bluuebunny/crossref_metadata_2025 huggingface dataset:
Silencing of FRO1 gene affects iron homeostasis and nutrient balance in tomato plants
Authors: Gama Florinda , Saavedra Teresa , Dandlen Susana , García‐Caparrós Pedro , de Varennes Amarilis , Nolasco Gustavo , Correia Pedro José , Pestana Maribela
Published: July 2023

Background

Iron chlorosis is an abiotic stress of worldwide importance affecting several agronomic crops. It is important to understand how plants maintain nutrient homeostasis under Fe deficiency and recovery.

Aims

We used the virus‐induced gene silencing (VIGS) method to elucidate the role of the FRO1 gene in tomato plants and identify the impact on regulation of the root ferric‐chelate reductase (FCR) activity and nutritional homeostasis.

Methods

Tomato plantlets cv. “Cherry” were transferred into half‐strength Hoagland's nutrient solution containing 0.5 µM of Fe (Fe0.5). In phase I, two treatments were established: control (Fe0.5) plants and VIGS‐0.5 plants corresponding to plants with the FRO1 gene silenced. In phase II, plants from Fe0.5 and VIGS‐0.5 were transferred to new nutrient solution and then grown for a further 14 days under 0 and 10 µM of Fe (as 0.5 µM would not be enough for the larger plants during phase II). Therefore, four treatments were imposed: Fe0, Fe10, VIGS‐0, and VIGS‐10.

Results

VIGS‐0.5 plants had significantly lower chlorophyll (Chl) and root FCR activity compared to the respective non‐silenced plants and retained more Cu and Zn in the roots at the expense of stems (Cu) or young leaves (Zn). Iron concentration in roots and stems decreased in FRO1 gene‐silenced plants, compared to control plants, but the allocation to different organs was similar in both treatments.

Conclusions

There was a partial recovery of leaf Chl in the VIGS‐10 plants and a higher concentration of Fe in all organs. In contrast, the allocation of Cu to roots decreased in the VIGS‐10 plants.
Deuterated PET: The new verification target of the Raman spectrometer for the MMX mission to explore Phobos
Authors: Moral Andoni G. , Mora Julio , Prieto‐Ballesteros Olga , Ercilla Oscar , Lopez‐Reyes Guillermo , Canora Carlos P. , Bonales Laura J. , Fernandez‐Sampedro Maite , Sanz‐Arranz J.A. , Herrera Alejandro , Alonso Rafael , Rull Fernando , Böttger Ute , Cho Yuichiro , Schröder Susanne , Hübers Heinz‐Wilhelm
Published: July 2023

JAXA's upcoming MMX (Martian Moons eXploration) mission will deliver a small rover to Phobos, to explore its surface complementary to the MMX orbiter and the sample return lander. On board this rover is a Raman spectrometer, the RAX Instrument (RAman Spectrometer for MMX), a payload to science. RAX has been designed for being capable to analyze the mineral composition of the Phobos' surface, in order to help reveal the nature and distribution of materials on the surface and ultimately the origin and evolution of the moon. Attached to MMX spacecraft, with direct view from the RAX instrument, a polyethylene terephthalate (PET) target will be placed for on‐ground and during cruise, spectral instrument performances verification, before the MMX rover is released and dropped to the Phobos surface for developing its scientific tasks. A novel deuterated PET material was proposed as verification target (VT) to check the spectral instrument performances. INTA‐CAB developed, manufactured and qualified for the MMX‐RAX space mission, 13 mm diameter and 2‐mm thick pellets of this material, which incorporates two relevant improvement characteristics: reduction in fluorescence and additional Raman bands with regard to ordinary PET used with this purpose. The material was selected as RAX VT and delivered to DLR for performance tests and later integration into the MMX rover together with the RAX flight model. The RAX VT will be critical to check the instrument performances during the several months cruise phase after launch and just before its landing on Phobos surface. This paper reports the development and characterization of the deuterated PET.
Effect of molecular weight and drying temperature on the physicochemical properties of chitosan edible film
Authors: Sutharsan Jenani , Boyer Cyrille Andre , Zhao Jian
Published: July 2023

Background

Chitosan is the second most abundant polysaccharide abundant in nature after cellulose. In this study chitosan edible films with three different molecular weights (low [LMW], medium [MMW] and high [HMW] molecular weights) were prepared by drying them at room (21°C), 40 and 50°C and their physicochemical properties were characterized.

Results

Molecular weight had a positive effect on the thickness, tensile strength (TS), elongation at break (EAB) and swelling ability (SA) of the films. However, film solubility(S) and water vapor permeability (WVP) were negatively affected. Higher drying temperatures increased the TS of the films whereas lower drying temperatures increased the MC, S, WVP and the EAB of the films. All the films prepared were transparent; however, films made with LMW chitosan were yellowish color. FTIR spectra of the films were influenced by the molecular weight of chitosan and the drying temperature, which revealed that there was an interaction between MW and the drying temperature.

