bluuebunny/crossref_metadata_2025 huggingface dataset:
Semisynthetic Chlorophyll Derivatives Toward Solar Energy Applications
Authors: Duan Shengnan , Zhou Qiang , Li Aijun , Wang Xiao-Feng , Sasaki Shin-ichi , Tamiaki Hitoshi
Published: April 2020

Plenty of thin‐film solar cell technologies using organic materials have been developed to alleviate energy shortages. As developing devices for solar energy applications, artificial photosynthesis is a trend inspired from natural photosynthesis. Although the sophisticated system that exists in nature is fascinating, the development of photovoltaic devices focusing on the usage of natural chlorophylls has been quite limited, compared with the application of other counterparts such as artificial porphyrins or phthalocyanines. Herein, the development of semisynthetic chlorophyll derivatives as functional materials for solar cells are focused on. (Bacterio)chlorins possessing a carboxylic acid moiety as a binding site to semiconductors are synthesized to improve the efficiencies of dye‐sensitized solar cells, which are now leading to another application: photocatalysts for hydrogen evolution. In contrast, derivatives without a carboxy group can be applied to organic solar cells. As for the application for perovskite solar cells, self‐assembling aggregates of a kind of derivatives are proven to be suitable as hole‐transporting materials. In addition, a new type of solid‐state biosolar cells is proposed, in which chlorophyll derivatives act solely as the photoactive materials. This Report can enlarge the scope of advanced functional materials in the field of solar energy applications.
Verifying Visibility-Based Weak Consistency
Authors: Krishna Siddharth , Emmi Michael , Enea Constantin , Jovanović Dejan
Published: April 2020

Multithreaded programs generally leverage efficient and thread-safe concurrent objects like sets, key-value maps, and queues. While some concurrent-object operations are designed to behave atomically, each witnessing the atomic effects of predecessors in a linearization order, others forego such strong consistency to avoid complex control and synchronization bottlenecks. For example, contains (value) methods of key-value maps may iterate through key-value entries without blocking concurrent updates, to avoid unwanted performance bottlenecks, and consequently overlook the effects of some linearization-order predecessors. While such weakly-consistent operations may not be atomic, they still offer guarantees, e.g., only observing values that have been present.

In this work we develop a methodology for proving that concurrent object implementations adhere to weak-consistency specifications. In particular, we consider (forward) simulation-based proofs of implementations against relaxed-visibility specifications, which allow designated operations to overlook some of their linearization-order predecessors, i.e., behaving as if they never occurred. Besides annotating implementation code to identify linearization points, i.e., points at which operations’ logical effects occur, we also annotate code to identify visible operations, i.e., operations whose effects are observed; in practice this annotation can be done automatically by tracking the writers to each accessed memory location. We formalize our methodology over a general notion of transition systems, agnostic to any particular programming language or memory model, and demonstrate its application, using automated theorem provers, by verifying models of Java concurrent object implementations.
Local Reasoning for Global Graph Properties
Authors: Krishna Siddharth , Summers Alexander J. , Wies Thomas
Published: April 2020

Separation logics are widely used for verifying programs that manipulate complex heap-based data structures. These logics build on so-called separation algebras, which allow expressing properties of heap regions such that modifications to a region do not invalidate properties stated about the remainder of the heap. This concept is key to enabling modular reasoning and also extends to concurrency. While heaps are naturally related to mathematical graphs, many ubiquitous graph properties are non-local in character, such as reachability between nodes, path lengths, acyclicity and other structural invariants, as well as data invariants which combine with these notions. Reasoning modularly about such graph properties remains notoriously difficult, since a local modification can have side-effects on a global property that cannot be easily confined to a small region.

In this paper, we address the question: What separation algebra can be used to avoid proof arguments reverting back to tedious global reasoning in such cases? To this end, we consider a general class of global graph properties expressed as fixpoints of algebraic equations over graphs. We present mathematical foundations for reasoning about this class of properties, imposing minimal requirements on the underlying theory that allow us to define a suitable separation algebra. Building on this theory, we develop a general proof technique for modular reasoning about global graph properties expressed over program heaps, in a way which can be directly integrated with existing separation logics. To demonstrate our approach, we present local proofs for two challenging examples: a priority inheritance protocol and the non-blocking concurrent Harris list.
Continualization of Probabilistic Programs With Correction
Authors: Laurel Jacob , Misailovic Sasa
Published: April 2020

Probabilistic Programming offers a concise way to represent stochastic models and perform automated statistical inference. However, many real-world models have discrete or hybrid discrete-continuous distributions, for which existing tools may suffer non-trivial limitations. Inference and parameter estimation can be exceedingly slow for these models because many inference algorithms compute results faster (or exclusively) when the distributions being inferred are continuous. To address this discrepancy, this paper presents Leios. Leios is the first approach for systematically approximating arbitrary probabilistic programs that have discrete, or hybrid discrete-continuous random variables. The approximate programs have all their variables fully continualized. We show that once we have the fully continuous approximate program, we can perform inference and parameter estimation faster by exploiting the existing support that many languages offer for continuous distributions. Furthermore, we show that the estimates obtained when performing inference and parameter estimation on the continuous approximation are still comparably close to both the true parameter values and the estimates obtained when performing inference on the original model.
Connecting Higher-Order Separation Logic to a First-Order Outside World
Authors: Mansky William , Honoré Wolf , Appel Andrew W.
Published: April 2020

