bluuebunny/crossref_metadata_2025 huggingface dataset:
Innovative Environmentally Safe Processes for the Extraction of Rare and Rare-Earth Elements from Complex Ores of Perplexed Material Composition
Authors: Chanturia V. A. , Nikolaev A. I. , Aleksandrova T. N.
Published: October 2023

Domestic and world tendencies of involvement in the processing of ores of rare metals (RMs) and rare-earth metals (REMs) are shown. It is shown that the main direction of innovative activity is the development and application of modern breakthrough technologies for complex processing of mineral raw materials with the production of high-quality products while minimizing environmental damage. The main deposits of rare and rare-earth metals are systematized from the standpoint of the content of the main components, concentrator minerals and the main enrichment methods. The main principal technological schemes of processing of some deposits of RMs and REMs in Russia (Lovozer, Tomtor, and Afrikand deposits) are given. Options for involving technogenic and off-balance raw materials in the processing in order to extract strategic metals are considered. It is substantiated that innovative environmentally friendly processes for the extraction of rare and rare-earth metals from complex ores of complex material composition are being actively developed in Russia at present.
Accuracy of using the axial length of the fellow eye for IOL calculation in retinal detachment eyes undergoing silicone oil removal
Authors: Lwowski Christoph , Kaiser Klemens Paul , Bucur Julian , Schicho Philipp , Kohnen Thomas
Published: October 2023

Purpose

Evaluate whether the axial length of the fellow eye can be used to calculate the intraocular lens (IOL) in eyes with retinal detachment.

Design

Retrospective, consecutive case series.

Methods

Our study was conducted at the Goethe University and included patients who underwent silicone oil (SO) removal combined with phacoemulsification and IOL implantation. Preoperative examinations included biometry (IOLMaster 700, Carl Zeiss). We measured axial length (AL) of operated eye (OE) or fellow eye (FE) and compared mean prediction error and mean and median absolute prediction error (MedAE) using four formulas and AL of the OE (Barrett Universal II (BUII)-OE). Additionally, we compared the number of eyes within ±0.50, ±1.00 and ±2.00 dioptre (D) from target refraction.

Results

In total, 77 eyes of 77 patients met our inclusion criteria. MedAE was lowest for the BUII-OE (0.42 D) compared with Kane-FE (1.08 D), BUII-FE (1.02 D) and Radial Basis Function 3.0 (RBF3.0)-FE (1.03 D). This was highly significant (p<.001). The same accounts for the number of eyes within ±0.50 D of the target refraction with the BUII-OE (44 eyes, 57%) outperforming the RBF3.0-FE (20 eyes, 25.9%), Kane-FE and BUII-FE formula (21 eyes, 27.2%) each.

Conclusion

Our results show a statistically and clinically highly relevant reduction of IOL power predictability when using the AL of the FE for IOL calculation. Using the AL of the SO filled eye after initial vitrectomy results in significantly better postoperative refractive results. A two-step procedure using the AL of the OE after reattachment of the retina is highly recommended.
Characteristics of clinician input in Canadian funding decisions for cancer drugs: a cross-sectional study based on CADTH reimbursement recommendations
Authors: Jenei Kristina , Meyers Daniel E
Published: October 2023

Objective

To examine characteristics of clinician input to the pan-Canadian Oncology Drug Review (pCODR) for cancer drug funding recommendations from 2016 to 2020.

Design, setting and participants

Descriptive, cross-sectional study including 62 reimbursement decisions from pCODR from 2016 to 2020.

Interventions

pCODR recommendations were analysed for the number of clinicians consulted on each submission, affiliation, number of submissions per clinician, declared financial conflicts of interest (FCOIs), randomisation, type of blinding, primary endpoint, study phase, and whether the study demonstrated improvement in overall survival (OS) and progression-free survival (PFS).

Main outcome measures

The main outcome was clinician support for the initial funding recommendation. Secondary outcome measures were the association between clinician FCOIs and clinical benefit in positive recommendations.

Results

The study consisted of 62 submissions, in which 48 included clinician input. A total of 129 unique clinicians provided 342 consultations. The majority (59%) provided input on less than 5 submissions; however, a small proportion (4%) consulted on over 10. Nearly all clinicians were physicians (125; 96%). From the 342 consultations, 228 declared financial conflicts (67%). The most common conflicts were payments for advisory roles (51%) and honorariums (23%). Of the 48 cancer drugs under review, clinicians recommended funding 46 (96%). Only 12 (25%) demonstrated substantial benefit, according to the European Society for Medical Oncology Magnitude of Clinical Benefit Scale score. Drugs recommended for funding were more likely to have improved PFS and OS data. However, most cancer drugs supported by clinicians demonstrated no change in health-related quality of life (HRQoL), including one that demonstrated worsened HRQoL. There was no statistically significant difference between FCOI status and recommending drugs with health gains.

