping
Authors: Hong Dongpyo , Kim Gyung Hyun , Lee Eun Jung , Moon Young Il , Jeon Ok Sung , Lee Se Hun , Lee Sang-Hwa , Yoo Young Jun , Park Sang Yoon 
Published: November 2024

Abstract
The fundamental tradeoff has made it difficult to enhance the low permittivity of wide bandgap semiconductors without sacrificing the bandgap. In this work we demonstrate that high-concentration substitutional Be doping can enhance NiO’s dielectric properties and simultaneously widen the bandgap. Up to 5 at% of Ni in NiO could be substituted by Be while maintaining the rocksalt crystalline structure. The real part of permittivity at low frequencies was found to be significantly increases (40%) while bandgap also increases from 3.06 to 3.37. These findings offer engineering insights for developing high-K wide bandgap materials, essential for various electronic and optoelectronic applications.
Effects of yittria stabilised ZrO2 nanoparticles on the strengthening mechanisms in AlSi10Mg fabricated by LPBF
Authors: Clement Catherine Dolly , Kabir Abu Syed 
Published: November 2024

Abstract
In this study, AlSi10Mg powder mixed with 2.83 vol% of Yittria Stabilised nano ZrO2 (YSZ) was prepared using ball milling, and the composite parts were fabricated via Laser Powder Bed Fusion (LPBF). The effects of YSZ on the microstructure, grain size, and mechanical properties of AlSi10Mg were systematically investigated to uncover the underlying strengthening mechanisms. The results indicated that the addition of YSZ nanoparticles induce an equiaxed grain structure, promoting microstructural homogeneity, which in turn influences the mechanical properties. The strengthening mechanisms, attributed to dislocation pinning by the nanoparticles as explained by the Orowan strengthening effect, are also discussed. Due to the differences in atomic structure between ZrO2 and AlSi10Mg, the bonding interface effect when nano YSZ is added to the aluminum alloy system is significant and crucial for the material’s mechanical characteristics. This study examines the influence of the bonding interface on the material’s mechanical properties. Tensile results revealed that the predominant mode of failure is ductile fracture, typical for aluminum-based alloys; however, the material failed prematurely due to the presence of lack of fusion pores, indicating a need for optimization of printing process parameters.
Measuring above-ground carbon stock using spatial analysis and the InVEST model: application in the Thoria Watershed, India
Authors: Guo Zhe , Sharma Himani , Jadav Mahesh , Hettiarachchi Upeksha , Guha Chiranjit , Zhang Wei , Priyadarshini Pratiti , Meinzen-Dick Ruth S 
Published: November 2024

Abstract
Understanding and quantifying above-ground carbon stock is critical for assessing the impact of land use choices on carbon emissions which can inform conservation and management strategies to protect and increase carbon stocks. This study introduces a novel methodology for evaluating above-ground carbon storage and sequestration in the Thoria watershed, India, using time-series open-access remotely sensed datasets and the InVEST (Integrated Valuation of Environmental Services and Tradeoffs) carbon model. Our spatially explicit analysis examines land cover and land use changes over the past 20 years. Using high-resolution NDVI (Normalized Difference Vegetation Index) data from Sentinel satellites, we disaggregate land cover types into high and low NDVI classes, which allows enhanced assessment of carbon stocks by capturing the spatial variation within the same land cover types. To assess the potential impacts of land cover changes on carbon stock, we generated two future scenarios suggested by local experts: a 20% expansion of cropland and a 20% expansion of wooded land. Using a proximity-based approach, we create these future land use maps and estimate the corresponding carbon stock with the InVEST carbon model. We demonstrate the utility of the methodology in informing land use decisions through spatially explicitly assessing how carbon stock changes in response to cropland expansion and wooded land growth. Our findings indicate that while urban development contributes to carbon losses, increasing wooded land and tree cover helps mitigate these losses, highlighting the importance of afforestation in maintaining ecological balance and reducing environmental impact.
Near-infrared transparent conductive electrodes based on composite GaAs-metal deep sub-wavelength high contrast grating
Authors: Monvoisin Natan , Głowadzka Weronika , Carcenac Franck , Calvez Stéphane , Gauthier-Lafaye Olivier , Monmayrant Antoine , Gȩbski Marcin , Czyszanowski Tomasz , Almuneau Guilhem 
Published: November 2024

Abstract
This paper demonstrates the fabrication of near-infrared transparent electrodes customized for specific light polarization. We achieve this by employing semiconductor deep subwavelength monolithic high-contrast gratings (MHCG) integrating metal stripes. Through the combination of GaAs-based MHCG with TiAu or Au stripes within a deep sub-wavelength grating, polarization selective transmission exceeding 80% over a wide spectral range is achieved for structures designed to operate around a wavelength of 940 nm for either TE or TM excitation. At maximum 85% transmission is reached which relates to 122% transmission with respect to the transmission through plain GaAs-air interface. Additionally, these structures exhibit low sheet resistance (1.4

