bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modulation of muscle-tendon interaction in the human triceps surae during an energy dissipation task
Authors: Werkhausen Amelie , Albracht Kirsten , Cronin Neil J. , Meier Rahel , Bojsen-Møller Jens , Seynnes Olivier R. 
Published: September 2017

The compliance of elastic elements allows muscles to dissipate energy safely during eccentric contractions. This buffering function is well documented in animal models but our understanding of its mechanism in humans is confined to non-specific tasks, requiring a subsequent acceleration of the body. The present study aimed to examine the behaviour of the human triceps surae muscle-tendon unit (MTU) during a pure energy dissipation task, under two loading conditions.
Thirty-nine subjects performed a single-leg landing task, with- and without added mass. Ultrasound measurements were combined with 3D kinematics and kinetics to determine instantaneous length changes of MTUs, muscle fascicles, Achilles tendon and combined elastic elements.
Gastrocnemius and soleus MTUs lengthened during landing. After a small concentric action, fascicles contracted eccentrically during most of the task, when the highest muscle activity occurred. Combined elastic elements lengthened until peak ankle moment and recoiled thereafter, whilst no recoil was observed for the Achilles tendon. Adding mass resulted in greater negative work and MTU lengthening, which were accompanied by a greater stretch of tendon and elastic elements and a greater recruitment of the soleus muscle, without any further fascicle strain.
Hence, the buffering action of elastic elements delimits the maximal strain and lengthening velocity of active muscle fascicles and is commensurate with loading constraints. In the present task, energy dissipation was modulated via greater MTU excursion and more forceful eccentric contractions. The distinct strain pattern of the Achilles tendon supports the notion that different elastic elements may not systematically fulfil the same function.
Association between physical activity patterns and anthropometric characteristics of adults: an issue of public health?
Authors: Clemente Filipe Manuel , Martins Fernando Manuel Lourenço , Nikolaidis Pantelis Theodoros , Mendes Rui Sousa 
Published: September 2017

Summary
Study aim: The aim of this study was to evaluate the association between objectively measured daily physical activity (PA) and body fat mass (BF) and body mass index (BMI). A further aim was to analyse the variance of PA between quartiles of BF and BMI.
Material and methods: A cross-sectional, observational study of 126 university students (53 males aged 20.46 ± 2.04 years and 73 female aged 19.69 ± 1.32 years) was conducted.
Results: The female participants and PA characteristics explain 57.10% of BF variance and the model was statistically signifi­cant (F(6, 875) = 196.38; p = 0.001). BMI was also included in the model. Standard binary logistic regression was used to test the hypothesis that female sex and PA characteristics can influence overweight. The full model containing all variables was statistically significant (G2(6) = 58.598, p-value = 0.001). Analysis of variance between BF quartiles revealed statistically sig­nificant differences in male participants in light PA (p = 0.001; ES = 0.09), moderate PA (p = 0.001; ES = 0.042) and vigorous PA (p = 0.001; ES = 0.130).
Conclusions: The statistical model in the regression analysis suggests that low and vigorous levels of PA explain 57% of BF variance in female participants.
Analysis and classification of ECG-waves and rhythms using circular statistics and vector strength
Authors: Janßen Jan-Dirk , Schanze Thomas 
Published: September 2017

Abstract
The most common way to analyse heart rhythm is to calculate the RR-interval and the heart rate variability. For further evaluation, descriptive statistics are often used. Here we introduce a new and more natural heart rhythm analysis tool that is based on circular statistics and vector strength. Vector strength is a tool to measure the periodicity or lack of periodicity of a signal. We divide the signal into non-overlapping window segments and project the detected R-waves around the unit circle using the complex exponential function and the median RR-interval. In addition, we calculate the vector strength and apply circular statistics as wells as an angular histogram on the R-wave vectors. This approach enables an intuitive visualization and analysis of rhythmicity. Our results show that ECG-waves and rhythms can be easily visualized, analysed and classified by circular statistics and vector strength.
Enhancing the smoothness of joint motion induced by functional electrical stimulation using co-activation strategies
Authors: Ruppel Mirjana , Klauer Christian , Schauer Thomas 
Published: September 2017

Abstract
The motor precision of today’s neuroprosthetic devices that use artificial generation of limb motion using Functional Electrical Stimulation (FES) is generally low. We investigate the adoption of natural co-activation strategies as present in antagonistic muscle pairs aiming to improve motor precision produced by FES. In a test in which artificial knee-joint movements were generated, we could improve the smoothness of FES-induced motion by 513% when applying co-activation during the phases in which torque production is switched between muscles – compared to no co-activation. We further demonstrated how the co-activation level influences the joint stiffness in a pendulum test.
Automatic anatomical calibration for IMU-based elbow angle measurement in disturbed magnetic fields
Authors: Laidig Daniel , Müller Philipp , Seel Thomas 
Published: September 2017