Conclusion

Clinicians offer crucial information on funding decisions. However, we found clinicians strongly supported funding nearly all cancer drugs under review, despite most not offering substantial benefit to patients nor gains in quality of life. While these drugs might be helpful options in clinical practice, funding numerous cancer drugs may be unsustainable for public health systems.
Effect of oxycodone combined with ultrasound-guided thoracic paravertebral nerve block on postoperative analgesia in patients with lung cancer undergoing thoracoscopic surgery: protocol for a randomised controlled study
Authors: Wang Yujie , Wu Guanghan , Liu Zheng , Wei Xiumin , Feng Hai , Su Jian , Shi Pengcai
Published: October 2023

Introduction

Postoperative pain is a main component influencing the recovery of patients with lung cancer. The combination of patient-controlled intravenous analgesia (PCIA) and paravertebral nerve block for postoperative analgesia in patients undergoing thoracoscopic lobectomy for lung cancer can achieve a satisfactory analgesic effect and promote early rehabilitation of patients. The objective is to investigate the optimal dose of oxycodone for PCIA combined with paravertebral nerve block, to achieve effective multimodal analgesia management in patients undergoing thoracoscopic lung cancer lobectomy.

Methods and analysis

This prospective, double-blind, single-centre, parallel-group, superiority study from 7 April 2023 to 31 December 2024 will include 160 participants scheduled for thoracoscopic lobectomy for lung cancer. Participants will be randomly assigned to four groups in a 1:1:1:1 ratio: OCA group (oxycodone: 0.5 mg/kg), OCB group (oxycodone: 1.0 mg/kg), OCC group (oxycodone: 1.5 mg/kg) and one sufentanil group (sufentanil: 2 µg/kg). Flurbiprofen 50 mg and ondansetron 16 mg are added to each group. All the drugs are diluted with 0.9% saline in a 100 mL volume, with a background infusion rate of 2 mL/hour, a bolus dose of 0.5 mL and a lockout interval of 15 min. The primary outcome is pain scores at rest and dynamic at 24 hours after surgery using a Numeric Rating Scale (NRS). Dynamic NRS scores are defined as NRS when coughing. NRS scores will be assessed at 2, 4, 12, 24 and 48 hours postoperatively. The secondary outcomes include the following variables: (1) NRS score at rest and dynamic at 2, 4, 12 and 48 hours postoperatively; (2) total dose of sufentanil or oxycodone consumption in PCIA; (3) the times of patient-controlled analgesia; (4) Ramsay Sedation Score (RSS) at 2, 4, 12, 24 and 48 hours after the surgery; (5) extubation time; (6) serum C-reactive protein and interleukin six levels; (7) incidence of postoperative nausea and vomiting; (8) incidence of itching; (9) incidence of respiratory depression and (10) gastrointestinal recovery (exhaust time).

Ethics and dissemination

The First Affiliated Hospital of Shandong First Medical University’s Ethics Committee granted consent for this study (approval number: YXLL-KY-2022(116)). To enable widespread use of the data gathered, we plan to publish the trial’s findings in an appropriate scientific journal after it is complete.

Trial registration number

NCT05742256.
Association of proton pump inhibitor use with risk of kidney stones: an analysis of cross-sectional data from the US National Health and Nutrition Examination Survey (2007–2018)
Authors: Liu Wen , Wang Jia , Wang Miao , Wang Miaomiao , Liu Ming
Published: October 2023

Objective

Several studies have suggested a potential link between use of proton pump inhibitors (PPIs) and the risk of kidney stones, attributed to alterations in urine mineral levels. Our study aimed to investigate the association between PPI use and kidney stones in US adults.

Design

Cross-sectional study.

Setting

National Health and Nutrition Examination Survey (2007–2018).

Participants

27 075 individuals with complete information on PPI use and history of kidney stones were included in this study.

Outcomes and analyses

Non-linear analysis, logistic regression analysis and subgroup analysis were conducted to estimate the relationship between PPI use and the occurrence and recurrence of kidney stones, after adjusting for potential confounding factors.

Results

Multivariable logistic regression analysis revealed a significant association between PPI use and kidney stones (OR 1.31, 95% CI 1.07 to 1.60), with a 4% increase in the prevalence of kidney stones for each additional year of PPI use (p<0.001). Similarly, PPI use was significantly associated with recurrent kidney stones (OR 1.49, 95% CI 1.04 to 2.13), with a 7% increase in the recurrence of kidney stones for each additional year of PPI use (p<0.001). Furthermore, these associations remained significant even after conducting propensity score matching analysis on a subset of PPI users and non-users (all p≤0.001). Subgroup analyses showed that the effects of PPI use on kidney stones differed by age, sex, race and body mass index.

