bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computational flow analysis of the washout of an aortic valve by means of Eulerian transport equation
Authors: Stiehm Michael , Borowski Finja , Kaule Sebastian , Ott Robert , Pfensig Sylvia , Siewert Stefan , Schmitz Klaus-Peter , Öner Alper Ö , Grabow Niels 
Published: September 2019

Abstract
Although the development of the transcatheter aortic valve (TAV) has saved many lives of inoperable patients and has a very good clinical outcome, concerns about valve thrombosis are increasing. Due to the potential risk of late clinically relevant events, the US Food and Drug Administration (FDA) suggests a careful systematic investigation of thrombosis and reduced leaflet motion related to hemodynamic changes induced by TAV implantation. Furthermore, recently published position papers of the ISO working group address numerical and experimental flow field assessment of TAV. In particular, pathologically high shear rates and a reduced washout of the sinuses may increase the risk of valve thrombosis and should therefore be investigated. By means of fluid-structure interaction (FSI) as a powerful in silico tool, the transient flow field in an aortic valve was analyzed. A linear elastic behavior was assumed for leaflet material properties (Young modulus: 10 MPa, Poisson ratio: 0.46 and leaflet material density: 1000 kg/m3) and blood was specified as a homogeneous, Newtonian and incompressible fluid (fluid density: 1060 kg/m3 and a dynamic viscosity: 0.0035 Pa s). In this numerical study we present a Eulerian approach, which is based on transport equation of the residence time (RT) as a passively transported scalar. It can be clearly seen that the RT is significantly higher in the sinus referred to the main flow. At time step t = 0.25 s, the average residence time in the main flow is RTavg ≈ 0.05 s, whereas RT ≈ 0.25 s in the sinus. In particular, RT is a valuable hemodynamic metric to quantify the washout of the sinus in order to evaluate the thrombogenic potential of TAV devices. Further studies will concentrate on particle image velocimetry measurements for validation purposes. In particular the velocity in the sinus and therefore the washout is one important hemodynamic key feature that has to be improved for future TAV designs.
Usability assessment of patient hoists as a purchasing guide for health facilities
Authors: Müller Lorenz , Sobkowicz Saskia , Ibenthal Elisabeth , Backhaus Claus 
Published: September 2019

Abstract
Nurses suffer from musculoskeletal strains because of frequent patient mobilizations. Therefore, mobile patient hoists were developed. However, patient hoists are rarely used. A possible reason is a low user acceptance due to poor usability of available products. To increase the user acceptance in health facilities and thus the frequency of use, a comparative usability assessment was conducted. The goal is to support health facilities in future purchasing decisions. 12 hoists were tested by 40 nurses in three everyday scenarios. Every nurse tested three hoists in randomized order. In total, each hoist was tested ten times. The success rate was used to measure the effectiveness. To identify poorly designed components, success rates were clustered into categories, which describe different hoist parts. User acceptance was quantified in the range of 0 to 100 using a standardized questionnaire. The success rate over all hoists was high and ranges from 88 % to 95 % (M = 92 %, SD = 2 %). However, serious use errors occurred in 24 % of the scenarios. The slingbars of the hoists showed the lowest effectiveness (M = 82 %, SD = 6 %). The user acceptance of the hoists ranges from 49 to 86 (M = 68, SD = 10). Besides structural problems like limited space or product availability, design deficits are a possible reason, why hoists are not used. All in all, the study identifies ergonomically better-designed hoists. Based on the results, health facilities can take usability aspects into account when making purchasing decisions.
Biodegradable magnetic microspheres for drug targeting, temperature controlled drug release, and hyperthermia
Authors: Zahn Diana , Weidner Andreas , Saatchi Katayoun , Häfeli Urs O. , Dutz Silvio 
Published: September 2019

