bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical properties and microstructural analysis of an AgPd alloy cast under different temperatures
Authors: Olivieri Karina Andrea Novaes , Neisser Maximiliano Piero , Bottino Marco Antônio , Miranda Milton Edson , Wernek Rafael Dario 
Published: December 2021

The metal restorations are used in Dentistry a long time ago. Nowadays we have resources that can get casting more accurate, with new material and equipments and techniques more precise. The purpose of this study was to evaluate the metallurgical and mechanical aspects of the AgPd dental alloy when it was submitted to different casting temperatures. It was used 30 specimens, divided in three groups (n=10): a) control group (no cast); b) casting temperature in accordance with the manufactures’ instructions (T1); b) casting temperature above manufactures´ instructions (like a torch) (T2). It was evaluated chemical and metallographic aspects, mechanical properties and Vickers hardness. The results showed a microstructure similar to T1 and T2 conditions, but with greater amount of light phase and particles in this last one. It was observed that the rupture tensile strength for the T1 condition was greater than the T2. The alloy in the no cast condition presented greater hardness but there was no statistically significant difference between T1 and T2. Supporting by the metallographic and mechanical results, it may predict that when elevated temperatures was used, above manufacture´s recommendations, it can occur failures in the prosthesis, like porosities, fissures or cracks.
Knowledge about composite restorations repair vs replacement- a survey among a subpopulation of saudi dental students
Authors: Alqarni Mohammed , Khalil Shamsun Nahar , Obied Eman Saeed Saeed , Alshehri Maha M , Assiri Manar Ali Abdulgader , Mualwi Sara Abdullah Muhammed , Thabet Sultanah Mohammed Saeed , Khateeb Shafait Ullah 
Published: December 2021

Objectives: the purpose of this study was to evaluate the knowledge among dental students at King Khalid University, Jazan University, and Najran University in the kingdom of Saudi Arabia about when to repair or replace defective direct composite restoration. Materials and Methods: A questionnaire-based survey was formulated, pursuing the information about management (repair/replacement) of defective composite restorations and distributed among 200 dental students of three universities in the southern region of the kingdom of Saudi Arabia.The data were collected with the help of an online questionnaire. Data entry and the analysis were done using the statistical software package SPSS version 20.0. It was presented using descriptive statistics in the form of frequencies and percentages for qualitative variables, and range means and standard deviations for age, quantitative variable. Analytic statistics ere done using Chi-Square tests (x2) to test the significant difference between categorical variables. The level of significance, the p-value was 0.01 (p < 0.01). Results: The decision to choose between composite repair or replacement was influenced by whether this topic was taught to them at various undergraduate levels during Bachelor of Dental Surgery. The reason associated with the decision to repair defective composite restorations, 76% reported as cost-effective followed by Increased longevity (71%), the permanent filling (70%), patient’s preference for repair (65%), and least time consuming (50%). 67% participants preferred significantly (p<0.001) repair due to secondary caries in the previously restored tooth with composite, followed by the small surface defect in a composite restoration (65%), risk of pulpal damage significantly (p<0.001) in a defective composite restoration (62.5%) and more invasive and destructive treatment option (35%). More than half of respondents 123 (61.5%) reported that they were not taught about composite repair during the Bachelor of Dental Surgery. Conclusion: It is suggested with the help of our study that didactic and clinical training components regarding composite repair should be seriously included in the teaching curriculum of dental institutions as it is in the best interest of the patient. Dental students should be provided with clinical training on this topic so that they can follow proper decision-making protocols available during repair or replacement of defective resin composite restorations. Other researches in the future can be carried out for refining the guidelines and techniques utilized for composite repair.
KEYWORDS
Composite restoration; Discoloration; Polymerization shrinkage; Secondary caries.
Supervised Skeleton-Based Reference Movement Adjustment
Authors: Lehmann Lars , Seidel Roman , Hirtz Gangolf 
Published: December 2021