Conclusions

This study indicated that long-term use of PPI was associated with a higher risk of both the presence and recurrence of kidney stones.
Non-convulsive status epilepticus associated with Whipple’s disease
Authors: Diab Eva , Aubignat Mickael , Sarba Ruxandra , Wannepain Sandrine , Godefroy Olivier , Masmoudi Ines
Published: October 2023

A 69-year-old woman developed non-convulsive status epilepticus during inpatient investigation for abdominal pain. Initial detailed investigations did not identify the cause of seizures, but a jejunal biopsy and PCR testing in various fluids led to the diagnosis of Whipple’s disease with neurological involvement. The seizures were controlled but she subsequently had moderate cognitive impairment. Whipple’s disease is an important diagnosis, being treatable with antibiotics. Testing for Whipple’s disease is not part of the recommended workup in for status epilepticus, but this case highlights the importance of considering this condition.
Environmental persistence, bioaccumulation, and hazards of chemicals in e-cigarette e-liquids: short-listing chemicals for risk assessments
Authors: Venugopal P Dilip , Addo Ntim Susana , Goel Reema , Reilly Samantha M , Brenner William , Hanna Shannon K
Published: October 2023

Background/Methods

Increased use and sales of e-cigarettes raises concerns about the potential environmental impacts throughout their life-cycle. However, few available research studies focus on the environmental impacts and ecotoxicity of e-cigarettes. In this study, we short-list e-liquid chemicals from published literature that should be considered in future environmental impact and risk assessments. We used a combination of available laboratory bioassays-based data and predictive methods (eg, Structure-Activity Relationships) to characterise the hazards of the e-liquid chemicals (environmental persistence, bioaccumulation, and aquatic toxicity including hazardous concentration values (concentration affecting specific proportion of species)) for short-listing.

Results

Of the 421 unique e-liquid chemicals compiled from literature, 35 are US Environmental Protection Agency’s hazardous constituents, 42 are US Food and Drug Administration’s harmful or potentially harmful constituents in tobacco products and smoke, and 20 are listed as both. Per hazard characteristics, we short-listed 81 chemicals that should be considered for future environmental impact and risk assessments, including tobacco-specific compounds (eg, nicotine, N'-nitrosonornicotine), polycyclic aromatic hydrocarbons (eg, chrysene), flavours (eg, (-)caryophyllene oxide), metals (eg, lead), phthalates (eg, di(2-ethylhexyl)phthalate) and flame retardants (eg, tris(4-methylphenyl)phosphate).

Implications

Our findings documenting various hazardous chemicals in the e-liquids underscore the importance of awareness and education when handling or disposing of e-liquids/e-cigarettes and aim to inform strategies to prevent and reduce hazards from e-cigarettes. This includes any scenario where e-liquids can come into contact with people or the environment during e-liquid storage, manufacturing, use, and disposal practices. Overall, our study characterises the environmental hazards of e-liquid chemicals and provides regulators and researchers a readily available list for future ecological and health risk assessments.
Pilot study: decoding the skin microbiome of bowhead (Balaena mysticetus) and killer whales (Orcinus orca) in Nunavut, Canada
Authors: Dominguez-Sanchez Carlos A. , Ferguson Steven H. , Edkins Tera , Young Brent G. , Kringorn Joshua
Published: October 2023

Given the increasing challenges that Arctic cetaceans face, it is critical to investigate novel methods for assessing their health. Skin microbiomes have emerged as a promising method of detecting health issues that can help guide conservation efforts for free-ranging cetaceans. This study characterized the skin microbiome of 17 bowhead (BW) and 2 killer whales (KW). Fifty-six amplicon sequence variants were identified exclusively from cetacean samples, 20 belonged to BW, 13 to KW, and 23 to BW and KW. We identified bacteria from the genera Tenacibaculum and Psychrobacter, which have been previously described as bacteria that play a role in the health of cetaceans. In addition, in the healthy bowhead whale (H-BW) samples, we identified Clostridium sensu stricto 1 and 7, Carnobacterium spp., and Yersinia spp. which are of concern because these bacteria are opportunistic pathogens. Stranded BW had a less diverse microbiome than H-BW and had pathogens, including Aeromonas species and Streptococcus agalactia. Opportunistic pathogens of the genera Moritella (previously Vibrio spp.), Shewanella, Psychrilyobacter, and Legionella were discovered in KW. Due to their predator–prey relationships, the findings of this pilot study support the importance of keeping a close eye on the bowhead and killer whale populations in the Arctic.
Copper crosslinked silicone elastomers in RGB colors: degradable on demand
Authors: Hrabowyj Daniel , Wittenberg Liam A. , Donahue-Boyle Erin M. , Chen Yang , Brook Michael A.
Published: October 2023

Increasing demand for fully recyclable polymers has prompted an interest in materials crosslinked via non-covalent interactions. Aggressive depolymerization can cleave backbone SiO bonds to generate linear oils or cyclic monomers from silicone rubbers, but one would rather recover the starting material oils simply by selectively breaking crosslinks. We demonstrate that ligand binding to metals can be used to reversibly crosslink silicone chains. Aminopropylsilicones were crosslinked via complexation with copper (II) acetate to form blue silicone oils. These oils slowly cured in air at room temperature to form soft, green elastomers over a month, or overnight at 50–55 °C in air to give robust, hard red elastomers. Potential explanations for the observed color changes are discussed. Elastomers prepared by either pathway underwent ready degradation by removal of the copper ions via competitive ligand binding using ethylenediamine, allowing for recovery of the unmodified silicone oil; the recovered amine could be reused with more copper to form a (softer) elastomer. This process provides a method for the synthesis of stable elastomeric silicones that are degradable on demand.
Calculations of branching ratios and longitudinal polarization fractions in B0 → K*0K̄*0 and B0s → K*0K̄*0 decays
Authors: Mohammadi Behnam
Published: October 2023

