bluuebunny/crossref_metadata_2025_split huggingface dataset:
Paravalvular leakage of transcatheter aortic valve replacements depending on aortic annulus calcification
Authors: Kaule Sebastian , Oener Alper , Grabow Niels , Schmitz Klaus-Peter , Siewert Stefan , Stiehm Michael 
Published: December 2021

Abstract
Paravalvular leakage (PVL) has a crucial impact on clinical outcomes of transcateheter aortic valve replacements (TAVR), especially the mortality increases dramatically with high-grade PVL. Furthermore, the calcification of the aortic annulus has a decisive influence on the PVL of TAVR. Therefore, we developed a technical model of a calcified aortic annulus and used it for the investigation of PVL in steady-state back-flow conditions. We investigated an Evolut PRO (Medtronic, Minneapolis, MN, USA), implanted the TAVR at different depths in the aortic annulus model ranging between 0 mm and -6 mm and characterized PVL in steady-state retrograde flow from 0 mmHg up to a maximum achievable pressure. The used test bench and detailed test method was described in previous studies. The aortic annulus model exhibits three elevations symmetrically distributed around the circumference. Depending on the degree of calcification the elevations reached 1 mm to 3 mm into the lumen. For the Evolut PRO bioprosthesis, a decreasing PVL was measured with increasing implantation depth. At an implantation depth of 0 mm (inflow of TAVR and annulus model at same height) maximum PVL was measured. Minimum PVL was measured at a height of -6 mm. Furthermore, even a small calcification of 1 mm led to a large increase in PVL. This trend continued with increasing height of the calcification. The maximum regurgitation of (2,025.21 ± 12.47) ml (n = 3 measurements) was measured at a pressure of 6 mmHg in the annulus model with 3 mm calcification. A test method to quantify PVL depending on annular calcification was successfully developed. Additionally, the influence of implantation depth on PVL was characterized. Due to the technical operating principle of the test bench, only a limited increase in pressure was possible when large PVL occurred. In this respect, the test bench must be optimized in the future.
Polymer selection for Eustachian tube stent application based on mechanical, thermal and degradation behavior
Authors: Lebahn Kerstin , Stöffler Kerstin , Oschatz Stefan , Arbeiter Daniela , Reske Thomas , Schmitz Klaus-Peter , Paasche Gerrit , Lenarz Thomas , Grabow Niels 
Published: December 2021

Abstract
The novel concept of stenting the Eustachian tube was established to provide an effective and safe therapy of Eustachian tube dysfunction. Biodegradable polymer stents are being developed to restore impaired tube function. As the supporting effect may be required for different time periods, PLA-co-PEG copolymers, PLLGA, PDLLA and PDS, having shorter degradation times compared to PLLA, were evaluated as potential stent materials. Since tensile tests and thermal analyses of solvent cast films from PLA-co-PEG copolymers showed comparable properties to PLLA, stent samples were manufactured from these materials. Mechanical stent testing revealed an increase of elastic recoil and slight decrease of collapse pressure compared to PLLA. In a short term accelerated degradation study a considerable percentage molar mass reduction and an increasing degree of crystallinity depending on PEG content was found. Based on the results obtained, the tested polymers offer a promising, faster degradable alternative to the established stent material PLLA.
Thermal welding of polymeric biomaterials: Development of a novel device for temperature controlled local application
Authors: Tautorat Carsten , Lebahn Kerstin , Oschatz Stefan , Arbeiter Daniela , Schmitz Klaus-Peter , Grabow Niels , Schmidt Wolfram 
Published: December 2021