Separation logic is a useful tool for proving the correctness of programs that manipulate memory, especially when the model of memory includes higher-order state: Step-indexing, predicates in the heap, and higher-order ghost state have been used to reason about function pointers, data structure invariants, and complex concurrency patterns. On the other hand, the behavior of system features (e.g., operating systems) and the external world (e.g., communication between components) is usually specified using first-order formalisms. In principle, the soundness theorem of a separation logic is its interface with first-order theorems, but the soundness theorem may implicitly make assumptions about how other components are specified, limiting its use. In this paper, we show how to extend the higher-order separation logic of the Verified Software Toolchain to interface with a first-order verified operating system, in this case CertiKOS, that mediates its interaction with the outside world. The resulting system allows us to prove the correctness of C programs in separation logic based on the semantics of system calls implemented in CertiKOS. It also demonstrates that the combination of interaction trees + CompCert memories serves well as a lingua franca to interface and compose two quite different styles of program verification.
Modular Relaxed Dependencies in Weak Memory Concurrency
Authors: Paviotti Marco , Cooksey Simon , Paradis Anouk , Wright Daniel , Owens Scott , Batty Mark
Published: April 2020

We present a denotational semantics for weak memory concurrency that avoids thin-air reads, provides data-race free programs with sequentially consistent semantics (DRF-SC), and supports a compositional refinement relation for validating optimisations. Our semantics identifies false program dependencies that might be removed by compiler optimisation, and leaves in place just the dependencies necessary to rule out thin-air reads. We show that our dependency calculation can be used to rule out thin-air reads in any axiomatic concurrency model, in particular C++. We present a tool that automatically evaluates litmus tests, show that we can augment C++ to fix the thin-air problem, and we prove that our augmentation is compatible with the previously used compilation mappings over key processor architectures. We argue that our dependency calculation offers a practical route to fixing the longstanding problem of thin-air reads in the C++ specification.
ARMv8-A System Semantics: Instruction Fetch in Relaxed Architectures
Authors: Simner Ben , Flur Shaked , Pulte Christopher , Armstrong Alasdair , Pichon-Pharabod Jean , Maranget Luc , Sewell Peter
Published: April 2020

Computing relies on architecture specifications to decouple hardware and software development. Historically these have been prose documents, with all the problems that entails, but research over the last ten years has developed rigorous and executable-as-test-oracle specifications of mainstream architecture instruction sets and “user-mode” concurrency, clarifying architectures and bringing them into the scope of programming-language semantics and verification. However, the system semantics, of instruction-fetch and cache maintenance, exceptions and interrupts, and address translation, remains obscure, leaving us without a solid foundation for verification of security-critical systems software.

In this paper we establish a robust model for one aspect of system semantics: instruction fetch and cache maintenance for ARMv8-A. Systems code relies on executing instructions that were written by data writes, e.g. in program loading, dynamic linking, JIT compilation, debugging, and OS configuration, but hardware implementations are often highly optimised, e.g. with instruction caches, linefill buffers, out-of-order fetching, branch prediction, and instruction prefetching, which can affect programmer-observable behaviour. It is essential, both for programming and verification, to abstract from such microarchitectural details as much as possible, but no more. We explore the key architecture design questions with a series of examples, discussed in detail with senior Arm staff; capture the architectural intent in operational and axiomatic semantic models, extending previous work on “user-mode” concurrency; make these models executable as test oracles for small examples; and experimentally validate them against hardware behaviour (finding a bug in one hardware device). We thereby bring these subtle issues into the mathematical domain, clarifying the architecture and enabling future work on system software verification.
On the Versatility of Open Logical Relations
Authors: Barthe Gilles , Crubillé Raphaëlle , Lago Ugo Dal , Gavazzo Francesco
Published: April 2020

Logical relations are one among the most powerful techniques in the theory of programming languages, and have been used extensively for proving properties of a variety of higher-order calculi. However, there are properties that cannot be immediately proved by means of logical relations, for instance program continuity and differentiability in higher-order languages extended with real-valued functions. Informally, the problem stems from the fact that these properties are naturally expressed on terms of non-ground type (or, equivalently, on open terms of base type), and there is no apparent good definition for a base case (i.e. for closed terms of ground types). To overcome this issue, we study a generalization of the concept of a logical relation, calledopen logical relation, and prove that it can be fruitfully applied in several contexts in which the property of interest is about expressions of first-order type. Our setting is a simply-typed$$\lambda $$λ-calculus enriched with real numbers and real-valued first-order functions from a given set, such as the one of continuous or differentiable functions. We first prove a containment theorem stating that for any collection of real-valued first-order functions including projection functions and closed under function composition, any well-typed term of first-order type denotes a function belonging to that collection. Then, we show by way of open logical relations the correctness of the core of a recently published algorithm for forward automatic differentiation. Finally, we define a refinement-based type system for local continuity in an extension of our calculus with conditionals, and prove the soundness of the type system using open logical relations.
Neural Flocking: MPC-Based Supervised Learning of Flocking Controllers
Authors: Mehmood Usama , Roy Shouvik , Grosu Radu , Smolka Scott A. , Stoller Scott D. , Tiwari Ashish
Published: April 2020