In this paper, I have investigated the two-body pure penguin decays of [Formula: see text] and [Formula: see text], that these were collected with the LHCb detector, and the branching fractions were measured to be [Formula: see text] and [Formula: see text]. I have studied these decay modes within the framework of the factorization approach by using three different energy scales; while in calculating the amplitude of these decays, the multiplications of four vectors of the polarization vectors, such as [Formula: see text], [Formula: see text], and [Formula: see text] appear. These parameters have been calculated based on helicity amplitudes [Formula: see text]; the results obtained for branching fractions in the μ = mb/2 scale are [Formula: see text] and [Formula: see text]. I have also estimated the fractions of longitudinal polarizations in [Formula: see text] and [Formula: see text] decay modes by considering the transverse amplitudes [Formula: see text]; at the μ = mb/2 scale the results are obtained to be [Formula: see text] and [Formula: see text], which are comparable to the experimental results, 0.724 ± 0.051 ± 0.016 and 0.694 ± 0.016 ± 0.012, respectively, reported by the LHCb collaboration.
Non-conserved modified gravity theory
Authors: Fazlollahi H. R.
Published: October 2023

In the curved spacetime the conservation of stress-energy tensor $${\mathcal {T}}_{\,\,\,\,\, \mu ;\nu }^{\nu }=0$$

T

μ
;
ν

ν

=
0

has been questioned by Rastall. However, this idea in which $${\mathcal {T}}_{\,\,\,\,\, \mu ;\nu }^{\nu }=\lambda R_{,\mu }$$

T

μ
;
ν

ν

=
λ

R

,
μ

is own questionable. In this study and in follows the covariant form of thermodynamics law proposed by Israel and his colleagues, the new non-conserved modified gravity is introduced. As its application, we have explored spherically symmetric solutions and evolution of the Universe for very early and late time Universe in the presence of the cosmological constant. As shown, the model gives no new result with respect to Einstein gravity for vacuum solutions, while during inflation only scalar spectra index deviates from standard model. Also, we have considered late-time and constraint model with observations through using MCMC algorithm.
Hardware-Aware Static Optimization of Hyperdimensional Computations
Authors: Yi Pu (Luke) , Achour Sara
Published: October 2023

Binary spatter code (BSC)-based hyperdimensional computing (HDC) is a highly error-resilient approximate computational paradigm suited for error-prone, emerging hardware platforms. In BSC HDC, the basic datatype is a
hypervector
, a typically large binary vector, where the size of the hypervector has a significant impact on the fidelity and resource usage of the computation. Typically, the hypervector size is dynamically tuned to deliver the desired accuracy; this process is time-consuming and often produces hypervector sizes that lack accuracy guarantees and produce poor results when reused for very similar workloads. We present Heim, a hardware-aware static analysis and optimization framework for BSC HD computations. Heim analytically derives the minimum hypervector size that minimizes resource usage and meets the target accuracy requirement. Heim
guarantees
the optimized computation converges to the user-provided accuracy target on expectation, even in the presence of hardware error. Heim deploys a novel static analysis procedure that unifies theoretical results from the neuroscience community to systematically optimize HD computations.

We evaluate Heim against dynamic tuning-based optimization on 25 benchmark data structures. Given a 99% accuracy requirement, Heim-optimized computations achieve a 99.2%-100.0% median accuracy, up to 49.5% higher than dynamic tuning-based optimization, while achieving 1.15x-7.14x reductions in hypervector size compared to HD computations that achieve comparable query accuracy and finding parametrizations 30.0x-100167.4x faster than dynamic tuning-based approaches. We also use Heim to systematically evaluate the performance benefits of using analog CAMs and multiple-bit-per-cell ReRAM over conventional hardware, while maintaining iso-accuracy – for both emerging technologies, we find usages where the emerging hardware imparts significant benefits.
Compiling Structured Tensor Algebra
Authors: Ghorbani Mahdi , Huot Mathieu , Hashemian Shideh , Shaikhha Amir
Published: October 2023

Tensor algebra is essential for data-intensive workloads in various computational domains. Computational scientists face a trade-off between the specialization degree provided by dense tensor algebra and the algorithmic efficiency that leverages the structure provided by sparse tensors. This paper presents StructTensor, a framework that symbolically computes structure at compilation time. This is enabled by Structured Tensor Unified Representation (STUR), an intermediate language that can capture tensor computations as well as their sparsity and redundancy structures. Through a mathematical view of lossless tensor computations, we show that our symbolic structure computation and the related optimizations are sound. Finally, for different tensor computation workloads and structures, we experimentally show how capturing the symbolic structure can result in outperforming state-of-the-art frameworks for both dense and sparse tensor algebra.
Mutually Iso-Recursive Subtyping
Authors: Rossberg Andreas
Published: October 2023

Iso-recursive types are often taken as a type-theoretic model for type recursion as present in many programming languages, e.g., classes in object-oriented languages or algebraic datatypes in functional languages. Their main advantage over an equi-recursive semantics is that they are simpler and algorithmically less expensive, which is an important consideration when the cost of type checking matters, such as for intermediate or low-level code representations, virtual machines, or runtime casts. However, a closer look reveals that iso-recursion cannot, in its standard form, efficiently express essential type system features like mutual recursion or non-uniform recursion. While it has been folklore that mutual recursion and non-uniform type parameterisation can nicely be handled by generalising to higher kinds, this encoding breaks down when combined with subtyping: the classic “Amber” rule for subtyping iso-recursive types is too weak to express mutual recursion without falling back to encodings of quadratic size.

