bluuebunny/crossref_metadata_2025_split huggingface dataset:
Correlation of arterial blood pressure to synchronous piezo, impedance and photoplethysmographic signal features
Authors: Pielmuş Alexandru-Gabriel , Osterland Dennis , Klum Michael , Tigges Timo , Feldheiser Aarne , Hunsicker Oliver , Orglmeister Reinhold 
Published: September 2017

Abstract
In this paper we investigate which pulse wave pick-up technologies are well suited for blood pressure trend estimation. We use custom built hardware to acquire electrocardiographic, applanation-tonometric, photo- and impedance-plethysmographic signals during low intensity workouts. Beat-to-beat features and pulse wave runtimes are correlated to the reference arterial blood pressure. Temporal lag adjustment is performed to determine the latency of feature response. Best results are obtained for systolic arterial blood pressure. These suggest that every subject has a range of well-performing features, but it is not consistent among all. Spearman Rho values reach in excess of 0.8, with their significance being validated by p-values lower than 0.01.
Improvement of a multi-stage model for the modeling of a functionalized nursing bed as support for the sensor-assisted function-alization of furniture in the hospital and care sector
Authors: Kitzig Andreas , Schröter Stefan , Naroska Edwin , Stockmanns Gudrun , Viga Reinhard , Grabmaier Anton 
Published: September 2017

Abstract
Development of preparation-free functionalized furniture based patient monitoring systems for use in the area of home- or stationary- care is often empirically driven. In particular, functionalization of furniture by means of different sensors is strongly affected by this development methodology. As a result, the systems are often not extensive-ly extendable or cannot be optimized because basic mechanisms are not comprehensible. In order to support development or optimization, a modelling approach is often useful. Thus, using a more comprehensive approach the required sensitivity of the sensors as well as their position in the system can be derived from a simulation model. In order to solve this problem, a multi-stage model was introduced at the BMT conference in 2014 by the authors, which allows the designer to model the entire system. The model has been extended and improved in the meantime and the achieved progress is presented in this work. The presented modelling approach can be divided into three main components. These are the person under supervision, the furniture (in our case a nursing bed) and the sensors (force measuring cells) which are modelled separately. In this work the main focus will be on improving the modelling of the human movement process and its implementation. Furthermore, the modelling of the sensor behavior in the nursing bed is described in detail with regard to their oscillation behavior and the influence on the model.
Toward steerable electrodes. An overview of concepts and current research.
Authors: Rau Thomas S. , Hügl Silke , Lenarz Thomas , Majdani Omid 
Published: September 2017

Abstract
Restoration of hearing is a demanding surgical task which requires the insertion of a cochlear implant electrode array into the inner ear while preserving the delicate basilar membrane inside the cochlea for an atraumatic insertion. Already shortly after the first clinical success with early versions of cochlear implants the desire for a controlled insertion of the electrode array arose. Such a steerable electrode should be in its shape adaptable to the individual path of the helical inner ear in order to avoid any contact between the implant and the surrounding tissue. This article provides a short overview of concepts and actuator mechanisms investigated in the past and present with the objective of developing a steerable electrode array for an individualized insertion process. Although none of these concepts has reached clinical implementation, there are promising experimental results indicating that insertion forces can be reduced up to 60% compared to straight and not steerable electrodes. Finally, related research topics are listed which require considerable further improvements until steerable electrodes will reach clinical applicability.
Reconstruction of biological functions: novel implant concepts for cardiovascular, ophthal-mologic and otolaryngologic applications
Authors: Grabow Niels , Schmitz Klaus-Peter 
Published: September 2017

