bluuebunny/crossref_metadata_2025 huggingface dataset:
Sector showers for hadron collisions
Authors: Brooks Helen , Preuss Christian T , Skands Peter
Published: July 2020

Abstract

In conventional parton showers (including ones based on dipoles/antennae), a given (Born + m)-parton configuration can typically be reached via O(m!) different “shower histories”. In the context of matrix-element-correction and merging procedures, accounting for these histories mandates fairly complex and resource-intensive algorithms. A so far little-explored alternative in the shower context is to divide the branching phase spaces into distinct “sectors”, each of which only receives contributions from a single branching kernel. This has a number of consequences including making the shower operator bijective; i.e., each parton configuration now has a single unique “inverse”. As a first step towards developing a full-fledged matrix-element-correction and merging procedure based on such showers, we here extend the sector approach for antenna showers to hadron-hadron collisions, including mass and helicity dependence.
On AdS7 stability
Authors: Apruzzi Fabio , De Luca G. Bruno , Gnecchi Alessandra , Monaco Gabriele Lo , Tomasiello Alessandro
Published: July 2020

Abstract

AdS7 supersymmetric solutions in type IIA have been classified, and they are infinitely many. Moreover, every such solution has a non-supersymmetric sister. In this pa- per, we study the perturbative and non-perturbative stability of these non-supersymmetric solutions, focusing on cases without orientifolds. Perturbatively, we first look at the KK spectrum of spin-2 excitations. This does not exhibit instabilities, but it does show that there is no separation of scales for either the BPS and the non-BPS case, thus proving for supersymmetric AdS7 a well-known recent conjecture. We then use 7d gauged supergravity and a brane polarization computation to access part of the spectrum of KK scalars. The result signals an instability for all non-supersymmetric solutions except those that have a single D8 on each side. We finally look at non-perturbative instabilities, and find that NS5 bubbles make these remaining solutions decay.
Bootstrapping massive quantum field theories
Authors: Karateev Denis , Kuhn Simon , Penedones João
Published: July 2020

Abstract

We propose a new non-perturbative method for studying UV complete unitary quantum field theories (QFTs) with a mass gap in general number of spacetime dimensions. The method relies on unitarity formulated as positive semi-definiteness of the matrix of inner products between asymptotic states (in and out) and states created by the action of local operators on the vacuum. The corresponding matrix elements involve scattering amplitudes, form factors and spectral densities of local operators. We test this method in two-dimensional QFTs by setting up a linear optimization problem that gives a lower bound on the central charge of the UV CFT associated to a QFT with a given mass spectrum of stable particles (and couplings between them). Some of our numerical bounds are saturated by known form factors in integrable theories like the sine-Gordon, E8 and O(N) models.
Emergence of ghosts in Horndeski theory
Authors: Babichev Eugeny
Published: July 2020

Abstract

We show that starting from initial conditions with stable perturbations, evolution of a galileon scalar field results in the appearance of a ghost later on. To demonstrate this, we consider a theory with k-essence and cubic galileon Lagrangians on a fixed Minkowski background. Explicit analytical solutions of simple waves are constructed, on top of which a healthy scalar degree of freedom is shown to be converted onto a ghost. Such a transformation is smooth and moreover perturbations remain hyperbolic all the time (until a caustic forms). We discuss a relation between the ghost and the appearance of closed causal curves for such solutions.
Effects of sodium chloride on the gene expression profile of periodontal ligament fibroblasts during tensile strain
Authors: Schröder Agnes , Gubernator Joshua , Nazet Ute , Spanier Gerrit , Jantsch Jonathan , Proff Peter , Kirschneck Christian
Published: July 2020

Purpose

During orthodontic tooth movement, pressure and tension zones develop in the periodontal ligament, and periodontal ligament fibroblasts (PDLF) become exposed to mechanical strain. Enhanced salt (NaCl) concentrations are known to modulate responses of PDLF and immune cells to different stimuli like mechanical strain. Here, we investigated the impact of tensile strain on the gene expression profile of PDLF under normal (NS) and high salt (HS) conditions.

Methods

After preincubation under NS or HS (+40 mM NaCl in medium) conditions for 24 h, PDLF were stretched 16% for 48 h using custom-made spherical cap silicone stamps using an established and published setup. After determination of cell number and cytotoxicity, we analyzed expression of genes involved in extracellular matrix reorganization, angiogenesis, bone remodeling, and inflammation by quantitative real-time polymerase chain reaction (RT-qPCR).

Results

Tensile strain did not affect the expression of genes involved in angiogenesis or extracellular matrix reorganization by PDLF, which however modulate inflammatory responses and bone remodeling in reaction to 16% static tensile strain. Salt (NaCl) treatment triggered enhanced extracellular matrix formation, expression of cyclooxygenase 2 and bone metabolism in PDLF during tensile strain.

