bluuebunny/crossref_metadata_2025 huggingface dataset:
On the impact of the jerk on structural dynamics
Authors: Steiner Wolfgang
Published: December 2021

In mechanics, the term jerk, which is usually defined as the time derivative of acceleration, is often used incorrectly to interpret shock loads. Unfortunately, it is often very difficult to convince technicians with less insight into the basic laws of mechanics that their views are invalid, since jerky motions undoubtedly have certain effects on the dynamics of mechatronic systems. The fact is, however, that according to Newton the magnitude of the force acting on a body is determined exclusively by the acceleration itself and not by its derivative. From Newton's law follows only the trivial statement that the change of force is proportional to the change of acceleration. The effects of the jerk only become apparent in structural‐dynamic applications, such as in robotics or in biomechanics. In this presentation, such effects are discussed for a simple mechanical model to make fundamental phenomena such as component vibrations, which are related to the jerk, understandable. Quantitative relations between the jerk and the amplitude of such vibrations are derived analytically.
Existence of weak solutions of diffuse interface models for magnetic fluids
Authors: Kalousek Martin , Mitra Sourav , Schlömerkemper Anja
Published: December 2021

In this article we collect some recent results on the global existence of weak solutions for diffuse interface models involving incompressible magnetic fluids. We consider both the cases of matched and unmatched specific densities. For the model involving fluids with identical densities we consider the free energy density to be a double well potential whereas for the unmatched density case it is crucial to work with a singular free energy density.
Modeling of wear processes by a regularized damage‐plasticity model based on the emulated RVE
Authors: Hoormazdi Golnaz , Hackl Klaus
Published: December 2021

Wear is defined as damage to the surface of a solid body, involving progressive material removal, due to relative motion and frictional contact with another surface. This process is usually slow but is considered as one of the major factors causing damage and consequently failure of component parts during the lifetime of tools or machines in different applications such as tunneling.

The implementation of conventional local material models in finite element simulations involving softening behavior (e.g., softening plasticity or damage) tends toward an ill‐posed boundary value problem after the onset of softening due to non‐convex and non‐coercive energy functions and suffers from strongly mesh‐dependent results. Therefore, different regularization strategies are developed to overcome the mentioned problem, such as integral or gradient enhancement, introducing an internal length scale and subsequently increasing computation effort.

In this study, we present a variational approach for regularization of damage material model coupled with local plasticity based on emulated representative volume element (ERVE). This model shall be applied for the numerical investigation of wear processes, where a fine resolution of the involved constituents (cut sheet and abrasive particles in the soil) are required. We start with the theoretical derivation of material model, briefly present the numerical treatment, and prove the efficiency of this new approach via some numerical examples. Furthermore, results to the simulation of different wear modes in single scratch tests are presented.
On the orbital stability of periodic trajectories of a class of discontinuous systems
Authors: Zuyev Alexander , Benner Peter , Seidel-Morgenstern Andreas
Published: December 2021

This paper focuses on the stability analysis of periodic trajectories for non‐autonomous systems whose right‐hand sides are time‐periodic discontinuous functions. Such systems arise, in particular, in optimal control problems for nonlinear control systems with periodic bang‐bang inputs. We obtain sufficient orbital stability conditions of the Andronov–Witt type for this class of systems. The proposed stability conditions are applied to the analysis of periodic extremal trajectories of the controlled nonlinear chemical reaction model.
Efficient computation of coupled bending and torsion vibrations of slender structures with an axially moving eccentric load
Authors: Holl Helmut J. , Keplinger Lukas
Published: December 2021

Frequently slender structures are excited by moving loads and show the corresponding transient vibrations. A model is derived using a simply supported Bernoulli‐Euler beam and the coupled bending and torsion vibration equations are derived. An analytical solution of the decoupled partial differential equations is derived based on the eigenmode expansion considering the boundary and initial conditions. For the pure bending and the pure Saint‐Venant torsion the analysis is performed and the beam vibrations are calculated. The coupled bending and torsion deformations are computed using a modal transformation, where it is essential that the eigenmodes are the same for both kinds of vibrations. The resulting modal decoupling yields two separated ordinary differential equations in time with the assumed constant velocity of the axially moving excitation load. Closed form solutions are used which show a very good convergence. A transformation into the original coordinates results in the solutions of the coupled equations. The results are plotted in a dimensionless form. The evaluation and comparison with a suitable numerical calculation using a finite element model shows a good agreement of the results. It turns out that a fine discretization is necessary and the computation effort for computing the transient dynamic solution is very much higher.
Efficient surrogate strategy for investigating stick‐slip instability
Authors: Fau Amelie , Fuhg Jan N.
Published: December 2021

An innovative sampling strategy called MiVor coupled with kriging metamodeling is employed for detecting stick‐slip instabilities within a parametric domain based on very few simulations. The interest of the approach is here exposed on an oscillator of Duffing's type in combination with an elasto‐plastic friction force model, more details can be found in [3].
Adjoint based optimal control of nonlocal advection with bilinear mixed constraints in H1
Authors: Linn Dominik , Mohring Jan , Pinnau René
Published: December 2021