Abstract
Inertial Measurement Units (IMUs) are increasingly used for human motion analysis. However, two major challenges remain: First, one must know precisely in which orientation the sensor is attached to the respective body segment. This is commonly achieved by accurate manual placement of the sensors or by letting the subject perform tedious calibration movements. Second, standard methods for inertial motion analysis rely on a homogeneous magnetic field, which is rarely found in indoor environments. To address both challenges, we introduce an automatic calibration method for joints with two degrees of freedom such as the combined radioulnar and elbow joint. While the user performs arbitrary movements, the method automatically identifies the sensor-to-segment orientations by exploiting the kinematic constraints of the joint. Simultaneously, the method identifies and compensates the influence of magnetic disturbances on the sensor orientation quaternions and the joint angles. In experimental trials, we obtain angles that agree well with reference values from optical motion capture. We conclude that the proposed method overcomes mounting and calibration restrictions and improves measurement accuracy in indoor environments. It therefore improves the practical usability of IMUs for many medical applications.
Home monitoring of nocturnal cough in COPD patients
Authors: Fischer Patrick , Sohrabi Keywan , Ashraf Osman , Schneider Henning , Weissflog Andreas , Gross Volker 
Published: September 2017

Abstract
Telemedicine approaches in the treatment of COPD can be useful for the detection of upcoming exacerbations. Specifically productive cough can serve as an effective monitoring parameter. By using modern technologies, we developed a smartphone application to record and analyze nocturnal cough in an outpatient environment. All results will be displayed through a web interface by patients, physicians and relatives. Monitoring cough could lead to an individual therapy and an increased quality of life.
Analysis of the foetal heart rate in cardiotocographic recordings through a progressive characterization of decelerations
Authors: Fuentealba Patricio , Illanes Alfredo , Ortmeier Frank 
Published: September 2017

Abstract
The main purpose of this work is to propose a new method for characterization and visualization of FHR deceleration episodes in terms of their depth, length and location. This is performed through the estimation of a progressive baseline computed using a median filter allowing to identify and track the evolution of decelerations in cardiotocographic CTG recordings. The proposed method has been analysed using three representative cases of normal and pathological CTG recordings extracted from the CTU-UHB database freely available on the PhysioNet Website. Results show that both the progressive baseline and the parameterized deceleration episodes can describe different time-variant behaviour, whose characteristics and progression can help the observer to discriminate between normal and pathological FHR signal patterns. This opens perspectives for classification of non-reassuring CTG recordings as a sign of foetal acidemia.
Performance behavior of prediction filters for respiratory motion compensation in radiotherapy
Authors: Jöhl Alexander , Berdou Yannick , Guckenberger Matthias , Klöck Stephan , Meboldt Mirko , Zeilinger Melanie , Tanadini-Lang Stephanie , Daners Marianne Schmid 
Published: September 2017

Abstract
Introduction: In radiotherapy, tumors may move due to the patient’s respiration, which decreases treatment accuracy. Some motion mitigation methods require measuring the tumor position during treatment. Current available sensors often suffer from time delays, which degrade the motion mitigation performance. However, the tumor motion is often periodic and continuous, which allows predicting the motion ahead. Method and Materials: A couch tracking system was simulated in MATLAB and five prediction filters selected from literature were implemented and tested on 51 respiration signals (median length: 103 s). The five filters were the linear filter (LF), the local regression (LOESS), the neural network (NN), the support vector regression (SVR), and the wavelet least mean squares (wLMS). The time delay to compensate was 320 ms. The normalized root mean square error (nRMSE) was calculated for all prediction filters and respiration signals. The correlation coefficients between the nRMSE of the prediction filters were computed. Results: The prediction filters were grouped into a low and a high nRMSE group. The low nRMSE group consisted of the LF, the NN, and the wLMS with a median nRMSE of 0.14, 0.15, and 0.14, respectively. The high nRMSE group consisted of the LOESS and the SVR with both a median nRMSE of 0.34. The correlations between the low nRMSE filters were above 0.87 and between the high nRMSE filters it was 0.64. Conclusion: The low nRMSE prediction filters not only have similar median nRMSEs but also similar nRMSEs for the same respiration signals as the high correlation shows. Therefore, good prediction filters perform similarly for identical respiration patterns, which might indicate a minimally achievable nRMSE for a given respiration pattern.
Handling images of patient postures in arms up and arms down position using a biomechanical skeleton model
Authors: Teske Hendrik , Bartelheimer Kathrin , Bendl Rolf , Stoiber Eva M. , Giske Kristina 
Published: September 2017