Conclusions

Salt (NaCl) consumption may influence orthodontic tooth movement and periodontal bone loss via modulation of extracellular matrix and bone metabolism. Excessive salt intake during orthodontic therapy may cause adverse effects regarding periodontal inflammation and bone resorption.
Akute Appendizitis nach Knochenentnahme am rechten Beckenkamm – erschwerte Differenzialdiagnostik
Authors: Förch S. , Ritter B. , Mayr E.
Published: July 2020

Zur knöchernen Defektauffüllung wird regelhaft Knochen vom vorderen Beckenkamm entnommen. Typische Komplikationen sind postoperatives Hämatom, Nervenverletzungen, Infektionen oder Schmerzen an der Entnahmestelle. Wir beschreiben einen Fall, in dem es nach Knochenentnahme am rechten Beckenkamm bei einem jungen Patienten als Koinzidenz zu einer akuten Appendizitis kam. Durch die durchgeführte Knochenentnahme kam es zu einer erschwerten Diagnosestellung, die nur durch eine differenzierte klinische Untersuchung und daraufhin eingeleitete laborchemische und apparative Diagnostik möglich war.
Cartan subalgebras and the UCT problem, II
Authors: Barlak Selçuk , Li Xin
Published: July 2020

We study the connection between the UCT problem and Cartan subalgebras in C*-algebras. The UCT problem asks whether every separable nuclear C*-algebra satisfies the UCT, i.e., a noncommutative analogue of the classical universal coefficient theorem from algebraic topology. This UCT problem is one of the remaining major open questions in the structure and classification theory of simple nuclear C*-algebras. Since the class of separable nuclear C*-algebras is closed under crossed products by finite groups, it is a natural and important task to understand the behaviour of the UCT under such crossed products. We make a contribution towards a better understanding by showing that for certain approximately inner actions of finite cyclic groups on UCT Kirchberg algebras, the crossed products satisfy the UCT if and only if we can find Cartan subalgebras which are invariant under the actions of our finite cyclic groups. We also show that the class of actions we are able to treat is big enough to characterize the UCT problem, in the sense that every such action (even on a particular Kirchberg algebra, namely the Cuntz algebra$$\mathcal O_2$$O2) leads to a crossed product satisfying the UCT if and only if every separable nuclear C*-algebra satisfies the UCT. Our results rely on a new construction of Cartan subalgebras in certain inductive limit C*-algebras. This new tool turns out to be of independent interest. For instance, among other things, the second author has used it to construct Cartan subalgebras in all classifiable unital stably finite C*-algebras.
Asymptotic Solution of a Boundary Value Problem for a Spring–Mass Model of Legged Locomotion
Authors: Okrasińska-Płociniczak Hanna , Płociniczak Łukasz
Published: July 2020

Running is the basic mode of fast locomotion for legged animals. One of the most successful mathematical descriptions of this gait is the so-called spring–mass model constructed upon an inverted elastic pendulum. In the description of the grounded phase of the step, an interesting boundary value problem arises where one has to determine the leg stiffness. In this paper, we find asymptotic expansions of the stiffness. These are conducted perturbatively: once with respect to small angles of attack, and once for large velocities. Our findings are in agreement with previous results and numerical simulations. In particular, we show that the leg stiffness is inversely proportional to the square of the attack angle for its small values, and proportional to the velocity for large speeds. We give exact asymptotic formulas to several orders and conclude the paper with a numerical verification.
PTV measurements of oscillating grid turbulence in water and polymer solutions
Authors: Lacassagne Tom , Vatteville Judith , Degouet Cedric , El Hajem Mahmoud , Simoëns Serge
Published: July 2020

Particle Tracking Velocimetry (PTV) is applied to measure the flow in an oscillating grid stirred tank filled with either water or shear thinning dilute polymer solutions (DPS) of Xanthan Gum (XG). There are many interests of studying turbulence in such complex non-Newtonian fluids (e.g. in the pharmaceutical, cosmetic, or food industry), and grid stirred tanks are commonly used for fundamental studies of turbulence in Newtonian fluids. Yet the case of oscillating grid flows in shear thinning solutions has been addressed recently by Lacassagne et al. (Exp Fluids 61(1):15, Phys Fluids 31(8):083102, 2019a, b), with only a single two dimensional (2D) Particle Image Velocimetry (PIV) characterization of mean flow and turbulence properties in the central vertical plane of the tank. Here, PTV data processed by the Shake The Box algorithm allows for the time resolved, three dimensional (3D) 3 components (3C) measurement of Lagrangian velocities for a large number of tracked particles in a central volume of interest of the tank. The possibility of projecting this Lagrangian information on an Eulerian grid is explored, and projected Eulerian results are compared with 2D PIV data from the previous work. Even if the mean flow is difficult to reproduce at the lowest polymer concentrations, a good agreement is found between measured turbulent decay laws, thus endorsing the use of this 3D-PTV metrology for the study of oscillating grid turbulence in DPS. The many possibilities of further analysis offered by the 3D3C nature of the data, either in the original Lagrangian form or in the projected Eulerian one, are finally discussed.

Graphic Abstract
Study of disturbance wave development in downwards annular flows with a moving frame-of-reference brightness-based laser-induced fluorescence method
Authors: An Jae Sik , Cherdantsev Andrey V. , Zadrazil Ivan , Markides Christos N.
Published: July 2020

A novel moving frame-of-reference brightness-based laser-induced fluorescence (MFoR-BBLIF) method was developed and demonstrated in downwards co-current air–water annular flows. The method was applied to study the downstream development of individual disturbance waves in flows over a range of conditions (ReL = 276–1321, ReG = 39,500–79,000). In this method, the optical measurement system, and hence, the region of interrogation (ROI) was translated physically along the length of the test-section with a velocity close to that of individual disturbance waves to obtain the velocities of individual disturbance-waves as a function of downstream distance from the inlet. It was found that the velocities of individual disturbance waves increase with both downstream distance and gas–liquid flow conditions. In addition, the variation in the wave velocities was more significant at higher gas and liquid Reynolds numbers. The approach can be integrated with many other contactless measurement methods, and can also be used over a range of translation speeds (not necessarily in a “Lagrangian” manner) to study the evolution of important advecting flow phenomena.