We show how a symmetric and fully distributed flocking controller can be synthesized using Deep Learning from a centralized flocking controller. Our approach is based on Supervised Learning, with the centralized controller providing the training data, in the form of trajectories of state-action pairs. We use Model Predictive Control (MPC) for the centralized controller, an approach that we have successfully demonstrated on flocking problems. MPC-based flocking controllers are high-performing but also computationally expensive. By learning a symmetric and distributed neural flocking controller from a centralized MPC-based one, we achieve the best of both worlds: the neural controllers have high performance (on par with the MPC controllers) and high efficiency. Our experimental results demonstrate the sophisticated nature of the distributed controllers we learn. In particular, the neural controllers are capable of achieving myriad flocking-oriented control objectives, including flocking formation, collision avoidance, obstacle avoidance, predator avoidance, and target seeking. Moreover, they generalize the behavior seen in the training data to achieve these objectives in a significantly broader range of scenarios. In terms of verification of our neural flocking controller, we use a form of statistical model checking to compute confidence intervals for its convergence rate and time to convergence.
Non-idempotent Intersection Types in Logical Form
Authors: Ehrhard Thomas
Published: April 2020

Intersection types are an essential tool in the analysis of operational and denotational properties of lambda-terms and functional programs. Among them, non-idempotent intersection types provide precise quantitative information about the evaluation of terms and programs. However, unlike simple or second-order types, intersection types cannot be considered as a logical system because the application rule (or the intersection rule, depending on the presentation of the system) involves a condition stipulating that the proofs of premises must have the same structure. Using earlier work introducing an indexed version of Linear Logic, we show that non-idempotent typing can be given a logical form in a system where formulas represent hereditarily indexed families of intersection types.
A Curry-style Semantics of Interaction: From Untyped to Second-Order Lazy $$\lambda \mu $$-Calculus
Authors: Laird James
Published: April 2020

We propose a “Curry-style” semantics of programs in which a nominal labelled transition system of types, characterizing observable behaviour, is overlaid on a nominal LTS of untyped computation. This leads to a notion of program equivalence as typed bisimulation.

Our semantics reflects the role of types as hiding operators, firstly via an axiomatic characterization of “parallel composition with hiding” which yields a general technique for establishing congruence results for typed bisimulation, and secondly via an example which captures the hiding of implementations in abstract data types: a typed bisimulation for the (Curry-style) lazy$$\lambda \mu $$λμ-calculus with polymorphic types. This is built on an abstract machine for CPS evaluation of$$\lambda \mu $$λμ-terms: we first give a basic typing system for this LTS which characterizes acyclicity of the environment and local control flow, and then refine this to a polymorphic typing system which uses equational constraints on instantiated type variables, inferred from observable interaction, to capture behaviour at polymorphic and abstract types.
An Auxiliary Logic on Trees: on the Tower-Hardness of Logics Featuring Reachability and Submodel Reasoning
Authors: Mansutti Alessio
Published: April 2020

We describe a set of simple features that are sufficient in order to make the satisfiability problem of logics interpreted on trees Tower-hard. We exhibit these features through an Auxiliary Logic on Trees (), a modal logic that essentially deals with reachability of a fixed node inside a forest and features modalities from sabotage modal logic to reason on submodels. After showing that admits a Tower-complete satisfiability problem, we prove that this logic is captured by four other logics that were independently found to be Tower-complete: two-variables separation logic, quantified computation tree logic, modal logic of heaps and modal separation logic. As a by-product of establishing these connections, we discover strict fragments of these logics that are still non-elementary.
The Inconsistent Labelling Problem of Stutter-Preserving Partial-Order Reduction
Authors: Neele Thomas , Valmari Antti , Willemse Tim A. C.
Published: April 2020

In model checking, partial-order reduction (POR) is an effective technique to reduce the size of the state space. Stubborn sets are an established variant of POR and have seen many applications over the past 31 years. One of the early works on stubborn sets shows that a combination of several conditions on the reduction is sufficient to preserve stutter-trace equivalence, making stubborn sets suitable for model checking of linear-time properties. In this paper, we identify a flaw in the reasoning and show with a counter-example that stutter-trace equivalence is not necessarily preserved. We propose a solution together with an updated correctness proof. Furthermore, we analyse in which formalisms this problem may occur. The impact on practical implementations is limited, since they all compute a correct approximation of the theory.
Quantum Programming with Inductive Datatypes: Causality and Affine Type Theory
Authors: Péchoux Romain , Perdrix Simon , Rennela Mathys , Zamdzhiev Vladimir
Published: April 2020