Conclusion

This study demonstrated that films made with medium MW chitosan by drying at room temperature had the most favorable properties for food packaging applications.
1927nm fractional thulium fiber laser combined with 30% salicylic acid for the treatment of acne and acne scars: A prospective, randomized, and split‐face study
Authors: Huang Shi‐Liu , Ye Dan , Xue Huan , Wang Zhao‐Yang , Yang Meng‐Yao , Qiao Si‐Meng , Li You‐Bao , Zhu Yu , Mu Sheng‐Zhi , Yang Fan , Wang Zhao , Zeng Wei‐Hui
Published: July 2023

Objectives

Patients with acne usually develops acne scars subsequently, early intervention of scars is crucial in acne management. 1927nm fractional thulium fiber laser (TFL) is effective in scars improvement and chemical peels with 30% supramolecular salicylic acid (SSA) can be applied for the treatment of acne. The purpose of this study is to evaluate and compare the efficacy and safety of TFL monotherapy versus the concomitant application of TFL and 30% SSA on acne and acne scars.

Materials and Methods

Thirty‐three patients with acne and acne scars were enrolled, and two sides of the face were randomly divided to receive either TFL and SSA chemical peeling or TFL. Four sessions of TFL treatments were applied with 4‐week intervals for both sides, SSA combined treatment side received eight SSA chemical peels with 2‐week intervals additionally. GAGS, ECCA score, the number of acne lesions, melanin index (MI) and erythema index (EI), transepidermal water loss (TEWL), and side effects were recorded at Weeks 0, 4, 8, 12, and 18. Satisfaction of patients was recorded on both sides at the end of the study.

Results

Thirty patients completed the study. Both control group (TFL monotherapy) and SSA group (TFL combined with SSA chemical peeling) significantly improved GAGS and ECCA score. SSA group showed higher efficacy in terms of GAGS and ECCA score, acne lesion count, TEWL, MI, EI, and satisfaction than control group. All the side effects were temporary and tolerable, no adverse effects were observed.

Conclusions

Both TFL and the TFL combined with 30% SSA chemical peeling are safe and effective for the treatment and prevention of acne and acne scars, though the combined group has higher efficacy.
Remodeling of Gut Microbiota by Probiotics Alleviated Heat Stroke‐Induced Necroptosis in Male Germ Cells
Authors: Cai Hui , Qin Dezhe , Liu Yundie , Guo Xinrui , Liu Yang , Ma Baohua , Hua Jinlian , Peng Sha
Published: July 2023

Scope

Systemic heat stress (or heatstroke; HS) induces germ cell death and spermatogenesis disorders in men and male mammals. Also, it affects the immune environment of the circulatory system promoting gut inflammation and intestinal permeability, leading to pathogenic infection. In this study, the crosstalk between the gut and testis (gut‐testis axis) under HS is explored, by examining the effects of intestinal immune status on the health of the male reproductive system in mice.

Methods and results

A mouse model of systemic heat stress is established to investigate the effect of probiotics on testis health. The results reveal that pro‐inflammatory factor receptor activation pathway and pathogen infection response pathway are significantly upregulated in HS testes, leading to necroptosis, while pro‐inflammatory factor and endotoxin are detected locally in the intestine and then entered the blood. The study then uses probiotics to intervene in gut microbiota, which results in milder gut microbial changes, lower inflammatory responses in the HS gut, and less necroptosis in the HS testes.

Conclusion

Probiotics‐based remodeling of gut microbiota (GM) reduces the proliferation of abnormal bacteria and decreases the spread of gut‐derived inflammatory mediators into the blood circulation under long‐term systemic heat stress, which relieves inflammation on germ cells.
Nonlocal geometric fracture theory: A nonlocal‐local asymptotically compatible framework for continuous–discontinuous deformation of solid materials
Authors: Yu Haitao , Sun Yuqi
Published: July 2023

One of the fundamental but unsolved problems in fracture mechanics of solid materials is how to describe the continuous and discontinuous deformation of continuum in a unified manner. This paper aims to develop a novel nonlocal geometric fracture theory attempting to address this essential issue. Using the concepts of nonlocal calculus, a new nonlocal equation for the deformation of continuum is obtained by minimizing a nonlocal Lagrangian. This is done to ensure that the proposed nonlocal model can be used to describe the continuous and discontinuous deformation of a continuum in a unified geometric manner, as well as to be asymptotically compatible with the classical continuum theory. Inspired by the phase field fracture theory, a nonlocal geometric crack surface functional is proposed to approximate the Griffith fracture energy in continuum. Note, however, that a distinguished feature of the proposed functional is that it enables strong discontinuities appear in the crack phase fields, which is difficult for the phase field fracture theory. After obtaining the nonlocal fracture energy, a nonlocal elastic energy is phenomenologically decomposed into volumetric and deviatoric parts, and then a system of nonlocal geometric fracture equations is derived to describe the damage nucleation, cracks initiation and propagation, which covers the whole physical process of fracture in solid materials. A staggered discontinuous Galerkin method is developed to reach an accurate and stable numerical solution. Numerical examples demonstrate the proposed theory can well capture the transition from the continuous to discontinuous deformation of the continuum and accurately describe the topological evolution of cracks in a unified framework.
Fluid hunter motivation in Central Africa: Effects on behaviour, bushmeat and income
Authors: Froese Graden Z. L. , Ebang Mbélé Alex , Beirne Christopher , Bazza Blaise , Dzime N’noh Sylvain , Ebeba Jovin , Edzidzie Jocelin , Ekazama Koto Serge , Metandou Jonas Landry , Mossindji Clotaire , Ngoboutseboue Irma , Nzemfoule Eric , Ingram Daniel J. , Krapu Christopher , Baral Abhishek , Saha Srishti , Poulsen John R.
Published: July 2023

Individual motivation for the rural use of common‐pool resources (CPRs) can be fluid, with the line between subsistence and commercial often unclear and in flux.

