bluuebunny/crossref_metadata_2025_split huggingface dataset:
Time-domain analysis of distortion-product otoacoustic emissions using a hydrodynamic cochlea model
Authors: Zelle Dennis , Dalhoff Ernst , Gummer Anthony W. 
Published: September 2017

Abstract
As a by-product of nonlinear amplification in the cochlea, the inner ear emits sound waves in response to two tones with different frequencies. These sound waves are measurable in the ear canal as distortion-product otoacoustic emissions (DPOAEs). DPOAEs putatively consist of two components emerging at different locations in the cochlea. Wave interference between the two components limits the accuracy of DPOAEs as a noninvasive measure of cochlear function. Using short stimulus pulses instead of continuous stimuli, the two DPOAE components can be separated in the time domain due to their different latencies. The present work utilizes a nonlinear hydrodynamic cochlea model to simulate short-pulse DPOAEs in the time domain. When adding irregularities to the mechanical parameters of the model, the simulated DPOAE signals show two distinguishable components and long-lasting beat tones, similar to band-pass filtered experimental data from normal-hearing human subjects. The model results suggest that the beat tones can occur solely due to interference of the coherent-reflection component with the fading nonlinear-distortion component.
Radiofrequency applicator concepts for simultaneous MR imaging and hyperthermia treatment of glioblastoma multiforme
Authors: Oberacker Eva , Kuehne Andre , Nadobny Jacek , Zschaeck Sebastian , Weihrauch Mirko , Waiczies Helmar , Ghadjar Pirus , Wust Peter , Niendorf Thoralf , Winter Lukas 
Published: September 2017

Abstract
Glioblastoma multiforme is the most frequent and most aggressive malignant brain tumor with de facto no long term curation by the use of current multimodal therapeutic approaches. The efficacy of brachytherapy and enhancing interstitial hyperthermia has been demonstrated. RF heating at ultrahigh fields (B0=7.0T, f=298MHz) has the potential of delivering sufficiently large thermal dosage for hyperthermia of relatively large tumor areas. This work focuses on electromagnetic field (EMF) simulations and provides realistic applicator designs tailored for simultaneous RF heating and MRI. Our simulations took advantage of target volumes derived from patient data, and our preliminary results suggest that RF power can be focused to both a small tumor area and a large clinical target volume.
Heart rate from face videos under realistic conditions for advanced driver monitoring
Authors: Pilz Christian S. , Zaunseder Sebastian , Canzler Ulrich , Krajewski Jarek 
Published: September 2017

Abstract
The role of physiological signals has a large impact on driver monitoring systems, since it tells something about the human state. This work addresses the recursive probabilistic inference problem in time-varying linear dynamic systems to incorporate invariance into the task of heart rate estimation from face videos under realistic conditions. The invariance encapsulates motion as well as varying illumination conditions in order to accurately estimate vitality parameters from human faces using conventional camera technology. The solution is based on the canonical state space representation of an Itô process and a Wiener velocity model. Empirical results yield to excellent real-time and estimation performance of heart rates in presence of disturbing factors, like rigid head motion, talking, facial expressions and natural illumination conditions making the process of human state estimation from face videos applicable in a much broader sense, pushing the technology towards advanced driver monitoring systems.
Forecasting transient sleep episodes by pupil size variability
Authors: Schumann Andy , Ebel Juliane , Bär Karl-Jürgen 
Published: September 2017

Abstract
The ability to predict when a person is about to fall asleep is an important challenge in recent biomedical research and has various possible applications. Sleepiness and fatigue are known to increase pupillary fluctuations and the occurrence of eye blinks. In this study, we evaluated the use of the pupil diameter to forecast sleep episodes of short duration (>1s). We conducted multi-channel physiological and pupillometric recordings (diameter, gaze position) in 91 healthy volunteers at rest in supine position. Although they were instructed to keep their eyes open, short sleep episodes were detected in 20 participants (16 males, age: 26.2±5.6 years), 53 events in total. Before each sleep event, pupil size was extracted in a window of 30s (without additional sleep event). Mean pupil diameter and its standard deviation, Shannon entropy and wavelet entropy in the first half (15s) were compared to the second half of the window (15s). Linear and nonlinear measures demonstrated an elevation of pupil size variability before sleep onset. Most obviously, WE and SD increased significantly from 0.054±0.056 and 0.38±0.16 mm to 0.113±0.103 (T(102)=2.44, p<0.001) and 0.46±0.18 mm (T(104)=3.67, p<0.05) in the second half of each analysis window. We were able to identify 83% of the pre-sleep segments by linear discriminant analysis. Although our data was acquired in an experimental condition, it suggests that pupillary unrest might be a suitable predictor of events related to transient sleep or inattentiveness. In the future, we are going to involve the other recorded physiological signals into the analysis.
Optimizing a perfusion CT protocol for head and neck cancer
Authors: Stüssi Anja , Bogowicz Marta , Weichselbaumer Verena , Veit-Haibach Patrick , Riesterer Oliver , Guckenberger Matthias , Tanadini-Lang Stephanie 
Published: September 2017