Ω

sq

−
1

). Hybrid metal-stripes/MHCG grating (MetalMHCG) enables record-breaking polarized light transmission and electrical conductivity simultaneously. Our work represents the first demonstration of MetalMHCG in the near-infrared range, thanks to an advanced nanofabrication process of this sub-λ hybrid semiconductor/metal grating, showing optical and electrical properties not seen in alternative transparent conductive electrode designs. The proposed approach has the potential to enhance electrical injection uniformity in optoelectronic devices such as LEDs, semiconductor lasers and photodetectors.
Flexible nanogenerators for intelligent robotics: design, manufacturing, and applications
Authors: Zhao Hongfa , Ruan Liguang , Wang Zihan , Shu Mingrui , Lyu Chuqiao , Lakshan Bulathsinghala Rameesh , Ishara Dharmasena , Wu Changsheng , Ding Wenbo 
Published: November 2024

Abstract
The embodied artificial intelligence (EAI) is driving a significant transformation in robotics, enhancing their autonomy, efficiency and evolution ability. In this rapidly evolving technological landscape, robots need numerous sensors to realize high levels of perception, precision, safety, adaptability, and intelligence. Triboelectric and piezoelectric sensors address these needs by providing high sensitivity, flexibility, and the capability of self-powered sensing, leveraging the revolutionary nature of nanogenerators to convert mechanical energy into electrical energy on basis of Maxwell’s displacement current. These sensors surpass externally powered passive sensors by offering continuous operation, reduced maintenance, and the capability to function in remote or harsh environments. The integration of EAI with advanced nanogenerators sensors could position robotics to perform autonomously, efficiently, and safely, paving the way for innovative applications in various domains such as industrial automation, environmental monitoring, healthcare, and smart homes. In this paper, the fundamental theories, design, manufacturing, and applications of nanogenerators are comprehensively reviewed as a foundation of the advanced sensors for intelligent robotics in the new era, with three major application fields: sensing (including human–robot interaction, exteroceptive sensing and proprioceptive sensing), computing and actuating. Perspectives are addressed for nanogenerators systems in future development.
Hybrid data-driven and physics-informed regularized learning of cyclic plasticity with neural networks
Authors: Hildebrand Stefan , Klinge Sandra 
Published: November 2024

Abstract
An extendable, efficient and explainable Machine Learning approach is proposed to represent cyclic plasticity and replace conventional material models based on the Radial Return Mapping algorithm. High accuracy and stability by means of a limited amount of training data is achieved by implementing physics-informed regularizations and the back stress information. The off-loading of the neural network (NN) is applied to the maximal extent. The proposed model architecture is simpler and more efficient compared to existing solutions from the literature using approximately only half the amount of NN parameters, while representing a complete three-dimensional material model. The validation of the approach is carried out by means of results obtained with the Armstrong–Frederick kinematic hardening model. The mean squared error is assumed as the loss function which stipulates several restrictions: deviatoric character of internal variables, compliance with the flow rule, the differentiation of elastic and plastic steps and the associativity of the flow rule. The latter, however, has a minor impact on the accuracy, which implies the generalizability of the model for a broad spectrum of evolution laws for internal variables. Numerical tests simulating several load cases are presented in detail. The validation shows cyclic stability and deviations in normal directions of less than 2% at peak values which is comparable to the order of measurement inaccuracies.
Service-based off-grid solar for productive use in poor urban settings: insights from an informal settlement in Cape Town, South Africa
Authors: Yaguma Penlope , Caprotti Federico , Parikh Priti 
Published: November 2024

Abstract
The productive use of energy (PUE) is a critical pathway to development, as it enhances productivity and facilitates income-generating activities. However, PUE is little understood in low-resource urban settings in the context of off-grid energy. Drawing on two projects implemented between 2019 and 2022, this paper presents a case of off-grid solar for PUE in a young, unelectrified informal settlement in Cape Town, South Africa. The projects investigated the state of energy access in the settlement using household surveys and interviews, and installed solar microgrids in partnership with a local off-grid solar provider who deployed a ‘service-based’ provision model. We find that limited energy options in the settlement commensurately limited energy usage mainly to domestic applications. The microgrids provided reliable refrigeration and lighting for small businesses which improved their operations, delivered energy autonomy, and stimulated aspirations for growth. Energy consumption from the microgrids revealed seasonal and temporal variations which requires flexible demand-responsive energy systems, and holds implications for sizing, storage, and scaling. Although targeted, the ‘service-based’ model limited productive uses to only those that fit within the remit of the model and high costs particularly for appliances prohibited wider PUE adoption. These challenges impact the scalability of off-grid solar in informal settlements which calls for innovative financing approaches and increased policy support for off-grid providers operating in these communities. Off-grid solar has the potential to stimulate PUE and alleviate energy poverty in informal settlements, but more case studies are required to widen the evidence-base, thereby advancing South Africa’s energy transitions agenda.