Abstract
In Medical Training Therapy (MTT) the exact execution of training exercises developed by the therapist is crucial for the success of the therapy. Currently, a therapist has to treat up to 15 patients at the same time on an outpatient basis. The aim of this paper is to provide an assistance system that can evaluate both the quantity and the quality of the movement performed using a goal-oriented model which gives the patient direct recommendations for action through automated, machine-monitored feedback. To implement the therapeutic measures in a targeted manner, it is advantageous to transfer their knowledge to the patients. This would be possible by transferring the therapist's movement into a patient's movement. Under this assumption a movement sequence of the therapist is recorded and a movement reference frame is extracted with the help of a smart sensor, which is made available to the patient as a target movement. The assistance system records the patient's movement in real time, extracts the its skeleton and compares this movement with the reference. Due to anatomical body differences, the reference skeleton must be adapted to the current patient skeleton, otherwise no movement evaluation can take place. By adjusting the bone lengths and angles in the individual frames of the patient's movement the selected sequence can be compared and any movement deviations that occur can be projected in directly in real time onto the patient's 3D avatar as an error image. The patient tries to reduce the errors and in doing so comes closer and closer to the ideal movement of the therapist which guarantees the best possible therapy success.
Cell colonization potential of thermoplastic silicone-based polyurethane nonwovens for novel heart valve prosthesis
Authors: Ratna Tuladhar Sugat , Teske Michael , Oschatz Stefan , Illner Sabine , Schilling Tobias , Schmidt Wolfram , Grabow Niels , Haverich Axel , Schmitz Klaus-Peter 
Published: December 2021

Abstract
Heart valve tissue engineering aims at creating living valves through colonization of scaffolds with patient’s own cells. Various cell sources have been explored focusing mainly on endothelialization of the scaffold surface. Endothelial like cells, such as endothelial progenitor cells (EPCs), which can be isolated from peripheral blood or bone marrow could be a suitable option. In this study we investigated cell colonization potential of ovine EPCs (OEPCs) on thermoplastic silicone-based polyurethane (TSPU) polymer scaffolds. TSPU nonwovens with and without vascular endothelial growth factor (VEGF) functionalization were used. SEM images showed that by day 3 the cells were growing as patches on the surface of both polymer groups. The cell patches continued growing and started covering more of the nonwoven surface. On day 7 the cells had almost covered the scaffold surface. The cells were more uniformly distributed as monolayer on the functionalized TSPU compared to the non-functionalized nonwovens. Live/Dead staining provided bright green fluorescence on the samples, indicating metabolically active alive cells. These static cell seeding experiments demonstrated that functionalized TPSU nonwovens support endothelialization. The feasibility of TPSU nonwovens as heart valve prosthesis scaffold could be further explored with animal studies in an ovine model.
Towards an intraoperative feedback system for laparoscopic access with the Veress needle
Authors: Spiller Moritz , Esmaeili Nazila , Sühn Thomas , Boese Axel , Turial Salmai , Friebe Michael , Illanes Alfredo 
Published: December 2021

Abstract
About 50 % of complications during laparoscopy occur when surgical access is created. The Veress needle and proposed technical alternatives do not provide reliable information to support the surgeons in guiding the needle, or the feedback is not clearly perceivable. Based on acoustic emissions, Surgical Audio Guidance (SURAG) proposes a non-invasive and efficient way to enhance the perception of guidance information through acoustic and visual feedback displayed in real-time. This article demonstrates that the developed feedback matches the information about tissue layer crossings provided by force measurements. This indicates that SURAG can provide an effective means to make laparoscopic access more precise and safe, especially in pediatric surgery, where space for placing the needle is minimal.
Multispectral single chip reconstruction using DNNs with application to open neurosurgery
Authors: Göb Stephan , Götz Theresa Ida , Wittenberg Thomas 
Published: December 2021

