bluuebunny/crossref_metadata_2025 huggingface dataset:
“Most of” leads to undecidability: Failure of adding frequencies to LTL
Authors: Bednarczyk Bartosz , Michaliszyn Jakub
Published: March 2021

Linear Temporal Logic (LTL) interpreted on finite traces is a robust specification framework popular in formal verification. However, despite the high interest in the logic in recent years, the topic of their quantitative extensions is not yet fully explored. The main goal of this work is to study the effect of adding weak forms of percentage constraints (e.g. that most of the positions in the past satisfy a given condition, or that $$\sigma $$
σ
is the most-frequent letter occurring in the past) to fragments of LTL. Such extensions could potentially be used for the verification of influence networks or statistical reasoning. Unfortunately, as we prove in the paper, it turns out that percentage extensions of even tiny fragments of LTL have undecidable satisfiability and model-checking problems. Our undecidability proofs not only sharpen most of the undecidability results on logics with arithmetics interpreted on words known from the literature, but also are fairly simple. We also show that the undecidability can be avoided by restricting the allowed usage of the negation, and discuss how the undecidability results transfer to first-order logic on words.
Combining Semilattices and Semimodules
Authors: Bonchi Filippo , Santamaria Alessio
Published: March 2021

We describe the canonical weak distributive law $$\delta :\mathcal S\mathcal P\rightarrow \mathcal P\mathcal S$$

δ
:
S
P
→
P
S

of the powerset monad $$\mathcal P$$
P
over the S-left-semimodule monad $$\mathcal S$$
S
, for a class of semirings S. We show that the composition of $$\mathcal P$$
P
with $$\mathcal S$$
S
by means of such $$\delta $$
δ
yields almost the monad of convex subsets previously introduced by Jacobs: the only difference consists in the absence in Jacobs’s monad of the empty convex set. We provide a handy characterisation of the canonical weak lifting of $$\mathcal P$$
P
to $$\mathbb {EM}(\mathcal S)$$

EM
(
S
)

as well as an algebraic theory for the resulting composed monad. Finally, we restrict the composed monad to finitely generated convex subsets and we show that it is presented by an algebraic theory combining semimodules and semilattices with bottom, which are the algebras for the finite powerset monad $$\mathcal P_f$$

P
f

.
Deductive Stability Proofs for Ordinary Differential Equations
Authors: Tan Yong Kiam , Platzer André
Published: March 2021

Stability is required for real world controlled systems as it ensures that those systems can tolerate small, real world perturbations around their desired operating states. This paper shows how stability for continuous systems modeled by ordinary differential equations (ODEs) can be formally verified in differential dynamic logic (). The key insight is to specify ODE stability by suitably nesting the dynamic modalities of with first-order logic quantifiers. Elucidating the logical structure of stability properties in this way has three key benefits: i) it provides a flexible means of formally specifying various stability properties of interest, ii) it yields rigorous proofs of those stability properties from ’s axioms with ’s ODE safety and liveness proof principles, and iii) it enables formal analysis of the relationships between various stability properties which, in turn, inform proofs of those properties. These benefits are put into practice through an implementation of stability proofs for several examples in KeYmaera X, a hybrid systems theorem prover based on .
Deductive Verification of Floating-Point Java Programs in KeY
Authors: Abbasi Rosa , Schiffl Jonas , Darulova Eva , Ulbrich Mattias , Ahrendt Wolfgang
Published: March 2021

Deductive verification has been successful in verifying interesting properties of real-world programs. One notable gap is the limited support for floating-point reasoning. This is unfortunate, as floating-point arithmetic is particularly unintuitive to reason about due to rounding as well as the presence of the special values infinity and ‘Not a Number’ (NaN). In this paper, we present the first floating-point support in a deductive verification tool for the Java programming language. Our support in the KeY verifier handles arithmetic via floating-point decision procedures inside SMT solvers and transcendental functions via axiomatization. We evaluate this integration on new benchmarks, and show that this approach is powerful enough to prove the absence of floating-point special values—often a prerequisite for further reasoning about numerical computations—as well as certain functional properties for realistic benchmarks.
Helmholtz: A Verifier for Tezos Smart Contracts Based on Refinement Types
Authors: Nishida Yuki , Saito Hiromasa , Chen Ran , Kawata Akira , Furuse Jun , Suenaga Kohei , Igarashi Atsushi
Published: March 2021

A smart contract is a program executed on a blockchain, based on which many cryptocurrencies are implemented, and is being used for automating transactions. Due to the large amount of money that smart contracts deal with, there is a surging demand for a method that can statically and formally verify them.