Abstract
Perfusion computed tomography (CTP) images tumor angiogenesis and can assess tumor aggressiveness. However, the CTP examinations are dose intensive. This study aimed to optimize a routinely used CTP protocol for the head and neck region in oncology in order to reduce the effective dose to the patient and simultaneously achieve the same image quality.
The Alderson phantom was scanned on a GE Revolution CT scanner. A scan with our standard protocol for head and neck cancer patients was used (100kV, 80mAs, 5mm slice thickness and backprojection algorithm) and in seven predefined regions (ROI) the signal to noise ratio (SNR) was measured. For the dose optimized protocol, the tube voltage was lowered and the mAs adaptation protocol was used. To improve image quality different percentage of an adaptive statistical iterative reconstruction (ASiR) was applied. For a better resolution we set the slice thickness to 2.5 mm. The mAs adaption range and the percentage of the ASiR reconstruction were varied until we found a combination with the same median SNR in the seven defined ROIs as for our old protocol. For the old and the optimized protocol dose measurements were performed using 25 LiF-TLDs. Organ doses were calculated and the effective dose was determined based on the weighting factors of ICRP103.
The optimized scanning protocol used a voltage of 80kV, a mAs range between 15 and 80, a noise level of 10%, and 50% ASiR reconstruction. The median SNR ratio was slightly better (14% better SNR) with the new protocol. An effective dose of 8 mSv was measured with the original protocol and 4 mSv with the optimized scanning protocol. For organs in the scanning field the dose was reduced by a factor of 2 and outside the field by a factor of 2.2.
Advanced reconstruction algorithms allow a significant dose reduction and an improvement of image resolution, while maintaining the image quality.
A multi-institutional survey evaluating patient related QA – phase II
Authors: Teichmann Tobias , Salz Henning , Schwedas Michael , Howitz Simon , Wiezorek Tilo 
Published: September 2017

Abstract
In phase I of the survey a planning intercomparison of patient-related QA was performed at 12 institutions. The participating clinics created phantom based IMRT and VMAT plans which were measured utilizing the ArcCheck diode array. Mobius3D (M3D) was used in phase II. It acts as a secondary dose verification tool for patient-specific QA based on average linac beam data collected by Mobius Medical Systems. All Quasimodo linac plans will be analyzed for the continuation of the intercomparison. We aim to determine if Mobius3D is suited for use with diverse treatment techniques, if beam model customization is needed. Initially we computed first Mobius3D results by transferring all plans from phase I to our Mobius3D server. Because of some larger PTV mean dose differences we checked if output factor customization would be beneficial. We performed measurements and output factor correction to account for discrepancies in reference conditions. Compared to Mobius3D's preconfigured average beam data values, these corrected output factors differed by ±1.5% for field sizes between 7x7cm2 and 30x30cm2 and to −3.9% for 3x3cm2. Our method of correcting the output factors turns out good congruence to M3D's reference values for these medium field sizes.
Electrospinning of polyimide nanofibres – effects of working parameters on morphology
Authors: Kohse Stefanie , Grabow Niels , Schmitz Klaus-Peter , Eickner Thomas 
Published: September 2017

Abstract
The use of the electrospinning technique is a promising and versatile method for producing fibrous nonwovens from various polymers. Here we present fibre formation via direct electrospinning of a soluble polyimide, a class of polymers that is typically insoluble. In this study solution parameters as the solvent and the polymer concentration are investigated. Furthermore relevant process parameters are varied for optimization of the performance. The presented data indicate polyimide as a promising material for the fabrication of nanofibrous nonwovens via direct electrospinning.
Cyclic stress-strain behavior of polymeric nonwoven structures for the use as artificial leaflet material for transcatheter heart valve prostheses
Authors: Arbeiter Daniela , Brandt-Wunderlich Christoph , Siewert Stefan , Kohse Stefanie , Pfensig Sylvia , Schmitz Klaus-Peter , Grabow Niels 
Published: September 2017

Abstract
Xenogenic leaflet material, bovine and porcine pericardium, is widely used for the fabrication of surgically implanted and transcatheter heart valve prostheses. As a biological material, long term durability of pericardium is limited due to calcification, degeneration and homogeneity. Therefore, polymeric materials represent a promising approach for a next generation of artificial heart valve leaflets with improved durability. Within the current study we analyzed the mechanical performance of polymeric structures based on elastomeric materials. Polymeric cast films were prepared and nonwovens were manufactured in an electrospinning process. Analysis of cyclic stress-strain behavior was performed, using a universal testing machine. The uniaxial cyclic tensile experiments of the elastomeric samples yielded a non-linear elastic response due to viscoelastic behavior with hysteresis. Equilibrium of stress-strain curves was found after a specific number of cycles, for cast films and nonwovens, respectively. In conclusion, preconditioning was found obligatory for the evaluation of the mechanical performance of polymeric materials for the use as artificial leaflet material for heart valve prostheses.
Automatic particle analysis by Raman spectroscopy – evaluation of sample preparation and optimum background material
Authors: Kurzhals Anja , Teske Michael , Reske Thomas , Eickner Thomas , Grabow Niels , Schmidt Wolfram , Schmitz Klaus-Peter 
Published: September 2017