Graphic abstract
OLBVH: octree linear bounding volume hierarchy for volumetric meshes
Authors: Ströter Daniel , Mueller-Roemer Johannes S. , Stork André , Fellner Dieter W.
Published: July 2020

We present a novel bounding volume hierarchy for GPU-accelerated direct volume rendering (DVR) as well as volumetric mesh slicing and inside-outside intersection testing. Our novel octree-based data structure is laid out linearly in memory using space filling Morton curves. As our new data structure results in tightly fitting bounding volumes, boundary markers can be associated with nodes in the hierarchy. These markers can be used to speed up all three use cases that we examine. In addition, our data structure is memory-efficient, reducing memory consumption by up to 75%. Tree depth and memory consumption can be controlled using a parameterized heuristic during construction. This allows for significantly shorter construction times compared to the state of the art. For GPU-accelerated DVR, we achieve performance gain of 8.4$$\times $$
×
–13$$\times $$
×
. For 3D printing, we present an efficient conservative slicing method that results in a 3$$\times $$
×
–25$$\times $$
×
speedup when using our data structure. Furthermore, we improve volumetric mesh intersection testing speed by 5$$\times $$
×
–52$$\times $$
×
.
Effects of surgical and FFP2/N95 face masks on cardiopulmonary exercise capacity
Authors: Fikenzer Sven , Uhe T. , Lavall D. , Rudolph U. , Falz R. , Busse M. , Hepp P. , Laufs U.
Published: July 2020

Background

Due to the SARS-CoV2 pandemic, medical face masks are widely recommended for a large number of individuals and long durations. The effect of wearing a surgical and a FFP2/N95 face mask on cardiopulmonary exercise capacity has not been systematically reported.

Methods

This prospective cross-over study quantitated the effects of wearing no mask (nm), a surgical mask (sm) and a FFP2/N95 mask (ffpm) in 12 healthy males (age 38.1 ± 6.2 years, BMI 24.5 ± 2.0 kg/m2). The 36 tests were performed in randomized order. The cardiopulmonary and metabolic responses were monitored by ergo-spirometry and impedance cardiography. Ten domains of comfort/discomfort of wearing a mask were assessed by questionnaire.

Results

The pulmonary function parameters were significantly lower with mask (forced expiratory volume: 5.6 ± 1.0 vs 5.3 ± 0.8 vs 6.1 ± 1.0 l/s with sm, ffpm and nm, respectively; p = 0.001; peak expiratory flow: 8.7 ± 1.4 vs 7.5 ± 1.1 vs 9.7 ± 1.6 l/s; p < 0.001). The maximum power was 269 ± 45, 263 ± 42 and 277 ± 46 W with sm, ffpm and nm, respectively; p = 0.002; the ventilation was significantly reduced with both face masks (131 ± 28 vs 114 ± 23 vs 99 ± 19 l/m; p < 0.001). Peak blood lactate response was reduced with mask. Cardiac output was similar with and without mask. Participants reported consistent and marked discomfort wearing the masks, especially ffpm.

Conclusion

Ventilation, cardiopulmonary exercise capacity and comfort are reduced by surgical masks and highly impaired by FFP2/N95 face masks in healthy individuals. These data are important for recommendations on wearing face masks at work or during physical exercise.
Intra- and intermuscular variations of postmortem protein degradation for PMI estimation
Authors: Pittner Stefan , Gotsmy Walther , Zissler Angela , Ehrenfellner Bianca , Baumgartner Dominik , Schrüfer Anna , Steinbacher Peter , Monticelli Fabio
Published: July 2020

In recent years, protein decomposition has become of increasing interest for the use in forensic estimation of the postmortem interval (PMI). Especially skeletal muscle tissue has proven to be a prime target tissue, among other reasons, due to its large abundance in the human body. In this regard, it is important to know whether there are any intra- and intermuscular differences in the behavior of protein degradation. Thus, samples from different locations within several skeletal muscles as well as from cardiac and smooth muscle tissue samples were collected from three autopsy cases with varying degree of decomposition. Samples were analyzed by SDS-PAGE and Western blotting and compared for protein degradation patterns. Intramuscular variations turned out to be minimal and without major influence for the use of the method. Observed intermuscular differences provide possibilities for future improvement of the precision and temporal application range. The results of this study show the strengths and current limitations of protein degradation-based PMI estimation and provide a deeper understanding of intraindividual postmortem protein degradation processes.
Finding Needles in a Haystack
Authors: Kurusa Árpád
Published: July 2020

Convex polygons are distinguishable among the piecewise $$C^\infty $$

C
∞

convex domains by comparing their visual angle functions on any surrounding circle. This is a consequence of our main result, that every segment in a $$C^\infty $$

C
∞

multicurve can be reconstructed from the masking function of the multicurve given on any surrounding circle.
Perioperative and oncological outcomes following minimally invasive versus open pancreaticoduodenectomy for pancreatic duct adenocarcinoma
Authors: Sun Rui , Yu Jiawen , Zhang Yifan , Liang Zhika , Han Xianlin
Published: July 2020

Background

The outcomes of minimally invasive pancreaticoduodenectomy have not been adequately compared with those of open pancreaticoduodenectomy in patients with pancreatic ductal adenocarcinoma. We performed a meta‐analysis to compare the perioperative and oncological outcomes of these two pancreaticoduodenectomy procedures specifically in patients with pancreatic ductal adenocarcinoma.