This tool paper describes our type-based static verification tool Helmholtz for Michelson, which is a statically typed stack-based language for writing smart contracts that are executed on the blockchain platform Tezos. Helmholtz is designed on top of our extension of Michelson’s type system with refinement types. Helmholtz takes a Michelson program annotated with a user-defined specification written in the form of a refinement type as input; it then typechecks the program against the specification based on the refinement type system, discharging the generated verification conditions with the SMT solver Z3. We briefly introduce our refinement type system for the core calculus Mini-Michelson of Michelson, which incorporates the characteristic features such as compound datatypes (e.g., lists and pairs), higher-order functions, and invocation of another contract. Helmholtz successfully verifies several practical Michelson programs, including one that transfers money to an account and that checks a digital signature.
AMulet 2.0 for Verifying Multiplier Circuits
Authors: Kaufmann Daniela , Biere Armin
Published: March 2021

AMulet 2.0 is a fully automatic tool for the verification of integer multipliers using computer algebra. Our tool models multiplier circuits given as and-inverter graphs as a set of polynomials and applies preprocessing techniques based on elimination theory of Gröbner bases. Finally it uses a polynomial reduction algorithm to verify the correctness of the given circuit. AMulet 2.0 is a re-factorization and improved re-implementation of our previous multiplier verification tool AMulet 1.0.
A Web Interface for Petri Nets with Transits and Petri Games
Authors: Gieseking Manuel , Hecking-Harbusch Jesko , Yanich Ann
Published: March 2021

Developing algorithms for distributed systems is an error-prone task. Formal models like Petri nets with transits and Petri games can prevent errors when developing such algorithms. Petri nets with transits allow us to follow the data flow between components in a distributed system. They can be model checked against specifications in LTL on both the local data flow and the global behavior. Petri games allow the synthesis of local controllers for distributed systems from safety specifications. Modeling problems in these formalisms requires defining extended Petri nets which can be cumbersome when performed textually.

In this paper, we present a web interface (The web interface is deployed at http://adam.informatik.uni-oldenburg.de.) that allows an intuitive, visual definition of Petri nets with transits and Petri games. The corresponding model checking and synthesis problems are solved directly on a server. In the interface, implementations, counterexamples, and all intermediate steps can be analyzed and simulated. Stepwise simulations and interactive state space generation support the user in detecting modeling errors.
Dartagnan: Leveraging Compiler Optimizations and the Price of Precision (Competition Contribution)
Authors: Ponce-de-León Hernán , Haas Thomas , Meyer Roland
Published: March 2021

We describe the new features of the bounded model checkerDartagnanforSV-COMP’21. We participate, for the first time, in theReachSafetycategory on the verification of sequential programs. In some of these verification tasks, bugs only show up after many loop iterations, which is a challenge for bounded model checking. We address the challenge by simplifying the structure of the input program while preserving its semantics. For simplification, we leverage common compiler optimizations, which we get for free by using LLVM. Yet, there is a price to pay. Compiler optimizations may introduce bitwise operations, which require bit-precise reasoning. We evaluated an SMT encoding based on the theory of integers + bit conversions against one based on the theory of bit-vectors and found that the latter yields better performance. Compared to the unoptimized version ofDartagnan, the combination of compiler optimizations and bit-vectors yields a speed-up of an order of magnitude on average.
Towards String Support in JayHorn (Competition Contribution)
Authors: Shamakhi Ali , Hojjat Hossein , Rümmer Philipp
Published: March 2021

is a Horn clause-based model checker for Java programs that has been competing at SV-COMP since 2019. An ongoing research and implementation effort is to add support for data-type to . Since current Horn solvers do not support strings natively, we consider a representation of (unbounded) strings using algebraic data-types, more precisely as lists. This paper discusses Horn clause encodings of different string operations, and presents preliminary results.
VeriAbs: A Tool for Scalable Verification by Abstraction (Competition Contribution)
Authors: Darke Priyanka , Agrawal Sakshi , Venkatesh R.
Published: March 2021

VeriAbs is a strategy selection-based reachability verifier for C programs. The selection of a suitable strategy is from a pre-defined set of strategies and by taking into account the syntax and semantics of the code to be verified. This year we present VeriAbs version 1.4.1 in which a novel preprocessor to strategy selection is introduced. The preprocessor checks for the feasibility of performing a lightweight slicing of the input code using function call graph and variable reference information. By this if the program is found to besliceable, sub-programs or slices are generated, and the known strategy selection algorithm of VeriAbs is applied to each slice. The verification results of each slice are then composed to derive that of the entire program. This compositional verification has improved the scalability of VeriAbs and presented in this paper.
Certifying Proofs in the First-Order Theory of Rewriting
Authors: Mitterwallner Fabian , Lochmann Alexander , Middeldorp Aart , Felgenhauer Bertram
Published: March 2021

The first-order theory of rewriting is a decidable theory for linear variable-separated rewrite systems. The decision procedure is based on tree automata techniques and recently we completed a formalization in the Isabelle proof assistant. In this paper we present a certificate language that enables the output of software tools implementing the decision procedure to be formally verified. To show the feasibility of this approach, we present , a reincarnation of the decision tool with certifiable output, and the formally verified certifier .
Do Judge a Test by its Cover
Authors: Goldstein Harrison , Hughes John , Lampropoulos Leonidas , Pierce Benjamin C.
Published: March 2021

Property-based testing uses randomly generated inputs to validate high-level program specifications. It can be shockingly effective at finding bugs, but it often requires generating a very large number of inputs to do so. In this paper, we apply ideas from combinatorial testing, a powerful and widely studied testing methodology, to modify the distributions of our random generators so as to find bugs with fewer tests. The key concept is combinatorial coverage, which measures the degree to which a given set of tests exercises every possible choice of values for every small combination of input features.