In district heating, it is often required to control the system in such a way, that temperature and supply power are simultaneously bounded [1], which results in a set of box constraints for the control variable, and mixed bilinear state‐control‐constraint. The latter one is relaxed using a Moreau‐Yosida penalty approach, leading to a parametrized series of optimization problem, whereas the former one is handled by projection. This problem is studied at the example simplified one‐pipeline model, and numerically solved using a projected gradient algorithm. Due to the regularity required by the nonlocal boundary condition, the control variable has to be a function in H1 , such that the gradient computation and projection steps require an additional elliptic subproblem, which has to be solved.
Phase‐field fracture simulations of a four‐point bending test
Authors: Bilgen Carola , Schmidt Christopher , Weinberg Kerstin
Published: December 2021

Phase‐field fracture simulations have been established to simulate crack propagation in solid structures. The method employs a variational framework which has been proven to converge to Griffith' classical model for brittle fracture. Here we investigate the predictiveness of phase‐field fracture through a four‐point bending test in a mixed mode condition, and we discuss the possibilities to perform such simulation with the finite element software ABAQUS. The comparison with the experiments allows estimating the quality of the method with respect to failure loads, crack initiation angles, propagation path, and fracture surface.
A data‐driven approach for the structural analysis of hybrid metal‐plastic composites
Authors: Hürkamp André , Rothe Felix , Dröder Klaus
Published: December 2021

The manufacturing of hybrid composites has an important impact on the final structural properties. Manufacturing induced defects influence the mechanical performance and thus need to be considered for the structural design. In this contribution, we present a data‐driven approach for the structural analysis of hybrid metal‐plastic composites. Based on numerical analyses, a surrogate model based on Proper Orthogonal Decomposition and Machine Learning is derived that can be implemented in early design optimizations.
Identification of the concentration‐dependent viscoelastic constitutive parameters of gelatin by combining computational mechanics and machine learning
Authors: Abdolazizi Kian P. , Linka Kevin , Sprenger Johanna , Neidhardt Maximilian , Schlaefer Alexander , Cyron Christian J.
Published: December 2021

Since the mechanical properties of gelatin are similar to those of soft biological tissues, gelatin is a commonly used surrogate for real tissues, for example in safety engineering or medical engineering. Additional advantages of gelatin over real tissues are lower costs and better reproducibility of experiments. Therefore, constitutive models of gelatin are of great interest. In particular, it is important to capture the concentration dependence of the mechanical properties since the gelatin mass concentration significantly affects the constitutive behavior. To this end, we propose a hybrid approach linking artificial neural networks (ANN) and classical constitutive modeling to relate the gelatin's concentration to its viscoelastic material properties using indentation data.
A machine learning approach for identifying an effective dimension in parametric dynamical systems
Authors: Pulch Roland
Published: December 2021

We consider dynamical systems including physical parameters. An operator maps a realisation of the parameters to a trajectory of a quantity of interest. The operator is approximated by an artificial neural network, i.e., an approach of machine learning. We arrange modified neural networks, which determine a kind of effective dimension in the parameter space.
Morphology evolution and mechanical property enhancement of linear low‐density polyethylene by adding disentangled ultrahigh molecular weight polyethylene
Authors: Zhang Yu , Di Yutao , Ye Chunlin , Zhang Letian , Tang Xin , Shu Baoqiang , Yan Xiang , Li Wei , Wang Jingdai , Yang Yongrong
Published: December 2021

Ultra‐high molecular weight polyethylene (UHMWPE) and linear low‐density polyethylene (LLDPE) with different ratios were melt‐blended in an internal mixer. Results of rheological tests and scanning electron microscopy indicate that the blends are well miscible in the range of small addition amount of UHMWPE. The content of UHMWPE is suggested to be less than 5.0 wt%, to guarantee good compatibility of biphasic blends. Differential scanning calorimetry studies indicate that co‐crystallization occurs between UHMWPE and LLDPE. The crystallinity increases with the increase of UHMWPE as a nucleating agent. As a result, an improvement in mechanical properties is achieved. When the addition amount of UHMWPE is 5.0 wt%, the impact strength, breaking elongation, Young's modulus, and tensile strength are significantly increased by 27%, 25%, 75%, and 21% respectively.
Generation of inhibitory peptides for IKKε from a kinase‐focused phage library of helix‐loop‐helix peptides
Authors: Mihara Kousuke , Nakajima Natsumi , Fujii Ikuo , Fujiwara Daisuke
Published: December 2021

Conformationally constrained peptides are attracting attention as peptide‐based molecular tools in chemical biology and drug discovery because of their desirable properties such as high selectivity for target binding and stability toward proteolytic enzymes. We previously reported a protein kinase–focused helix‐loop‐helix (HLH) peptide library. The library was constructed by phage display and subsequent chemical modification with adenosine that was employed as an anchor molecule binding to the ATP‐binding pocket of kinase. Here, we discovered and characterized HLH peptides that bind to and inhibit the serine/threonine protein kinase IKKε, a member of the IκB kinase (IKK) family. Screening the library against IKKε identified de novo HLH peptides binding to the kinase. One of the peptides, IKK‐05, showed a high α‐helical content and inhibited IKKε with a mixed‐inhibition mechanism with respect to ATP. The adenosine‐tethering peptide Adc‐IKK‐05 demonstrated significantly enhanced enzyme inhibition activity, indicating a bivalency effect in binding to IKKε. In addition, Adc‐IKK‐05 showed the highest inhibitory activity against IKKε of the IKK family members and other families tested. The peptides obtained in this research can be developed as molecular tools to study the biological functions of IKKε and to obtain structural insights for the design of selective IKKε inhibitors.
Association of nutritional status and mortality risk in patients with primary pulmonary hypertension
Authors: Luo Dongling , Xie Nanshan , Yang Ziyang , Zhang Caojin
Published: December 2021