Methods

Before this study was initiated, a specific protocol was designed and has been registered in PROSEPRO (ID: CRD42020149438). Using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, PubMed, EMBASE, Web of Science, Cochrane Central Register, and ClinicalTrials.gov databases were systematically searched for studies published between January 1994 and October 2019. Overall survival, disease-free survival, and time to commencing adjuvant chemotherapy were the primary endpoint measurements, whereas perioperative and short-term outcomes were the secondary endpoints.

Results

The final analysis included 9 retrospective cohorts comprising 11,242 patients (1377 who underwent minimally invasive pancreaticoduodenectomy and 9865 who underwent open pancreaticoduodenectomy). There were no significant differences in the patients’ overall survival, operative time, postoperative complications, 30-day mortality, rate of vein resection, number of harvested lymph nodes, or rate of positive lymph nodes between the two approaches. However, disease-free survival, time to starting adjuvant chemotherapy, length of hospital stay, and rate of negative margins in patients who underwent minimally invasive pancreaticoduodenectomy showed improvements relative to those in patients who underwent open surgery.

Conclusions

Minimally invasive pancreaticoduodenectomy provides similar or even improved perioperative, short-term, and long-term oncological outcomes when compared with open pancreaticoduodenectomy for patients with pancreatic ductal adenocarcinoma.
One-session laparoscopic management of Mirizzi syndrome: feasible and safe in specialist units
Authors: Nassar Ahmad H. M. , Nassar Mahmoud K. , Gil Ines C. , Ng Hwei J. , Yehia Ahmad M.
Published: July 2020

Background

To evaluate the laparoscopic management of Mirizzi syndrome, seldom diagnosed preoperatively causing difficulty when performing cholecystectomy and increasing complication risks.

Methods

Analysis of a prospective single-surgeon database of 5700 laparoscopic cholecystectomies found 58 Mirizzi syndrome cases. They were managed with an intention to treat during the index admission according to protocol of single-session management of bile duct stones.

Results

38/58 patients were females (65.5%). The median age was 55 years. 53 cases were emergency admissions. 34 cases (58.6%) only had ultrasound scanning. Operative difficulty was Grade IV in 34 cases (58.6%) and Grade V in 20 (34.5%) (Nassar Scale). There were 33 Mirizzi Type IA, 7 Type IB, 16 Type II and one each of Type III and Type IV. Bile duct exploration was performed in 94.8% through choledochotomy/ transfistula in 58.6% or transcystic in 36.2%. Four cases required conversion to open. Postoperative morbidity occurred in 29%. Two 30-day mortalities occurred from pneumonia in two elderly patients who were late referrals.

Conclusion

Although the utilization of the laparoscopic approach in managing bile duct stones is not currently widely practiced it was safer in this series than in reported series of open surgery in Mirizzi Syndrome. The optimal approach to Mirizzi Type II is via cholecystocholedochal fistula to explore the bile duct then drain with T-tube through the fistula. It is unnecessary to perform bilioenteric bypass in majority of cases, reducing the morbidity and mortality.
Memetic algorithms for training feedforward neural networks: an approach based on gravitational search algorithm
Authors: García-Ródenas Ricardo , Linares Luis Jimenez , López-Gómez Julio Alberto
Published: July 2020

The backpropagation (BP) algorithm is a gradient-based algorithm used for training a feedforward neural network (FNN). Despite the fact that BP is still used today when FNNs are trained, it has some disadvantages, including the following: (i) it fails when non-differentiable functions are addressed, (ii) it can become trapped in local minima, and (iii) it has slow convergence. In order to solve some of these problems, metaheuristic algorithms have been used to train FNN. Although they have good exploration skills, they are not as good as gradient-based algorithms at exploitation tasks. The main contribution of this article lies in its application of novel memetic approaches based on the Gravitational Search Algorithm (GSA) and Chaotic Gravitational Search Algorithm (CGSA) algorithms, called respectively Memetic Gravitational Search Algorithm (MGSA) and Memetic Chaotic Gravitational Search Algorithm (MCGSA), to train FNNs in three classical benchmark problems: the XOR problem, the approximation of a continuous function, and classification tasks. The results show that both approaches constitute suitable alternatives for training FNNs, even improving on the performance of other state-of-the-art metaheuristic algorithms such as ParticleSwarm Optimization (PSO), the Genetic Algorithm (GA), the Adaptive Differential Evolution algorithm with Repaired crossover rate (Rcr-JADE), and the Covariance matrix learning and Bimodal distribution parameter setting Differential Evolution (COBIDE) algorithm. Swarm optimization, the genetic algorithm, the adaptive differential evolution algorithm with repaired crossover rate, and the covariance matrix learning and bimodal distribution parameter setting differential evolution algorithm.
Hans Peter Cornelius (1888–1950): a perfect mapping geologist and scientific explorer of the Alps
Authors: Dullo Wolf-Christian , Pfaffl Fritz A.
Published: July 2020