In its “classical” form, combinatorial coverage only applies to programs whose inputs have a very particular shape—essentially, a Cartesian product of finite sets. We generalize combinatorial coverage to the richer world of algebraic data types by formalizing a class of sparse test descriptions based on regular tree expressions. This new definition of coverage inspires a novel combinatorial thinning algorithm for improving the coverage of random test generators, requiring many fewer tests to catch bugs. We evaluate this algorithm on two case studies, a typed evaluator for System F terms and a Haskell compiler, showing significant improvements in both.
Correctness of Sequential Monte Carlo Inference for Probabilistic Programming Languages
Authors: Lundén Daniel , Borgström Johannes , Broman David
Published: March 2021

Probabilistic programming is an approach to reasoning under uncertainty by encoding inference problems as programs. In order to solve these inference problems, probabilistic programming languages (PPLs) employ different inference algorithms, such as sequential Monte Carlo (SMC), Markov chain Monte Carlo (MCMC), or variational methods. Existing research on such algorithms mainly concerns their implementation and efficiency, rather than the correctness of the algorithms themselves when applied in the context of expressive PPLs. To remedy this, we give a correctness proof for SMC methods in the context of an expressive PPL calculus, representative of popular PPLs such as WebPPL, Anglican, and Birch. Previous work have studied correctness of MCMC using an operational semantics, and correctness of SMC and MCMC in a denotational setting without term recursion. However, for SMC inference—one of the most commonly used algorithms in PPLs as of today—no formal correctness proof exists in an operational setting. In particular, an open question is if the resample locations in a probabilistic program affects the correctness of SMC. We solve this fundamental problem, and make four novel contributions: (i) we extend an untyped PPL lambda calculus and operational semantics to include explicit resample terms, expressing synchronization points in SMC inference; (ii) we prove, for the first time, that subject to mild restrictions, any placement of the explicit resample terms is valid for a generic form of SMC inference; (iii) as a result of (ii), our calculus benefits from classic results from the SMC literature: a law of large numbers and an unbiased estimate of the model evidence; and (iv) we formalize the bootstrap particle filter for the calculus and discuss how our results can be further extended to other SMC algorithms.
Bayesian strategies: probabilistic programs as generalised graphical models
Authors: Paquet Hugo
Published: March 2021

We introduce Bayesian strategies, a new interpretation of probabilistic programs in game semantics. This interpretation can be seen as a refinement of Bayesian networks.

Bayesian strategies are based on a new form of event structure, with two causal dependency relations respectively modelling control flow and data flow. This gives a graphical representation for probabilistic programs which resembles the concrete representations used in modern implementations of probabilistic programming.

From a theoretical viewpoint, Bayesian strategies provide a rich setting for denotational semantics. To demonstrate this we give a model for a general higher-order programming language with recursion, conditional statements, and primitives for sampling from continuous distributions and trace re-weighting. This is significant because Bayesian networks do not easily support higher-order functions or conditionals.
Query Lifting
Authors: Ricciotti Wilmer , Cheney James
Published: March 2021

Language-integrated query based on comprehension syntax is a powerful technique for safe database programming, and provides a basis for advanced techniques such as query shredding or query flattening that allow efficient programming with complex nested collections. However, the foundations of these techniques are lacking: although SQL, the most widely-used database query language, supports heterogeneous queries that mix set and multiset semantics, these important capabilities are not supported by known correctness results or implementations that assume homogeneous collections. In this paper we study language-integrated query for a heterogeneous query language $$\mathcal {NRC}_{\lambda }( Set,Bag )$$

NRC
λ

(
S
e
t
,
B
a
g
)

that combines set and multiset constructs. We show how to normalize and translate queries to SQL, and develop a novel approach to querying heterogeneous nested collections, based on the insight that “local” query subexpressions that calculate nested subcollections can be “lifted” to the top level analogously to lambda-lifting for local function definitions.
Nested Session Types
Authors: Das Ankush , DeYoung Henry , Mordido Andreia , Pfenning Frank
Published: March 2021

Session types statically describe communication protocols between concurrent message-passing processes. Unfortunately, parametric polymorphism even in its restricted prenex form is not fully understood in the context of session types. In this paper, we present the metatheory of session types extended with prenex polymorphism and, as a result, nested recursive datatypes. Remarkably, we prove that type equality is decidable by exhibiting a reduction to trace equivalence of deterministic first-order grammars. Recognizing the high theoretical complexity of the latter, we also propose a novel type equality algorithm and prove its soundness. We observe that the algorithm is surprisingly efficient and, despite its incompleteness, sufficient for all our examples. We have implemented our ideas by extending the Rast programming language with nested session types. We conclude with several examples illustrating the expressivity of our enhanced type system.
Erratum zu: Professoren mit Migrationshintergrund
Authors: Engel Ole
Published: March 2021

