bluuebunny/crossref_metadata_2025 huggingface dataset:
Verifying the Verifier: eBPF Range Analysis Verification
Authors: Vishwanathan Harishankar , Shachnai Matan , Narayana Srinivas , Nagarakatte Santosh
Published: July 2023

This paper proposes an automated method to check the correctness of range analysis used in the Linux kernel ’s eBPF verifier. We provide the specification of soundness for range analysis performed by the eBPF verifier. We automatically generate verification conditions that encode the operation of the eBPF verifier directly from the Linux kernel ’s C source code and check it against our specification. When we discover instances where the eBPF verifier is unsound, we propose a method to generate an eBPF program that demonstrates the mismatch between the abstract and the concrete semantics. Our prototype automatically checks the soundness of 16 versions of the eBPF verifier in the Linux kernel versions ranging from 4.14 to 5.19. In this process, we have discovered new bugs in older versions and proved the soundness of range analysis in the latest version of the Linux kernel.
Boolean Abstractions for Realizability Modulo Theories
Authors: Rodríguez Andoni , Sánchez César
Published: July 2023

In this paper, we address the problem of the (reactive) realizability of specifications of theories richer than Booleans, including arithmetic theories. Our approach transforms theory specifications into purely Boolean specifications by (1) substituting theory literals by Boolean variables, and (2) computing an additional Boolean requirement that captures the dependencies between the new variables imposed by the literals. The resulting specification can be passed to existing Boolean off-the-shelf realizability tools, and is realizable if and only if the original specification is realizable. The first contribution is a brute-force version of our method, which requires a number of SMT queries that is doubly exponential in the number of input literals. Then, we present a faster method that exploits a nested encoding of the search for the extra requirement and uses SAT solving for faster traversing the search space and uses SMT queries internally. Another contribution is a prototype in Z3-Python. Finally, we report an empirical evaluation using specifications inspired in real industrial cases. To the best of our knowledge, this is the first method that succeeds in non-Boolean LTL realizability.
Early Verification of Legal Compliance via Bounded Satisfiability Checking
Authors: Feng Nick , Marsso Lina , Sabetzadeh Mehrdad , Chechik Marsha
Published: July 2023

Legal properties involve reasoning about data values and time. Metric first-order temporal logic (MFOTL) provides a rich formalism for specifying legal properties. While MFOTL has been successfully used for verifying legal properties over operational systems via runtime monitoring, no solution exists for MFOTL-based verification in early-stage system development captured by requirements. Given a legal property and system requirements, both formalized in MFOTL, the compliance of the property can be verified on the requirements via satisfiability checking. In this paper, we propose a practical, sound, and complete (within a given bound) satisfiability checking approach for MFOTL. The approach, based on satisfiability modulo theories (SMT), employs a counterexample-guided strategy to incrementally search for a satisfying solution. We implemented our approach using the Z3 SMT solver and evaluated it on five case studies spanning the healthcare, business administration, banking and aviation domains. Our results indicate that our approach can efficiently determine whether legal properties of interest are met, or generate counterexamples that lead to compliance violations.
Formula Normalizations in Verification
Authors: Guilloud Simon , Bucev Mario , Milovančević Dragana , Kunčak Viktor
Published: July 2023

We apply and evaluate polynomial-time algorithms to compute two different normal forms of propositional formulas arising in verification. One of the normal form algorithms is presented for the first time. The algorithms compute normal forms and solve the word problem for two different subtheories of Boolean algebra: orthocomplemented bisemilattice (OCBSL) and ortholattice (OL). Equality of normal forms decides the word problem and is a sufficient (but not necessary) check for equivalence of propositional formulas. Our first contribution is a quadratic-time OL normal form algorithm, which induces a coarser equivalence than the OCBSL normal form and is thus a more precise approximation of propositional equivalence. The algorithm is efficient even when the input formula is represented as a directed acyclic graph. Our second contribution is the evaluation of OCBSL and OL normal forms as part of a verification condition cache of the Stainless verifier for Scala. The results show that both normalization algorithms substantially increase the cache hit ratio and improve the ability to prove verification conditions by simplification alone. To gain further insights, we also compare the algorithms on hardware circuit benchmarks, showing that normalization reduces circuit size and works well in the presence of sharing.
Automated Tail Bound Analysis for Probabilistic Recurrence Relations
Authors: Sun Yican , Fu Hongfei , Chatterjee Krishnendu , Goharshady Amir Kafshdar
Published: July 2023

Probabilistic recurrence relations (PRRs) are a standard formalism for describing the runtime of a randomized algorithm. Given a PRR and a time limit $$\kappa $$
κ
, we consider the tail probability $$\Pr [T \ge \kappa ]$$

Pr
[
T
≥
κ
]

, i.e., the probability that the randomized runtime T of the PRR exceeds $$\kappa $$
κ
. Our focus is the formal analysis of tail bounds that aims at finding a tight asymptotic upper bound $$u \ge \Pr [T\ge \kappa ]$$

u
≥
Pr
[
T
≥
κ
]

. To address this problem, the classical and most well-known approach is the cookbook method by Karp (JACM 1994), while other approaches are mostly limited to deriving tail bounds of specific PRRs via involved custom analysis.