Abstract
Biomedical engineering innovations towards the reconstruction of biological functions seek to improve the quality of patients’ lives. The coordinated research project “RESPONSE – Partnership for Innovation in Implant Technology” (BMBF program Twenty20 – Partnership for Innovation, 2014 - 2021) is focusing on the development of novel concepts for (i) cardiovascular scaffolds, glaucoma and ENT stents, (ii) transcatheter heart valves and venous valves, (iii) polymeric implants and polymer/drug formulations. Current clinical paradigm shifts, fostered by the progress in implant technology and a growing global demand, frame the background for the joint research efforts of academia and industry in the RESPONSE consortium.
Effects of replacing the nasal cavity with a simple pipe like structure in CFD simulations of the airflow within the upper airways of OSA patients with patient individual flow rates
Authors: Hagen Christina , Gurumurthy Pragathi , Buzug Thorsten M. 
Published: September 2017

Abstract
OSA is characterized by repetitive collapses of the upper airways during sleep. Computational fluid dynamics can be used to investigate the abnormal pressure distribution in the patient’s airways. The computational costs and model reconstruction effort can be reduced by focusing the simulations on the pharynx and replacing the nasal cavity by a simple pipe structure. In this work, the effects of the mentioned replacement on the simulated flow are evaluated. Airflow simulations using the k-ω turbulence model are performed in the anatomically correct airway of a patient having a high difference in the inspiratory volume flow rates of both nostrils, as well as in a model with replaced nasal cavity by a simple pipe structure. The simulated pressure distributions of both models are in very good agreement indicating the acceptability of replacing the nasal cavity by simple pipe structures in in-silico airflow analyses of OSA patients.
Deep bilinear features for Her2 scoring in digital pathology
Authors: Rodner Erik , Simon Marcel , Denzler Joachim 
Published: September 2017

Abstract
We present an automated approach for rating HER2 over-expressions in given whole-slide images of breast cancer histology slides. The slides have a very high resolution and only a small part of it is relevant for the rating.
Our approach is based on Convolutional Neural Networks (CNN), which are directly modelling the whole computer vision pipeline, from feature extraction to classification, with a single parameterized model. CNN models have led to a significant breakthrough in a lot of vision applications and showed promising results for medical tasks. However, the required size of training data is still an issue. Our CNN models are pre-trained on a large set of datasets of non-medical images, which prevents over-fitting to the small annotated dataset available in our case. We assume the selection of the probe in the data with just a single mouse click defining a point of interest. This is reasonable especially for slices acquired together with another sample. We sample image patches around the point of interest and obtain bilinear features by passing them through a CNN and encoding the output of the last convolutional layer with its second-order statistics.
Our approach ranked second in the Her2 contest held by the University of Warwick achieving 345 points compared to 348 points of the winning team. In addition to pure classification, our approach would also allow for localization of parts of the slice relevant for visual detection of Her2 over-expression.
Functional modeling of the craniospinal system for in-vitro parameter studies on the pathogenesis of NPH
Authors: Benninghaus Anne , Goffin Christine , Leonhardt Steffen , Radermacher Klaus 
Published: September 2017

Abstract
Normal Pressure Hydrocephalus (NPH) has become a common disease in the elderly coming along with typical symptoms of dementia, gait ataxia and urinary incontinence, which make the differential diagnosis with other forms of dementia difficult. Furthermore the pathogenesis of NPH is still not understood. About 10% of all demented patients might be suffering from NPH [1]. Many hypotheses suggest that modified biomechanical boundary conditions affect the craniospinal dynamics inducing the pathogenesis of NPH. We present a novel approach for an in-vitro model of the craniospinal system to investigate important hydrodynamic influences on the system such as (dynamic) compliance of the vascular system and especially the spinal subarachnoid space (SAS) as well as reabsorption and hydrostatics. The experimental set-up enables the individual adjustment of relevant parameters for sensitivity analyses regarding the impact of resulting CSF dynamics on the pathogenesis of NPH.
3D detection of the central sleep apnoea syndrome
Authors: Garn Heinrich , Kohn Bernhard , Wiesmeyr Christoph , Dittrich Klaus , Wimmer Markus , Mandl Magdalena , Kloesch Gerhard , Boeck Marion , Stefanic Andrijana , Seidel Stefan 
Published: September 2017

