bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thrombocytosis is associated with complications after microvascular surgery: An NSQIP data analysis
Authors: Tarabishy Sami P. , Inglesby Dani , Tapp Marion , Corral Gabriel Del , Herrera Fernando A. 
Published: November 2019

BackgroundComplications after microvascular surgery, such as partial flap loss, and arterial/venous compromise cannot only increase morbidity for the patient but also tax the healthcare system. Thrombocytosis, both essential and reactive, can predispose patients to thrombosis and hemorrhage and thus should intuitively have an effect on the outcome of microvascular free tissue transfers. We sought to evaluate the effect of preoperative thrombocytosis on outcomes after microvascular free flap surgery.MethodsA retrospective review of the 2013–2016 American Collges of Surgeons, National Surgical Quality Improvement Program (ACS NSQIP) database identified 4,299 patients who had microsurgical flaps. Of these 3,744 had preoperative platelet levels recorded. Fifty‐four patients had preoperative thrombocytosis, defined as a platelet count >450 K/CUMM, while 3,690 did not. The groups were compared; demographics, comorbidities, and smoking status were recorded. We then examined outcomes between groups including average operative time, length of hospital stay, need for transfusion, deep vein thrombosis (DVT) postoperatively, and need for reoperation.ResultsWhen comparing the two cohorts, there was no statistical difference in comorbidities. We found a significant difference between the thrombocytosis and control cohort in need for transfusion (29.6 vs. 12.8%, p = .0002), average days till discharge (8.36 vs. 5.75, p = .009), and need for reoperation (27.8 vs. 13.8%, p = .003). There was no difference in DVT occurrence (0 vs. 0.1%, p = .46) or average operation time (535 m vs. 482 min, p = .088).ConclusionPatients with thrombocytosis undergoing microvascular free flaps are at increased risk for complications, including the need for a blood transfusion, prolonged hospital stays, and reoperation.
Global transcriptome analysis of porcine oocytes in correlation with follicle size
Authors: Gad Ahmed , Nemcova Lucie , Murin Matej , Kinterova Veronika , Kanka Jiri , Laurincik Jozef , Benc Michal , Pendovski Lazo , Prochazka Radek 
Published: November 2019

AbstractAlthough our knowledge regarding oocyte quality and development has improved significantly, the molecular mechanisms that regulate and determine oocyte developmental competence are still unclear. Therefore, the objective of this study was to identify and analyze the transcriptome profiles of porcine oocytes derived from large or small follicles using RNA high‐throughput sequencing technology. RNA libraries were constructed from oocytes of large (LO; 3–6 mm) or small (SO; 1.5–1.9 mm) ovarian follicles and then sequenced in an Illumina HiSeq4000. Transcriptome analysis showed a total of 14,557 genes were commonly detected in both oocyte groups. Genes related to the cell cycle, oocyte meiosis, and quality were among the top highly expressed genes in both groups. Differential expression analysis revealed 60 up‐ and 262 downregulated genes in the LO compared with the SO group. BRCA2, GPLD1, ZP3, ND3, and ND4L were among the highly abundant and highly significant differentially expressed genes (DEGs). The ontological classification of DEGs indicated that protein processing in endoplasmic reticulum was the top enriched pathway. In addition, biological processes related to cell growth and signaling, gene expression regulations, cytoskeleton, and extracellular matrix organization were among the highly enriched processes. In conclusion, this study provides new insights into the global transcriptome changes and the abundance of specific transcripts in porcine oocytes in correlation with follicle size.
Water–fat Dixon cardiac magnetic resonance fingerprinting
Authors: Jaubert Olivier , Cruz Gastão , Bustin Aurélien , Schneider Torben , Lavin Begoña , Koken Peter , Hajhosseiny Reza , Doneva Mariya , Rueckert Daniel , Botnar René M. , Prieto Claudia 
Published: November 2019