Abstract
We present a thermal processing device, equipped for local heating and welding of biomaterials, e.g. electrospun nonwovens or polymer films. Depending on the application and choice of materials, we aim to determine appropriate processing parameters for permanent and non-permanent welds. Due to the modular device structure, applicationspecific heating tools can be used. Process temperature up to 250 °C is feasible.
In this concept study, a welding tool with interchangeable small-size heating tips of different geometric shapes were investigated regarding their suitability for welding of polycarbonate urethane based silicone elastomer nonwovens. Generated welds were examined by imaging techniques and tensile testing. Regardless of the tip shape, welds were generated withstanding forces up to 3.0 N and 4.3 N for tensile and shear loading, respectively.
A hydrogel based quasi-stationary test system for in vitro dexamethasone release studies for middle ear drug delivery systems
Authors: Eickner Thomas , Teske Michael , Rekowska Natalia , Senz Volkmar , Schmitz Klaus-Peter , Grabow Niels 
Published: December 2021

Abstract
For the investigation of in vitro drug release, methods have been used in which samples of drug delivery systems are immersed in release medium. The medium is used to measure drug concentration via chromatography or photometry. These systems are suitable to investigate the drug release of different systems or to simulate tissue environments. When considering predominantly humid regions, e.g. for drug release into the cochlea through the round window membrane by a drug delivery system placed at that membrane, reproducible in vitro determination of drug release becomes particularly challenging. In this study the development of a system is reported that allows the investigation of the in vitro drug release simulating such conditions.
The presented test system consists of an alginate hydrogel in glass vials simulating the biological membrane, which separates the drug delivery system from the medium filled compartment. Saline is used as release medium and injected under the hydrogel. The samples are placed on top of the hydrogel, which slightly contacts the medium surface. The drug concentration in the release medium was determined by HPLC measurements.
This system allows for testing the release of dexamethasone without the samples being completely surrounded by medium. The hydrogel mediates the diffusion of the drug by ensuring the contact with the medium. Release was monitored for more than 23 days. The presented concept was successfully designed and manufactured. The system is inexpensive and can be duplicated easily. In this study, it was used to monitor the drug release of dexamethasone from PEGDA700 derived polymer. One challenge that remains to be considered is the low mechanical stability of the hydrogel, which results in a need for repeated manufacturing during the handling of the system.
Estimation of calendar age based on autonomic cardiovascular function by applying machine learning techniques
Authors: Sabeghi Rassoul , Bär Karl-Jürgen , Schumann Andy 
Published: December 2021

Abstract
Aging is accompanied by changes in the cardiovascular physiology that promote the development of age-related diseases. This paper presents a modern approach to quantify the physiological effects of age on the cardiovascular system by applying modern machine learning techniques to several indicators of autonomic cardiovascular function. In 885 healthy subjects, 33 different indices were calculated on resting state electrocardiogram and continuous blood pressure recordings. Based on those parameters, five different approaches were applied in order to reconstruct the calendar age of healthy subjects, i.e., linear regression (LR), neural network (NN), Gaussian process regression (GPR), support vector regression (SVR), and relevance vector regression (RVR). Hyper parameters of machine learning methods were optimized via grid search. After 20 repetitions of a five-fold cross-validation, the mean absolute error (MAE) was computed between the calendar and estimated age to assess the accuracy of each method. The results show that the lowest error for age estimation was achieved using SVR with a MAE of 5.49 years. GPR performed comparably well to SVR with a MAE of 5.55 years, while NN led to a MAE of 5.72 years. RVR and LR revealed MAE of more than six years (6.21 and 6.34 years). The error of age estimation could be further reduced by applying outlier correction to the input data leading to a minimum MAE of 4.53 years with GPR. In conclusion, our results suggest that machine learning can be used to quantify the effects of healthy aging on cardio-vascular function.
Validation of Finite Element Analysis of a selfexpanding polymeric microstent for treatment of Fallopian tube occlusions
Authors: Dierke Ariane , Kuske Thomas , Frank Hagen , Bohne Eric , Brandt-Wunderlich Christoph , Knorre Luise , Stiehm Michael , Bock Andrea , Grabow Niels , Wree Andreas , Zygmunt Marek , Schmitz Klaus-Peter , Siewert Stefan 
Published: December 2021