Malnutrition plays a crucial role in pulmonary hypertension (PH). The prognostic nutritional index (PNI) is a reliable indicator for nutritional status assessment. However, its relationship with mortality risk in PH patients has not yet been investigated. This study analyzed data from the Patient Registry for Primary PH. PNI was calculated through albumin and lymphocyte counts. Subjects with missing data for PNI calculation were excluded. The primary endpoint was all‐cause mortality. Cox proportional hazard model was used to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs). Of the 317 patients records available in the registry, we finally included 136 patients. The average age of the included subjects was 40.56 (14.91) years and 63.24% (86/136) were female. In our analysis of Cox regression, per 1‐point increment of PNI was associated with 4% decreased risk of mortality in PH patients (age‐ and sex‐adjusted HR: 0.96, 95% CI: 0.93–0.98, p = 0.002). We further categorized these subjects by quartiles of PNI. Compared to quartile 4, the age‐ and sex‐adjusted HRs of death for quartiles 1, 2, and 3 were 2.39 (95% CI: 1.21–4.72, p = 0.01), 2.25 (95% CI: 1.15–4.39, p = 0.02), and 1.72 (95% CI: 0.84–3.52, p = 0.14). In addition, logistic regression analyses suggested a positive correlation of PNI with total lung capacity (β = 0.98, p = 0.002) and forced expiratory volume in 1 min (β = 1.53, p = 0.03). This study demonstrates that low PNI was associated with an increased risk of death in PH patients. These findings help to enlighten our understanding of the nutritional status and adverse outcomes in PH patients.
Multiple occurrences of pathologies suggesting a common and severe bone infection in a population of the Australian Pleistocene giant, Genyornis newtoni (Aves, Dromornithidae)
Authors: McInerney Phoebe L. , Arnold Lee J. , Burke Carey , Camens Aaron B. , Worthy Trevor H.
Published: December 2021

Vertebrate fossils showing pathological lesions are incredibly rare, and even more so is the identification of an ailment affecting multiple individuals in a population. However, the unique Lake Callabonna fossil deposit of South Australia has produced several such fossils from a single species of giant bird. Examination of the Lake Callabonna fossils of Genyornis newtoni, an extinct Pleistocene dromornithid, representing at least 34 individuals, has resulted in the identification of six osseous pathologies. These lesions are typical of the bone infection osteomyelitis, and affect a sternum, a tarsometatarsus and four phalanges across four individuals. The identification and description of osteomyelitis in these bones is the first of its kind for extinct galloanseres. Optically stimulated luminescence dating of host deposits shows that these animals were mired in lakebed sediments ranging from 54.2 to 50.4 kyr in age, probably becoming entrapped during a protracted drought phase previously identified as beginning at c. 48 ka and which would have resulted in the lakebed becoming exposed. Additional pathologies are recognized in phalanges of two other dromornithids, Dromornis stirtoni and Ilbandornis woodburnei, from the Miocene Alcoota deposit of the Northern Territory that are also interpreted as drought associated. It is possible that drought‐driven stress and consequent immunosuppressive effects may have contributed to the high frequency of lesions observed in the sampled birds.
Evaluation of damage in GFRP repaired steel fiber reinforced concrete beams using acoustic emission technique
Authors: Goyal Priya , Sharma Shruti , Kwatra Naveen
Published: December 2021

In the present study, monitoring of damage initiation and progression in steel fiber reinforced beams (SFRBs) subjected to half cyclic loading under flexure is attempted using acoustic emission (AE) technique. Variation in AE parameters of cumulative AE hits and acoustic energy with damage progression in these beams along with their flexural performance is studied and compared. Further SFRB beams failed to 90% damage level are repaired using GFRP wraps and are subjected to flexural loading and simultaneous AE monitoring. Variation in AE parameters along with load deflection behavior for control SFRB and retrofitted SFRB beams have been discussed and compared. Based on AE and load–deflection data, Damage Index values were calculated and Damage States have been proposed which can help in providing an early warning of failure proximity. Subsequently empirical relationships have been developed between Damage Index and AE parameters using genetic programming (GP) technique and are in excellent coherence with experimental results. It can be concluded from the study that AE analysis is an effective tool for damage monitoring in SFRB and GFRP repaired SFRB beams.
Longitudinal shear in the tension flanges of composite concrete beams made continuous
Authors: Kytölä Ulla , Tulonen Joonas , Laaksonen Anssi
Published: December 2021