Abstract
Magnetic microspheres (MMS) used for magnetic drug targeting consist of magnetic nanoparticles (MNP) and a pharmaceutical agent embedded in a polymeric matrix material. The application of MNP for drug targeting enables guiding the MMS to a target area, imaging the position of the MMS with magnetic particle imaging, and finally inducing drug release. As latter takes place by degradation of the MMS or diffusion through the matrix, an increase in temperature, e.g. through magnetic hyperthermia, leads to an accelerated drug release. Here, MMS consisting of poly(lactic-coglycolic) acid (PLGA) with different monomer ratios were prepared by an oil-in-water emulsion evaporation method. The model drug Camptothecin (CPT) and magnetic multicore nanoparticles (MCNP) with a high specific heating rate were embedded into the microspheres. We obtained MMS in the preferred size range of 1 to 2 μm with a concentration of MCNP of 16wt%, a drug load of about 0.5wt% and an excellent heating performance of 161 W/gMMS. Investigations of the drug release behaviour showed an accelerated drug release when increasing the temperature from 20 °C to 37 °C or 43 °C by using a water bath. In addition, an increase in drug release of about 50% through magnetic heating of the MMS up to 44 °C compared to 37 °C was observed. By this, a magnetic hyperthermia induced CPT release from PLGA MMS is demonstrated for the very first time.
Experimental Study on Cell-free Approach for Articular Cartilage Treatment
Authors: Dursun Gözde , Markert Bernd , Stoffel Marcus 
Published: September 2019

Abstract
Cell-free based approaches are introduced as a promising treatment method for articular cartilage. The success of this method requires cell colonisation from resident tissue into cell-free implants. The objective of our study is to promote the cell colonisation into cell-free collagen I based implants by mechanical stimulation. Therefore, a new in vitro cellular model consisting chondrocyte-seeded matrix and cell-free implants was developed in a polydimethylsiloxan (PDMS) mold. These constructs were cultured under dynamic and static culture conditions. For the dynamic culture, we have developed an in-house bioreactor system where both the load and the deformation applied to the specimen are recorded. Cyclic compression, with a strain of 5% and frequency of 0.1 Hz, was applied to constructs without any break. At the end of three days of dynamic and static cultivation, the cell-free implants were seperated from cell-seeded matrix and cultured in a petri dish three days long. Afterwards, they were analysed using fluoresence dyes. The microscopic assessment indicated that there was a cell migration into the cell-free implants which were cultured dynamically.
Intelligent Assistant System for the Automatic Assessment of Fall Processes in Sports Climbing for Injury Prevention based on Inertial Sensor Data
Authors: Munz Michael , Engleder Thomas 
Published: September 2019

Abstract
In this work, an assistant system is presented for the automatic assessment of falling and belaying in sport climbing. Both climber and belayer are equipped with inertial measurement unit (IMU) sensors. Forces as well as movements in the form of multi-dimensional accelerations on the legs and torso are captured. It can be shown that forces can be estimated by means of IMU sensors, thus eliminating a complex force measurement unit in the safety chain. Furthermore, the data can be used to assess both falling and belaying by automatic segmentation and evaluation algorithms. The sensor data should later be evaluated automatically in order to objectively measure faulty behavior by climber or belayer (for example wrong jump-off behavior, too hard protection, etc.). The overall goal is to provide quantified feedback in fall training for injury and accident prevention.
Development of an antifibrotic drug-eluting coating for a minimally invasive implantable glaucoma microstent
Authors: Siewert Stefan , Reske Thomas , Pfensig Sylvia , Großmann Swen , Stiehm Michael , Schmitz Klaus-Peter , Schmidt Wolfram , Grabow Niels , Stahnke Thomas , Guthoff Rudolf 
Published: September 2019