Hans Peter Cornelius was a squeamishly and accurately mapping field geologist with an eye for the finest detail as well as for the large-scale architectural structure of mountain ranges. His excellent work concerned the Rhaetian and Allgäu Alps, South Tyrol, the Valais and Ticino in Switzerland and many regions in Austria. His publications on the Err-Julier Group, the Insubric Line, the Großglockner Group, the Rax-Schneeberg Group, the alpine Grauwackenzone, and the Penninic series of the Western and Eastern Alps became particularly important.
CoVeriTest: interleaving value and predicate analysis for test-case generation
Authors: Jakobs Marie-Christine
Published: July 2020

Verification techniques are well-suited for automatic test-case generation. They basically need to check the reachability of every test goal and generate test cases for all reachable goals. This is also the basic idea of our CoVeriTest submission. However, the set of test goals is not fixed in CoVeriTest , instead we can configure the set of test goals. For Test-Comp’19, we support the set of all ___ calls as well as the set of all branches. Thus, we can deal with the two test specifications considered in Test-Comp’19. Since the tasks in Test-Comp are diverse and verification techniques have different strengths and weaknesses, we also do not stick to a single verification technique, but use a hybrid approach that combines multiple techniques. More concrete, CoVeriTest interleaves different verification techniques and allows to configure the cooperation (i.e., information exchange and time limits). To choose from a large set of verification techniques, CoVeriTest is integrated into the analysis framework CPAchecker. For the competition, we interleave CPAchecker’s value and predicate analysis and let both analyses resume their analysis performed in the previous iteration.
Cost and effects of integrated care: a systematic literature review and meta-analysis
Authors: Rocks Stephen , Berntson Daniela , Gil-Salmerón Alejandro , Kadu Mudathira , Ehrenberg Nieves , Stein Viktoria , Tsiachristas Apostolos
Published: July 2020

Background

Health and care services are becoming increasingly strained and healthcare authorities worldwide are investing in integrated care in the hope of delivering higher-quality services while containing costs. The cost-effectiveness of integrated care, however, remains unclear. This systematic review and meta-analysis aims to appraise current economic evaluations of integrated care and assesses the impact on outcomes and costs.

Methods

CINAHL, DARE, EMBASE, Medline/PubMed, NHS EED, OECD Library, Scopus, Web of Science, and WHOLIS databases from inception to 31 December 2019 were searched to identify studies assessing the cost-effectiveness of integrated care. Study quality was assessed using an adapted CHEERS checklist and used as weight in a random-effects meta-analysis to estimate mean cost and mean outcomes of integrated care.

Results

Selected studies achieved a relatively low average quality score of 65.0% (± 18.7%). Overall meta-analyses from 34 studies showed a significant decrease in costs (0.94; CI 0.90–0.99) and a statistically significant improvement in outcomes (1.06; CI 1.05–1.08) associated with integrated care compared to the control. There is substantial heterogeneity in both costs and outcomes across subgroups. Results were significant in studies lasting over 12 months (12 studies), with both a decrease in cost (0.87; CI 0.80–0.94) and improvement in outcomes (1.15; 95% CI 1.11–1.18) for integrated care interventions; whereas, these associations were not significant in studies with follow-up less than a year.

Conclusion

Our findings suggest that integrated care is likely to reduce cost and improve outcome. However, existing evidence varies largely and is of moderate quality. Future economic evaluation should target methodological issues to aid policy decisions with more robust evidence on the cost-effectiveness of integrated care.
Karlsruhe verdient Anerkennung — Zum PSPP-Urteil des Bundesverfassungsgerichts vom 5. Mai 2020
Authors: Höpner Martin
Published: July 2020

Am 5. Mai 2020 verkündete das Bundesverfassungsgericht sein Urteil zur deutschen Beteiligung am Public Sector Purchase Programme (PSPP) der Europäischen Zentralbank. Dieses Urteil ist vielfach kritisiert worden. Der Autor stellt dem eine alternative Deutung entgegen. So sieht er es als wichtige Aufgabe des Bundesverfassungsgerichts an, darüber zu wachen, ob die europäischen Organe die Grenzen ihrer Ermächtigung durch die Mitgliedstaaten achten. In praktischer Hinsicht erkennt er eine weit geöffnete Schere zwischen den Vertragsgrundlagen und den Abläufen im Euroraum. Er hält das Urteil für vorsichtig und schonend.
Virtual Description of Non-Crimp Fabrics at the Scale of Filaments Including Orientation Variability in the Fibrous Layers
Authors: Colin David , Bel Sylvain , Hans Thorsten , Hartmann Mathias , Drechsler Klaus
Published: July 2020

A numerical description of dry non-crimp fabrics is proposed at the scale of the filaments using a commercially available finite element software package. Deviations in the filament orientation of the fibrous layer is a dominant factor in the occurrence of local defects, which influences the mechanical response of the textile. Therefore, the introduction of variability in the orientation distribution is proposed in this paper. This approach enables to capture the entanglement of the filaments and models all interaction mechanisms. A stepwise generation of the numerical non-crimp fabric is proposed considering the main manufacturing steps to reproduce the local defects in the fibrous mat appropriately. Averaged periodic boundary conditions are developed ensuring an overall periodicity of the model while allowing reorientation at the scale of the filaments. Two various non-crimp fabrics are investigated and modelled. The distribution of the filaments in the simulation results correlate well with measurements of the filament orientation performed on the textiles. Moreover, a detailed comparison of the local defects shows a good agreement with measurements on the specimens. The presented approach can be used to generate geometries for subsequent virtual characterization.
Versatile application of a modern scanning electron microscope for materials characterization
Authors: Sun Cheng , Lux Stefan , Müller Erich , Meffert Matthias , Gerthsen Dagmar
Published: July 2020