Abstract
Deformable image registration is gradually becoming the tool of choice for motion extraction during adaptive radiotherapy. Achieving a motion vector field that accurately represents the anatomical changes requires a tissue specific transformation model. Therefore, widely used spline based models most likely fail in appropriately reproducing large anatomical changes such as the arms of the patient being positioned up and down. We present the application of a tissue specific biomechanical model with the goal to mimic patient motion even in presence of large motion. Based on the planning CT, delineated bones are used to represent the rigid anatomy of the patient. We implement ball-and-socket joints between corresponding bones in order to achieve mobility of the skeleton. An inverse kinematics approach enables the propagation of motion between individual bones across their joints, leading to an articulated skeleton that can be controlled by feature points on one or more bones. The transformation of each bone initializes a chainmail based soft tissue model to also propagate the motion into the surrounding heterogeneous soft tissue. Representation of different postures like arms up and down can be achieved within less than 1 s for the skeleton and ∼10 s for the soft tissue. Especially for large anatomical changes, the kinematics approach benefits from the direct articulation at specific joints, considerably lowering the degrees of freedom for motion description. Being the input for the chainmail based soft tissue model, the transformed bones guarantee for its meaningful initialization. The proposed biomechanical skeleton model is promising to facilitate the registration of patients’ anatomy, being positioned with arms up and arms down. The results encourage further refinement of the joints and the soft tissue model.
Evaluation of low contrast resolution and radiation dose in abdominal CT protocols by a difference detail curve (DDC) method
Authors: Sommer Christian , Icken Niels , Özden Ismail , Lutters Gerd , Scheidegger Stephan 
Published: September 2017

Abstract
The use of optimised CT protocols regarding radiation exposure is a legal requirement. Since low contrast visibility is intrinsically varying within the CT slice, there is no adequate method for optimisation of dose and image quality. We developed a method to access image quality in a way that represents the situation closer to a real patient. This method is based on a novel difference detail curve (DDC) phantom with low contrast objects representing native tissue contrast and contrast media with different densities and diameters. The position of the contrast objects have been evaluated by a noise level analysis of CT slices of different manufactures. The dose – length – product can be measured within the phantom simultaneously. For all tested manu-factures and CT protocols, the noise analysis revealed a similar spatial variation of the signal -to-noise ratio (SNR). For the DDC method, contrast steps of 6 (4-8) Hounsfield Units (HU) are adequate. For the different CT units, comparable low contrast detectability is associated with remarkably varying dose levels (CTDI range from 8 to 18 mGy for native contrast and 9-16 mGy for contrast media). The novel DDC phantom is sensitive to protocol optimisations and therefore suitable for rating subtle effects caused by protocol optimisation.
A robust algorithm for optic disc segmentation and fovea detection in retinal fundus images
Authors: Rust Caterina , Häger Stephanie , Traulsen Nadine , Modersitzki Jan 
Published: September 2017

Abstract
Accurate optic disc (OD) segmentation and fovea detection in retinal fundus images are crucial for diagnosis in ophthalmology. We propose a robust and broadly applicable algorithm for automated, robust, reliable and consistent fovea detection based on OD segmentation. The OD segmentation is performed with morphological operations and Fuzzy C Means Clustering combined with iterative thresholding on a foreground segmentation. The fovea detection is based on a vessel segmentation via morphological operations and uses the resulting OD segmentation to determine multiple regions of interest. The fovea is determined from the largest, vessel-free candidate region. We have tested the novel method on a total of 190 images from three publicly available databases DRIONS, Drive and HRF. Compared to results of two human experts for DRIONS database, our OD segmentation yielded a dice coefficient of 0.83. Note that missing ground truth and expert variability is an issue. The new scheme achieved an overall success rate of 99.44% for OD detection and an overall success rate of 96.25% for fovea detection, which is superior to state-of-the-art approaches.
Mechanical anisotropy of titanium scaffolds
Authors: Rüegg Jasmine , Schumacher Ralf , Weber Franz E , de Wild Michael 
Published: September 2017

Abstract
The clinical performance of an implant, e.g. for the treatment of large bone defects, depends on the implant material, anchorage, surface topography and chemistry, but also on the mechanical properties, like the stiffness. The latter can be adapted by the porosity. Whereas foams show isotropic mechanical properties, digitally modelled scaffolds can be designed with anisotropic behaviour. In this study, we designed and produced 3D scaffolds based on an orthogonal architecture and studied its angle-dependent stiffness. The aim was to produce scaffolds with different orientations of the microarchitecture by selective laser melting and compare the angle-specific mechanical behaviour with an in-silico simulation. The anisotropic characteristics of open-porous implants and technical limitations of the production process were studied.
Promising biocompatible hydrogels of crosslinked polyelectrolytes for biomedical applications
Authors: Brietzke Andreas , von der Ehe Christian , Illner Sabine , Matschegewski Claudia , Grabow Niels , Kragl Udo 
Published: September 2017