Abstract
Primary open angle glaucoma represents an eye disease that usually is associated with an increased intraocular pressure (IOP). Implants for micro-invasive glaucoma surgery (MIGS) are gaining importance as a promising option for IOP lowering. Currently available devices are implanted into the eye ab interno based on a clear corneal incision and drain aqueous humour into the schlemm’s canal, suprachoroidal or subconjunctival space. Fibrosis is known as a major limitation for long term success and often leads to the necessity of an additional medication or a surgical re-intervention. The current work focusses on the development of an antifibrotic drug-eluting coating for a minimally invasive implantable glaucoma microstent. Tubular microstent base bodies manufactured from a polycarbonate based silicone elastomer were spray-coated with a chloroform based mixture of the same polymer and the antifibrotic drug pirfenidone (PFD, P2116, Merck KGaA, Germany) in a polymer/drug ratio of 85/15% (w/w). Coating mass of 89 μg according to a drug loading of 1.96 μg mm-2 was aspired. Coating mass was measured using an ultramicrobalance (XP6U, Mettler-Toledo International, Inc., Switzerland). Glaucoma microstent prototypes with a drugeluting coating mass of (84 ± 19) μg (n = 12) were manufactured. Characterization by means of scanning electron microscopy (Quattro S, Thermo Fisher Scientific, FEI Deutschland GmbH, Germany) yielded a reproducible smooth surface of the coating. High performance liquid chromatography (KNAUER Wissenschaftliche Geräte GmbH, Germany) was used for analysis of drug release behaviour in 0.9% NaCl solution at 37°C. The in vitro PFDrelease is characterized by an initial burst phase of approximately 6 h followed by a more retarded release phase. The entire drug was released within 36 h (n = 3). Sterilization processing has a minor impact on drug release kinetics. Appropriate drug stability after sterilization could be proven. Future studies will focus on the antifibrotic properties of drug-eluting glaucoma microstents in animal studies.
Validation System for Digital Stethoscopes
Authors: Klum Michael , Stehling Julian , Pielmus Alexandru , Tigges Timo , Orglmeister Reinhold 
Published: September 2019

Abstract
Stethoscope auscultation is a diagnostic method widely used by medical professionals. With the introduction of digital stethoscopes, auscultation sound analysis has been objectified, which led to an increased interest in the field. Until today, however, no standard to assess the acoustical properties of stethoscopes is available. Some approaches use phantoms mimicking the properties of human soft tissue. In most cases, however, the properties of the phantoms have not been analyzed with respect to environmental variables. In our work, we propose a stethoscope characterization system for the frequency range between 50 Hz and 2.5 kHz with a small financial footprint. We analyzed its frequency behavior over temperature, time and position on the phantom and derived quantitative recommendations for environmental variables. Finally, the frequency response of a commercial digital stethoscope was characterized at different pressure levels. We conclude that the presented system is capable to stably and reproducibly assess the transfer function of digital stethoscopes. We hope that future stethoscope designs will be characterized with respect to their acoustical properties.
Integrating Label Uncertainty in Ultrasound Image Classification using Weighted Support Vector Machines
Authors: Hagenah Jannis , Leymann Sascha , Ernst Floris 
Published: September 2019

AbstractInference from medical image data using machine learning still suffers from the disregard of label uncertainty. Usually, medical images are labeled by multiple experts. However, the uncertainty of this training data, assessible as the unity of opinions of observers, is neglected as training is commonly performed on binary decision labels. In this work, we present a novel method to incorporate this label uncertainty into the learning problem using weighted Support Vector Machines (wSVM). The idea is to assign an uncertainty score to each data point. The score is between 0 and 1 and is calculated based on the unity of opinions of all observers, where u = 1 if all observers have the same opinion and u = 0 if the observers opinions are exactly 50/50, with linear interpolation in between. This score is integrated in the Support Vector Machine (SVM) optimization as a weighting of errors made for the corresponding data point. For evaluation, we asked 15 observers to label 48 2D ultrasound images of aortic roots addressing whether the images show a healthy or a pathologically dilated anatomy, where the ground truth was known. As the observers were not trained experts, a high diversity of opinions was present in the data set. We performed image classification using both approaches, i.e. classical SVM and wSVM with integrated uncertainty weighting, utilizing 10-fold Cross Validation, respectively (linear kernel, C = 7). By incorporating the observer uncertainty, the classification accuracy could be improved by 3.1 percentage points (SVM: 83.5%, wSVM: 86.6%). This indicates that integrating information on the observers’ unity of opinions increases the generalization performance of the classifier and that uncertainty weighted wSVM could present a promising method for machine learning in the medical domain.
Aspects of Multimodal Hybrid Biomaterials
Authors: Jennissen H. P. 
Published: September 2019