In continuous concrete T‐beams, tension flange plays a remarkable role for the hogging moment capacity at the support area. When precast beams are connected as a continuous structure, longitudinal reinforcement is spread in the flange overhangs at the negative moment area of the continuity connection, which causes longitudinal shear in the tension flange's web‐flange junction. The level of reinforcement spreading influences the magnitude of in‐plane forces at the junction, which can cause the flanges to crack and eventually separate from the web. This separation must be prevented by providing transversal reinforcement in the flanges. Longitudinal shear between web and flange and the required transversal reinforcement are experimentally and computationally studied in cantilever composite T‐beams with the flange in tension. A comparison of the experimental and computational results revealed that longitudinal shear distribution in accordance with conventional beam theory does not always yield safe side results. Analyses made with a particularly drawn truss model and the modified compression field theory are in better agreement with the experimental results.
Report of the Special‐purpose Committee on Virtual Participation in the Nomenclature Section
Authors:   Members of the Special‐purpose Committee:, Landrum Leslie R. , Fortunato Renée , Barkworth Mary , Breitwieser Ilse , Demissew Sebsebe , Dönmez Ali A. , Dutta Suchandra , Freire‐Fierro Alina , Kim Young‐Dong , León Blanca , Moore Gerry , Mosyakin Sergei L. , Oh Sang‐Hun , Parra‐O Carlos , Prado Jefferson , Rico Arce Lourdes , Sennikov Alexander N. , Smith Gideon F.
Published: December 2021

The Special‐purpose Committee on Virtual Participation in the Nomenclature Section was established by the XIX International Botanical Congress (IBC) in Shenzhen, China in 2017, with the mandate “to investigate the possibility of and mechanisms for virtual participation and voting in the Nomenclature Section of an International Botanical Congress via the internet” and to report to the XX IBC. The wide access to the World Wide Web and availability of software for virtual meetings makes the possibility for virtual (online) attendance and voting at a Nomenclature Section seem attainable and advisable. In order to make informed recommendations, we discussed various aspects of online attendance and voting, such as: who should be able to observe?; what would qualify a person to cast institutional votes and personal votes?; if the accumulation of institutional votes should be allowed by an online voter; registration of online voters; how costs would be covered; and recommendations for online attendees. This report provides a synthesis of our discussions and is necessary for interpreting the proposals of this Special‐purpose Committee to change aspects of Div. III (Provisions for governance) of the Code (Landrum & al. in Taxon 70: 1397–1398. 2021). This report and those proposals should be consulted together.
Report of the General Committee: 22
Authors: Wilson Karen L.
Published: December 2021

Decisions of the General Committee are reported on various older proposals that had been deferred, as well as proposals in Reports 18–20 of the Permanent Nomenclature Committee for Algae.
Measurement and desert: Why grades cannot be deserved
Authors: Napoletano Toby ,   Philosophy Documentation Center
Published: December 2021

It is typically thought that a student deserves—or at least can deserve—a grade in a class. The students who perform well on assessments, who display a high degree of competence, and who complete all of the required work, deserve a good grade. Students who perform poorly on assessments, who fail to understand the course material, and who fail to complete the required work, deserve a bad grade. In this paper, I raise a challenge to this conventional view about grades. In particular, I challenge the idea that grades—understood appropriately—can be objects of desert for class performance. In other words, grades are simply not the kind of thing that can be deserved. The argument is roughly as follows. In general, when some property or quality of ours is measured, where that property or quality is something that makes us deserving of something, the measurement, itself, is not the thing that is or could be deserved. Grades, however, are a measure of student performance, where performance is meant to be the basis on which students deserve their grades. Since they are mere measures of performance, grades are not and could not be deserved on the basis of performance, and so are not possible objects of desert. Rather, they serve as evidence of the desert basis (academic performance, e.g.) that grounds a student's being deserving of other objects (praise or recognition, e.g.). In short, grades, at best, measure how deserving one is, but grades themselves are not deserved.
Wielding the power of interactive molecular simulations
Authors: Lanrezac André , Férey Nicolas , Baaden Marc
Published: December 2021

Since the dawn of the computer age, scientists have designed devices to represent molecular structures and developed tools to simulate their dynamic behavior in silico. To this day, these tools remain central to our understanding of biomolecular phenomena. In contrast to other fields such as fluid mechanics or meteorology, the observation of molecular motions at the atomic level remains a major experimental challenge. Continuous advances in computer graphics and numerical computation, combined with the emergence of human–computer interaction approaches, led to the methodology of so‐called “interactive molecular simulations”, characterized by two main features. First, the possibility to visualize a running simulation in interactive time, that is, compatible with human perception. Second, the possibility to manipulate the simulation interactively by imposing a force, changing a biophysical property, or editing runtime parameters on the fly. Such simulations are still little used in computational biology, where it is more common to run a series of offline simulations and then visualize and analyze the results. However, interactive molecular simulation tools promise to handle time‐consuming tasks such as the modeling of particularly complex biomolecular structures more efficiently or to support approaches such as Rational Drug Design with regard to pharmaceutical applications.

