bluuebunny/crossref_metadata_2025 huggingface dataset:
Natural riparian vegetation as corridors to promote bee diversity and pollination services in an urban landscape
Authors: Lan Yang , Zhao Qing , Zhang Xin , Huang Junlong , Shao Ying , Chen Zhongli
Published: September 2024

Understanding how landscape structure and riparian vegetation impact bee diversity is important for maintaining pollination service in urban areas. We explored spatial and temporal variation of bee communities across land use types in a riparian zone of a mountainous megacity in 2018 and 2022, examined whether riparian vegetation functions as corridors that maintain gene flow of bee populations, and mapped pollination supply at the landscape scale.

Pielou index was higher in 2018 than in 2022, while no significant differences in abundance, Shannon and richness index were observed. The abundance of bees and the Shannon index were significantly and positively correlated with the abundance of flowers on grassland and forested land, respectively, while both were negatively correlated with the area of the building.

The genetic differentiation of the bee communities in the riparian zone was lower than those outside, indicating the function of the riparian vegetation corridor. The pollination supply varied significantly between regions, with medium to high degree of pollination supply distributed primarily in residual habitats and the surrounding urban green spaces, while low degree in the remaining areas.

Our results stress the importance of maintaining the continuity of vegetation in riparian zones and increasing flower abundance, especially native plant species, for the conservation of bees in urban areas.

Read the free Plain Language Summary for this article on the Journal blog.
Tribological properties of perfluoropolymer fiber filled carbon fiber/polyphenylene sulfide composites: Effect of in‐situ fibrillated fiber or split fiber
Authors: Qiu Xiaotao , Luo Bin , Gu Aiqun , Tang Wenjian , Xie Meiju , Tang Siqi , Yu Zili
Published: September 2024

In this study, carbon fiber (CF) filled polyphenylene sulfide (PPS) composites are lubricated with perfluoropolymer (PFP) fiber by melt‐blending. The effect of double fibers (CF‐PFP fibers) on the tribological properties of PPS composites has been carefully investigated and correlated under various sliding conditions. The results indicated that the tribological performance of PPS composites with double fibers is better than that of the composites with a single fiber, especially under severe conditions. Mechanism exploration suggests that a double‐fiber hybrid structure between a hard CF and a soft PFP fiber could tightly entrap the CF by fibril entanglement, thus preventing the CF from being stripped out of the matrix under the steel ring shearing force. Under optimized conditions, the average friction coefficient of composites with PFP fiber is only about 0.1 at 300 N load under 200 rpm, even lower than half of the average friction coefficient of the composites with PTFE powder under the same condition. Notably, compared to commercial split PFP fibers, the in‐situ formed PFP fibers with more uniform distribution significantly improve the tribological properties. This work open up a novel perspective for improving the tribological performance of composites by systematically regulating the microstructure of self‐lubricating fibrous additives.

Highlights

PFA is subject to in‐situ fibrillation during melt blending.

Fibrous PFP effectively improves the tribological properties of PPS/CF composites.

The in‐situ formed PFP fiber contributes to better tribological properties.

The double‐fiber hybrid structure prevents the CF from being sheared out.

The number of processing cycles affects the tribological properties.
Effect of crystallization behavior on wear properties of polytetrafluoroethylene composites modified by irradiation above melting point
Authors: Wang Xiaojie , Huang Geng , Zhou Shuangquan , Wang Junyi , Wu Daming , Gao Xiaolong
Published: September 2024

In this paper, the reasons for the improved wear resistance of irradiation‐modified Polytetrafluoroethylene (RM‐PTFE) and its composites above the melting point were investigated from the microcrystalline point of view by using methods such as crystallization kinetics, and it was found that the linear wear rate of RM‐PTFE was only 0.3 um/km, with a 1000 times increase in wear resistance, which was due to the transformation of its crystals from flake crystals that were easily dislodged to spherical crystals that were more resistant to abrasion. It was also found that the linear wear rate of Polytetrafluoroethylene (PTFE) with coke and graphite was 0.2 and 0.1 μm/km, respectively, and the abrasion resistance was further improved, which was attributed to the lowering of spherical crystal grain size by coke and graphite, which had better mechanical properties. These studies lay the foundation for future research on the frictional wear mechanism of RM‐PTFE above the melting point.

Highlights

Irradiation‐modified PTFE above the melting point

Wear resistance of PTFE increases 1000 times

Changes in crystal morphology dramatically increase wear resistance

Use of crystallization kinetics to study the crystalline form of PTFE

Small grain size improves wear resistance
Research on defect identification of carbon fiber composite materials based on ultrasonic phased array
Authors: Jing Ziang , Cai Gaoshen , Yu Xiang , Wang Bingxu
Published: September 2024

It is more and more difficult to identify defects in carbon fiber composite materials due to the difficulty in making defect samples and the single signal analysis method. In order to better solve the problem of defect identification in carbon fiber composite materials, this study uses ultrasonic phased array equipment to quantitatively locate and detect carbon fiber composite laminates with embedded delamination defects, so as to more intuitively and effectively display the appearance of different delamination defects. The time domain analysis of the collected ultrasonic original signal and the time‐frequency domain analysis using wavelet packet are carried out. A total of 6 eigenvalues were extracted to reflect the ultrasonic signals of different delamination defects. By using genetic algorithm to optimize BP neural network, the recognition accuracy of delamination defects of different sizes is more than 95%, and the recognition accuracy of delamination defects of different depths is 100%, so as to realize the effective intelligent recognition of delamination defects of different sizes and depths of carbon fiber composites. This study is of great significance to improve the accuracy and reliability of defect identification of carbon fiber composite materials.