Abstract
In polysomnography, an oronasal thermal airflow sensor and respiratory inductance plethysmography (RIP) belts at thorax and abdomen are used to detect central sleep apnoea. These sensors are uncomfortable to wear, can disturb the patient’s sleep, and data quality can be significantly di-minished if a sensor slips off the patient. Contactless meas-urements would be a desirable alternative. We utilized a 3D time-of-flight sensor to monitor respiratory-related chest movements to decipher epochs of normal breathing and ap-noea in ten adult patients with a total of 467 apnoea events. Time-synchronized comparisons of 3D measurements of chest movements due to respiration to polysomnography signals from rip belts and nasal airflow proved that the 3D sensor provided largely equivalent results. This new tech-nique could support the diagnosis of central sleep apnoea and Cheyne-Stokes respiration.
Assessment of local high-density mapping for the analysis of radiofrequency ablation lesions in the left atrium
Authors: Stritt Michael , Oesterlein Tobias , Pollnow Stefan , Luik Armin , Schmitt Claus , Dössel Olaf 
Published: September 2017

Abstract
Recent studies about the development of endocardial radiofrequency (RF) ablation lesions (ALs) tried to identify reliable electrogram (EGM) markers for assessment of lesion transmurality. Additional clinically relevant information for physicians can be provided by examining endocardial EGM parameters like signal morphology, amplitude or time points in the signal. We investigated EGM features of the pulmonary vein ostia before and after RF ablation for three point-shaped lesions. Using high-density (HD) mapping, local activation time (LAT) and voltage maps were created, which provided information about the RF ALs regarding the lesion size and showed activation time delay as well as low-voltage areas with bipolar peak-to-peak voltages smaller than 2mV. The time delay of the depolarization front comparing the activation times anterior and posterior to the RF AL was up to 51.5 ms. In a circular area with 5mm radius around an RF AL the mean peak-to-peak voltage decreased by 62-94% to about 0.12-0.44mV and the mean maximal absolute EGM derivative was reduced by 65-96 %. Comparing the results of this study with EGMs of similar clinical settings confirmed our expectations regarding the low-voltage areas caused by the ablation procedure. An improved understanding of the electrophysiological changes is of fundamental importance to provide more information for enhanced RF ablation assessment.
Implementation and evaluation of segmentation algorithms according to multimodal imaging in personalized medicine
Authors: Stich Manuel , Vogt Jeannine , Lindner Michaela , Ringler Ralf 
Published: September 2017

Abstract
Multimodal imaging is gaining in importance in the field of personalized medicine and can be described as a current trend in medical imaging diagnostics. The segmentation, classification and analysis of tissue structures is essential. The goal of this study is the evaluation of established segmentation methods on different medical image data sets acquired with different diagnostic procedures. Established segmentation methods were implemented using the latest state of the art and applied to medical image data sets. In order to benchmark the segmentation performance quantitatively, medical image data sets were superimposed with artificial Gaussian noise, and the mis-segmentation as a function of the image SNR or CNR was compared to a gold standard. The evaluation of the image segmentation showed that the best results of pixel-based segmentation (< 3%) can be achieved with methods of machine learning, multithreshold and advanced level-set method - even at high artificial noise (SNR< 18). Finally, the complexity of the object geometry and the contrast of the ROI to the surrounding tissue must also be considered to select the best segmentation algorithm.
Determination of the excitation origin in the ventricles from the ECG using support vector regression
Authors: Pilia Nicolas , Ritter Christian , Potyagaylo Danila , Schulze Walther H. W. , Dössel Olaf , Lenis Gustavo 
Published: September 2017