Abstract
For the development of intelligent implant systems hydrogels (HG) from crosslinked ionic liquids feature a high potential to be utilised as a drug depot. Biocompatibility of the HGs is one key prerequisite for biomedical applications. HGs were polymerised from a variety of different ionic monomers based on methacrylate, methacrylamide, styrene or vinyl imidazolium derivatives in aqueous solution. N,N'-methylenebisacrylamide was used as crosslinker. CellQuanti-Blue™ Cell Viability Assay Kit was implemented to proof viability of L929 mouse fibroblasts. The predominant part of the HG eluates generated only a marginal reduction of less than 15% cell viability at 100% eluate concentration. This underlines the excellent suitability of these HGs for biomedical applications and revealed some promising candidates for the development of drug depots for implants.
Different encapsulation strategies for implanted electronics
Authors: Winkler Sebastian , Edelmann Jan , Welsch Christine , Ruff Roman 
Published: September 2017

Abstract
Recent advancements in implant technology include increasing application of electronic systems in the human body. Hermetic encapsulation of electronic components is necessary, specific implant functions and body environments must be considered. Additional functions such as wireless communication systems require specialized technical solutions for the encapsulation.
In this paper 3 different implant strategies based on the material groups silicone, ceramics and titanium alloys are evaluated. With the background of a specific application the requirements for the encapsulation are defined and include the implementation of electrical feedthroughs, wireless communication and wireless energy transfer as well as biomedical specifications such as hermetic sealing, mechanical stability and biocompatibility. The encapsulations are manufactured and qualified experimentally.
Development of a novel pediatric forearm fracture treatment: simulation, prototype and evaluation
Authors: El-Shaffey Hala , Klein Stephan , Hainer Franziska 
Published: September 2017

Abstract
A treatment gap exists for moderately displaced pediatric distal forearm fractures (DFF), which carry a potential risk of improper reduction when treated conservatively. Currently, no standard method for the correction of the initial reduction of pediatric DFF is available. A novel closed reduction method has been proposed to correct and maintain a successful reduction throughout the healing process. This study further develops this novel cast system and evaluates its mechanical behavior through the design, construction, and testing of a biomechanical CAD model and pediatric forearm phantom. Initial results support the novel system as an improved treatment for pediatric fractures. Both the CAD model and tissue phantom indicate the ability of the system to manipulate a 15° fracture, with 0-1° of residual angulation.
The impact of electronic health records on diagnosis
Authors: Graber Mark L. , Byrne Colene , Johnston Doug 
Published: September 2017

Abstract
Diagnostic error may be the largest unaddressed patient safety concern in the United States, responsible for an estimated 40,000–80,000 deaths annually. With the electronic health record (EHR) now in near universal use, the goal of this narrative review is to synthesize evidence and opinion regarding the impact of the EHR and health care information technology (health IT) on the diagnostic process and its outcomes. We consider the many ways in which the EHR and health IT facilitate diagnosis and improve the diagnostic process, and conversely the major ways in which it is problematic, including the unintended consequences that contribute to diagnostic error and sometimes patient deaths. We conclude with a summary of suggestions for improving the safety and safe use of these resources for diagnosis in the future.
Fast Methods for Power Quality Analysis
Authors: Upadhyaya S. , Mohanty S. 
Published: September 2017

AbstractIn this paper, the lifting based second generation Wavelet Transform (SGWT) is implemented along with the widely used discrete Wavelet Transform (DWT) for the detection and localization of ten different types of power quality (PQ) disturbance signals. The SGWT provides the time domain interpretation which is an opposition to the frequency domain analysis of DWT. Further, the selected features are extracted from the detail coefficient of the variants of WT and given as inputs to the classifiers in order to characterize the signals. Moreover, a comparative assessment of the PQ signal carried out with different classifiers such as Support Vector Machine (SVM), Decision Tree (DT) and Random Forest (RF) have been presented along with aforementioned detection techniques. The RF is an ensemble decision tree and used for the classification of large number of data set. Hence, various single as well as combined power quality disturbance signals have been simulated in noisy and noise free environment in order to demonstrate the efficiency of the proposed techniques. Moreover, in order to represent in realistic environment, these proposed techniques are tested with both the single phase and tree phase signals captured from different transmission panels. Further, to aid this PQ disturbance detection, different types of real time fault signals are characterized with these aforementioned approaches.