Inductive datatypes in programming languages allow users to define useful data structures such as natural numbers, lists, trees, and others. In this paper we show how inductive datatypes may be added to the quantum programming language QPL. We construct a sound categorical model for the language and by doing so we provide the first detailed semantic treatment of user-defined inductive datatypes in quantum programming. We also show our denotational interpretation is invariant with respect to big-step reduction, thereby establishing another novel result for quantum programming. Compared to classical programming, this property is considerably more difficult to prove and we demonstrate its usefulness by showing how it immediately implies computational adequacy at all types. To further cement our results, our semantics is entirely based on a physically natural model of von Neumann algebras, which are mathematical structures used by physicists to study quantum mechanics.
The Polynomial Complexity of Vector Addition Systems with States
Authors: Zuleger Florian
Published: April 2020

Vector addition systems are an important model in theoretical computer science and have been used in a variety of areas. In this paper, we consider vector addition systems with states over a parameterized initial configuration. For these systems, we are interested in the standard notion of computational time complexity, i.e., we want to understand the length of the longest trace for a fixed vector addition system with states depending on the size of the initial configuration. We show that the asymptotic complexity of a given vector addition system with states is either$$\varTheta (N^k)$$Θ(Nk)for some computable integerk, whereNis the size of the initial configuration, or at least exponential. We further show thatkcan be computed in polynomial time in the size of the considered vector addition system. Finally, we show that$$1 \le k \le 2^n$$1≤k≤2n, wherenis the dimension of the considered vector addition system.
Cartesian Difference Categories
Authors: Alvarez-Picallo Mario , Lemay Jean-Simon Pacaud
Published: April 2020

Cartesian differential categories are categories equipped with a differential combinator which axiomatizes the directional derivative. Important models of Cartesian differential categories include classical differential calculus of smooth functions and categorical models of the differential $$\lambda $$
λ
-calculus. However, Cartesian differential categories cannot account for other interesting notions of differentiation such as the calculus of finite differences or the Boolean differential calculus. On the other hand, change action models have been shown to capture these examples as well as more “exotic” examples of differentiation. However, change action models are very general and do not share the nice properties of a Cartesian differential category. In this paper, we introduce Cartesian difference categories as a bridge between Cartesian differential categories and change action models. We show that every Cartesian differential category is a Cartesian difference category, and how certain well-behaved change action models are Cartesian difference categories. In particular, Cartesian difference categories model both the differential calculus of smooth functions and the calculus of finite differences. Furthermore, every Cartesian difference category comes equipped with a tangent bundle monad whose Kleisli category is again a Cartesian difference category.
Parameterized Synthesis for Fragments of First-Order Logic Over Data Words
Authors: Bérard Béatrice , Bollig Benedikt , Lehaut Mathieu , Sznajder Nathalie
Published: April 2020

We study the synthesis problem for systems with a parameterized number of processes. As in the classical case due to Church, the system selects actions depending on the program run so far, with the aim of fulfilling a given specification. The difficulty is that, at the same time, the environment executes actions that the system cannot control. In contrast to the case of fixed, finite alphabets, here we consider the case of parameterized alphabets. An alphabet reflects the number of processes, which is static but unknown. The synthesis problem then asks whether there is a finite number of processes for which the system can satisfy the specification. This variant is already undecidable for very limited logics. Therefore, we consider a first-order logic without the order on word positions. We show that even in this restricted case synthesis is undecidable if both the system and the environment have access to all processes. On the other hand, we prove that the problem is decidable if the environment only has access to a bounded number of processes. In that case, there is even a cutoff meaning that it is enough to examine a bounded number of process architectures to solve the synthesis problem.
An O(m log n) algorithm for branching bisimilarity on labelled transition systems
Authors: Jansen David N. , Groote Jan Friso , Keiren Jeroen J. A. , Wijs Anton
Published: April 2020

Branching bisimilarity is a behavioural equivalence relation on labelled transition systems (LTSs) that takes internal actions into account. It has the traditional advantage that algorithms for branching bisimilarity are more efficient than ones for other weak behavioural equivalences, especially weak bisimilarity. With m the number of transitions and n the number of states, the classic $${O\left( {m n}\right) }$$ algorithm was recently replaced by an $$O({m (\log \left| { Act }\right| + \log n)})$$ algorithm [9], which is unfortunately rather complex. This paper combines its ideas with the ideas from Valmari [20], resulting in a simpler $$O({m \log n})$$ algorithm. Benchmarks show that in practice this algorithm is also faster and often far more memory efficient than its predecessors, making it the best option for branching bisimulation minimisation and preprocessing for calculating other weak equivalences on LTSs.
Partial-Order Reduction for Parity Games with an Application on Parameterised Boolean Equation Systems
Authors: Neele Thomas , Willemse Tim A. C. , Wesselink Wieger
Published: April 2020

Partial-order reduction (POR) is a well-established technique to combat the problem of state-space explosion. We propose POR techniques that are sound for parity games, a well-established formalism for solving a variety of decision problems. As a consequence, we obtain the first POR method that is sound for model checking for the full modal $$\mu $$-calculus. Our technique is applied to, and implemented for the fixed point logic called parameterised Boolean equation systems, which provides a high-level representation of parity games. Experiments indicate that substantial reductions can be achieved.
Dartagnan: Bounded Model Checking for Weak Memory Models (Competition Contribution)
Authors: Ponce-de-León Hernán , Furbach Florian , Heljanko Keijo , Meyer Roland
Published: April 2020