Abstract
Proximal occlusion of the Fallopian tube is one of the most common causes of female infertility. Due to the occlusion, the passage of the fallopian tubes is no longer given. Basically, there are two options for patients affected by this condition: cost-intensive in vitro fertilization (IVF) or surgery. The pregnancy rates of approximately 50% achieved with current treatment options are not satisfying. In this work, we present a Finite Element Analysis (FEA) model of a previously reported optimized microstent design for minimally invasive therapy of proximal tubal occlusion. Based on experimental investigations, the material model was set up and the simulation was validated. Comparison of the mechanical performance as an application related critical load case was in a good agreement. In this work, the proof of concept for the FEA model and the material model were carried out. In the future, the simulation will be used for further load cases such as the investigation of the bending stiffness and radial force and for the design optimization.
Method to determine particle release during long-term loading for assessment of coating durability of cardiovascular stents
Authors: Schmidt Wolfram , Brandt-Wunderlich Christoph , Kurzhals Anja , Schmitz Klaus-Peter , Grabow Niels 
Published: December 2021

Abstract
Many catheters and vascular implants are coated to increase biocompatibility or to reduce friction during catheter based implantation. Several regulations require assessment of coating durability over the implant’s life time. An in vitro method for stent testing is presented to measure released particulate matter at defined inspection intervals. The method was validated using polystyrene microspheres with a size of 10, 25 and 50 μm to check for particle recovery (n=6). Two cleaning steps followed. Particle counting was performed by light obscuration method. The recovery rate was 103±5% (10μm), 94±4% (25 μm) and 78±12% (50 μm), respectively, meeting the requirements of FDA guidance documents (i.e. FDA 1545). Less than 3% of the particles were found in the cleaning solutions. The method using a fixed volume during stent loading can be adapted to all durability testers where tubes are used to fix the stents (radial pulsatile, bending, axial compression, torsion).
Investigations of Surface Interactions between PEGDA-Polymer and Drug using Surface Plasmon Resonance
Authors: Lange Helge , Rekowska Natalia , Wulf Katharina , Grabow Niels , Eickner Thomas 
Published: December 2021

Abstract
For the development of combination products, the determination of the release kinetics of polymer-based drug delivery systems (DDS) is a central and often timeconsuming investigation. Classical methods are often unsuitable for large-scale screening of potential polymers for combination products. We present a rapid method based on surface plasmon resonance spectroscopy (SPR), using PEGDA700 (Poly(ethylene glycol) diacrylate, average molecular weight (Mn) 700) as an example. This method is capable of determinating the kinetics of drug association and subsequent release within minutes. The proportion of desorption and diffusion can be determined separately.
Surface plasmon resonance spectroscopy (SPR) is a label-free and very sensitive optical technique, which allows for real-time observation of surface interactions. The prepared SPR chips were spin-coated with PEGDA700 and crosslinked via photoinduced polymerization.
The association and dissociation kinetics of dexamethasone phosphate in swollen PEGDA700 have been studied at different concentrations. The maximum loading of the surface was also obtained by this method.
The study of PEGDA presented here identified the wellestablished SPR-based spectroscopy as a potential tool in the development of combination products.
Establishment of suitable parameters for laser machining based production of polymeric implants
Authors: Bohne Eric , Grossmann Swen , Dierke Ariane , Siewert Stefan , Grabow Niels , Schmitz Klaus-Peter , Stiehm Michael 
Published: December 2021

Abstract
Laser material processing enables precise machining of a wide variety of materials. In order to prevent an excessive heat input, which leads to irreversible material damage, the process parameters have to be adapted to the processed material. To keep the heat load as low as possible, the potential of femtosecond laser technology is exploited. The processing of semi-finished products using femtosecond laser technology is highly depending on the processed material. In this regard, we established a workflow and basic parameters for the processing of polymeric material. The performed parameter study varying cutting speed, cutting gas pressure and pulse energy to optimize the manufacturing process. Scanning electron microscopy (SEM) was utilized to analyze the cutting results, such as cut edge quality or possible melted areas. The established parameter set is also suitable for processing of very filigree material structures as used in innovative medical devices. The SEM analysis of the established parameter set showed that a homogeneous, nonwavy cut edge was created along the kerf.
Fixed Point Analysis Workflow for efficient Design of Convolutional Neural Networks in Hearing Aids
Authors: Klein Simon Christian , Kantic Jonas , Blume Holger 
Published: December 2021