Aufgrund eines technischen Fehlers wurde die EPUB- und HTML-Version des Buches mit falschem Copyrightholder und fehlenden Lizenztexten veröffentlicht. Dies wurde nun korrigiert. Der Inhalt des Werkes bleibt unverändert.
Tree-level S-matrix of superstring field theory with homotopy algebra structure
Authors: Kunitomo Hiroshi
Published: March 2021

Abstract

We show that the tree-level S-matrices of the superstring field theories based on the homotopy-algebra structure agree with those obtained in the first-quantized formulation. The proof is given in detail for the heterotic string field theory. The extensions to the type II and open superstring field theories are straightforward.
Constructing Carrollian CFTs
Authors: Gupta Nishant , Suryanarayana Nemani V.
Published: March 2021

Abstract

We construct classical theories for scalar fields in arbitrary Carroll spacetimes that are invariant under Carrollian diffeomorphisms and Weyl transformations. When the local symmetries are gauge fixed these theories become Carrollian conformal field theories. We show that generically there are at least two types of such theories: one in which only time derivatives of the fields appear and the other in which both space and time derivatives appear. A classification of such scalar field theories in three (and higher) dimensions up to two derivative order is provided. We show that only a special case of our theories arises in the ultra-relativistic limit of a covariant parent theory.
Suppressing blow-up by gradient-dependent flux limitation in a planar Keller–Segel–Navier–Stokes system
Authors: Winkler Michael
Published: March 2021

The flux-limited Keller–Segel–Navier–Stokes system $$\begin{aligned} \left\{ \begin{array}{lcl} n_t + u\cdot \nabla n &{}=&{} \Delta n - \nabla \cdot \Big ( n f(|\nabla c|^2) \nabla c\Big ), \\ c_t + u\cdot \nabla c &{}=&{} \Delta c - c + n, \\ u_t + (u\cdot \nabla ) u &{}=&{} \Delta u + \nabla P + n\nabla \Phi , \qquad \nabla \cdot u=0, \end{array} \right. \qquad \qquad (\star ) \end{aligned}$$

n
t

+
u
·
∇
n

=

Δ
n
-
∇
·

(

n
f
(
|
∇
c

|
2

)
∇
c

)

,

c
t

+
u
·
∇
c

=

Δ
c
-
c
+
n
,

u
t

+

(
u
·
∇
)

u

=

Δ
u
+
∇
P
+
n
∇
Φ
,

∇
·
u
=
0
,

(
⋆
)

is considered in a smoothly bounded domain $$\Omega \subset {\mathbb {R}}^2$$

Ω
⊂

R

2

. It is shown that whenever the suitably smooth function f models any asymptotically algebraic-type saturation of cross-diffusive fluxes in the sense that $$\begin{aligned} |f(\xi )| \le K_f\cdot (\xi +1)^{-\frac{\alpha }{2}} \end{aligned}$$

|
f

(
ξ
)

|

≤

K
f

·

(
ξ
+
1
)

-

α
2

holds for all $$\xi \ge 0$$

ξ
≥
0

with some $$K_f>0$$

K
f

>
0

and $$\alpha >0$$

α
>
0

, for any all reasonably regular initial data a corresponding no-flux/no-flux/Dirichlet problem admits a globally defined classical solution which is bounded, inter alia, in $$L^\infty (\Omega \times (0,\infty ))$$

L
∞

(
Ω
×

(
0
,
∞
)

)

with respect to all its components. By extending a corresponding result known for a fluid-free counterpart of ($$\star $$
⋆
), this confirms that with regard to the possible emergence of blow-up phenomena, the choice $$f\equiv const.$$

f
≡
c
o
n
s
t
.

retains some criticality also in the presence of fluid interaction.
Brain hemodynamic response in Examiner–Examinee dyads during spatial short-term memory task: an fNIRS study
Authors: Panico Francesco , De Marco Stefania , Sagliano Laura , D’Olimpio Francesca , Grossi Dario , Trojano Luigi
Published: March 2021

The Corsi Block-Tapping test (CBT) is a measure of spatial working memory (WM) in clinical practice, requiring an examinee to reproduce sequences of cubes tapped by an examiner. CBT implies complementary behaviors in the examiners and the examinees, as they have to attend a precise turn taking. Previous studies demonstrated that the Prefrontal Cortex (PFC) is activated during CBT, but scarce evidence is available on the neural correlates of CBT in the real setting. We assessed PFC activity in dyads of examiner–examinee participants while completing the real version of CBT, during conditions of increasing and exceeding workload. This procedure allowed to investigate whether brain activity in the dyads is coordinated. Results in the examinees showed that PFC activity was higher when the workload approached or reached participants’ spatial WM span, and lower during workload conditions that were largely below or above their span. Interestingly, findings in the examiners paralleled the ones in the examinees, as examiners’ brain activity increased and decreased in a similar way as the examinees’ one. In the examiners, higher left-hemisphere activity was observed suggesting the likely activation of non-spatial WM processes. Data support a bell-shaped relationship between cognitive load and brain activity, and provide original insights on the cognitive processes activated in the examiner during CBT.
Bimanual coordination associated with left- and right-hand dominance: testing the limb assignment and limb dominance hypothesis
Authors: Panzer Stefan , Kennedy Deanna , Leinen Peter , Pfeifer Christina , Shea Charles
Published: March 2021