Dartagnanis a bounded model checker for concurrent programs under weak memory models. What makes it different from other tools is that the memory model is not hard-coded inside Dartagnanbut taken as part of the input. For SV-COMP’20, we take as input sequential consistency (i.e. the standard interleaving memory model) extended by support for atomic blocks. Our point is to demonstrate that a universal tool can be competitive and perform well in SV-COMP. Being a bounded model checker, Dartagnan’s focus is on disproving safety properties by finding counterexample executions. For programs with bounded loops, Dartagnanperforms an iterative unwinding that results in a complete analysis. The SV-COMP’20 version of Dartagnanworks on Boogiecode. The C programs of the competition are translated internally to Boogieusing SMACK.
GACAL: Conjecture-Based Verification
Authors: Quiring Benjamin , Manolios Panagiotis
Published: April 2020

GACAL verifies C programs by searching over the space of possible invariants, using traces of the input program to identify potential invariants. GACAL uses the ACL2s theorem prover to verify these potential invariants, using an interface provided by ACL2s for connecting with external tools. GACAL iteratively searches for and proves invariants of increasing complexity until the program is verified.
Simulation Training in Neuroangiography—Validation and Effectiveness
Authors: Kreiser Kornelia , Ströber Lea , Gehling Kim G. , Schneider Frederick , Kohlbecher Stefan , Schulz Christian M. , Zimmer Claus , Kirschke Jan S.
Published: April 2020

Purpose

Simulators are increasingly used in the training of endovascular procedures; however, for the use of the Mentice vascular interventional system trainer (VIST) simulator in neuroradiology, the validity of the method has not yet been proven. The study was carried out to test the construct validity of such a simulator by demonstrating differences between beginner and expert neurointerventionalists and to evaluate whether a training effect can be demonstrated in repeated cases for different levels of experience.

Methods

In this study 4 experts and 6 beginners performed 10 diagnostic angiographies on the VIST simulator (Mentice AB, Gothenburg, Sweden). Of the cases four were non-recurring, whereas three were repeated once and ten subjects performed all tasks. Additionally, another expert performed only five non-recurring cases. The simulator recorded total time, fluoroscopy time, amount of contrast medium and number of material changes. Furthermore, gaze direction and heart rate were recorded, and subjects completed a questionnaire on workload.

Results

Beginners and experts showed significant differences in total duration time, fluoroscopy time and amount of contrast agent (all p < 0.05). Gaze direction, dwell time and heart rate were similar between both groups. Only beginners improved during training with respect to total duration time, fluoroscopy time and amount of contrast agent. If a case was previously known to them, the total duration and fluoroscopy time were significantly shortened (p < 0.001).

Conclusion

This study demonstrated both the construct validity of a diagnostic neuroangiography simulator as well as a significant training effect for beginners. Therefore, in particular beginner neurointerventionalists should use such simulation tools more extensively in their initial training.
Inpatient hypoglycaemia: understanding who is at risk
Authors: Ruan Yue , Moysova Zuzana , Tan Garry D. , Lumb Alistair , Davies Jim , Rea Rustam D.
Published: April 2020

Aims/hypothesis

We analysed data obtained from the electronic patient records of inpatients with diabetes admitted to a large university hospital to understand the prevalence and distribution of inpatient hypoglycaemia.

Methods

The study was conducted using electronic patient record data from Oxford University Hospitals NHS Foundation Trust. The dataset contains hospital admission data for patients coded for diabetes. We used the recently agreed definition for a level 1 hypoglycaemia episode as any blood glucose measurement <4 mmol/l and a level 2 hypoglycaemia episode as any blood glucose measurement <3 mmol/l. Any two or more consecutive low blood glucose measurements within a 2 h time window were considered as one single hypoglycaemic episode.

Results

We analysed data obtained from 17,658 inpatients with diabetes (1696 with type 1 diabetes, 14,006 with type 2 diabetes, and 1956 with other forms of diabetes; 9277 men; mean ± SD age, 66 ± 18 years) who underwent 32,758 hospital admissions between July 2014 and August 2018. The incidence of level 1 hypoglycaemia was 21.5% and the incidence of level 2 hypoglycaemia was 9.6%. Recurrent level 1 and level 2 hypoglycaemia occurred, respectively, in 51% and 39% of hospital admissions in people with type 2 diabetes with at least one hypoglycaemic episode, and in 55% and 45% in those with type 1 diabetes. The incidence of level 2 hypoglycaemia in people with type 2 diabetes, when corrected for the number of people who remained in hospital, remained constant for the first 100 h at approximately 0.15 events per h per admission. With regards to the hypoglycaemia distribution during the day, after correcting for the number of blood glucose tests per h, there were two clear spikes in the rate of hypoglycaemia approximately 3 h after lunch and after dinner. The highest rate of hypoglycaemia per glucose test was seen between 01:00 hours and 05:00 hours. Medication had a significant impact on the incidence of level 2 hypoglycaemia, ranging from 1.5% in people with type 2 diabetes on metformin alone to 33% in people treated with a combination of rapid-acting insulin analogue, long-acting insulin analogue and i.v.-administered insulin.