Abstract
Neural networks (NN) are a powerful tool to tackle complex problems in hearing aid research, but their use on hearing aid hardware is currently limited by memory and processing power. To enable the training with these constrains, a fixed point analysis and a memory friendly power of two quantization (replacing multiplications with shift operations) scheme has been implemented extending TensorFlow, a standard framework for training neural networks, and the Qkeras package [1, 2]. The implemented fixed point analysis detects quantization issues like overflows, underflows, precision problems and zero gradients. The analysis is done for each layer in every epoch for weights, biases and activations respectively. With this information the quantization can be optimized, e.g. by modifying the bit width, number of integer bits or the quantization scheme to a power of two quantization. To demonstrate the applicability of this method a case study has been conducted. Therefore a CNN has been trained to predict the Ideal Ratio Mask (IRM) for noise reduction in audio signals. The dataset consists of speech samples from the TIMIT dataset mixed with noise from the Urban Sound 8kand VAD-dataset at 0 dB SNR. The CNN was trained in floating point, fixed point and a power of two quantization. The CNN architecture consists of six convolutional layers followed by three dense layers. From initially 1.9 MB memory footprint for 468k float32 weights, the power of two quantized network is reduced to 236 kB, while the Short Term Objective Intelligibility (STOI) Improvement drops only from 0.074 to 0.067. Despite the quantization only a minimal drop in performance was observed, while saving up to 87.5 % of memory, thus being suited for employment in a hearing aid
Clinical case study in acoustic-kinetic joint analysis: Synchronization and Evaluation of kinetic measurement data in AEA (Acoustic Emission Analysis) based diagnosis of arthritic knee joint defects
Authors: Subke Joerg , Schneider Benedict , Hanitz Fiona , Krüger Sabine , Junker Heinz-Otto , Schwalbe Hans-Joachim , Wolf Udo 
Published: December 2021

Abstract
: In patients with arthritic knee joint defects the course of movement, the application of muscle forces and the degree of freedom of the joints of the lower limbs differs significantly from the corresponding data of a healthy proband. The enhanced acoustic-kinetic joint analysis based on AEA, ground force reaction measurements and video enhanced gait analysis permits the correlation of force data, joint angles and acoustic emission significant of defective joint cartilage regions. This diagnostic procedure permits a quantifiable and detailed non invasive diagnosis of lesion patterns in the arthritic knee joint by means of a synchronization algorithm. The AEA shows lesion signals in the first and third knee bend of the patient. The lesion signals are assigned to the joint angles and ground reaction force. Comparing the kinematical data there is a shift between the curves of the hip and the knee angle. Overall the force data represent an imbalance between the left and the right leg during the knee bends. The presentation of the three measurement systems, the method, the synchronization of the data sets and their final assessment as well as the occurring difficulties during a case of a clinical study are discussed. This would be helpful regarding further patients of the clinical study
Automatic Hypercube Acquisition with high spatial and spectral resolution using a HSI Linescan Camera
Authors: Pape Robin , Patzke Stefan , Zaunseder Sebastian , Thiem Jörg 
Published: December 2021

Abstract
Push-broom HSI-cameras have a high spectral resolution but require scanning and stitching to get a correct spatial and spectral representation of a scene. The conventional approach is to calculate a scanning velocity that matches the camera’s frame rate so that the stitching becomes trivial. For this to work one needs to be able to apply the velocity steadily and know the distance between camera and subject. This contribution presents a feature-based approach that directly determines the distance the subject was moved between the images and uses it to correctly stitch the images. It is used in a self-contained environment consisting of a lightprotected box with a light source inside and a linear guide unit that moves the object under examination. The distance between camera and object can be altered to increase the spatial resolution for small objects. It is shown that our stitching approach works even if the velocity changes during scanning. If the distance of the camera is altered, e. g. to scan a larger object, the stitching is adjusted automatically without the need for manual intervention.
Hyperinsulinemic hypoglycemia in growth restricted convalescent preterm neonates: clinical characteristics and impediments to early diagnosis
Authors: Rodrigues Megan , Rana Pratibha , Lee Gene , Mahajan Chaitali , Nyp Michael , Pandey Vishal 
Published: December 2021

Abstract

Objectives
Describe clinical characteristics, course, and risk factors for hyper-insulinemic hypoglycemia (HIH) in preterm infants and identify impediments to early diagnosis.