In this work, we propose a novel approach for deriving the common exponentially-decreasing tail bounds for PRRs whose preprocessing time and random passed sizes observe discrete or (piecewise) uniform distribution and whose recursive call is either a single procedure call or a divide-and-conquer. We first establish a theoretical approach via Markov’s inequality, and then instantiate the theoretical approach with a template-based algorithmic approach via a refined treatment of exponentiation. Experimental evaluation shows that our algorithmic approach is capable of deriving tail bounds that are (i) asymptotically tighter than Karp’s method, (ii) match the best-known manually-derived asymptotic tail bound for QuickSelect, and (iii) is only slightly worse (with a $$\log \log n$$

log
log
n

factor) than the manually-proven optimal asymptotic tail bound for QuickSort. Moreover, our algorithmic approach handles all examples (including realistic PRRs such as QuickSort, QuickSelect, DiameterComputation, etc.) in less than 0.1 s, showing that our approach is efficient in practice.
Kratos2: An SMT-Based Model Checker for Imperative Programs
Authors: Griggio Alberto , Jonáš Martin
Published: July 2023

This paper describes , a tool for the verification of imperative programs. operates on an intermediate verification language called , with a formally-specified semantics based on smt, allowing the specification of both reachability and liveness properties. It integrates several state-of-the-art verification engines based on sat and smt. Moreover, it provides additional functionalities such as a flexible Python api, a customizable C front-end, generation of counterexamples, support for simulation and symbolic execution, and translation into multiple low-level verification formalisms. Our experimental analysis shows that is competitive with state-of-the-art software verifiers on a large range of programs. Thanks to its flexibility, has already been used in various industrial projects and academic publications, both as a verification back-end and as a benchmark generator.
Making $$\textsf {IP}=\textsf {PSPACE}$$ Practical: Efficient Interactive Protocols for BDD Algorithms
Authors: Couillard Eszter , Czerner Philipp , Esparza Javier , Majumdar Rupak
Published: July 2023

We show that interactive protocols between a prover and a verifier, a well-known tool of complexity theory, can be used in practice to certify the correctness of automated reasoning tools.

Theoretically, interactive protocols exist for all $$\textsf {PSPACE}$$
PSPACE
problems. The verifier of a protocol checks the prover’s answer to a problem instance in probabilistic polynomial time, with polynomially many bits of communication, and with exponentially small probability of error. (The prover may need exponential time.) Existing interactive protocols are not used in practice because their provers use naive algorithms, inefficient even for small instances, that are incompatible with practical implementations of automated reasoning.

We bridge the gap between theory and practice by means of an interactive protocol whose prover uses BDDs. We consider the problem of counting the number of assignments to a QBF instance ($$\#\text {CP}$$

#
CP

), which has a natural BDD-based algorithm. We give an interactive protocol for $$\#\text {CP}$$

#
CP

whose prover is implemented on top of an extended BDD library. The prover has only a linear overhead in computation time over the natural algorithm.

We have implemented our protocol in $$\textsf {blic}$$
blic
, a certifying tool for $$\#\text {CP}$$

#
CP

. Experiments on standard QBF benchmarks show that is competitive with state-of-the-art QBF-solvers. The run time of the verifier is negligible. While loss of absolute certainty can be concerning, the error probability in our experiments is at most $$10^{-10}$$

10

-
10

and reduces to $$10^{-10k}$$

10

-
10
k

by repeating the verification k times.
R2U2 Version 3.0: Re-Imagining a Toolchain for Specification, Resource Estimation, and Optimized Observer Generation for Runtime Verification in Hardware and Software
Authors: Johannsen Chris , Jones Phillip , Kempa Brian , Rozier Kristin Yvonne , Zhang Pei
Published: July 2023

R2U2 is a modular runtime verification framework capable of monitoring sets of specifications in real time and in resource-constrained environments. Such environments demand that a runtime monitor be fast, easily integratable, accessible to domain experts, and have predictable resource requirements. Version 3.0 adds new features to R2U2 and its associated suite of tools that meet these needs including a new front-end compiler that accepts a custom specification language, a GUI for resource estimation, and improvements to R2U2’s internal architecture.
Efficient Sensitivity Analysis for Parametric Robust Markov Chains
Authors: Badings Thom , Junges Sebastian , Marandi Ahmadreza , Topcu Ufuk , Jansen Nils
Published: July 2023

We provide a novel method for sensitivity analysis of parametric robust Markov chains. These models incorporate parameters and sets of probability distributions to alleviate the often unrealistic assumption that precise probabilities are available. We measure sensitivity in terms of partial derivatives with respect to the uncertain transition probabilities regarding measures such as the expected reward. As our main contribution, we present an efficient method to compute these partial derivatives. To scale our approach to models with thousands of parameters, we present an extension of this method that selects the subset ofkparameters with the highest partial derivative. Our methods are based on linear programming and differentiating these programs around a given value for the parameters. The experiments show the applicability of our approach on models with over a million states and thousands of parameters. Moreover, we embed the results within an iterative learning scheme that profits from having access to a dedicated sensitivity analysis.
MDPs as Distribution Transformers: Affine Invariant Synthesis for Safety Objectives
Authors: Akshay S. , Chatterjee Krishnendu , Meggendorfer Tobias , Žikelić Đorđe
Published: July 2023

Markov decision processes can be viewed as transformers of probability distributions. While this view is useful from a practical standpoint to reason about trajectories of distributions, basic reachability and safety problems are known to be computationally intractable (i.e., Skolem-hard) to solve in such models. Further, we show that even for simple examples of MDPs, strategies for safety objectives over distributions can require infinite memory and randomization.