PurposeCardiac magnetic resonance fingerprinting (cMRF) has been recently introduced to simultaneously provide T1, T2, and M0 maps. Here, we develop a 3‐point Dixon‐cMRF approach to enable simultaneous water specific T1, T2, and M0 mapping of the heart and fat fraction (FF) estimation in a single breath‐hold scan.MethodsDixon‐cMRF is achieved by combining cMRF with several innovations that were previously introduced for other applications, including a 3‐echo GRE acquisition with golden angle radial readout and a high‐dimensional low‐rank tensor constrained reconstruction to recover the highly undersampled time series images for each echo. Water–fat separation of the Dixon‐cMRF time series is performed to allow for water‐ and fat‐specific T1, T2, and M0 estimation, whereas FF estimation is extracted from the M0 maps. Dixon‐cMRF was evaluated in a standardized T1–T2 phantom, in a water–fat phantom, and in healthy subjects in comparison to current clinical standards: MOLLI, SASHA, T2‐GRASE, and 6‐point Dixon proton density FF (PDFF) mapping.ResultsDixon‐cMRF water T1 and T2 maps showed good agreement with reference T1 and T2 mapping techniques (R2 > 0.99 and maximum normalized RMSE ~5%) in a standardized phantom. Good agreement was also observed between Dixon‐cMRF FF and reference PDFF (R2 > 0.99) and between Dixon‐cMRF water T1 and T2 and water selective T1 and T2 maps (R2 > 0.99) in a water–fat phantom. In vivo Dixon‐cMRF water T1 values were in good agreement with MOLLI and water T2 values were slightly underestimated when compared to T2‐GRASE. Average myocardium septal T1 values were 1129 ± 38 ms, 1026 ± 28 ms, and 1045 ± 32 ms for SASHA, MOLLI, and the proposed water Dixon‐cMRF. Average T2 values were 51.7 ± 2.2 ms and 42.8 ± 2.6 ms for T2‐GRASE and water Dixon‐cMRF, respectively. Dixon‐cMRF FF maps showed good agreement with in vivo PDFF measurements (R2 > 0.98) and average FF in the septum was measured at 1.3%.ConclusionThe proposed Dixon‐cMRF allows to simultaneously quantify myocardial water T1, water T2, and FF in a single breath‐hold scan, enabling multi‐parametric T1, T2, and fat characterization. Moreover, reduced T1 and T2 quantification bias caused by water–fat partial volume was demonstrated in phantom experiments.
Analytical solution of stochastic differential equation by multilayer perceptron neural network approximation of Fokker–Planck equation
Authors: Namadchian Ali , Ramezani Mehdi 
Published: November 2019

AbstractThe Fokker–Planck equation is a useful tool to analyze the transient probability density function of the states of a stochastic differential equation. In this paper, a multilayer perceptron neural network is utilized to approximate the solution of the Fokker–Planck equation. To use unconstrained optimization in neural network training, a special form of the trial solution is considered to satisfy the initial and boundary conditions. The weights of the neural network are calculated by Levenberg–Marquardt training algorithm with Bayesian regularization. Three practical examples demonstrate the efficiency of the proposed method.
A mixed variational‐based dynamic simulation method for fiber‐reinforced continua in non‐isothermal rotordynamical systems
Authors: Groß Michael , Dietzsch Julian , Röbiger Chris 
Published: November 2019

AbstractThree‐dimensional woven carbon‐fiber reinforced polymers (3D‐CFRP) are being increasingly used for blades in rotordynamical systems as turbine fans, shafts as well as disc brake rotors. By using dynamic mixed finite‐element methods, these materials can be simulated as anisotropic continua with non‐isothermal behaviour in the matrix as well as the fiber material. Therefore, we present a novel dynamic mixed finite‐element method which is variational‐based and capable to simulate these materials. This dynamic mixed finite‐element method preserves each basic balance law emanating from the variational principle exact in a discrete setting. We demonstrate this physically‐consistent simulation behaviour by using dynamic simulations of a disc brake rotor and a rotating pipe subject to thermal and mechanical loads.
Reconstruction of the genesis of a Renaissance algorithm to calculate sine tables
Authors: Ullrich Peter 
Published: November 2019