Highlights

The ultrasonic phased array equipment is used to quantitatively locate the carbon fiber composite laminates with embedded delamination defects, so that the appearance of different defects can be displayed more intuitively and effectively.

Using time domain analysis and time‐frequency domain analysis based on wavelet packet, the combination of the two can more comprehensively extract the effective features of the defect signal.

The BP neural network is optimized by genetic algorithm, and the results can effectively and automatically identify different layered defects, which lays a good foundation for the rapid and accurate identification of more defects in the future.
Enhanced Hyperpolarizabilities Through p‐Phenylene Bridges: Computational Studies on Metamerism and Functional Molecular Properties of Pyridinium–Dicyanomethanide‐Based Zwitterions
Authors: Sitha Sanyasi
Published: September 2024

Para‐phenylene‐bridged pyridinium (acceptor)–dicyanomethanide (donor)‐based zwitterions were computationally investigated and are reported here. Reichardt's metamer was found to be twisted and Brooker's metamer in near‐planar conformation. Natural bond orbital (NBO) analysis showed that mesomeric resonance is helping Brooker's metamer but found to be not helpful for Reichardt's metamer. To assess the impacts of metamerism and aromatic bridges, fundamental molecular properties like dipole moments (μ), polarizabilities (α), hyperpolarizabilities (β), and adiabatic absorptions of these two molecules were analyzed and then directly compared with their counterpart zwitterions without any bridges (previously reported). Results of impact of metamerism: Reichardt's metamer showed around three times enhanced hyperpolarizabilities (ωB97xD: β = 1577.1 × 10−30 esu) than the Brooker's metamer (ωB97xD: β = 532.5 × 10−30 esu). Impacts of p‐phenylene bridges: Compared to their respective D–A directly connected zwitterions reported previously (in ωB97xD methodology, Reichardt's: β = 257.2 × 10−30 esu and Brooker's: β = 67.2 × 10−30 esu), respective p‐phenylene‐bridged zwitterions showed five to eight times enhanced hyperpolarizabilities. This report highlights the better efficiencies of Reichardt's metamer over Brooker's metamer and aromatically bridged over the directly connected zwitterions. Current findings may be helpful in the designing of efficient functional molecular chromophores, and aromatic bridge combined with zwitterions can be solutions to nonlinear transparency trade‐off problem.
The causal relationship between drinking water and gastrointestinal cancers: a two‐sample mendelian randomization analysis
Authors: Gui Liang , Wang Jian
Published: September 2024

Cancers of the digestive tract are a series of diseases that seriously affects the health and life quality of the population worldwide, and the etiology is closely related to various daily habits. Drinking water is a daily human activity, but the intrinsic connection between water intake and gastrointestinal (GI) cancers is still unclear. We used the two‐sample mendelian randomization (TSMR) method to explore the potential causal relationship between water consumption and GI cancers. We obtained the integrated GWAS data of water intake (ukb‐b‐14 898), as well as the GWAS results of oral cavity cancer (ieu‐b‐4961), esophageal cancer (ebi‐a‐GCST90018841), gastric cancer (ebi‐a‐GCST90018849), liver cancer (ieu‐b‐4953), hepatic bile duct cancer (ebi‐a‐GCST90018803), pancreatic cancer (ebi‐a‐GCST90018893) and colorectal cancer (ebi‐a‐GCST90018588) through the online database “IEU OPEN GWAS PROJECT”. Using inverse variance weighting (IVW) method, weighted median method, MR Egger regression method, simple model method, and weighted model method to jointly study the causal relationship between water intake and GI cancers. Mendelian randomization analysis showed a negative correlation between water consumption and esophageal cancer (weighted media, OR = 0.215, p = .021; MR Egger, OR = 0.033, p = .040; weighted mode, OR = 0.162, p = .045), a positively association with pancreatic cancer (IVW, OR = 2.663, p = .033). There is a potential positive correlation between water intake and gastric cancer as well as colorectal cancer, but not statistically significant. The associations between water intake and oral cavity cancer, liver cancer and hepatic bile duct cancer remain uncertain. Therefore, Increased amount of drinking water may help to prevent the incidence of esophageal cancer, but might promote the development of pancreatic cancer.
Hypertension: a PCN Clinical Pharmacist‐led intervention
Authors: Watson Clare , Rushton Beth , Scullard Paul
Published: September 2024