Scanning electron microscopy (SEM) is an indispensable characterization technique for materials science. More recently, scanning electron microscopes can be equipped with scanning transmission electron microscopy (STEM) detectors, which considerably extend their capabilities. It is demonstrated in this work that the correlative application of SEM and STEM imaging techniques provides comprehensive sample information on nanomaterials. This is highlighted by the use of a modern scanning electron microscope, which is equipped with in-lens and in-column detectors, a double-tilt holder for electron transparent specimens and a CCD camera for the acquisition of on-axis diffraction patterns. Using multi-walled carbon nanotubes and Pt/Al2O3 powder samples we will show that a complete characterization can be achieved by combining STEM (mass-thickness and diffraction) contrast and SEM (topography and materials) contrast. This is not possible in a standard transmission electron microscope where topography information cannot be routinely obtained. We also exploit the large tilt angle range of the specimen holder to perform 180 degrees STEM tomography on multi-walled carbon nanotubes, which avoids the missing wedge artifacts.
Fluid flow through 3D-printed particle beds: a new technique for understanding, validating, and improving predictability of permeability from empirical equations
Authors: Gjengedal Sondre , Brøtan Vegard , Buset Ole T. , Larsen Erik , Berg Olav Å. , Torsæter Ole , Ramstad Randi K. , Hilmo Bernt O. , Frengstad Bjørn S.
Published: July 2020

The application of 3D technology for fabrication of artificial porous media samples improves porous media flow studies. The geometrical characteristics of a porous media pore channel: the channel shape, size, porosity, specific surface, expansion ratio, contraction ratio, and the tortuous pathway of the channel can be controlled through advanced additive manufacturing techniques (3D printing), computed tomography imagery (CT imaging) and image analysis methods. These 3D technologies have here been applied to construct and analyze four homogeneous porous media samples with predefined geometrical properties that are otherwise impossible to construct with conventional methods. Uncertainties regarding the geometrical properties are minimized because the 3D-printed porous media samples can be evaluated with CT imaging after fabrication. It is this combination of 3D technology that improves the data acquisition and data interpretation and contributes to new insight into the phenomenon of fluid flow through porous media. The effects of the individual geometrical properties on the fluid flow are then accounted for in permeability experiments in a Hassler flow cell. The results of the experimental work are used to test the theoretical foundation of the Kozeny–Carman equation and the extended version known as the Ergun equation. These equations are developed from analogies to the Hagen–Poiseuille flow equation. Based on the results from the laboratory experiments in this study, an analytical equation based on the analytical Navier–Stokes equations is presented as an alternative to the Hagen–Poiseuille analogy for porous media channels with non-uniform channel geometries. The agreement between experiment and the new equation reveals that the dissipating losses of mechanical energy in porous media flows are not a result of frictional shear alone. The mechanical losses are also a result of pressure dissipation that arise due to the non-uniformity of the channel geometry, which induced spatial variations to the strain rate field and induce acceleration of the velocity field in the flow through the porous medium. It is this acceleration that causes a divergence from linear flow conditions as the Stokes flow criterion (Re ≪ 1) is breached and causes the convective acceleration term to affect the flow behavior. The suggested modifications of theory and the presented experiments prove that the effects of surface roughness (1) do not alter the flow behavior in the Darcy flow regime or (2) in the Forchheimer flow regime. This implies that the flow is still laminar for the Forchheimer flow velocities tested.
Effect of the Al2O3 Content in the Slag on the Chemical Reactions and Nonmetallic Inclusions during Electroslag Remelting
Authors: Schneider Reinhold S. E. , Molnar Manuel , Klösch Gerald , Schüller Christopher
Published: July 2020

The service life of roller bearings is extremely sensitive to large and hard nonmetallic inclusions (NMIs), requesting the highest standards in their production. To determine the metallurgical possibilities, the effect of Al2O3 contents between 0 and 33 pct in the remelting slag was investigated by remelting a roller bearing steel in an experimental electroslag remelting (ESR) plant. Thereby, changes in the chemical composition of the materials (electrode vs ingots) and in the remelting slag during remelting, as well as the amount and composition of the NMIs prior to and after remelting, were investigated. Changes in the chemical composition can largely be explained by equilibrium reactions between the slag and the metal, thereby low Al contents in the remelted materials could only be achieved with the lowest Al2O3 contents in the slag. Furthermore, higher Al2O3 contents in the slag also lead to higher oxygen and sulfur contents in the steel as well as higher amounts of NMIs after remelting. The composition of the NMIs changed from alumina type for high Al2O3 contents to spinel type and other mixed MgO-SiO2 oxides for low Al2O3 contents. The results indicate solutions for the production of bearing steels with the lowest amounts of undesired large and hard NMIs.
Influence of Ceramic Foam Filters with Al2O3 Nanocoating on the Aluminum Filtration Behavior Tested With and Without Grain Refiner
Authors: Voigt Claudia , Fankhänel Beate , Dietrich Björn , Storti Enrico , Badowski Mark , Gorshunova Margarita , Wolf Gotthard , Stelter Michael , Aneziris Christos G.
Published: July 2020