Abstract
A common treatment of focal ventricular tachycardia is the catheter ablation of triggering sites. They have to be found manually by the physician during an intervention in a catheter lab. Thus, a method for determining the position of the focus automatically is desired. The inverse problem of electrocardiography addresses this problem by reconstructing the source of the ectopic beats using the surface ECG. This problem is ill-posed and therefore needs specific methods for solving it. We propose a machine learning approach for localisation of the ectopic foci in the heart to assist cardiologists with their therapy planning.We simulated 600 120-lead ECGs with different known excitation origins in the heart using a cellular automaton followed by a forward calculation. Features from the ECGs were used as input for a support vector regression (SVR). We assumed a functional relation between features from the ECG and the excitation origin. To benchmark SVR, we also used the well-known Tikhonov 0th order regularisation to reconstruct the transmembrane potentials in the heart and detect the location of the ectopic foci. Parameters for SVR and regularisation were chosen using a grid search minimising the error between estimated and true excitation origin. Compared to the Tikhonov regularisation method, SVR achieved a smaller deviation between estimated and real excitation origin evaluated with 6-fold cross validation. Future work could investigate on the behaviour on data from simulations with other torso and electrophysiological models, the influence of other methods for feature extraction and finally the evaluation with clinical data.
Estimating refractory periods during atrial fibrillation based on electrogram cycle lengths in a heterogeneous simulation setup
Authors: Unger Laura , Oesterlein Tobias , Seemann Gunnar , Dössel Olaf , Spector Peter , Loewe Axel 
Published: September 2017

Abstract
Acquiring adequate mapping data in patients with atrial fibrillation is still one of the main obstacles in the treatment of this atrial arrhythmia. Due to the lack of catheters with both a panoramic field of view and sufficient electrode density for simultaneous mapping, electrophysiologists are forced to fall back on sequential mapping techniques. But, because activation patterns change rapidly during atrial fibrillation, they cannot be mapped sequentially. We propose that mapping tissue properties which are time independent, in contrast, allows a sequential approach. Here, we use the shortest measured electrogram cycle length to estimate the effective refractory period of the underlying tissue in a simulation study. Atrial fibrillation was simulated in a spherical model of the left atrium comprised of regions with varied refractory period. We found that the minimal measured electrogram cycle length correlates with the effective refractory period of the underlying tissue if the regions with distinct refractory properties are large enough and if the absolute difference in effective refractory periods is sufficient. This approach is capable of identifying regions of lowered effective refractory period without the need for cardioversion. Those regions are likely to harbor drivers of atrial fibrillation, which emphasizes the necessity of their localization.
Relation between pulse pressure and the pulsation strength in camera-based photoplethysmograms
Authors: Trumpp Alexander , Rasche Stefan , Wedekind Daniel , Rudolf Matthias , Malberg Hagen , Matschke Klaus , Zaunseder Sebastian 
Published: September 2017

Abstract
Camera-based photoplethysmography (cbPPG) is an innovative measuring technique that enables the remote extraction of vital signs using video cameras. Most studies in the field focus on heart rate detection while other physiological quantities are often ignored. In this work, we analyzed the relation between the pulse pressure and the pulsation strengths of cbPPG signals for 70 patients after surgery. Our results show a high correlation between the two measures (r = 0.54). Furthermore, the influence of technical and medical factors was tested. The controlled impact of these factors proved to enhance the correlation by between 9 and 27 %.
Design of an experimental four-camera setup for enhanced 3D surface reconstruction in microsurgery
Authors: Marzi Christian , Wachter Andreas , Nahm Werner 
Published: September 2017