Cardiovascular disease (CVD) remains the second most common cause of death in England, after dementia and Alzheimer disease, causing a quarter of all deaths. Hypertension is the largest single known risk factor for CVD; however, as the condition rarely has noticeable symptoms, an estimated 4.2 million people in England are walking around with undiagnosed hypertension. This article presents how one primary care network (PCN), Nottingham West, is working in new ways to make a difference to the health of their local population about hypertension.
Magnetic Domain and Structural Defects Size in Ultrathin Films
Authors: Adanlété Adjanoh Assiongbon , Pakam Tchilabalo , Afenyiveh Serge Dzo Mawuefa
Published: September 2024

Herein, a model is proposed for measuring the structural defects size r0 in an ultrathin magnetic layer with perpendicular magnetic anisotropy. Based on the observations of magnetic domains in Ta/Pt/Co/Pt ultrathin films, using polar magneto‐optical Kerr effect microscopy and measurements of their magnetic anisotropies, the correlation between magnetic domains size D and structural defects size r0, as well as the defects concentration parameter αK, which designates the degree of pinning, has been modeled. The average r0 value found is high in the sample with unannealed buffer layers and considerably decreases with annealing. It is 6.17 nm with unannealed Ta/Pt buffer layers, 1.06 nm in sample with Ta/Pt buffer layers annealed at 423 K, and 0.49 nm in that with buffer layers annealed at 573 K. The significant drop of r0 is in good agreement with the high depinning noted with buffer layers annealing in recent work.
Quantum Effect Enables Large Elastocaloric Effect in Monolayer MoSi2N4${\rm MoSi}_2{\rm N}_4$ and Graphene
Authors: Yin Yan , He Weiwei , Tang Wei , Yi Min
Published: September 2024

Low‐dimensional materials with outstanding heat conductivity and elastocaloric effect (eCE) are significant for environmentally friendly and energy‐efficient nano refrigerators. However, most of elastocaloric materials with first/second‐order phase transition suffer from hysteresis loss. Herein, an emerging monolayer is theoretically demonstrated as a promising candidate, which exhibits no hysteresis loss enabled by reversible elastic response, as well as large eCE and high eC strength enabled by quantum effect (QE). Considering the remarkable influence of QE and thermo‐mechanical coupling (TMC) in the monolayer limit, the adiabatic temperature change () is evaluate by incorporating QE and TMC. Molecular dynamics simulation significantly underestimates , whereas method with QE slightly overestimates when compared to method with QE+TMC. At 300 K, of is –(11–42) K under biaxial tensile forces of 26–84 nN. The elastocaloric coefficients are –(0.3–0.9) , comparable to that of armchair carbon nanotubes. A large eCE ( around 15 K under a biaxial tensile load of 35 nN) is also revealed for graphene by incorporating QE and TMC. This study proposes a more comprehensive method for quantitatively predicting eCE in 2D materials by including QE and TMC, offering a theoretical guideline for refrigerating materials in the monolayer limit.
Effective leaders seek truth, rebound from adversity
Authors: McCarthy Claudine
Published: September 2024

CHARLOTTE, N.C. — Playing on the University of North Carolina's 1982 National Championship team with NBA stars Michael Jordan and James Worthy, Matt Doherty's future looked bright.
Magnetic Micromotors with Spiky Gold Nanoshells as SERS Sensors for Thiram and Bacteria Detection
Authors: Yang Tao , Zhou Jianping , Wang Yongkang , Fan Ben , Qiao Jing , Chen Lixiang , Wang Xiaoyu , Guo Lingxiang , Yang Hong , Li Quan
Published: September 2024

Surface‐enhanced Raman scattering (SERS) is widely used in all kinds of detection due to its ultrahigh sensitivity and selectivity. Micromotors, when used as SERS sensors, or the so‐called “hotspots on the fly”, can combine both controlled mobility and SERS sensing capacity, and are ideal for versatile in situ detection. In this work, mobile SERS sensors are successfully fabricated by growing gold nanospikes onto magnetic microsphere surfaces. These mobile micromotors can act as normal SERS sensors, characterized by the trace detection of thiram, a highly toxic fungicide. The detection limit can reach 0.1 nM, as good as most other noble metal deposited substrates. With significant magnetic gradient forces, separation of pathogenic bacteria from bulk solution is achieved once these magnetic micromotors bind with bacterial cells. Manipulated propulsion of micromotors, on the other hand, enables them to approach and contact pathogenic bacterial cells on command and further acquire Raman spectra under a controlled degree of contact, a capability never seen with passive sensors. The robotic SERS sensors have demonstrated unique sensing characteristics with controlled manipulations along with discriminative detection between bacterial species.
Exploring the Adaptability of 4D Printed Shape Memory Polymer Featuring Dynamic Covalent Bonds
Authors: Zhang Jing , Xu Mingkun , Zhang Nan , Tao Liming , Shao Mingchao , Wang Tingmei , Yang Zenghui , Wang Qihua , Zhang Yaoming
Published: September 2024