In light of this, we present a novel overapproximation approach to synthesize strategies in an MDP, such that a safety objective over the distributions is met. More precisely, we develop a new framework for template-based synthesis of certificates as affine distributional and inductive invariants for safety objectives in MDPs. We provide two algorithms within this framework. One can only synthesize memoryless strategies, but has relative completeness guarantees, while the other can synthesize general strategies. The runtime complexity of both algorithms is in PSPACE. We implement these algorithms and show that they can solve several non-trivial examples.
Search and Explore: Symbiotic Policy Synthesis in POMDPs
Authors: Andriushchenko Roman , Bork Alexander , Češka Milan , Junges Sebastian , Katoen Joost-Pieter , Macák Filip
Published: July 2023

This paper marries two state-of-the-art controller synthesis methods for partially observable Markov decision processes (POMDPs), a prominent model in sequential decision making under uncertainty. A central issue is to find a POMDP controller—that solely decides based on the observations seen so far—to achieve a total expected reward objective. As finding optimal controllers is undecidable, we concentrate on synthesising good finite-state controllers (FSCs). We do so by tightly integrating two modern, orthogonal methods for POMDP controller synthesis: a belief-based and an inductive approach. The former method obtains an FSC from a finite fragment of the so-called belief MDP, an MDP that keeps track of the probabilities of equally observable POMDP states. The latter is an inductive search technique over a set of FSCs, e.g., controllers with a fixed memory size. The key result of this paper is a symbiotic anytime algorithm that tightly integrates both approaches such that each profits from the controllers constructed by the other. Experimental results indicate a substantial improvement in the value of the controllers while significantly reducing the synthesis time and memory footprint.
AutoQ: An Automata-Based Quantum Circuit Verifier
Authors: Chen Yu-Fang , Chung Kai-Min , Lengál Ondřej , Lin Jyun-Ao , Tsai Wei-Lun
Published: July 2023

We present a specification language and a fully automated tool named AutoQ for verifying quantum circuits symbolically. The tool implements the automata-based algorithm from [14] and extends it with the capabilities for symbolic reasoning. The extension allows to specify relational properties, i.e., relationships between states before and after executing a circuit. We present a number of use cases where we used AutoQ to fully automatically verify crucial properties of several quantum circuits, which have, to the best of our knowledge, so far been proved only with human help.
Bounded Verification for Finite-Field-Blasting
Authors: Ozdemir Alex , Wahby Riad S. , Brown Fraser , Barrett Clark
Published: July 2023

Zero Knowledge Proofs (ZKPs) are cryptographic protocols by which a prover convinces a verifier of the truth of a statement without revealing any other information. Typically, statements are expressed in a high-level language and then compiled to a low-level representation on which the ZKP operates. Thus,a bug in a ZKP compiler can compromise the statement that the ZK proof is supposed to establish.This paper takes a step towards ZKP compiler correctness by partially verifying afield-blastingcompiler pass, a pass that translates Boolean and bit-vector logic into equivalent operations in a finite field. First, we define correctness for field-blasters and ZKP compilers more generally. Next, we describe the specific field-blaster using a set of encoding rules and define verification conditions for individual rules. Finally, we connect the rules and the correctness definition by showing that if our verification conditions hold, the field-blaster is correct. We have implemented our approach in the CirC ZKP compiler and have proved bounded versions of the corresponding verification conditions. We show that our partially verified field-blaster does not hurt the performance of the compiler or its output; we also report on four bugs uncovered during verification.
Local gradient theory of dielectrics incorporating polarization inertia and flexodynamic effect
Authors: Hrytsyna Olha , Tokovyy Yuriy , Hrytsyna Maryan
Published: July 2023

A higher-grade theory of non-ferromagnetic thermo-elastic dielectrics which incorporates the local mass displacement, the heat flux gradient, polarization inertia, and flexodynamic effects is developed. The process of local mass displacement is associated with changes in material microstructure. Using the fundamental principles of continuum mechanics, electrodynamics, and non-equilibrium thermodynamics, the gradient-type constitutive equations are derived. Due to accounting for the polarization inertia, the rheological constitutive equation for the polarization vector is obtained. In the balance equation of linear momentum, an additional term with the second time derivative of the polarization vector appears in comparison with the classical theory. This term controls the influence of the dynamic flexoelectric effect on the mechanical motion of dielectric solids. The propagation of a plane harmonic wave is analyzed within the context of the developed theory. It is shown that the theory allows for capturing the experimentally observed phenomenon of high-frequency dispersion of a longitudinal elastic wave. The theory may be useful for modeling coupled processes in nanodielectrics and heterogeneous polarized systems.
Control of nonlinear bulk deformation and large shear strain on first-order phase transformation kinetics
Authors: Utkin Ivan , Khakimova Liudmila , Schmalholz Stefan Markus , Podladchikov Yury
Published: July 2023