In an experiment conducted by Kennedy et al. (Exp Brain Res 233:181–195, 2016), dominant right-handed individuals were required to produce a rhythm of isometric forces in a 2:1 or 1:2 bimanual coordination pattern. In the 2:1 pattern, the left limb performed the faster rhythm, while in the 1:2 pattern, the right limb produced the faster pattern. In the 1:2 pattern, interference occurred in the limb which had to produce the slower rhythm of forces. However, in the 2:1 condition, interference occurred in both limbs. The conclusion was that interference was not only influenced by movement frequency, but also influenced by limb dominance. The present experiment was designed to replicate these findings in dynamic bimanual 1:2 and 2:1 tasks where performers had to move one wrist faster than the other, and to determine the influence of limb dominance. Dominant left-handed (N = 10; LQ = − 89.81) and dominant right-handed (N = 14; LQ = 91.25) participants were required to perform a 2:1 and a 1:2 coordination pattern using Lissajous feedback. The harmonicity value was calculated to quantify the interference in the trial-time series. The analysis demonstrated that regardless of limb dominance, harmonicity was always lower in the slower moving limb than in the faster moving limb. The present results indicated that for dominant left- and dominant right-handers the faster moving limb influenced the slower moving limb. This is in accordance with the assumption that movement frequency has a higher impact on limb control in bimanual 2:1 and 1:2 coordination tasks than handedness.
Sertraline concentrations in pregnant women are steady and the drug transfer to their infants is low
Authors: Heinonen E. , Blennow M. , Blomdahl-Wetterholm M. , Hovstadius M. , Nasiell J. , Pohanka A. , Gustafsson L. L. , Wide K.
Published: March 2021

Purpose

Sertraline, a selective serotonin reuptake inhibitor (SSRI), is one of the most commonly used antidepressant during pregnancy. Plasma sertraline concentrations vary markedly between individuals, partly explained by variability in hepatic drug metabolizing cytochrome P450-enzyme activity. Our purpose was to study the variability in the plasma concentrations in pregnant women and the passage to their infants.

Method

Pregnant women with moderate untreated depression were recruited in 2016–2019 in Stockholm Region and randomized to treatment with sertraline or placebo. All received Internet-based cognitive behavior therapy as non-medical treatment. Sertraline plasma concentrations were measured around pregnancy weeks 21 and 30, at delivery, 1-month postpartum, in cord blood and at 48 h of age in the infant. The clinical course of the infants was followed.

Results

Nine mothers and 7 infants were included in the analysis. Median dose-adjusted sertraline concentration in second trimester was 0.15(ng/mL) /(mg/day), in third trimester and at delivery 0.19 and 1-month postpartum 0.25, with a 67% relative difference between second trimester and postpartum. The interindividual variation was 10-fold. Median concentrations in the infants were 33% and 25% of their mothers’, measured in cord blood, and infant plasma, respectively. Only mild and transient adverse effects were seen on the infants.

Conclusion

Placental passage of sertraline to the infant is low. However, the interindividual variation in maternal concentrations during pregnancy is huge, why therapeutic drug monitoring might assist in finding the poor metabolizers at risk for adversity and increase the safety of the treatment.

Trial registration

The trial was registered at clinicaltrials.gov July 9, 2014 with TRN: NCT02185547.
Urogynecology in obstetrics: impact of pregnancy and delivery on pelvic floor disorders, a prospective longitudinal observational pilot study
Authors: Stroeder Russalina , Radosa Julia , Clemens Lea , Gerlinger Christoph , Schmidt Gilda , Sklavounos Panagiotis , Takacs Zoltan , Meyberg-Solomayer Gabriele , Solomayer Erich-Franz , Hamza Amr
Published: March 2021

Purpose

To assess changes in the pelvic floor anatomy that cause pelvic floor disorders (PFDs) in primigravidae during and after pregnancy and to evaluate their impact on women’s quality of life (QoL).

Methods

POP-Q and translabial ultrasound examination was performed in the third trimester and 3 months after delivery in a cohort of primigravidae with singleton pregnancy delivering in a tertiary center. Results were analyzed regarding mode of delivery and other pre- and peripartal factors. Two individualized detailed questionnaires were distributed at 3 months and at 12 months after childbirth to determinate QoL.

Results

We recruited 45 women, of whom 17 delivered vaginally (VD), 11 received a vacuum extraction delivery (VE) and 17 a Cesarean section in labor (CS). When comparing third-trimester sonography to 3 months after delivery, bladder neck mobility increased significantly in each delivery group and hiatal area increased significantly in the VD group. A LAM avulsion was found in two women after VE. Connective tissue weakness (p = 0.0483) and fetal weight at birth (p = 0.0384) were identified as significant risk factors for the occurrence of PFDs in a multivariant regression analysis. Urinary incontinence was most common with 15% and 11% of cases at 3, respectively, 12 months after delivery. 42% of women reported discomfort during sexual intercourse, 3 months after delivery and 24% 12 months postpartum. Although 93% of women engage a midwife after delivery, only 56% participated in pelvic floor muscle training.