Implications of fluid motivation are understudied yet important for social–ecological systems (SESs), such as bushmeat hunting throughout Central Africa that is essential to local protein/nutrition, income and culture.

Making locally informative predictions of multiple SESs nested within a landscape‐scale SES has been historically difficult, but community‐driven participatory approaches provide new kinds and quantities of data, opening previously inaccessible doors for research and governance.

We apply hierarchical Bayesian structural equation modelling to a novel dataset of 910 hunts from 111 gun and trap hunters across nine villages in Gabon, generated in a participatory process whereby hunters conducted GPS self‐follows in conjunction with paraecologist surveys of their motivation, behaviour and offtake. We (i) establish the human behaviour driving gun‐hunting and trapping success and predict its effect on offtake across villages and (ii) link fluid motivation of gun hunters to their behaviour, number of animals hunted, biomass yielded and income earned.

Gun hunts across villages yielded more animals during the night than the day, and when hunters brought high amounts of ammunition and walked far distances from villages. Gun hunts were less successful when coupled with trapping while per‐hunt success of trapping itself was generally low and difficult to predict. Fluid gun hunters hunted fewer animals when motivated strictly by subsistence, despite no reduction in ammunition brought or distance walked, while offtake from strictly commercial versus mixed motivation was the same. Numbers of animals hunted, biomass and income were tightly linked. We discuss the implications of these results for the ecological sustainability of hunting and participatory forecasting in bushmeat research and policy.

Read the free Plain Language Summary for this article on the Journal blog.
Effects of harvesting and stubble management on abundance of pest rodents (Mus musculus) in a conservation agriculture system
Authors: Ruscoe Wendy A. , Brown Peter R. , Henry Steve , van de Weyer Nikki , Robinson Freya , Hinds Lyn A. , Duncan Richard P.
Published: July 2023

BACKGROUND

The shift to more environmentally sensitive agricultural practices over the last several decades has changed farmland landscapes worldwide. Changes including no‐till and retaining high biomass mulch has been coincident with an increase in rodent pests in South Africa, India, South America and Europe, indicating a possible conflict between conservation agriculture (CA) and rodent pest management. Research on effects of various crop management practices associated with CA on pest rodent population dynamics is needed to anticipate and develop CA‐relevant management strategies.

RESULTS

During the Australian 2020–2021 mouse plague, farmers used postharvest stubble management practices, including flattening and/or cutting, to reduce stubble cover in paddocks to lessen habitat suitability for pest house mice. We used this opportunity to assess the effects of both harvest and stubble management on the movement and abundance of mice in paddocks using mouse trapping and radio tracking. We found that most tracked mice remained resident in paddocks throughout harvest, and that mouse population abundance was generally unaffected by stubble management.

CONCLUSION

Recent conversions to CA practices have changed how pest house mice use cropped land. Management practices that reduce postharvest habitat complexity do not appear to reduce the attractiveness of paddocks to mice, and further research into new management strategies in addition to toxic bait use is required as part of an integrated pest management approach. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
An Immunomodulatory Biomimetic Single‐Atomic Nanozyme for Biofilm Wound Healing Management
Authors: Zhang Juyang , Lv Mengdi , Wang Xinye , Wu Fan , Yao Cheng , Shen Jian , Zhou Ninglin , Sun Baohong
Published: July 2023

Nanozyme‐driven catalytic antibacterial therapy has become a promising modality for bacterial biofilm infections. However, current catalytic therapy of biofilm wounds is severely limited by insufficient catalytic efficiency, excessive inflammation, and deep tissue infection. Drawing from the homing mechanism of natural macrophages, herein, a hollow mesoporous biomimetic single‐atomic nanozyme (SAN) is fabricated to actively target inflamed parts, suppress inflammatory factors, and eliminate deeply organized bacteria for enhance biofilm eradication. In the formulation, this biomimetic nanozyme (Co@SAHSs@IL‐4@RCM) consists of IL‐4‐loaded cobalt SANs‐embedded hollow sphere encapsulate by RAW 264.7 cell membrane (RCM). Upon accumulation at the infected sites through the specific receptors of RCM, Co@SAHS catalyze the conversion of hydrogen peroxide into hydroxyl radicals and are further amplify by NIR‐II photothermal effect and glutathione depletion to permeate and destroy biofilm structure. This behavior subsequently causes the dissociation of RCM shell and the ensuing release of IL‐4 that can reprogram macrophages, enabling suppression of oxidative injury and tissue inflammation. The work paves the way to engineer alternative “all‐in‐one” SANs with an immunomodulatory ability and offers novel insights into the design of bioinspired materials.
The Evolution of MXenes Conductivity and Optical Properties Upon Heating in Air
Authors: Shamsabadi Ahmad A. , Fang Hui , Zhang Danzhen , Thakur Anupma , Chen Cindy Y. , Zhang Aixi , Wang Haonan , Anasori Babak , Soroush Masoud , Gogotsi Yury , Fakhraai Zahra
Published: July 2023