We present a foundational core calculus of iso-recursive types withdeclaredsubtyping that can express both inter- and intra-recursion subtyping without such blowup, including subtyping between constructors of higher or mixed kind. In a second step, we identify a syntactic fragment of this general calculus that allows for more efficient type checking without “deep” substitutions, by observing that higher-kinded iso-recursive types can be inserted to “guard” against unwanted β-reductions. This fragment closely resembles the structure of typical nominal subtype systems, but without requiring nominal semantics. It has been used as the basis for a proposed extension of WebAssembly with recursive types.
Getting into the Flow: Towards Better Type Error Messages for Constraint-Based Type Inference
Authors: Bhanuka Ishan , Parreaux Lionel , Binder David , Brachthäuser Jonathan Immanuel
Published: October 2023

Creating good type error messages for constraint-based type inference systems is difficult. Typical type error messages reflect implementation details of the underlying constraint-solving algorithms rather than the specific factors leading to type mismatches. We propose using subtyping constraints that capture data flow to classify and explain type errors. Our algorithm explains type errors as faulty data flows, which programmers are already used to reasoning about, and illustrates these data flows as sequences of relevant program locations. We show that our ideas and algorithm are not limited to languages with subtyping, as they can be readily integrated with Hindley-Milner type inference. In addition to these core contributions, we present the results of a user study to evaluate the quality of our messages compared to other implementations. While the quantitative evaluation does not show that flow-based messages improve the localization or understanding of the causes of type errors, the qualitative evaluation suggests a real need and demand for flow-based messages.
Two Birds with One Stone: Boosting Code Generation and Code Search via a Generative Adversarial Network
Authors: Wang Shangwen , Lin Bo , Sun Zhensu , Wen Ming , Liu Yepang , Lei Yan , Mao Xiaoguang
Published: October 2023

Automatically transforming developers' natural language descriptions into source code has been a longstanding goal in software engineering research.
Two types of approaches have been proposed in the literature to achieve this: code generation, which involves generating a new code snippet, and code search, which involves reusing existing code.
However, despite existing efforts, the effectiveness of the state-of-the-art techniques remains limited.
To seek for further advancement, our insight is that code generation and code search can help overcome the limitation of each other:
the code generator can benefit from feedback on the quality of its generated code, which can be provided by the code searcher, while the code searcher can benefit from the additional training data augmented by the code generator to better understand code semantics.
Drawing on this insight, we propose a novel approach that combines code generation and code search techniques using a generative adversarial network (GAN), enabling mutual improvement through the adversarial training.
Specifically, we treat code generation and code search as the generator and discriminator in the GAN framework, respectively, and incorporate several customized designs for our tasks.
We evaluate our approach in eight different settings, and consistently observe significant performance improvements for both code generation and code search.
For instance, when using NatGen, a state-of-the-art code generator, as the generator and GraphCodeBERT, a state-of-the-art code searcher, as the discriminator, we achieve a 32% increase in CodeBLEU score for code generation, and a 12% increase in mean reciprocal rank for code search on a large-scale Python dataset, compared to their original performances.
Fast and Efficient Boolean Unification for Hindley-Milner-Style Type and Effect Systems
Authors: Madsen Magnus , van de Pol Jaco , Henriksen Troels
Published: October 2023

As type and effect systems become more expressive there is an increasing need for efficient type inference. We consider a polymorphic effect system based on Boolean formulas where inference requires Boolean unification. Since Boolean unification involves semantic equivalence, conventional syntax-driven unification is insufficient. At the same time, existing Boolean unification techniques are ill-suited for type inference.
We propose a hybrid algorithm for solving Boolean unification queries based on Boole’s Successive Variable Elimination (SVE) algorithm. The proposed approach builds on several key observations regarding the Boolean unification queries encountered in practice, including: (i) most queries are simple, (ii) most queries involve a few flexible variables, (iii) queries are likely to repeat due similar programming patterns, and (iv) there is a long tail of complex queries. We exploit these observations to implement several strategies for formula minimization, including ones based on tabling and binary decision diagrams.
We implement the new hybrid approach in the Flix programming language. Experimental results show that by reducing the overhead of Boolean unification, the compilation throughput increases from 8,580 lines/sec to 15,917 lines/sec corresponding to a 1.8x speed-up. Further, the overhead on type and effect inference time is only 16% which corresponds to an overhead of less than 7% on total compilation time. We study the hybrid approach and demonstrate that each design choice improves performance.
Concrete Type Inference for Code Optimization using Machine Learning with SMT Solving
Authors: Ye Fangke , Zhao Jisheng , Shirako Jun , Sarkar Vivek
Published: October 2023

Despite the widespread popularity of dynamically typed languages such as Python, it is well known that they pose significant challenges to code optimization due to the lack of concrete type information. To overcome this limitation, many ahead-of-time optimizing compiler approaches for Python rely on programmers to provide optional type information as a prerequisite for extensive code optimization. Since few programmers provide this information, a large majority of Python applications are executed without the benefit of code optimization, thereby contributing collectively to a significant worldwide wastage of compute and energy resources.