Phase transformations play a key role in numerous coupled natural processes, and they are important for many industrial applications. However, the kinetics of phase transformations in coupled chemo-mechanical systems undergoing large mechanical deformations still needs to be better quantified. Here, we study the phase transformation kinetics of a two-phase binary mixture using the diffuse interface approach. We couple a Cahn–Hilliard type model with a mechanical model for a compressible viscous flow. The bulk compressibility is a nonlinear function of the pressure, and the shear viscosity is a nonlinear function of the concentration. The mechanical coupling is achieved by employing a pressure-dependent mechanical mixing term in the equation for the Gibbs energy. We derive a dimensionless system of equations which we solve numerically with a pseudo-transient method using conservative finite differences for discretization. We perform numerical simulations in 1D and 2D model setups considering far-field simple shear and pure shear. For a chemo-mechanically coupled system, we show that the velocity of the phase boundary is a linear function of the degree of metastability and, hence, confirm the hypothesis of “normal growth.” A stronger mechanical coupling and a larger volumetric effect of the chemical reaction result in lower phase boundary velocities. The 2D results show a significant impact of the mechanical coupling and the far-field deformation on the orientation and kinetics of the phase transformations. Under far-field simple shear and pure shear in 2D, the phase transformations generate string-like patterns. The orientation of these patterns is controlled by the applied far-field deformation and orientations differ by 45 degrees between simple shear and pure shear.
Ball-end micro-milling of material measures: wear behavior in field use
Authors: Klauer-Dobrowolski Katja , Eifler Matthias , Kirsch Benjamin , Seewig Jörg , Aurich Jan C.
Published: July 2023

Micro-milling
is a precise method for micro-structuring component surfaces. When complex or free-form structures like material measures are to be manufactured, ball-end milling tools are particularly suitable. In preliminary studies by the authors, areal material measures for the calibration of optical topography measuring instruments were manufactured via micro-milling. The demands on the surface quality of the material measures are extremely high. Therefore, worn tools must not be used if the wear has a direct effect on the resulting topography of the manufactured material measures. At the same time, the micro-milling tools used are very costly and should therefore be used as long as possible. A comprehensive experimental study was carried out on the wear behavior of different ball-end micro-milling tools for the specific use case of areal material measures. In the investigations, brass CuZn39Pb3 was machined and different areal material measures were manufactured. The tool life dependent wear was determined and critical wear was identified.
Disease activity and disease-related factors are drivers of patient global assessment in rheumatoid arthritis: a real-life cross-sectional study
Authors: Suardi Ilaria , Posio Cristina , Luconi Ester , Boracchi Patrizia , Caporali Roberto , Ingegnoli Francesca
Published: July 2023

Despite that the Patient Global Assessment (PGA) is widely used for measuring Rheumatoid Arthritis (RA) disease activity to define the remission state of the disease, the primary contributors influencing patients’ ratings are still debated. This study aims to determine which clinical, sociodemographic and lifestyle-related contextual factors might be key drivers of PGA in RA. This single-center cross-sectional study recruited 393 consecutive adult RA patients. Median age 60 years, females 306 (77.9%). Data related to disease activity were assessed by using Simplified Disease Activity Index (SDAI), severity by Health Assessment Questionnaire (HAQ), and impact by RA Impact of Disease (RAID). Sociodemographic/lifestyle features were collected. Disease remission was calculated using Boolean-based criteria 1.0 and 2.0. Quantile regression models were used for univariate and multivariate analysis. The remission rate progressively increased from 15% by using SDAI with a Boolean 1.0-based definition to 43.5% using a Boolean 2.0-based remission. Among factors related to disease activity, the use of low-dose corticosteroids, the RAID items pain and sleep difficulties were predictive for worse PGA scores (p = 0.01). Among factors related to disease severity HAQ score and RAID total were independent factors associated with higher median PGA (p = 0.02 and p < 0.001). RAID’s physical well-being was related to PGA scores (p = 0.01). An increasing trend in PGA was observed in longstanding diseases (> 15 years). Our results confirmed that there is no unambiguous interpretation of the PGA score. It is a measure related to some disease activity parameters, but it is also influenced by contextual factors related to disease severity and impact. These data highlighted that PGA should have a broad interpretation, thus supporting the proposal of a dual targets (biological and impact) approach to obtain a more accurate estimate of disease activity.
Magnetic Resonance Velocimetry for porous media: sources and reduction of measurement errors for improved accuracy
Authors: Ricke Adrian , Sadeghi Mehrdad , Dreher Wolfgang
Published: July 2023

Nuclear Magnetic Resonance (NMR) is a powerful tool for noninvasively investigating static and dynamic properties of fluids inside complex and opaque structures. Thus, Magnetic Resonance Velocimetry (MRV) allows for the in situ analysis of the local flow velocity of fluids. Such an analysis characterises mass transport properties and helps to validate or improve numerical predictions for porous media. The benefit of such validations is lowered by several problems worsening the measurement accuracy. This publication addresses systematic errors and the influence of noise, which may reduce the accuracy of MRV measurements. Techniques are described to minimise or correct displacement and phase errors. A new multi-echo MRV-sequence is proposed as a compromise between Velocity-to-Noise Ratio (VNR), total measurement time, spatial resolution and displacement errors. For improved VNR, a dual-VENC encoding scheme was used and repetition time $$T_{\text{R}}$$