4D printing (4DP) of high‐performance shape memory polymers (SMPs), particularly using digital light processing (DLP), has garnered intense global attention due to its capability for rapid and high‐precision fabrication of complex configurations, meeting diverse application requirements. However, the development of high‐performance dynamic shape memory polymers (DSMPs) for DLP printing remains a significant challenge due to the inherent incompatibilities between the photopolymerization process and the curing/polymerization of high‐strength polymers. Here, a mechanically robust DSMP compatible is developed with DLP printing, which incorporates dynamic covalent bonds of imine linking polyimide rigid segments, exhibiting remarkable mechanical performance (tensile strength ≈41.7 MPa, modulus ≈1.63 GPa) and thermal stability (Tg ∼ 113 °C, Td ∼ 208 °C). More importantly, benefiting from the solid‐state plasticity conferred by dynamic covalent bonds, 4D printed structures demonstrate rapid network adaptiveness, enabling effortless realization of reconfiguration, self‐healing, and recycling. Meanwhile, the extensive π‐π conjugated structures bestow DSMP with an intrinsic photothermal effect, allowing controllable morphing of the 4D configuration through dual‐mode triggering. This work not only greatly enriches the application scope of high‐performance personalized configurations but also provides a reliable approach to addressing environmental pollution and energy crises.
Metal Oxide vs Organic Semiconductor Charge Extraction Layers for Halide Perovskite Indoor Photovoltaics
Authors: Wang Shaoyang , Kodalle Tim , Millar Sam , Sutter‐Fella Carolin M. , Krishnan Jagadamma Lethy
Published: September 2024

Halide perovskite indoor photovoltaics (PVs) are highly promising to autonomously power the billions of microelectronic sensors in the emerging and disruptive technology of the Internet of Things (IoT). However, how the wide range of different types of hole extraction layers (HELs) impacts the indoor light harvesting of perovskite solar cells is still elusive, which hinders the material selection and industrial‐scale fabrication of indoor perovskite photovoltaics. In the present study, new insights are provided regarding the judicial selection of HELs at the buried interface of halide perovskite indoor photovoltaics. This study unravels the detrimental and severe light‐soaking effect of metal oxide transport layer‐based PV devices under the indoor lighting effect for the first time, which then necessitates the interface passivation/engineering for their reliant performance. This is not a stringent criterion under 1 sun illumination. By systematically investigating the charge carrier dynamics and sequence of measurements from dark, light‐soaked, interlayer‐passivated device, the bulk and interface defects are decoupled and reveal the gradual defect passivation from shallow to deep level traps. Thus, the present study puts forward a useful design strategy to overcome the deleterious effect of metal oxide HELs and employ them in halide perovskite indoor PVs.
Single Site W(0) versus Re(I)‐Dipyridophenazine‐ Based Conjugated Porous Polymer for CO2 Photoreduction
Authors: Matarín Ángela , Sánchez Félix , Collado Laura , Barawi Mariam , de la Peña O'Shea Victor A. , Arnanz Avelina , Liras Marta , Iglesias Marta
Published: September 2024

Herein, the synthesis and characterization of two robust tungsten and rhenium carbonyl complexes integrated into an organic polymer (CPP‐Re, CPP‐W) are reported. These polymers are obtained by a Suzuki coupling reaction between the corresponding dibromo metal‐carbonyl substituted dipyrido[3,2‐a:2′,3′‐c]phenazine complex and 1,3,5‐triphenylbenzene‐4′,4″,4″,4‴‐triboronic acid and integrated catalytic active sites and photosensitizer since they have not only nitrogen sites to coordinate metal active centers as rhenium or tungsten but photoactive units with good charge‐separating ability which can significantly improve the CO2 photoreduction reaction (CO2PRR). These polymers show similar activity in solid–gas CO2PRR in absence of sacrificial agents to produce syn gas (CO + H2) but CPP‐W selectivity to products change regarding CPP‐Re being able to produce also large amount of more demanding electron products such as methane and ethane. Moreover, the single‐site Re‐ or W‐CPP catalysts could prevent the dimerization of complexes that produces its deactivation. This work shows the potential of CPPs as matrices to support single active centers for heterogeneous catalysis.
Spatially Selective Ultraprecision Polishing and Cleaning by Collective Behavior of Micro Spinbots
Authors: Je Hyeongmin , Won Sukyoung , Wie Jeong Jae , Kim Sanha
Published: September 2024

Untethered magnetic actuation is an attractive technique for controlling a batch of micrometer‐sized soft robots. Recent advancements have enabled each robot to follow its path independently using a single magnetic device. However, applications of magnetic soft microrobots are mostly biased toward the biomedical field. In this study, thermoplastic polyurethane–Fe3O4 nanocomposite soft spinning microrobots, that is, spinbots that actuate on a tabletop magnetic stirrer, were utilized as innovative precision manufacturing tools for spatially selective precision polishing and cleaning. The pivot motion of the revolving spinbots, which involves repetitive sweeping during rotation cycles, is explored. This sweeping action physically removes nanometer‐sized surface contaminants from the workpiece, achieving a cleaning efficiency of 99.6%. Multiple spinbots, up to 42 in total, simultaneously operated along their own orbital pathways on three vertically stacked wafers, thereby demonstrating an unprecedented cleaning method. In addition, the spinbots precisely removed materials from the workpiece using a three‐body abrasion mechanism. Furthermore, the spinbots contributed to precise material removal, resulting in remarkable surface polishing (R
a ≈ 1.8 nm). This novel polishing system, which uses the collective behavior of multiple spinbots on a tabletop magnetic stirrer, is 1000‐fold lighter than current state‐of‐the‐art equipment aimed at achieving similar levels of fine finishing.
Pressure‐Enhanced Superconductivity and Structural Phase Transition in Layered Sn4P3
Authors: Ding Hao , Hou Jingyu , Zhai Kun , Gao Xin , Huang Junquan , Ke Feng , Yang Bingchao , Mu Congpu , Wen Fusheng , Xiang Jianyong , Wang Bochong , Xue Tianyu , Nie Anmin , Liu Xiaobing , Wang Lin , Zhou Xiang‐Feng , Liu Zhongyuan
Published: September 2024