MXenes, a family of 2D transition‐metal carbides and nitrides, have excellent electrical conductivity and unique optical properties. However, MXenes oxidize in ambient conditions, which is accelerated upon heating. Intercalation of water also causes hydrolysis accelerating oxidation. Developing new tools to readily characterize MXenes’ thermal stability can enable deeper insights into their structure–property relationships. Here, in situ spectroscopic ellipsometry (SE) is employed to characterize the optical properties of three types of MXenes (Ti3C2Tx, Mo2TiC2Tx, and Ti2CTx) with varied composition and atomistic structures to investigate their thermal degradation upon heating under ambient environment. It is demonstrated that changes in MXene extinction and optical conductivity in the visible and near‐IR regions correlate well with the amount of intercalated water and hydroxyl termination groups and the degree of oxidation, measured using thermogravimetric analysis. Among the three MXenes, Ti3C2Tx and Ti2CTx, respectively, have the highest and lowest thermal stability, indicating the role of transition‐metal type, synthesis route, and the number of atomic layers in MXene flakes. These findings demonstrate the utility of SE as a powerful in situ technique for rapid structure–property relationship studies paving the way for the further design, fabrication, and property optimization of novel MXene materials.
Recent Advances in III–V Compounds/Polymer Hybrid Solar Cells
Authors: Chen Jiaying , Mo Youtian , Guo Chaoying , Guo Jiansen , Xu Bingshe , Deng Xi , Xue Quan , Li Guoqiang
Published: July 2023

The combination of III–V compound semiconductor materials and organic semiconductor materials to construct hybrid solar cells is a potential pathway to resolve the problems of conventional doped p–n junction solar cells, such as complexities in fabrication process and high costs. This review presents the recent progress of organic–inorganic hybrid solar cells based on polymers and III–V semiconductors, from materials to devices. The available growth process for planar/nanostructured III–V semiconductor materials, along with patterning and etching processes for nanostructured materials, are reviewed. As an emphasis of this review, advanced device structure designs are reviewed for facilitation of carrier collection and high efficiency, at planar structure level and nanowire structure level, respectively. Optimization pathways for efficiency enhancement are discussed with respect to polymer layers and surface/interface passivation, respectively. Finally, perspectives on the future development of such hybrid cells are presented.
Strain Engineering Toward High‐Performance Formamidinium‐Based Perovskite Solar Cells
Authors: Zhou Yuqin , Guo Zhihao , Qaid Saif M. H. , Xu Zhiyuan , Zhou Yong , Zang Zhigang
Published: July 2023

The power conversion efficiency (PCE) of organic–inorganic halide perovskite solar cells (PSCs) has increased rapidly in recent years, with the certified best perovskite single‐junction photovoltaics reaching an astounding PCE of 26%. Formamidine (FA)‐based perovskites possess excellent photovoltaic properties and superior thermal stability, establishing them as one of the most promising perovskite materials for light absorption. However, the issue of the phase instability of black‐phase formamidinium lead iodide (α‐FAPbI3) perovskite has seriously impeded its commercialization process, with the strain found in perovskite films being regarded as a significant factor impacting the stability of PSCs. This article begins by examining the sources of strain and the characterization techniques related to perovskites. Subsequently, it outlines the effects of strain on FA‐based perovskites and presents strategies to modify lattice strain. Finally, the potential for strain engineering in the future is discussed. This review aims to clarify the impact of strain on FA‐based perovskite, determine potential methods of strain engineering to enhance device performance, and ultimately facilitate the commercialization of these materials.
Template‐Free Growth of High‐Temperature Superconductor Nanowires
Authors: Potticary Jason , Luke Emily J. , Christodoulou Ektor M. S. , Davies Rowena , Haughton Sorrel , Feuillet-Palma Cheryl , Recoba-Pawlowski Eliana , Leridon Brigitte , Griffin Sarah , Hall Simon R.
Published: July 2023

As devices become ever smaller and more efficient, the crystallochemically controlled synthesis of high‐performance materials that comprise their core has attracted enormous attention. Integration of complex functional materials into the next generation of electronic devices will require exquisite control of anisotropic form, either as nanotubes, nanotapes, or nanowires, yet the easy preparation of abundant quantities of them remains stubbornly challenging. Herein, a template‐free, flux‐mediated growth of vast quantities of three compositions of phase‐pure, high‐temperature superconductor nanowires, including for the first time, nanowires of the technologically important quinternary superconductor Bi2Sr2CaCu2O8+x (B2212) is demonstrated. The results of this work may provide an opportunity to investigate the physics and chemistry of highly anisotropic superconductor nanowires and enable their incorporation into nanoelectronics and energy generation systems.
Neutron Reflectometry Study of Solid Electrolyte Interphase Formation in Highly Concentrated Electrolytes
Authors: Rizell Josef , Zubayer Anton , Sadd Matthew , Lundin Filippa , Mozhzhukhina Nataliia , Eriksson Fredrik , Birch Jens , Vorobiev Alexei , Xiong Shizhao , Matic Aleksandar
Published: July 2023