T
R

was optimised. As an example, the proposed MRV sequence was used to measure the three-directional flow velocity of water in an Open Cell Foam (OCF) with 10 pores per inch with three-dimensional isotropic spatial resolution.
Clinical impact of a celiac axis stenosis in patients undergoing hepatobiliary surgery
Authors: Bieniek Pawel A. , Katou Shadi , Kraehling Hermann , Masthoff Max , Morgul Haluk , Pascher Andreas , Struecker Benjamin
Published: July 2023

Background

Celiac axis stenosis (CAS) often is an incidental finding in terms of diagnostic for hepatobiliary surgery since most cases remain asymptomatic. It remains unclear whether CAS is a risk factor for postoperative complications after hepatobiliary surgery. Therefore, the aim of this study was to evaluate the impact of an asymptomatic CAS on the postoperative morbidity and survival of patients undergoing hepatobiliary surgery.

Methods

We retrospectively analyzed CT scans and clinicopathological data of 250 consecutive patients undergoing hepatobiliary surgery between 2011 and 2018 in our tertiary center. We compared the postoperative course between patients with and without an incidental CAS as well as their overall survival.

Results

CAS was caused by atherosclerotic stenosis in 16 (64%) patients, by ligamentous stenosis in 4 (16%) and by combined conditions in 5 cases (20%). Mean age of patients in the CAS group was significantly higher in comparison to patients of the non-CAS group (71.0 vs. 59.1 years, p < 0.001). Major hepatectomy was conducted in 40% of the CAS patients and 19.6% of non-CAS patients, respectively (p = 0.036). Interestingly, no statistically significant differences in postoperative morbidity (40 vs. 46.2%, p = 0.673) or in overall survival between the groups (41.3 vs. 51.9 months, p = 0.611) were observed.

Conclusion

Our analysis found no correlation between an asymptomatic celiac axis stenosis and postoperative complications or overall survival after hepatobiliary surgery. Which impact the incidental CAS may have in highly complex cases remains unclear. Further studies are needed to identify patients who benefit from CAS treatment before hepatobiliary surgery.
Prospective phenotyping of CHAMP1 disorder indicates that coding mutations may not act through haploinsufficiency
Authors: Levy Tess , Pichardo Thariana , Silver Hailey , Lerman Bonnie , Zweifach Jessica , Halpern Danielle , Siper Paige M. , Kolevzon Alexander , Buxbaum Joseph D.
Published: July 2023

CHAMP1 disorder is a genetic neurodevelopmental condition caused by mutations in the CHAMP1 gene that result in premature termination codons. The disorder is associated with intellectual disability, medical comorbidities, and dysmorphic features. Deletions of the CHAMP1 gene, as part of 13q34 deletion syndrome, have been briefly described with the suggestion of a milder clinical phenotype. To date, no studies have directly assessed differences between individuals with mutations in CHAMP1 to those with deletions of the gene. We completed prospective clinical evaluations of 16 individuals with mutations and eight with deletions in CHAMP1. Analyses revealed significantly lower adaptive functioning across all domains assessed (i.e., communication, daily living skills, socialization, and motor skills) in the mutation group. Developmental milestones and medical features further showed difference between groups. The phenotypes associated with mutations, as compared to deletions, indicate likely difference in pathogenesis between groups, where deletions are acting through CHAMP1 haploinsufficiency and mutations are acting through dominant negative or gain of function mechanisms, leading to a more severe clinical phenotype. Understanding this pathogenesis is important to the future of novel therapies for CHAMP1 disorder and illustrates that mechanistic understanding of mutations must be carefully considered prior to treatment development.
Examining the Outcomes of Project ECHO® as an Interprofessional Community of Practice for Pediatric Feeding Clinicians
Authors: Raatz Madeline , Ward Elizabeth C. , Moss Perrin , Reilly Claire , Frederiksen Nadine , Dickinson Corrine , Clarke Sally , Beak Kelly , Marshall Jeanne
Published: July 2023

Project ECHO® is a virtual, interprofessional, cased-based peer-learning model. To date, no studies have explored ECHO as a model for pediatric feeding education. This study examined the outcomes of establishing a pediatric feeding ECHO network. Using a prospective, mixed-methods design, two cohorts of allied health professionals were recruited. Each cohort participated in eight, 90-min videoconference sessions incorporating a didactic presentation and clinical case presentation. The case was presented by a participant, with questions and recommendations provided by the ECHO network. Participants completed: (1) a learning needs analysis before the ECHO series, (2) a self-reported confidence questionnaire pre, post, and 3-month post, (3) a satisfaction questionnaire after each session, and (4) an overall satisfaction questionnaire post-ECHO series. Time spent by hospital allied health clinicians providing impromptu phone/email feeding support to external clinicians was recorded for 8 weeks prior to and 8 weeks during the ECHO series. Forty-seven participants were included in the study, attending an average of 5.8 sessions. Significant improvements in self-reported confidence were observed across the three time points (p < 0.01) with less experienced participants demonstrating greater improvements. Participants reported high satisfaction with ECHO, with 93% (40/43) wanting continued access to ECHO in future. The multidisciplinary format, interactivity, structure, and case-based nature of ECHO were considered beneficial. A 75% reduction in requests for support from clinicians in the same catchment area was noted during the ECHO series. Results demonstrated that Project ECHO is a viable model for pediatric feeding education for clinicians working in the field. Further research is needed to investigate the long-term effects and impacts on clinical care.
Circulating hormones and risk of gastric cancer by subsite in three cohort studies
Authors: Sanikini Harinakshi , Biessy Carine , Rinaldi Sabina , Navionis Anne-Sophie , Gicquiau Audrey , Keski-Rahkonen Pekka , Kiss Agneta , Weinstein Stephanie J. , Albanes Demetrius , Agudo Antonio , Jenab Mazda , Riboli Elio , Gunter Marc J. , Murphy Gwen , Cross Amanda J.
Published: July 2023