This article is categorized under:

Computer and Information Science > Computer Algorithms and Programming

Computer and Information Science > Visualization

Software > Simulation Methods
Modular curves and the refined distance conjecture
Authors: Kläwer Daniel
Published: December 2021

Abstract

We test the refined distance conjecture in the vector multiplet moduli space of 4D $$ \mathcal{N} $$
N
= 2 compactifications of the type IIA string that admit a dual heterotic description. In the weakly coupled regime of the heterotic string, the moduli space geometry is governed by the perturbative heterotic dualities, which allows for exact computations. This is reflected in the type IIA frame through the existence of a K3 fibration. We identify the degree d = 2N of the K3 fiber as a parameter that could potentially lead to large distances, which is substantiated by studying several explicit models. The moduli space geometry degenerates into the modular curve for the congruence subgroup Γ0(N)+. In order to probe the large N regime, we initiate the study of Calabi-Yau threefolds fibered by general degree d > 8 K3 surfaces by suggesting a construction as complete intersections in Grassmann bundles.
Partial islands and subregion complexity in geometric secret-sharing model
Authors: Bhattacharya Aranya , Bhattacharyya Arpan , Nandy Pratik , Patra Ayan K.
Published: December 2021

Abstract

We compute the holographic subregion complexity of a radiation subsystem in a geometric secret-sharing model of Hawking radiation in the “complexity = volume” proposal. The model is constructed using multiboundary wormhole geometries in AdS3. The entanglement curve for secret-sharing captures a crossover between two minimal curves in the geometry apart from the usual eternal Page curve present for the complete radiation entanglement. We compute the complexity dual to the secret-sharing minimal surfaces and study their “time” evolution. When we have access to a small part of the radiation, the complexity shows a jump at the secret-sharing time larger than the Page time. Moreover, the minimal surfaces do not have access to the entire island region for this particular case. They can only access it partially. We describe this inaccessibility in the context of “classical” Markov recovery.
Development and validation of an LC–MS/MS method for the quantitation of 30 legacy and emerging per- and polyfluoroalkyl substances (PFASs) in human plasma, including HFPO-DA, DONA, and cC6O4
Authors: Frigerio Gianfranco , Cafagna Simone , Polledri Elisa , Mercadante Rosa , Fustinoni Silvia
Published: December 2021

Per- and polyfluoroalkyl substances (PFASs) include persistent organic pollutants whose spread is still ubiquitous. Efforts to substitute substances of high concern with fluorinated alternatives, such as HFPO-DA (GenX), DONA (ADONA), and cC6O4, have been made. The aim of this work was to develop and validate an isotopic dilution liquid chromatography-tandem mass spectrometry (LC–MS/MS) method suitable to quantify 30 PFASs in human plasma. Analytes included legacy PFASs (PFOA, PFOS, and PFHxS), fluorinated alternatives (PFBA, PFBS, 6:2 FTSA, HFPO-DA, DONA, and cC6O4), and newly identified compounds (F-53B and PFECHS). The sample preparation was rapid and consisted of simple protein precipitation and centrifugation. Calibration standards and quality control solutions were prepared with a human pooled plasma containing relatively low background levels of the considered analytes. A complete validation was carried out: the lower limits of quantitation (LLOQs) ranged from 0.009 to 0.245 µg/L; suitable linearity (determination coefficients,R20.989–0.999), precision (2.0–19.5%, relative standard deviation), and accuracy (87.9–113.1% of theoretical) were obtained for considered concentration ranges. No significant variations of analyte responses were recorded under investigated storage conditions and during matrix effect tests. The external verification confirmed the accuracy of the method, although limited to 12 analytes. The method was also applied to 38 human plasma samples to confirm its applicability. The developed assay is suitable for large-scale analyses of a wide range of legacy and emerging PFASs in human plasma. To our knowledge, this is the first published method including cC6O4 for human biomonitoring.

Graphical abstract
N-Alkylpyridinium sulfonates for retention time indexing in reversed-phase-liquid chromatography-mass spectrometry–based metabolomics
Authors: Stoffel Rainer , Quilliam Michael A. , Hardt Normand , Fridstrom Anders , Witting Michael
Published: December 2021

Chromatographic retention time information is valuable, orthogonal information to MS and MS/MS data that can be used in metabolite identification. However, while comparison of MS data between different instruments is possible to a certain degree, retention times (RTs) can vary extensively, even when nominally the same phase system is used. Different factors such as column dead volumes, system extra column volume, and gradient dwell volume can influence absolute retention times. Retention time indexing (RTI), routinely employed in gas chromatography (e.g., Kovats index), allows compensation for deviations in experimental conditions. Different systems have been reported for RTI in liquid chromatography, but none of them have been applied to metabolomics to the same extent as they have with GC. Recently, a more universal RTI system has been reported based on a homologous series of N-alkylpyridinium sulfonates (NAPS). These reference standards ionize in both positive and negative ionization modes and are UV-active. We demonstrate the NAPS can be used for retention time indexing in reversed-phase-liquid chromatography-mass spectrometry (RP-LC–MS)–based metabolomics. Having measured >500 metabolite standards and varying flow rate and column dimension, we show that conversion of RT to retention indices (RI) substantially improves comparability of retention information and enables to use of RI for metabolite annotation and identification.
PEGylation increases antitumoral activity of arginine deiminase of Streptococcus pyogenes
Authors: Schwarz Rico , Zitzow Eric , Fiebig Adina , Hering Silvio , Humboldt Yvonne , Schoenwaelder Nina , Kämpfer Neele , Volkmar Kerren , Hinz Burkhard , Kreikemeyer Bernd , Maletzki Claudia , Fiedler Tomas
Published: December 2021