High pressure provides a unique tuning method depending on structure modulation to explore the structure–property relationship. Herein, the pressure‐induced structural phase transformation and enhanced superconductivity in a layered binary phosphide Sn4P3 are reported. Comprehensive measurements using in situ synchrotron X‐Ray diffraction and Raman spectroscopy reveal a structural phase transition with mild distortion of SnP3 building blocks and interlayer shrinkage under high pressure. This differs from a conventional trigonal SnAs(P)3 to square SnAs(P)4 topotactic transition in SnAs(P)‐based compound. Through this structure reconstruction under high pressure, electron distribution has been reorganized and phonons have softened, facilitating a high superconducting temperature (Tc) value of 7.8 K at 34.9 GPa, which is almost six times higher than its ambient value. The study introduces a new transition route in layered SnAs/SnP‐based intermetallic materials and provides insight into the structural and electronic changes under high pressure for Sn4P3.
Oscillations of the Local pH Reverses Silver Micromotors in H2O2
Authors: Liu Xianghong , Peng Yixin , Yan Zuyao , Cao Dezhou , Duan Shifang , Wang Wei
Published: September 2024

Asymmetric chemical reactions on the surfaces of colloidal particles are known to propel them into directional motion. The dynamics of such chemical micromotors are sensitive to their local chemical environments, which also continually evolve with the reactions on motor surfaces. This two‐way coupling between the motor dynamics and the local environment may result in complex nonlinear behaviors. As an example, we report that Janus Ag microspheres, which self‐propel in hydrogen peroxide (H2O2), spontaneously reverse their direction of motion two or more times. We hypothesize that two distinct chemical reactions between Ag and H2O2 drive the micromotor in opposite directions, and which reaction dominates depends on the local pH. Interestingly, the local pH near a Ag micromotor oscillates spontaneously in H2O2, likely due to a complex interplay between the kinetics of the reaction between Ag and H2O2 and the diffusion of chemical species. Consequently, the pH‐sensitive Ag micromotor reverses its direction of motion in response to these pH oscillations. This study introduces a new mechanism for regulating the speed and directionality of micromotors, highlights the potential of Ag micromotors in chemical sensing, and sheds new light on the interplay between chemical kinetics and micromotor dynamics.
Subnational Institutional Differences and FDI Spillovers Behind the R&D–Performance Relationship in Russia
Authors: Lebedev Sergey , Peng Mike W.
Published: September 2024

This study explores how subnational institutional differences in a large emerging economy—Russia—influence the relationship between research and development (R&D), foreign direct investment (FDI) spillovers, and firm performance. We find that the relationship between R&D and firm performance is positively moderated by subnational institutional development. Furthermore, we find that FDI will more positively moderate the relationship between R&D and firm performance if subnational institutional development is also higher, thus showing that subnational institutional development may foster the positive spillover effect of FDI on local firms.
Reform bills in Jordan: A Dawn of a new era or continuous missed opportunities?
Authors: Alakayleh Moath , Bani Salameh Mohammed Torki , Emambocus Washad
Published: September 2024

This study aims to identify the concept, mechanisms and motives of political reform under the reign of King Abdullah II of Jordan. Concisely, the study attempts to identify obstacles to and opportunities for political reform in Jordan. To this end, the weaknesses and challenges facing the process of political reform in Jordan as well as opportunities to achieve political reform will be addressed. The opportunities are represented in the new constitutional amendments and the new laws governing political life (political parties and election laws). The main finding of this study is that since Jordan's problem today is not just economic, there is a pressing need for political reform. The political reform in Jordan, as a form of adjusting and accommodating, is the best alternative for the regime to face the popular pressures. This is probably so because Arab Spring regimes with minimal capacity to ‘bend’ or respond to change had eventually collapsed.
Mitigating thermal stratification in lakes/reservoirs through wind‐powered air diffusers
Authors: Hazar Oğuz , Elçi Sebnem
Published: September 2024

Thermal stratification can cause various water quality issues in large water bodies. To address this, a new wind‐powered artificial mixing system is designed and experimentally tested for various Savonius rotor combinations (three‐stage and four‐stage rotors). These turbines directly utilize wind energy to draw air into the water column for aeration, bypassing the need for electrical conversion. The rotor performances were tested in terms of power and torque coefficients. Additionally, these rotors were tested for artificial mixing efficiencies in a specially designed water tank that can mimic thermal stratification typically observed in an actual water supply reservoir. Among the rotors, the three‐stage rotor with a 60° phase shift was found to exhibit superior power and torque coefficients, achieving a power efficiency value of 0.14. As for the mixing efficiency, the four‐stage rotor with a 45° phase shift excelled in mixing efficiency, reaching 95%.