In industrial applications, filter materials are often chosen according to cost as well as their processing and thermomechanical properties, but rarely in terms of their behavior during filtration, which is largely due to there being insufficient information available on the influence of filter materials and surface quality on filtration behavior. In this study, the manufacture of functionalized Al2O3 nanofilters was investigated, along with their filtration performance in short- and long-term filtration trials. In addition, sessile drop tests were performed to measure the contact angle of the nanofunctionalized materials, and yielded an approximately 10 deg (11 pct) higher contact angle for nanocoated materials sintered at 800 °C and 1250 °C than for those sintered at 1600 °C and an approximately 23 deg (23 pct) higher contact angle compared to surfaces without a nanocoating. The filtration mechanism was assessed by means of Porous Disk Filtration Analysis (PoDFA) and Liquid Metal Cleanliness Analyzer (LiMCA) monitoring systems, as well as by analysis of the used and infiltrated filters using Scanning Electron Microscopy and Energy Dispersive X-ray analysis (SEM/EDX) technology. Both short-term and long-term filtration trials showed that the filtration behaviors of the reference and nanocoated filters were comparable. It was therefore determined that nanocoating of such filters with Al2O3 does not provide any improvement with regard to filtration performance.
Effect of Selenium on the Growth and Lipid Accumulation of Yarrowia lipolytica Yeast
Authors: Kieliszek Marek , Dourou Marianna
Published: July 2020

Nowadays, there is an increase attention on the effect of selenium (Se) on metabolic processes of microorganisms. Strains belonging to the genus of Yarrowia are of great biotechnological interest for various industries. In this study, we evaluated the effect of 10 mg/L of Se on the growth and lipid production of two Yarrowia lipolytica strains: the ACA DC 50109 and one more with increased oleagenicity, derived after ALE methodology (referred here as Y. lipolytica ALE_70). The presence of Se in the growth medium negatively affected both cell mass production and total lipid accumulation, for both Y. lipolytica strains. Fractionation of total lipids showed an inhibition on neutral lipid (NL) synthesis and consequently, an increase of polar lipids (glycolipids plus sphingolipids, and phospholipids) on the lipids of the Se-enriched ACA DC 50109 strain; however, the NL/polar ratio of the Se-enriched ALE_70 indicated that Se, apart from the inhibition of NL synthesis, provoked also the accumulation of polar lipids in this strain. In addition, the fatty acid (FA) composition was differently affected by Se. Se-enriched total lipids of the ALE_70 strain were enriched in linoleic acid (C18:2 n-6), which resulted in increase of the unsaturated index. On the other hand, Se-enriched lipids of the ACA DC 50109 strain were more saturated, as the percentage of palmitic (C16:0) and stearic (C18:0) acids increased in the total FAs. Moreover, it seems that Se influenced the activity or the expression of desaturases and elongase in both strains. Finally, the supplementation of growth medium with Se affected cell morphology, as well as the size and distribution of lipid droplets inside the yeast cells. According to our opinion, Se caused stress conditions and the consequence of that was the occurrence of metabolic disorders that affected cell mass, lipid content, and/or morphological structures. The results of the present study suggest that further research should be carried out to understand the background of the lipogenesis process in yeast cells cultured under stress conditions.
Novel Thunderstorm Alert System (NOTHAS)
Authors: Spiridonov Vlado , Curic Mladjen , Sladic Nedim , Jakimovski Boro
Published: July 2020

A “Novel Thunderstorm Alert System” (NOTHAS) has been developed and extensively tested for forecast and warnings of mid-latitude and tropical convective events. The design of the system showed some potential advantages compared to earlier alert systems, mainly in reducing uncertainties in predictions by taking the given maximum hourly local-scale signal. It represents a dynamic tool which allows the use of the probability concept of multivariate distribution and integrating it into general function by taking all convective parameters. It utilizes the latest developed microphysical parameterization scheme using a scale and aerosol awareness convective scheme and the sharpest criteria for mid-latitude storms. NOTHAS shows consistency and some kind of flexibility in post-processing applications, regardless of different parameterizations used in the ensemble or deterministic forecasts. The scientific verification shows a high level of accuracy in all significant scores which indicates that severe weather outlooks produced by NOTHAS for several hours ahead are in good alignment with observed thunderstorm activity. This novel tool shows a good performance which has sufficient merit for further additional testing and system evaluation of different severe mid-latitude and tropical storms, tropical cyclones and other severe weather cases across regions.
The prognostic impact of neoadjuvant chemoradiotherapy on lymph node sampling in patients with locally advanced rectal cancer
Authors: Li Destri Giovanni , Maugeri Andrea , Ramistella Alice , La Greca Gaetano , Conti Pietro , Trombatore Giovanni , Vecchio Giada Maria , Magro Gaetano Giuseppe , Barchitta Martina , Agodi Antonella
Published: July 2020