In this paper, we introduce a new approach to concrete type inference that is shown to be effective in enabling code optimization for dynamically typed languages, without requiring the programmer to provide any type information. We explore three kinds of type inference algorithms in our approach based on: 1) machine learning models including GPT-4, 2) constraint-based inference based on SMT solving, and 3) a combination of 1) and 2). Our approach then uses the output from type inference to generate multi-version code for a bounded number of concrete type options, while also including a catch-all untyped version for the case when no match is found. The typed versions are then amenable to code optimization. Experimental results show that the combined algorithm in 3) delivers far superior precision and performance than the separate algorithms for 1) and 2). The performance improvement due to type inference, in terms of geometric mean speedup across all benchmarks compared to standard Python, when using 3) is 26.4× with Numba as an AOT optimizing back-end and 62.2× with the Intrepydd optimizing compiler as a back-end. These vast performance improvements can have a significant impact on programmers’ productivity, while also reducing their applications’ use of compute and energy resources.
Initializing Global Objects: Time and Order
Authors: Liu Fengyun , Lhoták Ondřej , Hua David , Xing Enze
Published: October 2023

Object-oriented programming has been bothered by an awkward feature for a long time:
static members
. Static members not only compromise the conceptual integrity of object-oriented programming, but also give rise to subtle initialization errors, such as reading non-initialized fields and deadlocks.

The Scala programming language eliminated static members from the language, replacing them with
global objects
that present a unified object-oriented programming model. However, the problem of global object initialization remains open, and programmers still suffer from initialization errors.

We propose
partial ordering
and
initialization-time irrelevance
as two fundamental principles for initializing global objects. Based on these principles, we put forward an effective static analysis to ensure safe initialization of global objects, which eliminates initialization errors at compile time. The analysis also enables static scheduling of global object initialization to avoid runtime overhead. The analysis is modular at the granularity of objects and it avoids whole-program analysis. To make the analysis explainable and tunable, we introduce the concept of
regions
to make context-sensitivity understandable and customizable by programmers.
Formal Abstractions for Packet Scheduling
Authors: Mohan Anshuman , Liu Yunhe , Foster Nate , Kappé Tobias , Kozen Dexter
Published: October 2023

Early programming models for software-defined networking (SDN) focused on basic features for controlling network-wide forwarding paths, but more recent work has considered richer features, such as packet scheduling and queueing, that affect performance. In particular,PIFO trees, proposed by Sivaraman et al., offer a flexible and efficient primitive forprogrammablepacket scheduling. Prior work has shown that PIFO trees can express a wide range of practical algorithms including strict priority, weighted fair queueing, and hierarchical schemes. However, the semantic properties of PIFO trees are not well understood.

This paper studies PIFO trees from a programming language perspective. We formalize the syntax and semantics of PIFO trees in an operational model that decouples the scheduling policy running on a tree from the topology of the tree. Building on this formalization, we develop compilation algorithms that allow the behavior of a PIFO tree written against one topology to be realized using a tree with a different topology. Such a compiler could be used to optimize an implementation of PIFO trees, or realize a logical PIFO tree on a target with a fixed topology baked into the hardware. To support experimentation, we develop a software simulator for PIFO trees, and we present case studies illustrating its behavior on standard and custom algorithms.
Stuttering for Free
Authors: Cho Minki , Song Youngju , Lee Dongjae , Gäher Lennard , Dreyer Derek
Published: October 2023

One of the most common tools for proving behavioral refinements between transition systems is the method of
simulation
proofs, which has been explored extensively over the past several decades. Stuttering simulations are an extension of traditional simulations—used, for example, in CompCert—in which either the source or target of the simulation is permitted to “stutter” (stay in place) while the other side steps forward. In the interest of ensuring soundness, however, existing stuttering simulations restrict proofs to only perform a finite number of stuttering steps before making
synchronous progress
—a step of reasoning in which both sides of the simulation progress forward together. This restriction guarantees that a terminating program cannot be proven to simulate a non-terminating one.