AbstractRecently, a manuscript has been discovered in which Jost Bürgi (1552–1632) presented an algorithm to calculate sine tables of high precision with only a modest amount of numerical effort [1], [2]. Several modern proofs for the correctness of this algorithm have been given, all of which, however, use methods that were not at hand at Bürgi's time. This raises the question how Bürgi had found his algorithm.Building on [5], an educated guess is presented how Bürgi may have found his algorithm and also collected enough evidence for its correctness. For this, only methods are needed which were known at Bürgi's time, like prosthaphaeresis and the method of false position.
Green's function for a horizontally layered anisotropic soil
Authors: Waubke Holger , Kreuzer Wolfgang , Hrycak Tomasz , Schmutzhard Sebastian 
Published: November 2019

AbstractThe Green's function for an anisotropic horizontally layered soil can be determined in the wave‐number frequency domain. Only the vertical axis remains in the original domain. For a simulation in 2.5D a numerical inverse Fourier integral transformation, about one horizontal axis is needed. This leads to difficulties at the singularities of the function. For the boundary element method in 2.5D the integrals along the boundary are transformed to the wave‐number domain and solved analytically. The result is a filter that attenuates the spectrum of the Green's function and therefore allows for an inverse Fourier transformation using numerical methods. For an efficient inverse transformation the Filon method together with an adaptive algorithm are used.
Model hierarchy of upper‐convected Maxwell models with regard to simulations of melt‐blowing processes
Authors: Wieland Manuel , Arne Walter , Marheineke Nicole , Wegener Raimund 
Published: November 2019

AbstractIn melt‐blowing processes, polymeric jets are extruded into turbulent high‐speed airflow to produce fibers of micro‐ and nano‐scale. String models supplemented with viscoelastic material laws build a suitable basis for the modeling and simulation of fibrous jets in such processes. We present a model‐hierarchy of upper‐convected Maxwell models for the fibers and therein incorporate the turbulent velocity fluctuations of the underlying airflow by a reconstruction technique. Within the model hierarchy, simulation results are analyzed and evaluated with respect to accuracy and efficiency.
Time‐adaptive computations for the mortar finite element method
Authors: Grafenhorst Matthias , Hartmann Stefan 
Published: November 2019

AbstractIn recent years, mortar finite element methods have been successfully applied as space discretization scheme to a wide range of contact problems. The finite deformation contact formulation taken up is based on a mortar approach using so‐called dual Lagrange multipliers. If the constitutive models of the material bodies are of rate‐type, the entire system of equations represents a non‐smooth system of differential‐algebraic equations. This system will be investigated in connection with higher‐order time integration methods using diagonally implicit Runge‐Kutta methods.
Application of the fast nonlinear analysis method on a clamped beam with a cubic spring
Authors: Akar Özge , Willner Kai 
Published: November 2019

AbstractIn civil engineering reduction methods are used for the mechanical design of buildings in order to avoid unnecessary complexity and computational effort especially in the seismic design of structures. The determination of vibration modes by earthquake excitation is carried out by using Ritz vectors instead of eigenvectors. Thus, only the modes of interest are obtained. Furthermore, the Fast Nonlinear Analysis (FNA) method was formulated to easily insert nonlinearities like concentrated damping in a construction model. The main idea is to take the nonlinear forces to the right hand side of the equation of motion. In the context of this work, the FNA method is applied on a finite element model of a clamped beam with a cubic spring that works at the free end of the beam. First, a harmonic excitement is applied and the vibration modes of the system are obtained by using Ritz vectors. Then, a piecewise exact integration method is implemented to iteratively determine the results for displacement, velocity and acceleration of the discretized beam.
A locally conservative reduced flux reconstruction for elliptic problems
Authors: Rave Stephan , Schindler Felix 
Published: November 2019

AbstractIn the context of model order reduction of parametric elliptic problems, we present a methodology to reconstruct a conforming flux from a given a reduced solution, that is locally conservative with respect to the underlying finite element grid. All components of the procedure depend separably on the parameter and allow for further use in offline/online decomposed computations, for instance in the context of a posterior error estimation or flow problems.
Towards physiological conditions in total knee arthroplasty by a bionics‐inspired tibial implant design
Authors: Eidel Bernhard , Gote Ajinkya , Fritzen Claus-Peter , Ohrndorf Arne , Christ Hans-Jürgen 
Published: November 2019