Practitioner Points

A new wind‐powered artificial mixing system is designed and tested for various Savonius rotor combinations.

While keeping the total rotor height constant, the three‐stage Savonius rotor class shows superior performance against the four‐stage Savonius rotor class in terms of power and torque efficiency.

Apart from the rotor performance results, the four‐stage Savonius rotors show greater artificial mixing efficiency than the three‐stage Savonius rotors.

Single‐pump/diffuser artificial destratification system exhibits better mixing efficiency than multiple‐pump/diffuser systems.
Adversarial Robustness Certification for Bayesian Neural Networks
Authors: Wicker Matthew , Patane Andrea , Laurenti Luca , Kwiatkowska Marta
Published: September 2024

We study the problem of certifying the robustness of Bayesian neural networks (BNNs) to adversarial input perturbations. Specifically, we define two notions of robustness for BNNs in an adversarial setting: probabilistic robustness and decision robustness. The former deals with the probabilistic behaviour of the network, that is, it ensures robustness across different stochastic realisations of the network, while the latter provides guarantees for the overall (output) decision of the BNN. Although these robustness properties cannot be computed analytically, we present a unified computational framework for efficiently and formally bounding them. Our approach is based on weight interval sampling, integration and bound propagation techniques, and can be applied to BNNs with a large number of parameters independently of the (approximate) inference method employed to train the BNN. We evaluate the effectiveness of our method on tasks including airborne collision avoidance, medical imaging and autonomous driving, demonstrating that it can compute non-trivial guarantees on medium size images (i.e., over 16 thousand input parameters).
Efficient Formally Verified Maximal End Component Decomposition for MDPs
Authors: Hartmanns Arnd , Kohlen Bram , Lammich Peter
Published: September 2024

Identifying a Markov decision process’s maximal end components is a prerequisite for applying sound probabilistic model checking algorithms. In this paper, we present the first mechanized correctness proof of a maximal end component decomposition algorithm, which is an important algorithm in model checking, using the Isabelle/HOL theorem prover. We iteratively refine the high-level algorithm and proof into an imperative LLVM bytecode implementation that we integrate into the Modest Toolset ’s existing model checker. We bring the benefits of interactive theorem proving into practice by reducing the trusted code base of a popular probabilistic model checker and we experimentally show that our new verified maximal end component decomposition in performs on par with the tool’s previous unverified implementation.
Fast Attack Graph Defense Localization via Bisimulation
Authors: Busany Nimrod , Shalom Rafi , Klein Dan , Maoz Shahar
Published: September 2024

System administrators, network engineers, and IT managers can learn much about the vulnerabilities of an organization’s cyber system by constructing and analyzing analytical attack graphs (AAGs). An AAG consists of logical rule nodes, fact nodes, and derived fact nodes. It provides a graph-based representation that describes ways by which an attacker can achieve progress towards a desired goal, a.k.a. a crown jewel. Given an AAG, different types of analyses can be performed to identify attacks on a target goal, measure the vulnerability of the network, and gain insights on how to make it more secure. However, as the size of the AAGs representing real-world systems may be very large, existing analyses are slow or practically impossible. In this paper, we introduce and show how to compute an AAG’s defense core: a locally minimal subset of the AAG’s rules whose removal will prevent an attacker from reaching a crown jewel. Most importantly, in order to scale-up the performance of the detection of a defense core, we introduce a novel application of the well-known notion of bisimulation to AAGs. Our experiments show that the use of bisimulation results in significantly smaller graphs and in faster detection of defense cores, making them practical.
State Matching and Multiple References in Adaptive Active Automata Learning
Authors: Kruger Loes , Junges Sebastian , Rot Jurriaan
Published: September 2024

Active automata learning (AAL) is a method to infer state machines by interacting with black-box systems. Adaptive AAL aims to reduce the sample complexity of AAL by incorporating domain specific knowledge in the form of (similar) reference models. Such reference models appear naturally when learning multiple versions or variants of a software system. In this paper, we present state matching, which allows flexible use of the structure of these reference models by the learner. State matching is the main ingredient of adaptive $$L^{\#}$$

L
#

, a novel framework for adaptive learning, built on top of $$L^{\#}$$

L
#

. Our empirical evaluation shows that adaptive $$L^{\#}$$

L
#

improves the state of the art by up to two orders of magnitude.
Staged Specification Logic for Verifying Higher-Order Imperative Programs
Authors: Foo Darius , Song Yahui , Chin Wei-Ngan
Published: September 2024