Conclusion

Connective tissue weakness and high fetal weight at birth are important risk factors for the occurrence of PFDs. Nevertheless, more parturients should participate in postpartal care services to prevent future PFDs.
Temporal context effects are associated with cognitive status in advanced age
Authors: Maaß Sarah , Wolbers Thomas , van Rijn Hedderik , Riemer Martin
Published: March 2021

The perception of temporal intervals changes during the life-span, and especially older adults demonstrate specific impairments of timing abilities. Recently, we demonstrated that timing performance and cognitive status are correlated in older adults, suggesting that timing tasks can serve as a behavioral marker for the development of dementia. Easy-to-administer and retest-capable timing tasks therefore have potential as diagnostic tools for tracking cognitive decline. However, before being tested in a clinical cohort study, a further validation and specification of the original findings is warranted. Here we introduce several modifications of the original task and investigated the effects of temporal context on time perception in older adults (> 65 years) with low versus high scores in the Montreal Cognitive Assessment survey (MoCA) and a test of memory functioning. In line with our previous work, we found that temporal context effects were more pronounced with increasing memory deficits, but also that these effects are stronger for realistic compared to abstract visual stimuli. Furthermore, we show that two distinct temporal contexts influence timing behavior in separate experimental blocks, as well as in a mixed block in which both contexts are presented together. These results replicate and extend our previous findings. They demonstrate the stability of the effect for different stimulus material and show that timing tasks can reveal valuable information about the cognitive status of older adults. In the future, these findings could serve as a basis for the development of a diagnostic tool for pathological cognitive decline at an early, pre-clinical stage.
Thermo-electro-mechanical modeling of spark plasma sintering processes accounting for grain boundary diffusion and surface diffusion
Authors: Semenov A. S. , Trapp J. , Nöthe M. , Eberhardt O. , Kieback B. , Wallmersperger T.
Published: March 2021

In the present research, a numerical modeling approach of the initial stage of consolidation during spark plasma sintering on the microscopic scale is presented. The solution of a fully coupled thermo-electro-mechanical problem also accounting for grain boundary and surface diffusion is found by using a staggered way. The finite-element method is applied for solving the thermo-electro-mechanical problem while the finite-difference method is applied for the diffusion problem. A Lagrange-based non-linear formulation is used to deal with the detailed description of plastic and creep strain accumulation. The numerical model is developed for simulating the structural evolution of the involved particles during sintering of powder compacts taking into account both the free surface diffusion of the particles and the grain boundary diffusion at interparticle contact areas. The numerical results obtained by using the two-particle model—as a representative volume element of the powder—are compared with experimental results for the densification of a copper powder compact. The numerical and experimental results are in excellent agreement.
Metabasic rocks from the Variscan Schwarzwald (SW Germany): metamorphic evolution and igneous protoliths
Authors: Altherr Rainer , Hepp Stefan , Klein Hans , Hanel Michael
Published: March 2021

In the Variscan Schwarzwald metabasic rocks form small bodies included within anatectic plagioclase-biotite gneisses. Many metabasites first underwent an eclogite-facies metamorphism at about 2.0 GPa and 670–700 °C, resulting in the assemblage garnet + omphacite + rutile + quartz ± epidote ± amphibole ± kyanite. Since these eclogites are nearly free of an OH-bearing phase, they underwent almost complete dehydration during subduction, suggesting formation along an average to warm top-of-the-slab geotherm of 10–13 °C/km. The age of the Variscan high-P/high-T metamorphism is > 333 Ma. After partial exhumation from ~ 65 to ~ 15 km depth, the eclogites were overprinted under increasing activity of H2O by a number of retrograde reactions. The degree of this overprint under amphibolite-facies conditions (0.4–0.5 GPa/675–690 °C) was very different. Up to now, only retrograde eclogites have been found, but some samples still contain omphacite. Kyanite is at least partially transformed to aggregates of plagioclase + spinel ± corundum ± sapphirine. On the other hand, there are amphibolites that are extensively recrystallized and show the assemblage amphibole + plagioclase + ilmenite/titanite ± biotite ± quartz ± sulphides. The last relic phase that can be found in such otherwise completely recrystallized amphibolites is rutile. After the amphibolite-facies metamorphism at ~ 333 Ma, the metabasites underwent a number of low-temperature transformations, such as sericitization of plagioclase, chloritization of amphibole, and formation of prehnite. The intimate association of metabasite bodies with gneisses of dominantly meta-greywacke compositions suggests derivation from an active plate margin. This view is corroborated by bulk-rock geochemical data. Excluding elements that were mobile during metamorphism (Cs, Rb, Ba, K, Pb, Sr, U), the concentrations of the remaining elements in most of the metabasites are compatible with a derivation from island-arc tholeiites, back-arc basin basalts or calc-alkaline basalts. Only some samples have MORB precursor rocks.
Machine learning in oncology—Perspectives in patient-reported outcome research
Authors: Lehmann Jens , Cofala Tim , Tschuggnall Michael , Giesinger Johannes M. , Rumpold Gerhard , Holzner Bernhard
Published: March 2021

Background

Increasing data volumes in oncology pose new challenges for data analysis. Machine learning, a branch of artificial intelligence, can identify patterns even in very large and less structured datasets.