AbstractIn total knee arthroplasty (TKA) force is transmitted into the tibia by a combined plate‐stem device along with a fully or partially cemented fixation. The present work analyzes this force transmission in finite element simulations with the main aim to avoid reported post‐surgical bone density loss as a consequence of reduced tibial bone loading. In the numerical analysis different implant materials and implant‐to‐stem interface conditions are considered, from a stiff, fully cemented fixation to sliding contact conditions with a low friction coefficient. The impact of these variations on bone loading changes are measured by (i) decomposing the total force into parts mediated by the plate and by the stem and by (ii) post‐surgery strain energy density (SED) deviations. Based on a bionics‐inspired perspective on how nature in pre‐operative conditions carries out force transfer from the knee joint into the tibia, a modified implant‐bone interface is suggested that alters force transmission towards physiological conditions while preserving the geometries of the standard plate‐stem endoprosthesis design. As a result, stress shielding is avoided almost completely, pre‐surgery bone loading is preserved such that bone resorption is not likely to occur.
Implementation of generalized mechanical interfaces
Authors: Spannraft Lucie , Mergheim Julia , Steinmann Paul 
Published: November 2019

AbstractFor an accurate approximation of the mechanical behavior of interfaces undergoing tension, shear and in‐plane stretch deformation, the definition of an appropriate interface constitutive model is crucial. Distinct interface models, such as cohesive zone models are well investigated. However, only little research considering energetic interface models, especially inelastic models, and generalized mechanical interfaces is conducted. Although multiple possibilities to apply cohesive zone models in commercial software exist, to the authors' knowledge, the material properties provided are generally limited by basic cohesive laws and any definition of energetic interface models lacks. In order to benefit from the advantages of commercial FE software, a generalized mechanical interface model is implemented in ABAQUS. The employed constitutive model combines a cohesive zone model with an energetic interface model.
A bottom‐up continuum approach of crystal plasticity for the analysis of fcc microwires under torsion
Authors: Zoller Kolja , Schulz Katrin 
Published: November 2019

AbstractThe microstructural evolution of face‐centered cubic microwires is studied using a physical motivated, homogenized continuum model of crystal plasticity. The dislocation configuration in the three‐dimensional space is thereby described via a Continuum Dislocation Dynamics (CDD) theory including a dislocation source term. The resulting spatial distribution of dislocation densities and strain components are shown for a relaxation problem with torsional loading.
A Beam Propagation Method for Distorted Gaussian Beams
Authors: Pflaum Christoph 
Published: November 2019

AbstractDistorted Gaussian beams arise in several applications in optics. One of them is a laser amplifier. In a laser amplifier a Gaussian beam is distorted by thermal lensing effects, polarization effects and gain guiding. This leads to a decrease of the beam quality at the output of a laser amplifier. An important question is how to calculate this decrease of the beam quality and how to compute the amplified beam. There exist several difficulties of existing simulation techniques for the computation of optical beams. These are the high computational amount in order to resolve the phase of the beam and modelling non‐absorbing boundary conditions. We present a new beam propagation method, which circumvents these difficulties. The idea is to decompose the beam as a product of a Gaussian Beam TEM00 and an unknown distortion function Ξ. This leads to an interesting partial differential equation for Ξ, which contains a beam spreading convection term. This PDE is solved numerically by finite elements and a Crank‐Nicolson space stepping discretization. The resulting linear equation system is solved by GMRES. The q‐parameter of the Gaussian beam is calculated in advance by an ABCD matrix method. This leads to a highly efficient simulation technique. It can be applied to simulate the amplification of Gaussian beams in laser amplifiers.
A model order reduction method for finite strain FFT solvers using a compressed sensing technique
Authors: Gierden Christian , Kochmann Julian , Manjunatha Kiran , Waimann Johanna , Wulfinghoff Stephan , Svendsen Bob , Reese Stefanie 
Published: November 2019