Higher-order functions and imperative states are language features supported by many mainstream languages. Their combination is expressive and useful, but complicates specification and reasoning, due to the use of yet-to-be-instantiated function parameters. One inherent limitation of existing specification mechanisms is its reliance ononly two stages : an initial stage to denote the precondition at the start of the method and a final stage to capture the postcondition. Such two-stage specifications forceabstract propertiesto be imposed on unknown function parameters, leading to less precise specifications for higher-order methods. To overcome this limitation, we introduce a novel extension to Hoare logic that supportsmultiple stagesfor a call-by-value higher-order language with ML-like local references. Multiple stages allow the behavior of unknown function-type parameters to be captured abstractly as uninterpreted relations; and can also model the repetitive behavior of each recursion as a separate stage. In this paper, we define our staged logic with its semantics, prove its soundness and develop a new automated higher-order verifier, calledHeifer, for a core ML-like language.
Misconceptions in Finite-Trace and Infinite-Trace Linear Temporal Logic
Authors: Greenman Ben , Prasad Siddhartha , Di Stasio Antonio , Zhu Shufang , De Giacomo Giuseppe , Krishnamurthi Shriram , Montali Marco , Nelson Tim , Zizyte Milda
Published: September 2024

With the growing use of temporal logics in areas ranging from robot planning to runtime verification, it is critical that users have a clear understanding of what a specification means. Toward this end, we have been developing a catalog of semantic errors and a suite of test instruments targeting various user-groups. The catalog is of interest to educators, to logic designers, to formula authors, and to tool builders, e.g., to identify mistakes. The test instruments are suitable for classroom teaching or self-study.

This paper reports on five sets of survey data collected over a three-year span. We study misconceptions about finite-trace $$\textsc {ltl}_{f}$$

L
T
L

f

in three ltl-aware audiences, and misconceptions about standard ltl in novices. We find several mistakes, even among experts. In addition, the data supports several categories of errors in both $$\textsc {ltl}_{f}$$

L
T
L

f

and ltl that have not been identified in prior work. These findings, based on data from actual users, offer insights into what specific ways temporal logics are tricky and provide a groundwork for future interventions.
Practical Approximate Quantifier Elimination for Non-linear Real Arithmetic
Authors: Akshay S. , Chakraborty Supratik , Goharshady Amir Kafshdar , Govind R. , Motwani Harshit Jitendra , Varanasi Sai Teja
Published: September 2024

Quantifier Elimination (QE) concerns finding a quantifier-free formula that is semantically equivalent to a quantified formula in a given logic. For the theory of non-linear arithmetic over reals (NRA), QE is known to be computationally challenging. In this paper, we show how QE over NRA can be solved approximately and efficiently in practice using a Boolean combination of constraints in the linear arithmetic over reals (LRA). Our approach works by approximating the solution space of a set of NRA constraints when all real variables are bounded. It combines adaptive dynamic gridding with application of Handelman’s Theorem to obtain the approximation efficiently via a sequence of linear programs (LP). We provide rigorous approximation guarantees, and also proofs of soundness and completeness (under mild assumptions) of our algorithm. Interestingly, our work allows us to bootstrap on earlier work (viz. [38]) and solve quantified SMT problems over a combination of NRA and other theories, that are beyond the reach of state-of-the-art solvers. We have implemented our approach in a preprocessor for Z3 called POQER. Our experiments show that POQER+Z3EG outperforms state-of-the-art SMT solvers on non-trivial problems, adapted from a suite of benchmarks.
Bootstrapping pions at large N. Part II. Background gauge fields and the chiral anomaly
Authors: Albert Jan , Rastelli Leonardo
Published: September 2024

Abstract

We continue the program [1] of carving out the space of large N confining gauge theories by modern S-matrix bootstrap methods, with the ultimate goal of cornering large N QCD. In this paper, we focus on the effective field theory of massless pions coupled to background electromagnetic fields. We derive the full set of positivity constraints encoded in the system of 2 → 2 scattering amplitudes of pions and photons. This system probes a larger set of intermediate meson states, and is thus sensitive to intricate large N selection rules, especially when supplemented with expectations from Regge theory. It also has access to the coefficient of the chiral anomaly. We find novel numerical bounds on several ratios of Wilson coefficients, in units of the rho mass. By matching the chiral anomaly with the microscopic theory, we also derive bounds that contain an explicit N dependence.
Computing Typology: Generative Design for Creating Housing Solutions from Type Analysis in Bogota
Authors: Cifuentes Quin Camilo Andres
Published: September 2024

The article delves into the integration of a typological discourse within contemporary design practice, offering insights into a generative system aimed at processing design scenarios from typological analyses. By identifying architectural types within the context of Bogota’s periphery, this research showcases the potential of computational methods to formalize typological principles in design. It also explores the possibilities of digital design to facilitate the production of customized housing solutions on a mass scale. This study contributes to the debate about the role of typology in design practice, highlighting the possibilities inherent in leveraging computational tools to enhance architectural synthesis. Additionally, it investigates the potential of a digital design framework to offer alternative solutions to the housing crisis, addressing the growing demand for affordable, high-quality housing in Latin America.
Gaussian estimates vs. elliptic regularity on open sets
Authors: Böhnlein Tim , Ciani Simone , Egert Moritz
Published: September 2024