Objective

This article provides an overview of the possible applications for machine learning in oncology. Furthermore, the potential of machine learning in patient-reported outcome (PRO) research is discussed.

Materials and methods

We conducted a selective literature search (PubMed, MEDLINE, IEEE Xplore) and discuss current research.

Results

There are three primary applications for machine learning in oncology: (1) cancer detection or classification; (2) overall survival prediction or risk assessment; and (3) supporting therapy decision-making and prediction of treatment response. Generally, machine learning approaches in oncology PRO research are scarce and few studies integrate PRO data into machine learning models.

Discussion

Machine learning is a promising area of oncology, but few models have been transferred into clinical practice. The promise of personalized cancer therapy and shared decision-making through machine learning has yet to be realized. As an equally important emerging research area in oncology, PROs should also be incorporated into machine learning approaches. To gather the data necessary for this, broad implementation of PRO assessments in clinical practice, as well as the harmonization of existing datasets, is suggested.
Ecological Memory of Historical Contamination Influences the Response of Phytoplankton Communities
Authors: Baho Didier L. , Rizzuto Simone , Nizzetto Luca , Hessen Dag O. , Norberg Jon , Skjelbred Birger , Jones Kevin C. , Zhang Hao , Leu Eva
Published: March 2021

Ecological memory (EM) recognizes the importance of previous stress encounters in promoting community tolerance and thereby enhances ecosystem stability, provided that gained tolerances are preserved during non-stress periods. Drawing from this concept, we hypothesized that the recruitment of tolerant species can be facilitated by imposing an initial sorting process (conditioning) during the early stages of community assembly, which should result in higher production (biomass development and photosynthetic efficiency) and stable community composition. To test this, phytoplankton resting stages were germinated from lake sediments originating from two catchments that differed in contamination history: one impacted by long-term herbicides and pesticides exposures (historically contaminated lake) from an agricultural catchment compared to a low-impacted one (near-pristine lake) from a forested catchment. Conditioning was achieved by adding an herbicide (Isoproturon, which was commonly used in the catchment of the historically contaminated lake) during germination. Afterward, the communities obtained from germination were exposed to an increasing gradient of Isoproturon. As hypothesized, upon conditioning, the phytoplankton assemblages from the historically contaminated lake were able to rapidly restore photosynthetic efficiency (p > 0.01) and became structurally (community composition) more resistant to Isoproturon. The communities of the near-pristine lake did not yield these positive effects regardless of conditioning, supporting that EM was a unique attribute of the historically stressed ecosystem. Moreover, assemblages that displayed higher structural resistance concurrently yielded lower biomass, indicating that benefits of EM in increasing structural stability may trade-off with production. Our results clearly indicate that EM can foster ecosystem stability to a recurring stressor.
Monitoring and prediction of hurricane tracks using GPS tropospheric products
Authors: Ejigu Yohannes Getachew , Teferle Felix Norman , Klos Anna , Bogusz Janusz , Hunegnaw Addisu
Published: March 2021

We have reconstructed integrated water vapor (IWV) using the zenith wet delays to track the properties of hurricanes and explore their spatial and temporal distributions estimated from 922 GPS stations. Our results show that a surge in GPS-derived IWV occurred at least six hours prior to the landfall of two major hurricanes (Harvey and Irma) that struck the Gulf and East Coasts of the USA in 2017. We observed enhanced IWV, in particular, for the two hurricanes landfall locations. The observed variations exhibit a correlation with the precipitation value constructed from GPM/IMERG satellite mission coinciding with hurricane storm front passage. We used GPS-IWV data as inputs for spaghetti line plots for our path predictions, helping us predict the paths of Hurricanes Harvey and Irma. Hence, a directly estimable zenith wet delay sourced from GPS that has not been previously reported can serve as an additional resource for improving the monitoring of hurricane paths.
Associations between paid and unpaid work among Norwegian seniors: competition, complementarity or continuity?
Authors: Vangen Hanna , Hellevik Tale , Herlofson Katharina
Published: March 2021

A key issue in policy debates on active ageing is how to increase older people’s participation in both paid and unpaid work. This combined goal raises the question of whether the different activities compete for seniors’ time and energy or whether it is possible to achieve both, since such activities may instead complement one another. To address this issue, we examine associations between paid work, informal help provision and formal volunteering among 62- to 75-year-olds by using longitudinal data from the Norwegian Life Course, Ageing and Generation Study (2007, 2017). Our analyses show that both work exit and part-time work are associated with a higher probability of doing unpaid work in senior years compared with full-time work. However, previous engagement in unpaid activities matters considerably, regardless of paid work status. Individuals involved in informal help or formal voluntary work in 2007 were far more likely to do unpaid work 10 years later than those who were not involved. Since seniors who are already engaged in unpaid activities before leaving the labour market are likely to continue to provide informal help and volunteer, we argue that initiatives to stimulate combinations of paid and unpaid work in late careers may be advantageous.
Critical Properties and Complexity Measures of Read-Once Boolean Functions
Authors: Lozin Vadim , Moshkov Mikhail
Published: March 2021