AbstractWe present a model order reduction (MOR) method for finite strain FFT solvers to reduce the computational costs of the FFT simulation scheme of a two‐scale FE‐FFT simulation. The underlying method is based on a reduced set of frequencies which leads to a reduced fixed‐point scheme. The reduced set of frequencies is determined offline, based on the Fourier grid and predominantly consists of low frequencies. After performing the entire simulation with this reduced set of frequencies, the compressed sensing technique is used to reconstruct highly resolved micromechanical fields in a post‐processing step. Compared to the unreduced solution scheme, a significant speed‐up in the CPU time at a negligibly small loss of accuracy in the overall solution is observed. As a numerical example an elastic composite in a finite strain setting is investigated.
A framework and finite element formulation for incompatibility tensor‐based gradient plasticity
Authors: Kaiser Tobias , Menzel Andreas 
Published: November 2019

AbstractThe present contribution deals with a gradient plasticity formulation that accounts for energetic contributions of plastic incompatibilities that are interpreted in terms of dislocation densities. At the outset of the theory, an extended form of the dissipation inequality in terms of a nonlocality residual is assumed in accordance with [1]. Taking into account dislocation density tensors as additional arguments of the free energy density function, this form naturally gives rise to the balance equation of a generalised (quasi) nonlocal stress field that is energetically conjugated to the plastic deformation. Against this background one furthermore observes that the energetic dual to the dislocation density tensor is closely related to a back stress‐type part of the generalised stress field. For the solution of the resulting system of coupled partial differential equations, a multi‐field finite element approach is taken, with the plastic consistency conditions being accounted for on global level by means of Fischer‐Burmeister complementarity functions.
Drift‐diffusion problems with Gauss–Fermi statistics and field‐dependent mobility for organic semiconductor devices
Authors: Glitzky Annegret , Liero Matthias 
Published: November 2019

AbstractWe consider a drift‐diffusion model for organic semiconductor devices including Gauss–Fermi statistics and application‐specific mobility functions. The charge transport in organic materials is realized by hopping of carriers between adjacent energetic sites and is described by complicated mobility laws with a strong nonlinear dependence on temperature, carrier densities and the electric field strength. We report on the existence of weak solutions to the stationary problem as well as global weak solutions to the instationary problem. Moreover, L∞ bounds for the solutions are established.
Topological solvability analysis and its application to liquid flow networks coupled to Functional Mock‐up Units
Authors: Baum Ann-Kristin , Kolmbauer Michael , Offner Günter , Pöchtrager Bernhard 
Published: November 2019

AbstractWe present a unified topological analysis for physical networks coupled to black‐box models. While the governing equations of the physical network are derived by representing the network as a linear graph, the equations of the black‐box model are characterized as an abstract class of Differential‐Algebraic equations (DAEs) of a specific form (Functional Mock‐up Unit). Combining those two representations, existence and uniqueness results can be formulated based on the connectivity of the physical network and a concrete classification of the black‐box models. This is the natural extension of the approach derived in [3].
Time discretization of nonlinear hyperbolic systems on networks
Authors: Altmann Robert , Zimmer Christoph 
Published: November 2019

AbstractIn view of gas networks, the simulation of hyperbolic systems on networks has recently caused large interest. We consider the case with a nonlinear damping term and a small parameter ϵ such that – in the linear case – the system turns parabolic for ϵ =0. Based on this property and an expansion in ϵ, we derive a novel time integration scheme.
Prandtl‐Reuss model without safe‐load conditions
Authors: Kisiel Konrad 
Published: November 2019

AbstractWe consider the Prandtl‐Reuss dynamical model of elasto‐perfect plasticity. In the case of non‐homogeneous mixed boundary conditions we were able to omit the standard assumption of safe‐load conditions by introducing much easier one (admissibility of Neumann boundary data).
A higher‐order shear deformation approach to the mixed‐mode buckling problem in composite laminated beams
Authors: Mittelstedt Siham , Mittelstedt Christian 
Published: November 2019

AbstractThis paper presents a semi‐analytical method for the mixed‐mode buckling problem of composite beams, i.e. the interaction between the local buckling modes of the segments of shear deformable symmetrically laminated composite I‐beams. The buckling analysis employs Reddy's third‐order shear deformation theory and the Ritz‐method in conjunction with adequate series expansions for the buckling degrees of freedom wherein the webs and flanges are considered separately and are later on unified by employing Lagrangian multipliers. The results are compared with the buckling loads as obtained by finite element computations, and a very satisfying agreement is found.