Abstract
Immobilizing a single growth factor such as rhBMP-2 on Implant materials can significantly increase the integration of implants into bone in animals. Paradoxically the effective osteoinductive dose of rhBMP-2 in humans is ca. 100-1000-fold higher than in animals and may induce serious side effects in spine fusion surgery. In physiological bone healing at least 10 separate growth and differentiation factors are sequentially involved in the first two healing phases leading to a callus and/or woven bone. It is therefore hypothesized that a significant dose reduction for rhBMP-2 applications in humans may be achieved by a combination of rhBMP-2 with other growth factors in a biomimetically oriented manner. Some aspects involved in multimodal bioactive hybrid carriers with spatio-temporal release kinetics and a new phenomenon ("protein interference") are presented.
Interactive Image Segmentation for Cochlea Implant Planning based on DVT Data
Authors: Killguß Nathalie , Wittenberg Thomas , Franz Daniela , Eixelberger Thomas , Rupp Robin , Hofer Mathias 
Published: September 2019

Abstract
Cochlea Implant (CI) planning is usually based on preoperative obtained CT or MRI data, visualising risk structures in the petrosal bone. In the past years, Digital Volume Tomography (DVT) with an increased spatial resolution and reduced radiation has become more important in the clinical routine for otology. In this work we propose an extension of our interactive “wizard”-guided approach for the interactive segmentation of the middle and inner ear structures for the use with DVT data. Different filter pipelines enable the user to interactive segment the acoustic canal, ossicles, tympanic cavity, facial nerve, chorda tympani, round window, cochlea and semicircular canals. The approach has been evaluated on six pre-operative acquired DVT datasets by an ENT expert. Results imply that the proposed method can handle DVT well and can potentially be used for interactive OR planning.
Development of a smart fabric force-sensing glove for physiotherapeutic Applications
Authors: Spilz Andreas , Engleder Thomas , Munz Michael , Karge Marius 
Published: September 2019

Abstract
In this work, a low-priced smart fabric forcesensing glove is developed which is able to measure the total amount and direction of the force a person applies on a patient in a physiotherapeutic context. A device like this would be beneficial for the education of physiotherapists, to measure the progress of a patient and to evaluate the treatment. The proposed device uses a new sensor, which is based on a piezoresistive fabric. This fabric changes its electrical resistance according to the applied stress. The characterization of this sensor revealed that the change in resistance of the sensor is dependent of the amount of force, the loaded area, the total time the sensor is loaded and hysteresis. To compensate these behaviours, an additional sensor based on the same smart fabric was developed which measures the loaded area of the first sensor. By combining these two sensors, it is possible to calculate the applied force. The results show the feasibility to build a measurement system out of smart fabric material that can measure the applied force. Furthermore, the prototype shows promising results in determining the applied force in amount and direction.
Model of SpO2 signal of the neonate
Authors: Huttova Veronika , Rafl Jakub , Möller Knut , Bachman Thomas E. , Kudrna Petr , Rozanek Martin , Roubik Karel 
Published: September 2019

Abstract
The advantages of automatic control of the fraction of inspired oxygen in neonates have been documented in recently published clinical trials. Many control algorithms are available, but their comparison is missing in the literature. A mathematical model of neonatal oxygen transport could be a useful tool to compare and enhance both automatic control algorithms and manual control of fraction of inspired oxygen. Besides other components, the model of neonatal oxygen transport must include a module linking arterial (SaO2) and peripheral (SpO2) oxygen saturation. The pulse oximeter module must reflect issues of SpO2 measurement typical for clinical practice, such as overestimation of SpO2 over SaO2 documented by several studies, or inaccurate pulse oximeter readings due to high noise. The aim of this study was to describe both the bias between SaO2 and SpO2 and the noise, characteristic for continuous SpO2 recording, for a computer model of oxygenation of a premature infant. The SpO2-SaO2 bias, derived from available clinical data, describes a typical deviation of the SpO2 measurement as a function of the true SaO2 value in three different SaO2 intervals. The SpO2 measurement noise was considered as a random process that affects biased SpO2values at each time point with statistical properties estimated from SpO2 continuous recordings of 5 stable newborns. The results of the study will help to adjust a computer model of neonatal oxygenation to the real situations observed in the clinical practice.
Guiding and Accumulation of Magnetic Nanoparticles Employing High Intensity Focused Ultrasound for Drug Targeting Applications
Authors: George Benedikt , Fink Michael , Ermert Helmut , Rupitsch Stefan J. , Lyer Stefan , Alexiou Christoph 
Published: September 2019