In this paper, we define a quasi-order on the set of read-once Boolean functions and show that this is a well-quasi-order. This implies that every parameter measuring complexity of the functions can be characterized by a finite set of minimal subclasses of read-once functions, where this parameter is unbounded. We focus on two parameters related to certificate complexity and characterize each of them in the terminology of minimal classes.
Temperate fish detection and classification: a deep learning based approach
Authors: Knausgård Kristian Muri , Wiklund Arne , Sørdalen Tonje Knutsen , Halvorsen Kim Tallaksen , Kleiven Alf Ring , Jiao Lei , Goodwin Morten
Published: March 2021

A wide range of applications in marine ecology extensively uses underwater cameras. Still, to efficiently process the vast amount of data generated, we need to develop tools that can automatically detect and recognize species captured on film. Classifying fish species from videos and images in natural environments can be challenging because of noise and variation in illumination and the surrounding habitat. In this paper, we propose a two-step deep learning approach for the detection and classification of temperate fishes without pre-filtering. The first step is to detect each single fish in an image, independent of species and sex. For this purpose, we employ the You Only Look Once (YOLO) object detection technique. In the second step, we adopt a Convolutional Neural Network (CNN) with the Squeeze-and-Excitation (SE) architecture for classifying each fish in the image without pre-filtering. We apply transfer learning to overcome the limited training samples of temperate fishes and to improve the accuracy of the classification. This is done by training the object detection model with ImageNet and the fish classifier via a public dataset (Fish4Knowledge), whereupon both the object detection and classifier are updated with temperate fishes of interest. The weights obtained from pre-training are applied to post-training as a priori. Our solution achieves the state-of-the-art accuracy of 99.27% using the pre-training model. The accuracies using the post-training model are also high; 83.68% and 87.74% with and without image augmentation, respectively. This strongly indicates that the solution is viable with a more extensive dataset.
Preschool Gender-Typed Play Behavior Predicts Adolescent Gender-Typed Occupational Interests: A 10-Year Longitudinal Study
Authors: Kung Karson T. F.
Published: March 2021

There are significant gender differences in both play behavior and occupational interests. Play has been regarded as an important medium for development of skills and personal characteristics. Play may also influence subsequent preferences through social and cognitive processes involved in gender development. The present study investigated the association between gender-typed play behavior in early childhood and gender-typed occupational interests in early adolescence. Participants were drawn from a British longitudinal population study, the Avon Longitudinal Study of Parents and Children. Participants were recruited based on their parent-reported gender-typed play behavior assessed at age 3.5 years. There were 66 masculine boys and 61 masculine girls, 82 feminine boys and 69 feminine girls, and 55 randomly selected control boys and 67 randomly selected control girls. At age 13 years, the participants were administered a questionnaire assessing their interest in gender-typed occupations. It was found that masculine children showed significantly more interest in male-typical occupations than did control or feminine children. Compared with control children, feminine children had marginally significantly lower interest in male-typical jobs. Masculine children also had significantly lower interest in female-typical jobs than did control or feminine children. The associations were not moderated by gender and were observed after taking into account sociodemographic background, parental occupations, and academic performance. The degree of gender-typed play shown by preschoolers can predict their occupational interests 10 years later following transition into adolescence. Childhood gender-typed play has occupational implications that transcend developmental stages.
Antibiotic use prior to a lung cancer diagnosis: a population-based study
Authors: Löfling Lukas , Bahmanyar Shahram , Kieler Helle , Lambe Mats , Wagenius Gunnar
Published: March 2021

Aim

To examine patterns of recent pre-diagnostic fillings of antibiotics as an indicator of early symptoms of lung cancer.

Methods

Individuals diagnosed with lung cancer (cases) in 2009–2016 were identified in the Swedish National Lung Cancer Register, a population-based register, and randomly matched with up to five individuals free of lung cancer (controls) from the general population. Conditional logistic models were used to estimate odds ratios for the association between lung cancer and a recent history of filled antibiotic prescriptions.

Results

The study included 27,017 cases and 129,355 controls. The likelihood of recent exposure was approximately two times higher in cases compared to controls. The magnitude of the effect size became more pronounced with proximity to the diagnosis of lung cancer and an increasing number of filled prescriptions. While the magnitude of the effect size did not differ by sex or educational level, it became attenuated with increasing age. There was no evidence supporting a trend in the magnitude of the effect size for the association between lung cancer and a history of repeated fillings by cancer stage.

Conclusion

Lung cancer was associated with an increased likelihood of a recent history of filled antibiotic prescriptions. However, there was no evidence of an association between repeated fillings and a diagnostic delay, as reflected by stage. Our findings underscore the importance of clinical reassessment to rule out lung cancer following pneumonia treatment, especially for patients with multiple treatment cycles.