Conclusions/interpretation

Retrospective analysis of data from electronic patient records enables clinicians to gain a greater understanding of the incidence and distribution of inpatient hypoglycaemia. This information should be used to drive evidence-based improvements in the glycaemic control of inpatients through targeted medication adjustment for specific populations at high risk of hypoglycaemia.
Effect of Shoot Cutting on Trace Metal Concentration in Leaves and Capitula of Potential Phytoaccumulator, Invasive Erigeron annuus (Asteraceae)
Authors: Pliszko Artur , Klimek Beata , Kostrakiewicz-Gierałt Kinga
Published: April 2020

The effect of shoot cutting was tested on cadmium, lead and zinc concentration in leaves and capitula of Erigeron annuus, an invasive species, which is considered as a potential phytoremediator. Plant material and soil were collected in the city center of Kraków, southern Poland, considered as one of the most contaminated cities in Europe. We proved that the concentration of zinc in leaves and capitula was higher after regrowth, concentration of cadmium was lower in capitula than in leaves, and the average value of bio-concentration factor for zinc and cadmium was less than 1, whereas for lead it was greater than 1 in both plant organs. Our results suggested that E. annuus can be potentially used for phytoremediation of lead and cutting the shoots can promote effectiveness of zinc removal from the contaminated soil.
Research productivity during orthopedic surgery residency correlates with pre-planned and protected research time: a survey of German-speaking countries
Authors:   For the Society of Arthroscopy and Joint Surgery (AGA) Residents Forum, Research Working Group, Voss Andreas , Andreß Björn , Pauzenberger Leo , Herbst Elmar , Pogorzelski Jonas , John Dominik , Smolen Daniel , Roessler Philip P. , Tobert Daniel G. , Sieker Jakob T.
Published: April 2020

Purpose

The purpose of this study was to identify modifiable factors associated with research activity among residents working in orthopedic surgery and traumatology.

Methods

Residents at 796 university-affiliated hospitals in Austria, Germany, and Switzerland were invited to participate. The online survey consisted of questions that ascertained 13 modifiable and 17 non-modifiable factors associated with the residents’ current research activities. Responses of 129 residents were analyzed. Univariate linear regression was used to determine the association of individual factors with the current research activity (hours per week). The impact of significant non-modifiable factors (with unadjusted p values < 0.05) was controlled for using multivariate linear regression.

Results

The univariate analysis demonstrated six non-modifiable factors that were significantly associated with the current research activity: a University hospital setting (p < 0.001), an A-level hospital setting (p = 0.024), Swiss residents (p = 0.0012), the completion of a dedicated research year (p = 0.007), female gender (p = 0.016), and the department’s size (p = 0.048). Multivariate regression demonstrated that the number of protected research days per year (p < 0.029) and the percentage of protected days, that were known 1 week before (p < 0.001) or the day before (p < 0.001), were significantly associated with a higher research activity.

Conclusions

As hypothesized, more frequent and predictable protected research days were associated with higher research activity among residents in orthopedic surgery and traumatology.

Level of evidence

III.
A new technique of laparoscopic fixation of the uterus to the anterior abdominal wall with the use of overfascial mesh in the treatment of pelvic organ prolapse
Authors: Śliwa Jakub , Kryza-Ottou Anna , Zimmer-Stelmach Aleksandra , Zimmer Mariusz
Published: April 2020

Introduction and hypothesis

Pelvic organ prolapse is one of the most common pathological conditions in postmenopausal women. There is still a lack of fully effective and safe surgical techniques, especially in the advanced stages of apical defects. The purpose of the video is to present a new technique of laparoscopic treatment in women with an advanced stage of genital prolapse, stage III and IV according to the POP-Q scale. The technique involves uterine fixation for the anterior abdominal wall using overfascial mesh.

Methods

We used a live-action surgical demonstration to describe laparoscopic fixation of the uterus to the anterior abdominal wall with the use of overfascial mesh.

Results

This video provides a step-by-step approach to laparoscopic fixation of the uterus to the anterior abdominal wall with the use of overfascial mesh. The video can be used to educate and train those performing female pelvic reconstructive surgery.