Arginine auxotrophy is a metabolic defect that renders tumor cells vulnerable towards arginine-depleting substances, such as arginine deiminase (ADI) fromStreptococcus pyogenes(SpyADI). Previously, we confirmed SpyADI susceptibility on patient-derivedglioblastoma multiforme(GBM) models in vitro and in vivo. For application in patients, serum half-life of the enzyme has to be increased and immunogenicity needs to be reduced. For this purpose, we conjugated theS. pyogenes-derived SpyADI with 20 kDa polyethylene glycol (PEG20) moieties, achieving a PEGylation of seven to eight of the 26 accessible primary amines of the SpyADI. The PEGylation reduced the overall activity of the enzyme by about 50% without affecting the Michaelis constant for arginine. PEGylation did not increase serum stability of SpyADI in vitro, but led to a longer-lasting reduction of plasma arginine levels in mice. Furthermore, SpyADI-PEG20 showed a higher antitumoral capacity towards GBM cells in vitro than the native enzyme.

Key points

•PEGylation has no effect on the affinity of SpyADI for arginine

•PEGylation increases the antitumoral effects of SpyADI on GBM in vitro

•PEGylation prolongs plasma arginine depletion by SpyADI in mice
The effect of modern PET technology and techniques on the EANM paediatric dosage card
Authors: Dickson John , Eberlein Uta , Lassmann Michael
Published: December 2021

Aim

Recent advancements in PET technology have brought with it significant improvements in PET performance and image quality. In particular, the extension of the axial field of view of PET systems, and the introduction of semiconductor technology into the PET detector, initially for PET/MR, and more recently available long-field-of-view PET/CT systems (≥ 25 cm) have brought a step change improvement in the sensitivity of PET scanners. Given the requirement to limit paediatric doses, this increase in sensitivity is extremely welcome for the imaging of children and young people. This is even more relevant with PET/MR, where the lack of CT exposures brings further dose reduction benefits to this population. In this short article, we give some details around the benefits around new PET technology including PET/MR and its implications on the EANM paediatric dosage card.

Material and methods 

Reflecting on EANM adult guidance on injected activities, and making reference to bed overlap and the concept of MBq.min bed−1 kg−1, we use published data on image quality from PET/MR systems to update the paediatric dosage card for PET/MR and extended axial field of view (≥ 25 cm) PET/CT systems. However, this communication does not cover the expansion of paediatric dosing for the half-body and total-body scanners that have recently come to market.

Results

In analogy to the existing EANM dosage card, new parameters for the EANM paediatric dosage card were developed (class B, baseline value: 10.7 MBq, minimum recommended activity 10 MBq). The recommended administered activities for the systems considered in this communication range from 11 MBq [18F]FDG for a child with a weight of 3 kg to 149 MBq [18F]FDG for a paediatric patient weight of 68 kg, assuming a scan of 3 min per bed position. The mean effective dose over all ages (1 year and older) is 2.85 mSv.

Conclusion

With this, recommendations for paediatric dosing are given for systems that have not been considered previously.
Portal Vein Embolization Using N-Butyl Cyanoacrylate-Glue: What Impact Does a Central Vascular Plug Have?
Authors: Carling Ulrik , Røsok Bård , Berger Sigurd , Fretland Åsmund Avdem , Dorenberg Eric
Published: December 2021

Purpose

To examine if the addition of a central vascular plug (CVP) to portal vein embolization (PVE) with N-butyl cyanoacrylate-glue (NBCA) increases future liver remnant (FLR) growth.

Material and Methods

This is a single-center retrospective study of 115 consecutive patients with colorectal liver metastases undergoing PVE in 2013–2019. All patients were embolized with NBCA as the main embolic agent. In 2017–2019 NBCA was combined with a CVP in the central part of the right portal vein. Growth of the FLR and standardized FLR (sFLR) including degree of hypertrophy (DH) and kinetic growth rate (KGR) were analyzed, as well as procedure data such as use of cone-beam CT (CBCT), dose area product (DAP), fluoroscopy time and contrast dose.

Results

A total of 40 patients (35%) underwent PVE with a combination of CVP and NBCA. The DH was higher in these patients after 4 weeks, mean 13.6% (SD 7.8) vs. 10.5% (SD 6.4; p = 0.022), verified in multivariate analysis (coefficient 4.1, p = 0.015). A CVP did not significantly increase the resection rate (90% vs 82%, p = 0.4). Cone beam CT was used in 65 patients (57%). Use of CBCT did not affect FLR growth, and fluoroscopy time and contrast doses were not different in patients having a CBCT or not. Slightly lower DAP (median 3375 vs. 4499 cGy*cm2; p = 0.09) was seen in procedures where CBCT was used.