Highly concentrated electrolytes have been found to improve the cycle life and Coulombic efficiency of lithium metal anodes, as well as to suppress dendrite growth. However, the mechanism for these improvements is not well understood. Partly, this can be linked to the difficulty of accurately characterizing the solid electrolyte interphase (SEI), known to play an important role for anode stability and stripping/plating efficiency. Herein, in situ neutron reflectometry is used to obtain information about SEI formation in a highly concentrated ether‐based electrolyte. With neutron reflectometry, the thickness, scattering length density (SLD), and roughness of the SEI layer formed on a Cu working electrode are nondestructively probed. The reflectivity data point to the formation of a thin (5 nm) SEI in the highly concentrated electrolyte (salt:solvent ratio 1:2.2), while a considerably thicker (13 nm) SEI is formed in an electrolyte at lower salt concentration (salt:solvent ratio 1:13.7). Further, the SEI formed in the electrolyte with high salt concentration has a higher SLD, suggesting that the chemical composition of the SEI changes. The results from neutron reflectometry correlate well with the electrochemical data from SEI formation.
Active Learning of Deterministic Timed Automata with Myhill-Nerode Style Characterization
Authors: Waga Masaki
Published: July 2023

We present an algorithm to learn a deterministic timed automaton (DTA) via membership and equivalence queries. Our algorithm is an extension of the L* algorithm with a Myhill-Nerode style characterization of recognizable timed languages, which is the class of timed languages recognizable by DTAs. We first characterize the recognizable timed languages with a Nerode-style congruence. Using it, we give an algorithm with a smart teacher answering symbolic membership queries in addition to membership and equivalence queries. With a symbolic membership query, one can ask the membership of a certain set of timed words at one time. We prove that for any recognizable timed language, our learning algorithm returns a DTA recognizing it. We show how to answer a symbolic membership query with finitely many membership queries. We also show that our learning algorithm requires a polynomial number of queries with a smart teacher and an exponential number of queries with a normal teacher. We applied our algorithm to various benchmarks and confirmed its effectiveness with a normal teacher.
Overcoming Memory Weakness with Unified Fairness
Authors: Abdulla Parosh Aziz , Atig Mohamed Faouzi , Godbole Adwait , Krishna Shankaranarayanan , Vahanwala Mihir
Published: July 2023

We consider the verification of liveness properties for concurrent programs running on weak memory models. To that end, we identify notions of fairness that preclude demonic non-determinism, are motivated by practical observations, and are amenable to algorithmic techniques. We provide both logical and stochastic definitions of our fairness notions, and prove that they are equivalent in the context of liveness verification. In particular, we show that our fairness allows us to reduce the liveness problem (repeated control state reachability) to the problem of simple control state reachability. We show that this is a general phenomenon by developing a uniform framework which serves as the formal foundation of our fairness definition, and can be instantiated to a wide landscape of memory models. These models include SC, TSO, PSO, (Strong/Weak) Release-Acquire, Strong Coherence, FIFO-consistency, and RMO.
Unblocking Dynamic Partial Order Reduction
Authors: Kokologiannakis Michalis , Marmanis Iason , Vafeiadis Viktor
Published: July 2023

Existing dynamic partial order reduction (DPOR) algorithms scale poorly on concurrent data structure benchmarks because they visit a huge number of blocked executions due to spinloops.

In response, we develop Awamoche, a sound, complete, and strongly optimal DPOR algorithm that avoids exploring any useless blocked executions in programs with await and confirmation-CAS loops. Consequently, it outperforms the state-of-the-art, often by an exponential factor.
3D Environment Modeling for Falsification and Beyond with Scenic 3.0
Authors: Vin Eric , Kashiwa Shun , Rhea Matthew , Fremont Daniel J. , Kim Edward , Dreossi Tommaso , Ghosh Shromona , Yue Xiangyu , Sangiovanni-Vincentelli Alberto L. , Seshia Sanjit A.
Published: July 2023

We present a major new version of Scenic, a probabilistic programming language for writing formal models of the environments of cyber-physical systems. Scenic has been successfully used for the design and analysis of CPS in a variety of domains, but earlier versions are limited to environments that are essentially two-dimensional. In this paper, we extend Scenic with native support for 3D geometry, introducing new syntax that provides expressive ways to describe 3D configurations while preserving the simplicity and readability of the language. We replace Scenic’s simplistic representation of objects as boxes with precise modeling of complex shapes, including a ray tracing-based visibility system that accounts for object occlusion. We also extend the language to support arbitrary temporal requirements expressed in LTL, and build an extensible Scenic parser generated from a formal grammar of the language. Finally, we illustrate the new application domains these features enable with case studies that would have been impossible to accurately model in Scenic 2.
A Unified Model for Real-Time Systems: Symbolic Techniques and Implementation
Authors: Akshay S. , Gastin Paul , Govind R. , Joshi Aniruddha R. , Srivathsan B.
Published: July 2023

In this paper, we consider a model of generalized timed automata (GTA) with two kinds of clocks, history and future, that can express many timed features succinctly, including timed automata, event-clock automata with and without diagonal constraints, and automata with timers.