Conclusions

Based on our experience, this technique of laparoscopic suspension of the uterus to the anterior abdominal wall with the use of overfascial mesh is an effective, safe, and easy procedure for the treatment of advanced stages of pelvic organ prolapse.
Multimodal spectral focusing CARS and SFG microscopy with a tailored coherent continuum from a microstructured fiber
Authors: Herdzik Krzysztof P. , Bourdakos Konstantinos N. , Johnson Peter B. , Lister Adam P. , Pitera Aleksandra P. , Guo Chun-yu , Horak Peter , Richardson David J. , Price Jonathan H. V. , Mahajan Sumeet
Published: April 2020

We report a technologically novel microscopy system for bioimaging based on a 100 fs titanium:sapphire (Ti:Sa) laser pumped coherent continuum from a tailored, 9-cm long, all normal dispersion (ANDi) fiber, enabling concurrent image contrast with (a) spectral focusing coherent anti-Stokes Raman scattering (SF-CARS) (spanning 900–3200 cm−1) and (b) sum frequency generation (SFG). Both modalities were efficiently excited with power levels at the microscope focus compatible with biological samples. Moreover, using the continuum, images were recorded in the back-scattering (epi-detection) geometry, without the necessity for an expensive, computer-controlled, spatial light modulator (SLM), clearly demonstrating the strong signal levels achieved. Image contrast from the multiple modalities provided greater chemical and structural insights than imaging with any single technique in isolation. Numerical simulations supported these developments in regard to both the optimum fiber length for SC generation and the achievement of high spectral resolution in SF-CARS via careful group delay dispersion matching across the pump and Stokes pulses using just an inexpensive sequence of short glass blocks inserted into the Stokes beam. We show bio-images of mouse tissue recorded concurrently via label/stain-free contrast from multiple modalities: CARS, two-photon auto-fluorescence (TPaF) and second harmonic/sum frequency generation (SHG/SFG). Overall, our approach delivers optimum performance in back-scattered (epi-) detection configuration, suited for thick samples, at reduced complexity and cost. The addition of this simple fiber add-on to lasers already widely used for TPF microscopy can thus extend the capabilities of a significant number of existing microscopy laboratories.
High level of EZH2 expression is linked to high density of CD8-positive T-lymphocytes and an aggressive phenotype in renal cell carcinoma
Authors: Eichenauer Till , Simmendinger Luca , Fraune Christoph , Mandelkow Tim , Blessin Niclas C. , Kluth Martina , Hube-Magg Claudia , Möller Katharina , Clauditz Till , Weidemann Sören , Dahlem Roland , Fisch Margit , Riechardt Silke , Simon Ronald , Sauter Guido , Büscheck Franziska , Rink Michael
Published: April 2020

Purpose

Enhancer of zeste homolog 2 (EZH2), the catalytic part of the Polycomb repressive complex 2 (PRC2), has a prognostic role in renal cell carcinoma (RCC) and was recently shown to modulate the immune response by reducing tumor cell immunogenicity.

Methods

To investigate whether the prognostic role of EZH2 might be driven by a modified immune environment, more than 1800 RCCs were analyzed in a tissue microarray for EZH2 expression and CD8 positive lymphocytes were quantitated by automated digital imaging.

Results

EZH2 positivity was found in 75.2% of 1603 interpretable tumors. In clear cell RCC, high EZH2 expression was significantly linked to high ISUP, Furmann, and Thoenes grade (p < 0.0001 each), advanced stage (p < 0.0001), nodal (p = 0.0190) and distant metastasis (p < 0.0001) as well as shortened overall (p < 0.0027) and recurrence free survival (p < 0.0001). The density of CD8+ cells varied from 0 to 5048 cells/mm2 (Median 120 cells/mm2). A high CD8+ count was significantly associated with high ISUP, Fuhrmann, and Thoenes grade (p < 0.0001 each), advanced tumor stage (p = 0.0041), distant metastasis (p = 0.0026) as well as reduced overall survival (p = 0.0373) and recurrence free survival (p = 0.0450). The density of CD8+ cells continuously increased with raising EZH2 levels (p < 0.0001).

Conclusion

Our data support a striking prognostic role of both EZH2 expression and the density of CD8+ cells in RCC. The tight relationship of EZH2 expression and CD8+ cell counts in RCC is consistent with models suggesting that EZH2 overexpression can be caused by high lymphocyte content in certain tumor types. Such a mechanism could explain the unique finding of high lymphocyte counts driving poor prognosis in RCC patients.
Dynamical and thermodynamical drivers of variability in European summer heat extremes
Authors: Suarez-Gutierrez Laura , Müller Wolfgang A. , Li Chao , Marotzke Jochem
Published: April 2020

We use the 100-member Max Planck Institute Grand Ensemble (MPI-GE) to disentangle the contributions from colocated dynamic atmospheric conditions and local thermodynamic effects of moisture limitation as drivers of variability in European summer heat extremes. Using a novel extreme event definition, we find that heat extremes with respect to the evolving mean climate increase by 70% under a moderate warming scenario during the twenty-first century. With a multiple regression approach, we find that the dynamical mechanisms representing blocking and anticyclonic conditions are the main driver of variability in extreme European summer temperatures, both in past and future climates. By contrast, local thermodynamic drivers play a secondary role in explaining the total variability in extreme temperatures. We also find that considering both dynamical and thermodynamical sources of variability simultaneously is crucial. Assessing only one type of drivers leads to an overestimation of their effect on extreme temperatures, particularly when considering only thermodynamical drivers. Lastly, we find that although most past and future heat extremes occur under favorable dynamical atmospheric conditions; this occurs 10–40% less frequently over Central Europe in the twenty-first century. By contrast, heat extremes over Central Europe occur 40% more frequently under concurrent extreme moisture limitation in the twenty-first Century. Our findings highlight a new type of neutral-atmosphere, moisture-driven heat extremes, and confirm that the increase in European heat extremes and associated variability increase are dominated by the local thermodynamic effect of moisture limitation.
Assessment of heavy metal pollution in Vistula river (Poland) sediments by using magnetic methods
Authors: Szczepaniak-Wnuk Iga , Górka-Kostrubiec Beata , Dytłow Sylwia , Szwarczewski Piotr , Kwapuliński Piotr , Karasiński Jakub
Published: April 2020