Methods
Electronic records of infant–mother dyads were used to describe clinical characteristics, lab parameters, and course of HIH.

Results
All eight patients (gestational ages 26w0d–29w3d) had intrauterine growth restriction (IUGR) due to placental insufficiency, (4/8) were small for gestational age. All maintained normal glucose levels with glucose infusion during the first 48 h six of eight patients had cholestasis despite being on parenteral nutrition for short time (average 17 days). Four of eight patients were treated with diazoxide (average 22 days). Four of eight patients who recovered spontaneously (average 49 days after diagnosis) responded to continuous feeds and hydrocortisone for other clinical indications.

Conclusions
In IUGR preterms, HIH is asymptomatic, may be prolonged, requiring diazoxide treatment. Transient cholestasis is seen in majority of patients. Euglycemia should be demonstrated on bolus gavage feeds, off glucocorticoids before discontinuing blood glucose monitoring.
Internet Memes, Memory, and Orders of Repackaging
Authors: Korostenskiene Julija 
Published: December 2021

Abstract
The present study explores the construction of humor in internet memes along two dimensions. The external dimension is concerned with humor in internet memes as opposed to verbal humor on the one hand and as opposed to humor in comics and caricatures on the other. The perceptive differences, stemming from the workings of the human memory, and the medium are posited as the two main differentiating factors. On the internal dimension, we explore manifestations of humor in light of the communicative situation and taxonomic relations at both the intermedial and intramedial levels of internet memes, taking as an example a family of You Wouldn’t Get It image macros. Our analysis employs elements of intertextuality theory and the notion of orders of indexicality. The study aims to contribute to the growing theoretical and methodological framework for multifactorial analyses of internet memes.
Free-Range Philosophy: Modes of Philosophical Analysis across the Discipline … and across the Road
Authors: Gimbel Steven , Cisney Vernon 
Published: December 2021

Abstract
Philosophy’s richness comes in part from the wide range of conceptual frameworks from which meaning can be made of aspects of the world. Philosophy can be done from feminist, Marxist, positivist, or Freudian standpoints. The difference in the sorts of analyses produced by these different approaches can be tricky to explain to undergraduates. Contained here are short explanations of the nature of a collection of these frameworks and a fun example of each, an analysis of the chicken crossing the road joke to be used to give undergraduates a sense of the breadth of philosophical methodology.
Effect of infill density and pattern on the specific load capacity of FDM 3D-printed PLA multi-layer sandwich
Authors: Dobos József , Hanon Muammel M. , Oldal István 
Published: December 2021

Abstract
Three-dimensional (3D) printing settings allow the existence of differently filled sections together within a piece. That means the use of inhomogeneous internal material structure. Knowing the load capacity that 3D printed plastic parts can withstand leads to the reduction of the filling degree, thus the amount of the used material in certain places. This approach has two advantages during production: (i) less material use and (ii) reduced manufacturing time, both being cost-reducing factors. The present research aims to find the optimal proportions for fabricating a bending test piece with varying filling degrees. To achieve this goal, experimental tests were performed for obtaining tensile strength and modulus of elasticity using different pairs of infill density and pattern. This provided a basis for creating a working mechanical model based on accurate and realistic material properties. Hence, a series of virtual bending test experiments were conducted on a sandwich structure specimen employing Ansys Workbench software. By doing so, the optimal thickness (of the sandwich’s inner layer) with the highest specific load capacity for the given filling patterns and densities were determined. To the best of our knowledge, the current procedure of experiments and method of settings optimization were not discussed elsewhere.