Abstract
Multispectral imaging devices incorporating up to 256 different spectral channels have recently become available for various healthcare applications, as e.g. laparoscopy, gastroscopy, dermatology or perfusion imaging for wound analysis. Currently, the use of such devices is limited due to very high investment costs and slow capture times. To compensate these shortcomings, single sensors with spectral masking on the pixel level have been proposed. Hence, adequate spectral reconstruction methods are needed. Within this work, two deep convolutional neural networks (DCNN) architectures for spectral image reconstruction from single sensors are compared with each other. Training of the networks is based on a huge collection of different MSI imagestacks, which have been subsampled, simulating 16-channel single sensors with spectral masking. We define a training, validation and test set (‘HITgoC’) resulting in 351 training (631.128 sub-images), 99 validation (163.272 sub-images) and 51 test images. For the application in the field of neurosurgery an additional testing set of 36 image stacks from the Nimbus data collection is used, depicting MSI brain data during open surgery. Two DCNN architectures were compared to bilinear interpolation (BI) and an intensity difference (ID) algorithm. The DCNNs (ResNet-Shinoda) were trained on HITgoC and consist of a preprocessing step using BI or ID and a refinement part using a ResNet structure. Similarity measures used were PSNR, SSIM and MSE between predicted and reference images. We calculated the similarity measures for HitgoC and Nimbus data and determined differences of the mean similarity measure values achieved with the ResNet-ID and baseline algorithms such as BI algorithm and ResNet-Shinoda. The proposed method achieved better results against BI in SSIM (.0644 vs. .0252), PSNR (15.3 dB vs. 9.1 dB) and 1-MSE*100 (.0855 vs. .0273) and compared to ResNet-Shinoda in SSIM (.0103 vs. .0074), PSNR (3.8 dB vs. 3.6 dB) and 1-MSE*100 (.0075 vs. .0047) for HITgoC/Nimbus. In this study, significantly better results for spectral reconstruction in MSI images of open neurosurgery was achieved using a combination of ID-interpolation and ResNet structure compared to standard methods.
To improve patients’ empowerment by selfconnection in home parenteral nutrition
Authors: Völz Diana , Eisele Joshua , Benderoth Günther , Schulze Ulrike 
Published: December 2021

Abstract
One promising approach for patients who need parenteral nutrition to live an almost normal life, is to provide extra-hospital therapy. This therapy is supported by an ambulatory care service whose staff connects and disconnects the nutritional fluid day by day. The nutrition therapy takes a long time every day and studies show that this therapy significantly disturbs patients’ daily life. Although home parenteral nutrition is part of the range of services provided by the statutory health insurance (German GKV), it is also expensive in the long run. Therefore, the cost-effectiveness of this form of therapy is constantly reviewed on an individual basis. Aim of this project is to enable a more autonomous life for patients by self-determined in between disconnection and connection of the therapy independently of the ambulatory care service. It has to be taken into account that any interruption of the nutrition process poses health risks to the patient, e.g. if air bubbles or bio contaminants enter the tube system. Flushing with saline solution before and after connecting is therefore an elementary component of the nutrition process. The redesigning of the connecting/disconnecting system and the subsequent development of an automated port flushing system integrated into a mobile feeding pump to realize a safe interruption of the therapy is the overall goal of the project. This paper deals with redesigning the connecting system. After having analysed group discussions, detected impact factors are used as basis of an experimental setup to get the final requirements for redesigning the connector system. The experimental study is done according to the rules of Design of Experimental (DoE). DoE is a statistical method to determine the optimal number of tests by using a complete factorial design. Two repetitions of the tests were carried out to analyse the significance of the impact factors by ANOVA (Analysis of Variance).
Reliability of start and stop control of hydraulic actuation for the insertion of electrode arrays
Authors: Zuniga M. Geraldine , Schell Viktor , Cramer Jakob , Lenarz Thomas , Rau Thomas S. 
Published: December 2021