Abstract
Magnetic Drug Targeting (MDT) is a cancer treatment technique that enables a local chemotherapy. In MDT, chemotherapeutic drugs are bound to magnetic nanoparticles and are accumulated in the tumor area by means of an external magnetic field. Unfortunately, a single magnet can only generate a pulling magnetic force. However, in some applications a pushing force on the nanoparticles could be advantageous. One way to realize pushing forces is to exploit the acoustic radiation force based on the nonlinearity of sound propagation in fluid media generated by a high intensity focused ultrasonic transducer. In this context, we built a test setup was built to investigate the utility of High Intensity Focused Ultrasound (HIFU) to generate a pushing force on the magnetic nanoparticles. The results show that the acoustic radiation force can be employed for particle guidance to achieve concentration differences similar to those obtained by using an electromagnet.
Evaluation of MRI-compatible pneumatic muscle stepper motors
Authors: Odenbach Robert , Guthrie Alan , Friebe Michael 
Published: September 2019

Abstract
The automation of instruments and tools (e.g. bone drill) or robotic devices (e.g. needle positioning robot for prostate surgery) for use in interventional MRI (iMRI) is still challenging due to a lack of accurate, affordable and completely metal-free actuators and motors. Inspired by biological muscles, a bionic equivalent known as the fluid muscle actuator (which can be operated pneumatically or hydraulically) is well-known in the mechanical engineering industry. Fluid muscle actuators have multiple beneficial characteristics: they are simple, self-returning, low-friction and can produce relatively high actuation forces at low diameters and pressures. We present two novel designs for metal-free, pneumatic stepper motors for potential application in iMRI. Our stepper motors are powered by simple pneumatic muscles, which are assembled from low-cost off-the-shelf components. Besides, the components of the stepper motor demonstrators were 3Dprinted using a stereolithographic additive manufacturing process (SLA printing). We evaluate the effect of pneumatic muscle length on contractile force and length. Our results demonstrated the functional feasibility of the pneumatic muscle-powered and fully MRI-compatible stepper motor designs. In a next step, we will optimize the motor´s design, characterize their performance and reliability, and use the stepper motors to power a micropositioning device in iMRI-phantom tests.
Perspectives from the other side of the screen: how clinicians and radiologists communicate about diagnostic errors
Authors: Lama Anna , Hogg Jeffery , Olson Andrew P.J. 
Published: September 2019

Abstract

Background
Miscommunication amongst providers is a major factor contributing to diagnostic errors. There is a need to explore the current state of communications between clinicians and diagnostic radiologists. We compare and contrast the perceptions, experiences, and other factors that influence communication behaviors about diagnostic errors between clinicians and radiologists.

Methods
A survey with questions addressing (1) communication around diagnostic error, (2) types of feedback observed, (3) the manner by which the feedback is reported, and (4) length of time between the discovery of the diagnostic error and disclosing it was created and distributed through two large academic health centers and through listservs of professional societies of radiologists and clinicians.

Results
A total of 240 individuals responded, of whom 58% were clinicians and 42% diagnostic radiologists. Both groups of providers frequently discover diagnostic errors, although radiologists encounter them more frequently. From the qualitative analysis, feedback around diagnostic error included (1) timeliness of error, (2) specificity in description or terminology, (3) collegial in delivery, and (4) of educational value through means such as quality improvement.

Conclusions
Clinicians and radiologists discover diagnostic errors surrounding the interpretation of radiology images, although radiologists discover them more frequently. There is significant opportunity for improvement in education and practice regarding how radiologists and clinicians communicate as a team and, importantly, how feedback is given when an error is discovered. Educators and clinical leaders should consider designing, implementing, and evaluating strategies for improvement.