Background

Obesity has been positively associated with gastric cancer. Excess fat impacts hormones, which have been implicated in carcinogenesis. We investigated obesity-related hormones and cardia gastric cancer (CGC) and non-cardia gastric cancer (NCGC) risk.

Methods

Nested case–control studies were conducted within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort (61 CGCs, and 172 NCGCs and matched controls) and the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) study (100 CGCs and 65 NCGCs and matched controls); serum hormones were measured. In UK-Biobank (n = 458,713), we included 137 CGCs and 92 NCGCs. Sex-specific analyses were conducted. For EPIC and ATBC, odds ratios (ORs), and for UK-Biobank hazard ratios (HRs), were estimated using conditional logistic regression and Cox regression, respectively.

Results

Insulin-like growth-factor-1 was positively associated with CGC and NCGC in EPIC men (ORper 1-SD increase 1.94, 95% CI 1.03–3.63; ORper 1-SD increase 1.63, 95% CI 1.05–2.53, respectively), with similar findings for CGC in UK-Biobank women (HRper 1-SD increase 1.76, 95% CI 1.08–2.88). Leptin in EPIC men and C-peptide in EPIC women were positively associated with NCGC (ORT3 vs. T1 2.72, 95% CI 1.01–7.34 and ORper 1-SD increase 2.17, 95% CI 1.19–3.97, respectively). Sex hormone-binding globulin was positively associated with CGC in UK-Biobank men (HRper 1-SD increase 1.29, 95% CI 1.02–1.64). Conversely, ghrelin was inversely associated with NCGC among EPIC and ATBC men (ORper 1-SD increase 0.53, 95% CI 0.34–0.84; ORper 1-SD increase 0.22, 95% CI 0.10–0.50, respectively). In addition, dehydroepiandrosterone was inversely associated with CGC in EPIC and ATBC men combined.

Conclusions

Some obesity-related hormones influence CGC and NCGC risk.
Numerical investigation of transmission probability characteristics in the first low-density region of a laser wakefield accelerator
Authors: John Benzi , Middleman Keith , Malyshev Oleg B. , Gu Xiaojun , Symes Daniel R. , Emerson David R.
Published: July 2023

Transmission probability is an important parameter in vacuum science and technology that needs to be accurately characterised for system design. Typically, this is computed using the test particle Monte Carlo method. However, this approach is valid only in the free molecular regime. In this work, we propose a methodology to compute transmission probability using the direct simulation Monte Carlo method, which makes possible the characterisation of vacuum devices for a wider range of operating pressure conditions from viscous to molecular flow regimes. This is applied to study the gas expansion characteristics in the first low-density drift region of a laser wakefield accelerator. Validations are first made by comparing the results against the test particle Monte Carlo method in the free molecular regime. The transmission probability is then characterised for a wide range of operating conditions, revealing interesting insights helpful towards not only a fundamental understanding but also in making design considerations.
Comparing computational algorithms for team formation in the classroom: a classroom experience
Authors: Sanchez-Anguix Victor , Alberola Juan M. , Del Val Elena , Palomares Alberto , Teruel Maria Dolores
Published: July 2023

Throughout recent years, several researchers have proposed computational tools and algorithms to support team formation in the classroom. The result is that team formation algorithms have been widely applied in classroom environments to create well-balanced teams. One of the challenges in designing algorithms for automatic team formation is designing an appropriate function to estimate team performance, which is used as part of the optimization algorithm that divides students into teams. This function (referred to as a team evaluation heuristic) serves as an approximation to team performance, which is a complex phenomenon that is difficult to quantitatively assess in many settings and that cannot be accurately calculated prior to the task at hand. Despite showing their relative success compared to traditional and manual team formation strategies (manually employed by lecturers and teachers), there is a lack of research comparing team evaluation heuristics in a real classroom setting. Such a comparison would help teachers, practitioners, and system designers to appropriately select the most suitable team formation algorithms. In this article, we present an experimental evaluation that was carried out in a Bachelor’s Degree Program in Tourism that compares two team evaluation heuristics based on Belbin and Myer-Briggs. The experimental evaluation was carried out by means of an intelligent, extensible team formation tool whose optimization is based on an integer linear model that can be extended to support different team evaluation heuristics.
Running Out of Bank Runs
Authors: Libich Jan , Nguyen Dat Thanh , Kiss Hubert Janos
Published: July 2023