Abstract
Atraumatic insertions of electrode arrays (EA) into the cochlea aim to preserve natural structures and residual hearing. However, there is a limit as to how smooth and slow a surgeon can insert an EA. As a potential solution, we recently presented a tool (cochlea hydro drive, CHD) that makes use of an infusion pump to prompt and control the desired, continuous and very slow (< 1 mm/s) forward movement for such insertions. The present work further describes the onset, delay and cessation of the hydraulic actuation in response to different start and stop mechanisms, to better understand the safety of its application for cochlear implant surgery. Methods: Our previously designed tool was used to perform insertions of an EA into an artificial scala tympani model. The prototype is designed to hold an EA, which is then actuated by a standard infusion pump programmed to operate at 0.4 mm/ and 0.1 mm/s. A tubing system between the CHD and the pump includes a three-way valve. Ten insertions were operated using the functions of the pump and ten using the valve. Results: From the programmed start to the actual movement, we observed a larger average delay using the pump’s start function (5 s at 0.4 mm/s; 17 s at 0.1 mm/s) vs. opening the valve (< 0.7 s for both velocities). Moreover, the average cessation of movement with the valve closure was almost immediate (0.7 s for both velocities; this corresponds to < 0.1 mm with the slower tested velocity), as opposed to 60- 80 s delay when using the pump’s stop function. Conclusion: The use of a 3-way valve facilitates motion cessation to the high accuracy level required for cochlear implant surgery. These promising findings support future clinical translation of our tool.
Smart surgical template models for customized knee joint replacements
Authors: Sembdner Philipp , Bust Bernhard , Dornheim Lars , Holtzhausen Stefan , Stelzer Ralph 
Published: December 2021

Abstract
The paper introduces a method for the automated generation of patient-specific instruments (PSI), here in particular templates, for the implantation of customized implants. The basis is the derivation of data from the morphology of the bony situation and the medical planning. A developed methodological approach based on an Active Shape Model (ASM) is used for the morphological measurement. Determined geometric dimensions are placed on this ASM and automatically adjusted in each case. In addition, specially developed software tools for the planning and design of medical devices will be presented. This includes, among other things, the intuitive control of template parameters by the user when manual adjustments are necessary. The determined data is bundled and applied to previously methodically thought-out and categorized master CAD (Computer Aided Design) models of surgical templates. These master models are fully configurable and designed to be adjusted within defined ranges of values. The templates are printed from the biocompatible material PA12 using selective laser sintering (SLS).
Techniques of Recording Photoplethysmographic Signals
Authors: Herrmann Hans , Ewald Hartmut 
Published: December 2021

Abstract
The photoplethysmography optically measures blood volume changes within micro vascular tissue. Furthermore, photoplethysmographic signals are used within pulse oximeters in order to calculate the oxygen saturation of the blood. This standard measurement technique is performed as a non-invasive spot check method for human health conditions in hospitals or other health care facilities. Usually at least two light sources are used alternating in order to measure photoplethysmograms at different wavelengths. In this paper we will investigate different methods of optically recording photoplethysmographic signals.
A Robust Multi-Channel EMG System for Lower Back and Abdominal Muscles Training
Authors: Kusche Roman , Graßhoff Jan , Oltmann Andra , Boudnik Lukas , Rostalski Philipp 
Published: December 2021

Abstract
EMG is an established method to acquire the action potentials of contracted muscles. Although commercial EMG systems are available and it is one of the most researched biosignals, it has never become widely used in rehabilitation or fitness training monitoring. The reasons are technical challenges of wearable EMG systems regarding electrode placement, motion artefacts and the complex connectivity of multi-channel EMG measurements. We address this problem for the lower back and abdominal musculature, through a novel dry electrodes belt, multi-channel high density EMG circuitry and problem-specific signal processing. The subject can easily strap the dry electrodes belt around himself which provides 16 EMG channels. Interferences from the ECG and motion artefacts are reduced by a stationary wavelet decomposition. Afterwards, an inter-channel filter is applied to increase the robustness of the signals. Subject measurements during different kinds of typical abdominal and lower back training exercises were performed wearing the novel dry electrodes belt. The results show the possibility of robust EMG measurements from the lower back and abdominal muscles by utilizing the gathered redundancy, appropriately. The additional information obtained via the multi-channel EMG circuitry and spatial oversampling can be used to address current problems of EMG applications. It combines the advantages of robustness and the capability of using comfortable dry electrodes. Therefore, the proposed measurement method for acquiring spatial information about the muscle contractions from the lower trunk can be used for rehabilitation or fitness training monitoring.
Gesture-controlled image system positioning for minimally invasive interventions
Authors: Fritsch Benjamin , Hoffmann Thomas , Mewes André , Rose Georg 
Published: December 2021