Conclusion

A CVP in addition to NBCA embolization was associated with increased growth of the FLR compared to NBCA alone.
Mathematically optimal decisions in forensic age assessment
Authors: Mostad Petter , Schmeling Andreas , Tamsen Fredrik
Published: December 2021

Forensic age estimation generally involves considerable amounts of uncertainty. Forensic age indicators such as teeth or skeleton images predict age only approximately, and this is likely to remain true even for future forensic age indicators. Thus, forensic age assessment should aim to make the best possible decisions under uncertainty. In this paper, we apply mathematical theory to make statistically optimal decisions to age assessment. Such an application is fairly straightforward assuming there is a standardized procedure for obtaining age indicator information from individuals, assuming we have data from the application of this procedure to a group of persons with known ages, and assuming the starting point for each individual is a probability distribution describing prior knowledge about the persons age. The main problem is then to obtain such a prior. Our analysis indicates that individual priors rather than a common prior for all persons may be necessary. We suggest that caseworkers, based on individual case information, may select a prior from a menu of priors. We show how information may then be collected over time to gradually increase the robustness of the decision procedure. We also show how replacing individual prior distributions for age with individual prior odds for being above an age limit cannot be recommended as a general method. Our theoretical framework is applied to data where the maturity of the distal femur and the third molar is observed using MRI. As part of this analysis we observe a weak positive conditional correlation between maturity of the two body parts.
The effects of vertebral body tethering on sagittal parameters: evaluations from a 2-years follow-up
Authors: Baroncini Alice , Courvoisier Aurelien , Berjano Pedro , Migliorini Filippo , Eschweiler Jörg , Kobbe Philipp , Hildebrand Frank , Trobisch Per David
Published: December 2021

Introduction

While the effects of VBT on coronal parameters have been investigated in various studies, this has not yet been the case for sagittal parameters. This is of particular relevance considering that VBT does not allow direct correction of the sagittal profile. Thus, we investigated the effects of VBT on sagittal parameters in patients with adolescent idiopathic scoliosis.

Materials and methods

Retrospective, 2-Center study. Patients who underwent VBT and presented a 2-years follow-up were included. The differences in sagittal parameters were evaluated, along with modifications of sagittal profile following Abelin-Genevois’ classification.

Results

Data from 86 patients were obtained. Mean Cobb angle was 52.4 ± 13.9° at thoracic level and 47.6 ± 14.3° at lumbar level before surgery, and 28.5 ± 13.6 and 26.6 ± 12.7° at the 2-year follow-up, respectively. Mean thoracic kyphosis increased from 28.3 ± 13.8 to 33 ± 13°, the lumbar lordosis (LL) was unvaried (from 47.5 ± 13.1 to 48.4 ± 13.5°), PT decreased from 9.4 ± 8.5 to 7.4 ± 6.1°, the sagittal vertical axis SVA decreased from 4.5 ± 31.4 to − 3.6 ± 27.9 mm. No kyphotic effect on LL in patients who underwent lumbar instrumentation was observed. Before surgery, 39 patients had a type 1 sagittal profile, 18 were type 2a, 14 type 2b and 15 type 3. Postoperatively, 54 were type 1, 8 were 2a, 13 were 2b and 11 were type 3.

Conclusions

VBT positively influences sagittal parameters and does not have a kyphotic effect on LL.
Teardrops at the Lake: Chemistry of New Kingdom to Makuria Glass Beads and Pendants Between the First and Second Nile Cataracts
Authors: Then-Obłuska Joanna , Dussubieux Laure
Published: December 2021

International expeditions extensively excavated Lower Nubia (between the First and Second Nile Cataracts) before it was submerged under the waters of Lake Nasser and Lake Nubia. The expeditions concentrated on monumental architecture and cemeteries, including sites at Qustul and Serra East, where the New Kingdom, and Napatan, Meroitic, Nobadian, and Makurian-period elites and common people were buried, ca. 1400 BC–AD 1400. Although the finds abound in adornments, including bead imports from Egypt and South India/Sri Lanka, only a few traces of local glass bead-making have been recorded in Nubia so far. Based on results of laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) analysis of 76 glass beads, pendants, and chunks from Qustul and Serra East contexts, dated between the New Kingdom and the Makuria Kingdom periods, this paper discusses the composition and provenance of two types of plant-ash soda-lime (v-Na-Ca) glass, two types of mineral soda-lime glass (m-Na-Ca), and two types of mineral-soda-high alumina (m-Na-Al) glass. It also presents the remains of a probable local glass bead-making workshop dated to the period of intensive long-distance bead trade in Northeast Africa, AD 400–600.
Insight into the role of cyanobacterial bloom in the trophic link between ciliates and predatory copepods
Authors: Kosiba Joanna , Krztoń Wojciech
Published: December 2021