The theoretical literature on bank runs has modeled depositors’ withdrawal decision as a one-off choice, made simultaneously by all depositors. Our game-theoretic framework gives depositors a heterogeneous, stochastic opportunity to change their minds about withdrawing their money. They can run out of (or run into) the crowd in front of the bank based on their observation of what others have done. Depositors’ opportunity to change their decision supports implicit coordination, which in some circumstances reduces the probability that self-fulfilling bank runs will occur.
Trophic ecology of common bottlenose dolphins in a pelagic insular environment inferred by stable isotopes
Authors: Dias Ester , Dromby Morgane , Ferreira Rita , Gil Ágatha , Tejerina Raquel , Castro L. Filipe C. , Rosso Massimiliano , Sousa-Pinto Isabel , Hoffman Joel C. , Teodósio Maria A. , Dinis Ana , Alves Filipe
Published: July 2023

The common bottlenose dolphin (Tursiops truncatus) is a top marine predator widely dispersed in coastal and pelagic habitats and with a generalist feeding behavior. Yet, information on the trophic ecology of animals inhabiting pelagic environments is still scarce. Using carbon (δ13C: 13C/12C) and nitrogen (δ15N: 15N/14N) stable isotope ratios, we identified and quantified the main groups of prey assimilated by bottlenose dolphins inhabiting an oceanic habitat (Madeira Island, East Atlantic). Bottlenose dolphins assimilated pelagic, schooling fish (such as blue jack mackerel, Trachurus picturatus) and mesopelagic and demersal squids, which reinforces the pelagic dietary composition of insular/oceanic dolphins. Also, intra-seasonal differences were found in their stable isotope ratios, which suggest intraspecific variability in the feeding behavior among individuals living in the same area. Sex was not the main factor contributing to these differences, suggesting the lack of trophic niche segregation between adult males and females in this offshore environment. Nonetheless, further studies including different life stages and information on the ecophysiological requirements are necessary to disclose the factors responsible for the observed variability. This study showed that insular dolphins fed primarily on economically important pelagic prey, highlighting the need of developing management strategies that integrate conservation in fisheries plans.
Correlating the Density and Refractive Index of Ternary Liquid Mixtures
Authors: Dzingai Pethile , Focke Walter W. , Ramjee Shatish , Khosa Pretty , Nobunga Ripfumelo A.
Published: July 2023

Some physical properties of ideal solutions, e.g. the molar volume and the molar refraction, vary linearly with composition. Others can be expressed, either as ratios or as products of two other properties which vary with composition in this way. It is postulated that the non-ideal behaviour of real solutions can be adequately modelled by substituting these linear functions with higher order Scheffé polynomials. A suite of such models is presented for which the parameters are fully determined by knowledge of pure component properties and binary behaviour. Their binary data representation ability, and capacity to predict ternary properties, was tested using density and refractive index data for the acetic acid–ethanol-water ternary system as well as fourteen additional ternary data sets. Model performance was ranked on the basis of the Akaike Information criterion. With respect to predicting ternary density and refractive index behaviour from knowledge of binary data, it was found that lower-order models outperformed higher order models.
Model reduction for nonlinearizable dynamics via delay-embedded spectral submanifolds
Authors: Axås Joar , Haller George
Published: July 2023

Delay embedding is a commonly employed technique in a wide range of data-driven model reduction methods for dynamical systems, including the dynamic mode decomposition, the Hankel alternative view of the Koopman decomposition (HAVOK), nearest-neighbor predictions and the reduction to spectral submanifolds (SSMs). In developing these applications, multiple authors have observed that delay embedding appears to separate the data into modes, whose orientations depend only on the spectrum of the sampled system. In this work, we make this observation precise by proving that the eigenvectors of the delay-embedded linearized system at a fixed point are determined solely by the corresponding eigenvalues, even for multi-dimensional observables. This implies that the tangent space of a delay-embedded invariant manifold can be predicted a priori using an estimate of the eigenvalues. We apply our results to three datasets to identify multimodal SSMs and analyse their nonlinear modal interactions. While SSMs are the focus of our study, these results generalize to any delay-embedded invariant manifold tangent to a set of eigenvectors at a fixed point. Therefore, we expect this theory to be applicable to a number of data-driven model reduction methods.
Use of the gonadal tissue of the sea urchin Paracentrotus lividus as a target for environmental contamination by trace metals
Authors: Sarly Monique S. , Pedro Carmen A. , Bruno Catarina S. , Raposo Andreia , Quadros Helenita C. , Pombo Ana , Gonçalves Sílvia C.
Published: July 2023