In this paper, we observe that the requirement to eventually achieve synchronous progress is burdensome and, what’s more, unnecessary: it is possible to ensure soundness of stuttering simulations while only requiring
asynchronous progress
(progress on both sides of the simulation that may be achieved with only stuttering steps). Building on this observation, we develop a new simulation technique we call
FreeSim
(short for “freely-stuttering simulations”), mechanized in Coq, and we demonstrate its effectiveness on a range of interesting case studies. These include a simplification of the meta-theory of CompCert, as well as the
DTrees
library, which enriches the ITrees (Interaction Trees) library with dual non-determinism.
Data Extraction via Semantic Regular Expression Synthesis
Authors: Chen Qiaochu , Banerjee Arko , Demiralp Çağatay , Durrett Greg , Dillig Işıl
Published: October 2023

Many data extraction tasks of practical relevance require not only syntactic pattern matching but also semantic reasoning about the content of the underlying text. While regular expressions are very well suited for tasks that require only syntactic pattern matching, they fall short for data extraction tasks that involve both a syntactic and semantic component. To address this issue, we introduce semantic regexes, a generalization of regular expressions that facilitates combined syntactic and semantic reasoning about textual data. We also propose a novel learning algorithm that can synthesize semantic regexes from a small number of positive and negative examples. Our proposed learning algorithm uses a combination of neural sketch generation and compositional type-directed synthesis for fast and effective generalization from a small number of examples. We have implemented these ideas in a new tool called Smore and evaluated it on representative data extraction tasks involving several textual datasets. Our evaluation shows that semantic regexes can better support complex data extraction tasks than standard regular expressions and that our learning algorithm significantly outperforms existing tools, including state-of-the-art neural networks and program synthesis tools.
Historia: Refuting Callback Reachability with Message-History Logics
Authors: Meier Shawn , Mover Sergio , Kaki Gowtham , Chang Bor-Yuh Evan
Published: October 2023

This paper considers the callback reachability problem --- determining if a callback can be called by an event-driven framework in an unexpected state.
Event-driven programming frameworks are pervasive for creating user-interactive applications (apps) on just about every modern platform.
Control flow between callbacks is determined by the framework and largely opaque to the programmer.
This opacity of the callback control flow not only causes difficulty for the programmer but is also difficult for those developing static analysis.
Previous static analysis techniques address this opacity either by assuming an arbitrary framework implementation or attempting to eagerly specify all possible callback control flow,
but this is either too coarse to prove properties requiring callback-ordering constraints or too burdensome and tricky to get right.
Instead, we present a middle way where the callback control flow can be gradually refined in a targeted manner to prove assertions of interest.
The key insight to get this middle way is by reasoning about the history of method invocations at the boundary between app and framework code --- enabling a decoupling of the specification of callback control flow from the analysis of app code.
We call the sequence of such boundary-method invocations message histories and develop message-history logics to do this reasoning.
In particular, we define the notion of an application-only transition system with boundary transitions, a message-history program logic for programs with such transitions, and a temporal specification logic for capturing callback control flow in a targeted and compositional manner.
Then to utilize the logics in a goal-directed verifier, we define a way to combine after-the-fact an assertion about message histories with a specification of callback control flow.
We implemented a prototype message history-based verifier called Historia and provide evidence that our approach is uniquely capable of distinguishing between buggy and fixed versions on challenging examples drawn from real-world issues and that our targeted specification approach enables proving the absence of multi-callback bug patterns in real-world open-source Android apps.
Synthesizing Precise Static Analyzers for Automatic Differentiation
Authors: Laurel Jacob , Qian Siyuan Brant , Singh Gagandeep , Misailovic Sasa
Published: October 2023

We present Pasado, a technique for synthesizing precise static analyzers for Automatic Differentiation. Our technique allows one to automatically construct a static analyzer specialized for the Chain Rule, Product Rule, and Quotient Rule computations for Automatic Differentiation in a way that abstracts all of the nonlinear operations of each respective rule simultaneously. By directly synthesizing an abstract transformer for the composite expressions of these 3 most common rules of AD, we are able to obtain significant precision improvement compared to prior works which compose standard abstract transformers together suboptimally. We prove our synthesized static analyzers sound and additionally demonstrate the generality of our approach by instantiating these AD static analyzers with different nonlinear functions, different abstract domains (both intervals and zonotopes) and both forward-mode and reverse-mode AD.

We evaluate Pasado on multiple case studies, namely soundly computing bounds on a neural network’s
local Lipschitz constant, soundly bounding the sensitivities of financial models, certifying monotonicity, and lastly, bounding sensitivities of the solutions of differential equations from climate science and chemistry for verified ranges of initial conditions and parameters. The local Lipschitz constants computed by Pasado on our largest CNN are up to 2750× more precise compared to the existing state-of-the-art zonotope analysis. The bounds obtained on the sensitivities of the climate, chemical, and financial differential equation solutions are between 1.31 − 2.81× more precise (on average) compared to a state-of-the-art zonotope analysis.
Solving String Constraints with Lengths by Stabilization
Authors: Chen Yu-Fang , Chocholatý David , Havlena Vojtěch , Holík Lukáš , Lengál Ondřej , Síč Juraj
Published: October 2023