An important group of protozooplankton, the ciliates, are a crucial component of aquatic food webs. They are the main grazers on bacteria and algae transferring carbon to higher levels of the food web (metazooplankton and fish fry). Changes in the quality and quantity of protozooplankton can modify the quality and quantity of metazooplankton, especially predatory copepods, causing changes in energy transfer and the matter cycle. Observable climate change is one of the most significant factors promoting the increase of cyanobacterial blooms. Therefore, the aim of this study was to find out how cyanobacterial blooms modify relationships between ciliates (prey) and copepods (predator), and to discover possible pathways of changes in freshwater food webs. We analysed the relationship between the biomass of predatory copepods and feeding guilds of ciliates (algivorous, bacterivorous, bacteri-algivorous). The relationship of predators biomass with algivorous and bacteri-algivorous ciliate biomasses, with a simultaneous lack of relationship with bacterivorous ciliate biomass, demonstrates that bacterial fixed carbon may be only partially contributing to the total energy passed through this link. Results demonstrated that the bloom enhanced the relationship between prey and predator. Larger and free-swimming ciliate species appear to play a greater role in energy transfer than smaller sedentary species.
Learning network embeddings using small graphlets
Authors: le Gorrec Luce , Knight Philip A. , Caen Auguste
Published: December 2021

Techniques for learning vectorial representations of graphs (graph embeddings) have recently emerged as an effective approach to facilitate machine learning on graphs. Some of the most popular methods involve sophisticated features such as graph kernels or convolutional networks. In this work, we introduce two straightforward supervised learning algorithms based on small-size graphlet counts, combined with a dimension reduction step. The first relies on a classic feature extraction method powered by principal component analysis (PCA). The second is a feature selection procedure also based on PCA. Despite their conceptual simplicity, these embeddings are arguably more meaningful than some popular alternatives and at the same time are competitive with state-of-the-art methods. We illustrate this second point on a downstream classification task. We then use our algorithms in a novel setting, namely to conduct an analysis of author relationships in Wikipedia articles, for which we present an original dataset. Finally, we provide empirical evidence suggesting that our methods could also be adapted to unsupervised learning algorithms.
Lagrange-multiplier regularization of eigenproblem for Jx
Authors: Jung Dong-Won , Kim U-Rae , Lee Jungil , Yu Chaehyun ,   KPOPℰ Collaboration
Published: December 2021

We solve the eigenproblem of the angular momentum $$J_x$$

J
x

by directly dealing with the non-diagonal matrix unlike the conventional approach rotating the trivial eigenstates of $$J_z$$

J
z

. Characteristic matrix is reduced into a tri-diagonal form following Narducci–Orszag rescaling of the eigenvectors. A systematic reduction formalism with recurrence relations for determinants of any dimension greatly simplifies the computation of tri-diagonal matrices. Thus the secular determinant is intrinsically factorized to find the eigenvalues immediately. The reduction formalism is employed to find the adjugate of the characteristic matrix. Improving the recently introduced Lagrange-multiplier regularization, we identify that every column of that adjugate matrix is indeed the eigenvector. It is remarkable that the approach presented in this work is completely new and unique in that any information of $$J_z$$

J
z

is not required and only algebraic operations are involved. Collapsing of the large amount of determinant calculation with the recurrence relation has a wide variety of applications to other tri-diagonal matrices appearing in various fields. This new formalism should be pedagogically useful for treating the angular momentum problem that is central to quantum mechanics course.
Editorial
Authors: Mansfield-Devine Steve
Published: December 2021

A statement supporting the use of end-to-end encryption (E2EE) in video chat apps has potentially set up a conflict between certain national data protection authorities and their governments.
Keeping ahead of the phishing curve
Authors: Kohavi Lior
Published: December 2021

The Covid-19 pandemic flipped the world on its head and triggered major shifts in day-to-day activity. However, it also caused noticeable acceleration of the digital transformation already underway, forcing companies to develop and speed up their online presence in order to survive the volatile climate.
Numerical evidence of anomalous energy dissipation in incompressible Euler flows: towards grid-converged results for the inviscid Taylor–Green problem
Authors: Fehn Niklas , Kronbichler Martin , Munch Peter , Wall Wolfgang A.
Published: December 2021

The well-known energy dissipation anomaly in the inviscid limit, related to velocity singularities according to Onsager, still needs to be demonstrated by numerical experiments. The present work contributes to this topic through high-resolution numerical simulations of the inviscid three-dimensional Taylor–Green vortex problem using a novel high-order discontinuous Galerkin discretisation approach for the incompressible Euler equations. The main methodological ingredient is the use of a discretisation scheme with inbuilt dissipation mechanisms, as opposed to discretely energy-conserving schemes, which – by construction – rule out the occurrence of anomalous dissipation. We investigate effective spatial resolution up to

$8192^3$

(defined based on the

$2{\rm \pi}$

-periodic box) and make the interesting phenomenological observation that the kinetic energy evolution does not tend towards exact energy conservation for increasing spatial resolution of the numerical scheme, but that the sequence of discrete solutions seemingly converges to a solution with non-zero kinetic energy dissipation rate. Taking the fine-resolution simulation as a reference, we measure grid-convergence with a relative

$L^2$

-error of

$0.27\,\%$

for the temporal evolution of the kinetic energy and

$3.52\,\%$

for the kinetic energy dissipation rate against the dissipative fine-resolution simulation. The present work raises the question of whether such results can be seen as a numerical confirmation of the famous energy dissipation anomaly. Due to the relation between anomalous energy dissipation and the occurrence of singularities for the incompressible Euler equations according to Onsager's conjecture, we elaborate on an indirect approach for the identification of finite-time singularities that relies on energy arguments.