Many environmental monitoring works have been carried out using biomarkers as a tool to identify the effects of oil contamination on marine organisms; however, only a few studies have used sea urchin gonadal tissue for this purpose. Within this context, the present work aimed to understand the impact of an oil spill, proposing the use of sea urchin gonadal tissue as a biomarker for environmental contamination by trace metals in the species Paracentrotus lividus. Biometric analysis, quantification analyses of the elements Cd, Pb, Ni, Fe, Mn, Zn, and Cu, as well as histopathological evaluations were performed in gonads of P. lividus collected from an area affected by hydrocarbons, named as impacted shore (IS) and an area not affected, named reference shore (RS). The results showed that carapace diameter (DC), total wet weight (WW), and Cd concentrations in the gonads were significantly influenced by the interaction between the rocky shores of origin, the months of sampling, and by the sex of the individuals. Moreover, from July until September, the levels of Zn and Cd were significantly lower in male than in female gonads. In July (the month of the oil spill), the indexes of histopathological alterations (IHPA) of membrane dilation were significantly higher in individuals from the IS, compared to the individuals from the RS. In addition, there were significant correlations between biometric variables (wet weight, diameter of carapace, gonadal weight, and gonadosomatic index) and the elements Cd, Cu, Ni, and Mn concentrations. Lastly, a delay in the gametogenic cycle of the sea urchins from IS was also observed. Taken together, these findings suggest that direct exposure to trace metals induces histopathological lesions in P. lividus’ gonads and affects its reproductive cycle.

Graphical Abstract
Linking FDI and trade network topology with the COVID-19 pandemic
Authors: Antonietti Roberto , De Masi Giulia , Ricchiuti Giorgio
Published: July 2023

Globalization has considerably increased the movement of people and goods around the world, which constitutes a key channel of viral infection. Increasingly close economic links between countries speeds up the transfer of goods and information, and the knock-on effect of economic crises, but also the transmission of diseases. Foreign direct investment (FDI) and trade establish clear ties between countries of origin and destination, and it is along these chains that contagious phenomena can unfold. In this paper, we investigate whether countries’ centrality in both global production and trade network corresponds to higher COVID-19 infection and mortality rates. Merging data on EU-27 greenfield FDI and international trade with data on COVID-19 infections and deaths, we find that countries mostly exposed to the COVID-19 outbreak are those characterized by a higher eigenvector centrality. This result is robust to the use of an alternative measure of network centrality and to the inclusion of other possible confounding factors.
Accuracy of on-site teleoperated milling with haptic assistance
Authors: Drobinsky Sergey , de la Fuente Matías , Puladi Behrus , Radermacher Klaus
Published: July 2023

Purpose

In bone surgery specialties, like orthopedics, neurosurgery, and oral and maxillofacial surgery patient safety and treatment success depends on the accurate implementation of computer-based surgical plans. Unintentional plan deviations can result in long-term functional damage to the patient. With on-site teleoperation, the surgeon operates a slave robot with a physically-decoupled master device, while being directly present at the operation site. This allows the surgeon to perform surgical tasks with robotic accuracy, while always remaining in the control loop.

Methods

In this study the master- and slave-side accuracy of an on-site teleoperated miniature cooperative robot (minaroHD) is evaluated. Master-side accuracy is investigated in a user study regarding scale factor, target feed rate, movement direction and haptic guidance stiffness. Scale factors are chosen to correspond to primarily finger, hand, and arm movements. Slave-side accuracy is investigated in autonomous milling trials regarding stepover, feed rate, movement direction, and material density.

Results

Master-side user input errors increase with increasing target feed rate and scale factor, and decrease with increasing haptic guidance stiffness. Resulting slave-side errors decrease with increasing scale factor and are < 0.07 mm for optimal guidance parameters. Slave-side robot position errors correlate with the feed rate but show little correlation with stepover distance. For optimal milling parameters, the 95th percentile of tracked slave-side position error is 0.086 mm with a maximal error of 0.16 mm.

Conclusion

For optimal guidance and milling parameters, the combined error of 0.23 mm is in the range of the dura mater thickness (< 0.27 mm) or mandibular canal wall (~ 0.85 mm). This corresponds to safety margins in high-demand surgical procedures like craniotomies, laminectomies, or decortication of the jaw. However, for further clinical translation, the performance and usability of on-site teleoperated milling must be further evaluated for real-life clinical application examples with consideration of all error sources in a computer-assisted surgery workflow.
Metabolic dysfunction-associated gallstone disease: expecting more from critical care manifestations
Authors: Portincasa Piero , Di Ciaula Agostino , Bonfrate Leonilde , Stella Alessandro , Garruti Gabriella , Lamont John Thomas
Published: July 2023

About 20% of adults worldwide have gallstones which are solid conglomerates in the biliary tree made of cholesterol monohydrate crystals, mucin, calcium bilirubinate, and protein aggregates. About 20% of gallstone patients will definitively develop gallstone disease, a condition which consists of gallstone-related symptoms and/or complications requiring medical therapy, endoscopic procedures, and/or cholecystectomy. Gallstones represent one of the most prevalent digestive disorders in Western countries and patients with gallstone disease are one of the largest categories admitted to European hospitals. About 80% of gallstones in Western countries are made of cholesterol due to disturbed cholesterol homeostasis which involves the liver, the gallbladder and the intestine on a genetic background. The incidence of cholesterol gallstones is dramatically increasing in parallel with the global epidemic of insulin resistance, type 2 diabetes, expansion of visceral adiposity, obesity, and metabolic syndrome. In this context, gallstones can be largely considered a metabolic dysfunction-associated gallstone disease, a condition prone to specific and systemic preventive measures. In this review we discuss the key pathogenic and clinical aspects of gallstones, as the main clinical consequences of metabolic dysfunction-associated disease.