We present a new algorithm for solving string constraints. The algorithm builds upon a recent method for solving word equations and regular constraints that interprets string variables as languages rather than strings and, consequently, mitigates the combinatorial explosion that plagues other approaches. We extend the approach to handle linear integer arithmetic length constraints by combination with a known principle of equation alignment and splitting, and by extension to other common types of string constraints, yielding a fully-fledged string solver. The ability of the framework to handle unrestricted disequalities even extends one of the largest decidable classes of string constraints, the chain-free fragment. We integrate our algorithm into a DPLL-based SMT solver. The performance of our implementation is competitive and even significantly better than state-of-the-art string solvers on several established benchmarks obtained from applications in verification of string programs.
Explainable Program Synthesis by Localizing Specifications
Authors: Nazari Amirmohammad , Huang Yifei , Samanta Roopsha , Radhakrishna Arjun , Raghothaman Mukund
Published: October 2023

The traditional formulation of the program synthesis problem is to find a program that meets a logical correctness specification. When synthesis is successful, there is a guarantee that the implementation satisfies the specification. Unfortunately, synthesis engines are typically monolithic algorithms, and obscure the correspondence between the specification, implementation and user intent. In contrast, humans often include comments in their code to guide future developers towards the purpose and design of different parts of the codebase. In this paper, we introduce
subspecifications
as a mechanism to augment the synthesized implementation with explanatory notes of this form. In this model, the user may ask for explanations of different parts of the implementation; the subspecification generated in response is a logical formula that describes the constraints induced on that subexpression by the global specification and surrounding implementation. We develop algorithms to construct and verify subspecifications and investigate their theoretical properties. We perform an experimental evaluation of the subspecification generation procedure, and measure its effectiveness and running time. Finally, we conduct a user study to determine whether subspecifications are useful: we find that subspecifications greatly aid in understanding the global specification, in identifying alternative implementations, and in debugging faulty implementations.
Perception Contracts for Safety of ML-Enabled Systems
Authors: Astorga Angello , Hsieh Chiao , Madhusudan P. , Mitra Sayan
Published: October 2023

We introduce a novel notion of perception contracts to reason about the safety of controllers that interact with an environment using neural perception. Perception contracts capture errors in ground-truth estimations that preserve invariants when systems act upon them. We develop a theory of perception contracts and design symbolic learning algorithms for synthesizing them from a finite set of images. We implement our algorithms and evaluate synthesized perception contracts for two realistic vision-based control systems, a lane tracking system for an electric vehicle and an agricultural robot that follows crop rows. Our evaluation shows that our approach is effective in synthesizing perception contracts and generalizes well when evaluated over test images obtained during runtime monitoring of the systems.
Message Chains for Distributed System Verification
Authors: Mora Federico , Desai Ankush , Polgreen Elizabeth , Seshia Sanjit A.
Published: October 2023

Verification of asynchronous distributed programs is challenging due to the need to reason about numerous control paths resulting from the myriad interleaving of messages and failures. In this paper, we propose an automated bookkeeping method based on message chains. Message chains reveal structure in asynchronous distributed system executions and can help programmers verify their systems at the message passing level of abstraction. To evaluate our contributions empirically we build a verification prototype for the P programming language that integrates message chains. We use it to verify 16 benchmarks from related work, one new benchmark that exemplifies the kinds of systems our method focuses on, and two industrial benchmarks. We find that message chains are able to simplify existing proofs and our prototype performs comparably to existing work in terms of runtime. We extend our work with support for specification mining and find that message chains provide enough structure to allow existing learning and program synthesis tools to automatically infer meaningful specifications using only execution examples.
Bridging the Gap between Spatial and Spectral Domains: A Unified Framework for Graph Neural Networks
Authors: Chen Zhiqian , Chen Fanglan , Zhang Lei , Ji Taoran , Fu Kaiqun , Zhao Liang , Chen Feng , Wu Lingfei , Aggarwal Charu , Lu Chang-Tien
Published: October 2023

Deep learning’s performance has been extensively recognized recently. Graph neural networks (GNNs) are designed to deal with graph-structural data that classical deep learning does not easily manage. Since most GNNs were created using distinct theories, direct comparisons are impossible. Prior research has primarily concentrated on categorizing existing models, with little attention paid to their intrinsic connections. The purpose of this study is to establish a unified framework that integrates GNNs based on spectral graph and approximation theory. The framework incorporates a strong integration between spatial- and spectral-based GNNs while tightly associating approaches that exist within each respective domain.
Obesity does not alter vascular function and handgrip exercise hemodynamics in middle-aged patients with hypertension
Authors: Ratchford Stephen M. , Broxterman Ryan M. , La Salle D. Taylor , Kwon Oh Sung , Hopkins Paul N. , Richardson Russell S. , Trinity Joel D.
Published: October 2023

This study examined vascular function and handgrip exercise hemodynamics in obese and nonobese individuals with hypertension. Obesity, when combined with hypertension, was neither associated with additional vascular function impairments at baseline nor peripheral hemodynamics and vasodilation during exercise compared with nonobese hypertension. Interestingly, systolic blood pressure and pulse pressure were greater in the obese group during supine baseline and exercise. These findings should not be ignored and may be particularly important for rehabilitation strategies.