The present study evaluated the level of heavy metal (HM) pollution in Vistula river sediments in a highly urbanized Warsaw agglomeration (Poland). Magnetometry was used to assess the pollution level by measuring the fine fractions (0.071 mm and < 0.071 mm) of sediments collected from the surface layer of the riverbank. The magnetic methods (e.g., mass magnetic susceptibility χ, temperature-dependence magnetic susceptibility, and hysteresis loop parameters) were supplemented by microscopy observations and chemical element analyses. The results showed the local impact of Warsaw’s activity on the level of HM pollution, indicated by the maximum concentrations of magnetic particles and HM in the city center. The sediment fraction < 0.071 mm was dominated by magnetite and by a large amount of spherical-shaped anthropogenic magnetic particles. The pollution from the center of Warsaw was transported down-river over a relatively short distance of approximately 11 km. There was a gradual decrease in the concentrations of magnetic particles and HM in areas located to the north of the city center (down-river); furthermore, χ and concentrations of HM did not decrease to the values observed for the area to the south of Warsaw (up-river). The study showed two possible sources of sediment pollution: traffic-related and heat and power plant emissions. The influence of an additional source of pollution cannot be excluded as the amount of spherules in the sediments at the center was extremely high. The present study demonstrates that magnetometry has a practical application in detecting and mapping HM pollution in river systems.
Kommunikationspräfenzen im Kontext von Adipositas
Authors: Hansen Solveig Lena , Bammel Hendrik , Lübeck Nicole , Seibel Regina , Schankweiler Pia
Published: April 2020

Hintergrund

Das Thema Körpergewicht weist aktuelle einige Herausforderungen für die Arzt-Patienten-Kommunikation auf.

Ziel der Arbeit

Die vorliegende Studie untersucht Kommunikationspräferenzen von Personen mit Adipositas und erarbeitet praktische Empfehlungen für deren Beratung.

Material und Methoden

Qualitative Inhaltsanalyse halb strukturierter, leitfadengestützter Interviews mit 20 Teilnehmenden eines Gewichtsreduktionsprogramms.

Ergebnisse

Das Thema wurde meist von Ärzten im Zusammenhang mit anderen Erkrankungen angesprochen. Inhalte der Gespräche waren oft medizinische Informationen und Risiken. Es konnten sechs verschiedene Typen der Ansprache herausgearbeitet werden. Entscheidend für eine gelungene Kommunikation erwies sich weniger die konkrete Wortwahl als die Art der Ansprache und Haltung des Arztes. Wir entwickeln die Struktur für eine individualisierte Beratung und erarbeiten ein „5-G-Modell“ als Leitfaden.
Constitutive TSH receptor activation as a hallmark of thyroid autonomy
Authors: Führer Dagmar
Published: April 2020

Since its cloning more than 30 years ago, the thyrotropin receptor (TSHR) has emerged as a pivotal player in thyroid physiology and pathophysiology. In particular, hyperthyroidism due to autoimmune disease or thyroid autonomy is linked with TSHR activation via autoantibodies or mutations respectively. This review summarises clinical aspects of constitutive TSH receptor activation by naturally occurring somatic or germline TSHR mutations resulting in TSH-independent thyroid function and cell proliferation.
Coupling effects in QD dimers at sub-nanometer interparticle distance
Authors: Dibenedetto Carlo Nazareno , Fanizza Elisabetta , Brescia Rosaria , Kolodny Yuval , Remennik Sergei , Panniello Annamaria , Depalo Nicoletta , Yochelis Shira , Comparelli Roberto , Agostiano Angela , Curri Maria Lucia , Paltiel Yossi , Striccoli Marinella
Published: April 2020

Currently, intensive research efforts focus on the fabrication of meso-structures of assembled colloidal quantum dots (QDs) with original optical and electronic properties. Such collective features originate from the QDs coupling, depending on the number of connected units and their distance. However, the development of general methodologies to assemble colloidal QD with precise stoichiometry and particle-particle spacing remains a key challenge. Here, we demonstrate that dimers of CdSe QDs, stable in solution, can be obtained by engineering QD surface chemistry, reducing the surface steric hindrance and favoring the link between two QDs. The connection is made by using alkyl dithiols as bifunctional linkers and different chain lengths are used to tune the interparticle distance from few nm down to 0.5 nm. The spectroscopic investigation highlights that coupling phenomena between the QDs in dimers are strongly dependent on the interparticle distance and QD size, ultimately affecting the exciton dissociation efficiency.