Abstract
This work examines how a touchless interaction concept contributes to an efficient, direct, and sterile interaction workflow during CT-guided interventions. Two hand gesture sets were designed specifically under consideration of the clinical workflow and the hardware capabilities. These were used to change the position of an X-Ray tube and detector of a CT scanner without breaking sterility and are compared regarding usability and performance in a user study with 10 users. The user study revealed that it is possible to change the angle of the gantry within 10 seconds average in an experimental setup. A straight hand gesture showed higher acceptance than a pistol motivated gesture. Furthermore, the sequences were not optimal and confused the users. It turned out that it feels more natural to activate and confirm the system with the same gesture.
Effect of volume flows on the viability of MSCs during injection through a cannula
Authors: Nießen Lina , Facchinetti Giulia , Elsner Till , Wendlandt Robert , Gemoll Timo , Habermann Jens K. , Schulz Arndt-Peter 
Published: December 2021

Abstract
Introduction: Clinical trials currently evaluate the use of mesenchymal stem cells (MSCs) for the treatment of non-union bone fractures. The stem cells are injected directly into the non-union area of a bone via a cannula. During this injection process, pressure and shear forces affect the MSCs which could influence the viability of the cells. One parameter that influences the level of the shear forces is the volume flow. The aim of this study is to show whether the injection process with two different volume flows influences the cell viability. Methods: MSCs were isolated from bone tissue, harvested during arthroplasty. Afterwards, they were diluted to a concentration of 1 million cells/mL and 1 mL of this suspension was injected through a cannula with 200 mm length and 2 mm diameter (14 G) with volume flows of 38 and 100 mL/min. The evaluation was performed by detecting living, apoptotic, and dead cells using flow cytometry. The statistical analysis was performed with a Kruskal-Wallis-test to identify significant differences and with a TOST procedure for significant equivalence. The significance level was set to 5 % and the equivalence margin to 20 %. Results: The cell population of healthy cells was in the control group 85.88±2.98 %. After an injection with 38 mL/min the population of healthy cells was 86.04±2.53 % and with 100 ml/min 85.48±1.64 %. The statistical analysis revealed no significant difference between these groups (p = 0.99), but a significant equivalence between the control group and the two volume flows (38 mL/min: p = 0.002, 100 mL/min: p = 0.001). In addition the results show no increase of apoptotic and dead cells in the population after injection. Conclusion: The results indicate that the injection process through the cannula with these volume flows has no effect on the viability of the MSCs.
Exploitation of Kronecker Structure in Gaussian Process Regression for Efficient Biomedical Signal Processing
Authors: Prüßmann Jannik , Graßhoff Jan , Rostalski Philipp 
Published: December 2021

Abstract
Gaussian processes are a versatile tool for data processing. Unfortunately, due to storage and runtime requirements, standard Gaussian process (GP) methods are limited to a few thousand data points. Thus, they are infeasible in most biomedical, spatio-temporal problems. The methods treated in this work cover GP inference and hyperparameter optimization, exploiting the Kronecker structure of covariance matrices. To solve regression and source separation problems, two different approaches are presented. The first approach uses efficient matrix-vector-products, whilst the second approach is based on efficient solutions to the eigendecomposition. The latter also enables efficient hyperparameter optimization. In comparison to standard GP methods, the proposed methods can be applied to very large biomedical datasets without any further performance loss and perform substantially faster. The performance is demonstrated on esophageal manometry data, where the cardiac and respiratory signal components are to be inferred by source separation.