Our main contribution is a new simulation-based zone algorithm for checking reachability in this unified model. While such algorithms are known to exist for timed automata, and have recently been shown for event-clock automata without diagonal constraints, this is the first result that can handle event-clock automata with diagonal constraints and automata with timers. We also provide a prototype implementation for our model and show experimental results on several benchmarks. To the best of our knowledge, this is the first effective implementation not just for our unified model, but even just for automata with timers or for event-clock automata (with predicting clocks) without going through a costly translation via timed automata. Last but not least, beyond being interesting in their own right, generalized timed automata can be used for model-checking event-clock specifications over timed automata models.
Hybrid Controller Synthesis for Nonlinear Systems Subject to Reach-Avoid Constraints
Authors: Yang Zhengfeng , Zhang Li , Zeng Xia , Tang Xiaochao , Peng Chao , Zeng Zhenbing
Published: July 2023

There is a pressing need for learning controllers to endow systems with properties of safety and goal-reaching, which are crucial for many safety-critical systems. Reinforcement learning (RL) has been deployed successfully to synthesize controllers from user-defined reward functions encoding desired system requirements. However, it remains a significant challenge in synthesizing provably correct controllers with safety and goal-reaching requirements. To address this issue, we try to design a special hybrid polynomial-DNN controller which is easy to verify without losing its expressiveness and flexibility. This paper proposes a novel method to synthesize such a hybrid controller based on RL, low-degree polynomial fitting and knowledge distillation. It also gives a computational approach, by building and solving a constrained optimization problem coming from verification conditions to produce barrier certificates and Lyapunov-like functions, which can guarantee every trajectory from the initial set of the system with the resulted controller satisfies the given safety and goal-reaching requirements. We evaluate the proposed hybrid controller synthesis method on a set of benchmark examples, including several high-dimensional systems. The results validate the effectiveness and applicability of our approach.
Safe Environmental Envelopes of Discrete Systems
Authors: Meira-Góes Rômulo , Dardik Ian , Kang Eunsuk , Lafortune Stéphane , Tripakis Stavros
Published: July 2023

A safety verification task involves verifying a system against a desired safety property under certain assumptions about the environment. However, these environmental assumptions may occasionally be violated due to modeling errors or faults. Ideally, the system guarantees its critical properties even under some of these violations, i.e., the system is robust against environmental deviations. This paper proposes a notion of robustness as an explicit, first-class property of a transition system that captures how robust it is against possible deviations in the environment. We modeled deviations as a set of transitions that may be added to the original environment. Our robustness notion then describes the safety envelope of this system, i.e., it captures all sets of extra environment transitions for which the system still guarantees a desired property. We show that being able to explicitly reason about robustness enables new types of system analysis and design tasks beyond the common verification problem stated above. We demonstrate the application of our framework on case studies involving a radiation therapy interface, an electronic voting machine, a fare collection protocol, and a medical pump device.
Counterexample Guided Knowledge Compilation for Boolean Functional Synthesis
Authors: Akshay S. , Chakraborty Supratik , Jain Sahil
Published: July 2023

Given a specification as a Boolean relation between inputs and outputs, Boolean functional synthesis generates a function, called a Skolem function, for each output in terms of the inputs such that the specification is satisfied. In general, there may be many possibilities for Skolem functions satisfying the same specification, and criteria to pick one or the other may vary from specification to specification.

In this paper, we develop a technique to represent the space of Skolem functions in a criteria-agnostic form that makes it possible to subsequently extract Skolem functions for different criteria. Our focus is on identifying such a form and on developing a compilation algorithm for this form. Our approach is based on a novel counter-example guided strategy for existentially quantifying a subset of variables from a specification in negation normal form. We implement this technique and compare our performance with those of other knowledge compilation approaches for Boolean functional synthesis, and show promising results.
Guessing Winning Policies in LTL Synthesis by Semantic Learning
Authors: Křetínský Jan , Meggendorfer Tobias , Prokop Maximilian , Rieder Sabine
Published: July 2023

We provide a learning-based technique for guessing a winning strategy in a parity game originating from an LTL synthesis problem. A cheaply obtained guess can be useful in several applications. Not only can the guessed strategy be applied as best-effort in cases where the game’s huge size prohibits rigorous approaches, but it can also increase the scalability of rigorous LTL synthesis in several ways. Firstly, checking whether a guessed strategy is winning is easier than constructing one. Secondly, even if the guess is wrong in some places, it can be fixed by strategy iteration faster than constructing one from scratch. Thirdly, the guess can be used in on-the-fly approaches to prioritize exploration in the most fruitful directions.

In contrast to previous works, we (i) reflect the highly structured logical information in game’s states, the so-called semantic labelling, coming from the recent LTL-to-automata translations, and (ii) learn to reflect it properly by learning from previously solved games, bringing the solving process closer to human-like reasoning.
Policy Synthesis and Reinforcement Learning for Discounted LTL
Authors: Alur Rajeev , Bastani Osbert , Jothimurugan Kishor , Perez Mateo , Somenzi Fabio , Trivedi Ashutosh
Published: July 2023

The difficulty of manually specifying reward functions has led to an interest in using linear temporal logic (LTL) to express objectives for reinforcement learning (RL). However, LTL has the downside that it is sensitive to small perturbations in the transition probabilities, which prevents probably approximately correct (PAC) learning without additional assumptions. Time discounting provides a way of removing this sensitivity, while retaining the high expressivity of the logic. We study the use of discounted LTL for policy synthesis in Markov decision processes with unknown transition probabilities, and show how to reduce discounted LTL to discounted-sum reward via a reward machine when all discount factors are identical.
Synthesizing Trajectory Queries from Examples
Authors: Mell Stephen , Bastani Favyen , Zdancewic Steve , Bastani Osbert
Published: July 2023