According to the American Joint Committee on Cancer, at least 12 lymph nodes are required to accurately stage locally advanced rectal cancer (LARC). Neoadjuvant chemoradiation therapy (NACRT) reduces the number of lymph nodes retrieved during surgery. In this study, we evaluated the effect of NACRT on lymph node retrieval and prognosis in patients with LARC. We performed an observational study of 142 patients with LARC. Although our analysis was retrospective, data were collected prospectively. Half the patients were treated with NACRT and total mesorectal excision (TME) and the other half underwent TME only. The number of lymph nodes retrieved and the number of metastatic lymph nodes were significantly reduced in the NACRT group (P > 0.001). In the univariate and multivariate analyses, only NACRT and patient age were significantly associated with reduced lymph node retrieval. The number of metastatic lymph nodes and the lymph node ratio (LNR) both had a significant effect on prognosis when the patient population was examined as a whole (P = 0.003 and P = 0.001, respectively). However, the LNR was the only significant, independent prognostic factor in both treatment groups (P = 0.007 for the NACRT group; P = 0.04 for the no-NACRT group). NACRT improves patient prognosis only when the number of metastatic lymph nodes is reduced. The number of metastatic lymph nodes and the LNR are important prognostic factors. Lymph node retrieval remains an indispensable tool for staging and prognostic assessment of patients with rectal carcinoma treated with NACRT.
Crystal Structures, Stability, and Solubility Evaluation of a 2:1 Diosgenin–Piperazine Cocrystal
Authors: Gong Ningbo , Yu Hongmei , Wang Ying , Xing Cheng , Hu Kun , Du Guanhua , Lu Yang
Published: July 2020

A cocrystal of diosgenin with piperazine in 2:1 stoichiometry was successfully synthesized. The solid form was prepared by liquid assisted grinding, slurry and crystallization methods. The cocrystal was characterized by powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and structure determined by single crystal X-ray diffraction, the hydrogen bonds formed into fish bone structure along the [010] direction and all the molecules packed into 3D layer structure along a axis. After formation of cocrystal, the solubility of diosgenin was improved, and the solubility value in 0.2% SDS solution was approximately 1.5 times as large as that of the parent material.

Graphic Abstract
Application of numerical simulation to determine ability of air used in MQL method to clean grinding wheel active surface during sharpening of hob cutters
Authors: Stachurski Wojciech , Sawicki Jacek , Krupanek Krzysztof , Nadolny Krzysztof
Published: July 2020

This article presents the results of experiments concerning a computational fluid dynamics (CFD)/numerical analysis of the flow of air in the grinding zone during the sharpening of the face surface of hob cutters while using the MQL method. The carrying out of a simulation allows one to determine the influence of various settings of the angle of the spray nozzle on the amount of air directly reaching the zone of contact of the grinding wheel with the workpiece, as well as the grinding wheel active surface (GWAS). In the numerical analysis, the ‘SST k-ω’ model available in the Ansys CFX program was used, and to which the Kato and Lander’s modification was applied. With the aim of verifying the results obtained from the basis of the numerical simulations, experimental testing was conducted. As a verification parameter, the percentage rate of grinding wheel clogging was used. The measurement of clogging was conducted by the optical method taking microscopic images of the grinding wheel active surface (GWAS) and then analysing it which the use of digital processing and image analysis. As a result of the numerical simulations, it was confirmed that the greatest effectiveness in delivering air to the contact zone of the grinding wheel with the workpiece being machined was achieved by setting the nozzle at the lowest of the angles tested (90°). At the same time, the greatest efficiency in delivering air to the grinding wheel active surface was achieved by setting the nozzle at the largest of the angles tested (90°). The experimental tests allowed one to state that the change in the inclination of the spray nozzle does not significantly influence the effectiveness of chip removal from the surface of the inter-granular spaces of the grinding wheel. By setting the nozzle at a 90° angle, wall shear stresses τw have a decisive influence on cleaning the GWAS, while at an angle of 30° the cleaning function is taken on by air being delivered directly into the contact zone of the grinding wheel with the face surface of the hob cutter being sharpened. A comparison of the percentage rates of grinding wheel clogging obtained from using the flood method (WET), as well as the MQL method, indicates the insufficient cleaning ability of the MQL method. A solution to this problem may be the application of additional cleaning nozzles employing streams of compressed air (CA) or cold compressed air (CCA).
Hematopoietic Stem Cells in Health and Disease—Insights from Single-Cell Multi-omic Approaches
Authors: Haas Simon
Published: July 2020

Purpose of Review

Hematopoietic stem cells (HSCs) are responsible for the lifelong production of blood and immune cells. This review provides an overview of how single-cell (multi)-omic approaches have recently advanced our understanding of healthy hematopoiesis, hematological malignancies, and the stem cell niche.

Recent Findings

Single-cell technologies have revealed tremendous heterogeneity of the HSC compartment, conflicting with the classical view of hematopoiesis. Large-scale single-cell approaches mapping the entire hematopoietic system have enabled an ordering of the observed heterogeneity along meaningful differentiation and cell-state trajectories. These studies provided novel insights into lineage commitment pathways and led to the suggestion of advanced models of hematopoiesis. Single-cell multi-omic technologies, where several entities of individual cells are measured in parallel, have permitted the fine mapping of clonal and developmental differentiation hierarchies, and revealed the molecular consequences of clonal diversification.

Recent single-cell approaches have changed our perception of healthy hematopoiesis, provided an understanding of hematological malignancies at unprecedented depth, and revealed new insights into the stem cell niche.