Abstract
Future fully digital surgical visualization systems enable a wide range of new options. Caused by optomechanical limitations a main disadvantage of today’s surgical microscopes is their incapability of providing arbitrary perspectives to more than two observers. In a fully digital microscopic system, multiple arbitrary views can be generated from a 3D reconstruction. Modern surgical microscopes allow replacing the eyepieces by cameras in order to record stereoscopic videos. A reconstruction from these videos can only contain the amount of detail the recording camera system gathers from the scene. Therefore, covered surfaces can result in a faulty reconstruction for deviating stereoscopic perspectives. By adding cameras recording the object from different angles, additional information of the scene is acquired, allowing to improve the reconstruction. Our approach is to use a fixed four-camera setup as a front-end system to capture enhanced 3D topography of a pseudo-surgical scene. This experimental setup would provide images for the reconstruction algorithms and generation of multiple observing stereo perspectives. The concept of the designed setup is based on the common main objective (CMO) principle of current surgical microscopes. These systems are well established and optically mature. Furthermore, the CMO principle allows a more compact design and a lowered effort in calibration than cameras with separate optics. Behind the CMO four pupils separate the four channels which are recorded by one camera each. The designed system captures an area of approximately 28mm × 28mm with four cameras. Thus, allowing to process images of 6 different stereo perspectives. In order to verify the setup, it is modelled in silico. It can be used in further studies to test algorithms for 3D reconstruction from up to four perspectives and provide information about the impact of additionally recorded perspectives on the enhancement of a reconstruction.
Automatic lung segmentation in the presence of alveolar collapse
Authors: Noshadi Areg , Kircher Michael , Pollnow Stefan , Elke Gunnar , Frerichs Inéz , Dössel Olaf 
Published: September 2017

Abstract
Lung ventilation and perfusion analyses using chest imaging methods require a correct segmentation of the lung to offer anatomical landmarks for the physiological data. An automatic segmentation approach simplifies and accelerates the analysis. However, the segmentation of the lungs has shown to be difficult if collapsed areas are present that tend to share similar gray values with surrounding non-pulmonary tissue. Our goal was to develop an automatic segmentation algorithm that is able to approximate dorsal lung boundaries even if alveolar collapse is present in the dependent lung areas adjacent to the pleura. Computed tomography data acquired in five supine pigs with injured lungs were used for this purpose. First, healthy lung tissue was segmented using a standard 3D region growing algorithm. Further, the bones in the chest wall surrounding the lungs were segmented to find the contact points of ribs and pleura. Artificial boundaries of the dorsal lung were set by spline interpolation through these contact points. Segmentation masks of the entire lung including the collapsed regions were created by combining the splines with the segmentation masks of the healthy lung tissue through multiple morphological operations. The automatically segmented images were then evaluated by comparing them to manual segmentations and determining the Dice similarity coefficients (DSC) as a similarity measure. The developed method was able to accurately segment the lungs including the collapsed regions (DSCs over 0.96).
Portable XRF: A Tool for the Study of Corundum Gems
Authors: Barone Germana , Mazzoleni Paolo , Bersani Danilo , Raneri Simona 
Published: September 2017

AbstractOrigin of gemstones is a key aspect not only in gemological field but also in Cultural Heritage studies, for the correct evaluation of precious artifacts. The studies on gems require the application of non-invasive and non-destructive methods; among them, portable spectroscopic techniques has been demonstrated as powerful tools, providing a fingerprint of gems for origin and provenance determination. In this study, portable XRF spectroscopy has been applied to test the potential of the technique for the origin determination of corundum gems. The obtained results allowed distinguishing natural and synthetic rubies and sapphires.
Land Developers and Archaeological Information
Authors: Huvila Isto 
Published: September 2017

AbstractLand developers are significant stakeholders of archaeological work in the developed world. A better understanding of their information practices is crucial for the preservation and management of archaeological heritage. This study investigates land developers’ use, needs and conceptions of the usefulness- value of archaeological information and their views of development-led archaeological process. The findings are based on a survey of Finnish and Swedish land developers (N=34) that have contracted and financed archaeological fieldwork. The results show that the most useful information for land developers is data on the spatial location of archaeological sites but that the situation is much more nuanced than often suggested. Even if the most of the respondents were rather satisfied with the current situation, the lack of information can have major consequences and there are several obstacles to obtain relevant information. Extensive reliance on people sources can be seen both a symptom of the current problems and an indication of the importance of closer collaboration between archaeologists and land developers. Further, the study shows that the different levels of the perceived usefulness of specific types of archaeological information can be explained by the different regimes determining their worth in the two communities.