Data scientists often need to write programs to process predictions of machine learning models, such as object detections and trajectories in video data. However, writing such queries can be challenging due to the fuzzy nature of real-world data; in particular, they often include real-valued parameters that must be tuned by hand. We propose a novel framework calledQuivrthat synthesizes trajectory queries matching a given set of examples. To efficiently synthesize parameters, we introduce a novel technique for pruning the parameter space and a novel quantitative semantics that makes this more efficient. We evaluateQuivron a benchmark of 17 tasks, including several from prior work, and show both that it can synthesize accurate queries for each task and that our optimizations substantially reduce synthesis time.
Learning Assumptions for Compositional Verification of Timed Automata
Authors: Chen Hanyue , Su Yu , Zhang Miaomiao , Liu Zhiming , Mi Junri
Published: July 2023

Compositional verification, such as the technique of assume-guarantee reasoning (AGR), is to verify a property of a system from the properties of its components. It is essential to address the state explosion problem associated with model checking. However, obtaining the appropriate assumption for AGR is always a highly mental challenge, especially in the case of timed systems. In this paper, we propose a learning-based compositional verification framework for deterministic timed automata. In this framework, a modified learning algorithm is used to automatically construct the assumption in the form of a deterministic one-clock timed automaton, and an effective scheme is implemented to obtain the clock reset information for the assumption learning. We prove the correctness and termination of the framework and present two kinds of improvements to speed up the verification. We discuss the results of our experiments to evaluate the scalability and effectiveness of the framework. The results show that the framework we propose can reduce state space effectively, and it outperforms traditional monolithic model checking for most cases.
Process Equivalence Problems as Energy Games
Authors: Bisping Benjamin
Published: July 2023

We characterize all common notions of behavioral equivalence by one 6-dimensional energy game, where energies bound capabilities of an attacker trying to tell processes apart. The defender-winning initial credits exhaustively determine which preorders and equivalences from the (strong) linear-time–branching-time spectrum relate processes.

The time complexity is exponential, which is optimal due to trace equivalence being covered. This complexity improves drastically on our previous approach for deciding groups of equivalences where exponential sets of distinguishing HML formulas are constructed on top of a super-exponential reachability game. In experiments using the VLTS benchmarks, the algorithm performs on par with the best similarity algorithm.
Commutativity for Concurrent Program Termination Proofs
Authors: Lette Danya , Farzan Azadeh
Published: July 2023

This paper explores how using commutativity can improve the efficiency and efficacy of algorithmic termination checking for concurrent programs. If a program run is terminating, one can conclude that all other runs equivalent to it up-to-commutativity are also terminating. Since reasoning about termination involves reasoning about infinite behaviours of the program, the equivalence class for a program run may include infinite words with lengths strictly larger than $$\omega $$
ω
that capture the intuitive notion that some actions may soundly be postponed indefinitely. We propose a sound proof rule which exploits these as well as classic bounded commutativity in reasoning about termination, and devise a way of algorithmically implementing this sound proof rule. We present experimental results that demonstrate the effectiveness of this method in improving automated termination checking for concurrent programs.
Fast Termination and Workflow Nets
Authors: Hofman Piotr , Mazowiecki Filip , Offtermatt Philip
Published: July 2023

Petri nets are an established model of concurrency. A Petri net is terminating if for every initial marking there is a uniform bound on the length of all possible runs. Recent work on the termination of Petri nets suggests that, in general, practical models should terminate fast, i.e. in polynomial time. In this paper we focus on the termination of workflow nets, an established variant of Petri nets used for modelling business processes. We partially confirm the intuition on fast termination by showing a dichotomy: workflow nets are either non-terminating or they terminate in linear time.

The central problem for workflow nets is to verify a correctness notion called soundness. In this paper we are interested in generalised soundness which, unlike other variants of soundness, preserves desirable properties like composition. We prove that verifying generalised soundness is coNP-complete for terminating workflow nets.

In general the problem is PSPACE-complete, thus intractable. We utilize insights from the coNP upper bound to implement a procedure for generalised soundness using MILP solvers. Our novel approach is a semi-procedure in general, but is complete on the rich class of terminating workflow nets, which contains around 90% of benchmarks in a widely-used benchmark suite. The previous state-of-the-art approach for the problem is a different semi-procedure which is complete on the incomparable class of so-called free-choice workflow nets, thus our implementation improves on and complements the state-of-the-art.