Given an elliptic operator

$$L= - {{\,\textrm{div}\,}}(A \nabla \cdot )$$

L
=
-

div

(
A
∇
·
)

subject to mixed boundary conditions on an open subset of

$$\mathbb {R}^d$$

R

d

, we study the relation between Gaussian pointwise estimates for the kernel of the associated heat semigroup, Hölder continuity of L-harmonic functions and the growth of the Dirichlet energy. To this end, we generalize an equivalence theorem of Auscher and Tchamitchian to the case of mixed boundary conditions and to open sets far beyond Lipschitz domains. Yet, we prove the consistency of our abstract result by encompassing operators with real-valued coefficients and their small complex perturbations into one of the aforementioned equivalent properties. The resulting kernel bounds open the door for developing a harmonic analysis for the associated semigroups on rough open sets.
Jumping Automata over Infinite Words
Authors: Almagor Shaull , Yizhaq Omer
Published: September 2024

Jumping automata are finite automata that read their input in a non-consecutive manner, disregarding the order of the letters in the word. We introduce and study jumping automata over infinite words. Unlike the setting of finite words, which has been well studied, for infinite words it is not clear how words can be reordered. To this end, we consider three semantics: automata that read the infinite word in some order so that no letter is overlooked, automata that can permute the word in windows of a given size k, and automata that can permute the word in windows of an existentially-quantified bound. We study expressiveness, closure properties and algorithmic properties of these models.
Genetic basis and imaging findings of neurofibromatosis 1 and other somatic overgrowth disorders
Authors: Vittay Orsolya , Christopher Joseph , Mehta Sarju G. , Toms Andoni P.
Published: September 2024

Somatic overgrowth disorders comprise a wide range of rare conditions that present with focal enlargement of one or more tissue types. The PI3K-AKT-mTOR pathway is a signalling pathway that induces angiogenesis and cell proliferation, and is one of the most commonly overactivated signalling pathways in cancer. The PI3K-AKT-mTOR pathway can be up-regulated by genetic variants that code for proteins in this pathway, or down-regulated by proteins that inhibit the pathway. Mosaic genetic variations can result in cells that proliferate excessively in specific anatomical locations. The PIK3CA-related overgrowth spectrum (PROS) disorders include CLOVES syndrome, macrodystrophia lipomatosa, and Klippel-Trenaunay syndrome among many. The neurofibromatosis type 1 (NF1) gene encodes neurofibromin which down-regulates the PI3K-AKT-mTOR pathway. Thousands of pathological variants in the NF1 gene have been described which can result in lower-than-normal levels of neurofibromin and therefore up-regulation of the PI3K-AKT-mTOR pathway promoting cellular overgrowth. Somatic overgrowth is a rare presentation in NF1 with a wide range of clinical and radiological presentations. Hypertrophy of all ectodermal and mesodermal elements has been described in NF1 including bone, muscle, fat, nerve, lymphatics, arteries and veins, and skin. The shared signalling pathway for cellular overgrowth means that these radiological appearances can overlap with other conditions in the PIK3CA-related overgrowth spectrum. The aim of this review is to describe the genetic basis for the radiological features of NF1 and in particular compare the appearances of the somatic overgrowth disorders in NF1 with other conditions in the PIK3CA-related overgrowth spectrum.
The association between gout and subsequent cardiovascular events: a retrospective cohort study with 132,000 using propensity score matching in primary care outpatients in Germany
Authors: Sedighi Jamschid , Luedde Mark , Gaensbacher-Kunzendorf Julia , Sossalla Samuel , Kostev Karel
Published: September 2024

Background

Both the risk of developing heart disease and the course of the disease are determined in particular by comorbidities. In this context, gout has recently been identified as an important factor in influencing the development of cardiovascular events such as heart failure or coronary artery disease.

Methods

This retrospective cohort study compared the incidence of angina pectoris (AP) (ICD-10: I20), myocardial infarction (MI) (ICD-10: I21, I22), chronic coronary heart disease (CHD) (ICD-10: I25), atrial fibrillation (AF), and heart failure (HF) as a function of gout in Germany in a large collective of 66,000 gout patients in comparison to 66,000 individuals without gout between using propensity score matching (1:1) from January 2005 to December 2020.

Results

Within 10 years after the index date, AP was diagnosed in 5.2% of gout and 2.9% of non-gout patients (p < 0.001), MI in 3.1% of gout and 2.2% of non-gout patients (p < 0.001), CHD in 16.5% of gout and 11.8% of non-gout patients, AF in 12.6% of gout and 8.4% of non-gout patients (p < 0.001), and HF in 14.7% of gout and 8.5% of non-gout patients (p < 0.001). For all diagnoses except CHD, the association was stronger in male than in female patients.

Conclusion

The relationship shown between gout and cardiovascular disease indicates that gout could be one of a series of inflammatory conditions that increase the risk of cardiac disease. The association we have shown between gout and all major cardiac diseases suggests that there is a risk modifier, the treatment of which could help prevent these diseases. Further research is needed to determine whether treating gout can effectively reduce this risk.