Lastly, we analyse a variant of termination time that allows parallelism. This is a natural extension, as workflow nets are a concurrent model by design, but the prior termination time analysis assumes sequential behavior of the workflow net. The sequential and parallel termination times can be seen as upper and lower bounds on the time a process represented as a workflow net needs to be executed. In our experimental section we show that on some benchmarks the two bounds differ significantly, which agrees with the intuition that parallelism is inherent to workflow nets.
Lincheck: A Practical Framework for Testing Concurrent Data Structures on JVM
Authors: Koval Nikita , Fedorov Alexander , Sokolova Maria , Tsitelov Dmitry , Alistarh Dan
Published: July 2023

This paper presents , a new practical and user-friendly framework for testing concurrent algorithms on the Java Virtual Machine (JVM). provides a simple and declarative way to write concurrent tests: instead of describing how to perform the test, users specify what to test by declaring all the operations to examine; the framework automatically handles the rest. As a result, tests written with are concise and easy to understand. The framework automatically generates a set of concurrent scenarios, examines them using stress-testing or bounded model checking, and verifies that the results of each invocation are correct. Notably, if an error is detected via model checking, provides an easy-to-follow trace to reproduce it, significantly simplifying the bug investigation.

To the best of our knowledge, is the first production-ready tool on the JVM that offers such a simple way of writing concurrent tests, without requiring special skills or expertise. We successfully integrated in the development process of several large projects, such as Kotlin Coroutines, and identified new bugs in popular concurrency libraries, such as a race in Java’s standard and a liveliness bug in Java’s framework, which is used in most of the synchronization primitives. We believe that can significantly improve the quality and productivity of concurrent algorithms research and development and become the state-of-the-art tool for checking their correctness.
nekton: A Linearizability Proof Checker
Authors: Meyer Roland , Opaterny Anton , Wies Thomas , Wolff Sebastian
Published: July 2023

is a new tool for checking linearizability proofs of highly complex concurrent search structures. The tool’s unique features are its parametric heap abstraction based on separation logic and the flow framework, and its support for hindsight arguments about future-dependent linearization points. We describe the tool, present a case study, and discuss implementation details.
A Flexible Toolchain for Symbolic Rabin Games under Fair and Stochastic Uncertainties
Authors: Majumdar Rupak , Mallik Kaushik , Rychlicki Mateusz , Schmuck Anne-Kathrin , Soudjani Sadegh
Published: July 2023

We present a flexible and efficient toolchain tosymbolicallysolve (standard) Rabin games, fair-adversarial Rabin games, and "Image missing"-player Rabin games. To our best knowledge, our tools are the first ones to be able to solve these problems. Furthermore, using these flexible game solvers as a back-end, we implemented a tool for computing correct-by-construction controllers for stochastic dynamical systems under LTL specifications. Our implementations use the recent theoretical result that all of these games can be solved using the same symbolic fixpoint algorithm but utilizing different, domain specific calculations of the involved predecessor operators. The main feature of our toolchain is the utilization of two programming abstractions: one to separate the symbolic fixpoint computations from the predecessor calculations, and another one to allow the integration of different BDD libraries as back-ends. In particular, we employ a multi-threaded execution of the fixpoint algorithm by using the multi-threaded BDD library Sylvan, which leads to enormous computational savings.
SR-SFLL: Structurally Robust Stripped Functionality Logic Locking
Authors: Takhar Gourav , Roy Subhajit
Published: July 2023

Logic locking was designed to be a formidable barrier to IP piracy: given a logic design, logic locking modifies the logic design such that the circuit operates correctly only if operated with the “correct”secretkey. However, strong attacks (like SAT-based attacks) soon exposed the weakness of this defense.Stripped functionality logic locking(SFLL) was recently proposed as a strong variant of logic locking. SFLL was designed to be resilient against SAT attacks, which was the bane of conventional logic locking techniques. However, all SFLL-protected designs share certain “circuit patterns” that expose them to new attacks that employstructural analysisof the locked circuits.

In this work, we propose a new methodology—Structurally Robust SFLL($$\mathcal{S}\mathcal{R}$$SR-SFLL)—that uses the power of modern satisfiability and synthesis engines to produce semantically equivalent circuits that are resilient against such structural attacks. On our benchmarks,$$\mathcal{S}\mathcal{R}$$SR-SFLLwas able to defend all circuit instances against both structural and SAT attacks, while all of them were broken when defended using SFLL. Further, we show that designing such defenses is challenging: we design a variant of our proposal,$$\mathcal{S}\mathcal{R}$$SR-SFLL(0), that is also robust against existing structural attacks but succumbs to a new attack,SyntAk(also proposed in this work).SyntAkuses synthesis technology to compile$$\mathcal{S}\mathcal{R}$$SR-SFLL(0)locked circuits into semantically equivalent variants that have structural vulnerabilities.$$\mathcal{S}\mathcal{R}$$SR-SFLL, however, remains resilient toSyntAk.
Symbolic Quantum Simulation with Quasimodo
Authors: Sistla Meghana , Chaudhuri Swarat , Reps Thomas
Published: July 2023

The simulation of quantum circuits on classical computers is an important problem in quantum computing. Such simulation requires representations of distributions over very large sets of basis vectors, and recent work has used symbolic data-structures such as Binary Decision Diagrams (BDDs) for this purpose. In this tool paper, we present Quasimodo, an extensible, open-source Python library for symbolic simulation of quantum circuits. Quasimodo is specifically designed for easy extensibility to other backends. Quasimodo allows simulations of quantum circuits, checking properties of the outputs of quantum circuits, and debugging quantum circuits. It also allows the user to choose from among several symbolic data-structures—both unweighted and weighted BDDs, and a recent structure called Context-Free-Language Ordered Binary Decision Diagrams (CFLOBDDs)—and can be easily extended to support other symbolic data-structures.