Abstract
The particle generation of medical implants and drug coated balloons (DCB) is evaluated by simulating the implantation process and collecting the released particle material. In addition to size and particle counts their material composition is of interest. Raman spectroscopy and micros-copy are established methods for chemical identification. For the manual analysis of the particles different filter or rather background materials are suitable because different require-ments in height and intensity of the spectra can be compen-sated by the user. The aim of this study was to find suitable background materials for automatic particle identification.
Raman analysis of background and spherical polystyrene standard particles on filters and plain surfaces was performed manually to receive evaluable spectra for automation. Auto-matic analysis was done by a) single-point spectrum meas-urement using the coordinate list of all particles, and b) scan-ning a large sample area pixel by pixel measuring back-ground and particles.
For automatic analysis with method a) the polycarbonate membrane provided best results. With method b) the polysty-rene spectrum of the particles could be found on both plain surfaces and the polycarbonate membrane. Influences from the background spectrum could be kept small by thoroughly defining the focal plane with a wavelength specific autofocus mode for method a) and manually for method b).
Beat-to-beat blood pressure measurement from instantaneous harmonic phase-shifts in non-invasive photoplethysmographic signals
Authors: Kern Fabian , Bernhard Stefan 
Published: September 2017

Abstract
The state-of-the-art blood pressure measurement is beside common cuff-based methods the cuff-less estimation of pulse-transit-time, which is the time a blood pressure wave requires to travel from left ventricle of the heart to another peripheral point in the cardiovascular system. Within this work we present a novel estimation method for cuff-less blood pressure measurement by analysing a single photoplethysmographic signal in the frequency domain. The harmonic phase-shift of the fundamental frequency and the first harmonic within the photoplethysmographic signal has proven a strong correlation of r = 0.8514 and r = 0.9315 with systolic and diastolic blood pressure respectively.
EOG feature relevance determination for microsleep detection
Authors: Golz Martin , Wollner Sebastian , Sommer David , Schnieder Sebastian 
Published: September 2017

Abstract
Automatic relevance determination (ARD) was applied to two-channel EOG recordings for microsleep event (MSE) recognition. 10 s immediately before MSE and also before counterexamples of fatigued, but attentive driving were analysed. Two type of signal features were extracted: the maximum cross correlation (MaxCC) and logarithmic power spectral densities (PSD) averaged in spectral bands of 0.5 Hz width ranging between 0 and 8 Hz. Generalised learn-ing vector quantisation (GRLVQ) was used as ARD method to show the potential of feature reduction. This is compared to support-vector machines (SVM), in which the feature reduction plays a much smaller role. Cross validation yielded mean normalised relevancies of PSD features in the range of 1.6 - 4.9 % and 1.9 - 10.4 % for horizontal and vertical EOG, respectively. MaxCC relevancies were 0.002 - 0.006 % and 0.002 - 0.06 %, respectively. This shows that PSD features of vertical EOG are indispensable, whereas MaxCC can be neglected. Mean classification accuracies were estimated at 86.6±b 1.3 % and 92.3±b 0.2 % for GRLVQ and SVM, respec-tively. GRLVQ permits objective feature reduction by inclu-sion of all processing stages, but is not as accurate as SVM.
Definition, estimation and limitations of the dominant frequency in intracardiac electrograms
Authors: Schwaderlapp Gerald , Oesterlein Tobias , Dössel Olaf , Armin Luik , Schmitt Claus , Lenis Gustavo 
Published: September 2017

Abstract
Intracardiac electrogram recordings during atrial fibrillation (AFib) are characterized by irregular rhythms and complex morphologies. Hence, analysis in the time domain is a difficult task. The so called dominant frequency DF is a spectrum based approach that aims at finding the most relevant frequency in a signal providing information about the rate and dynamics of AFib. However, in recent years various studies reported controversial results regarding the clinical relevance of the DF. In this work, a definition of the DF at a fundamental scale is proposed as the rate at which action potentials are triggered in atrial cells. The most common method to estimate the DF in literature, labeled as DFSpec
, is examined in comparison to the proposed definition. A signal processing study using synthetic signals verified that the DFSpec
is stable for all changes in morphology of atrial activations. However, it is also demonstrated that the DFSpec
becomes unstable for variations above 20% in the cycle length of a signal. Spectrum based DF estimation should be interpreted in a critical manner and is not advisable for study endpoints or clinical markers.
Modelling of patient-specific Purkinje activation based on measured ECGs
Authors: Kahlmann Willi , Poremba Emanuel , Potyagaylo Danila , Dössel Olaf , Loewe Axel 
Published: September 2017

Abstract
The Purkinje system is part of the fast-conducting ventricular excitation system. The anatomy of the Purkinje system varies from person to person and imposes a unique excitation pattern on the ventricular myocardium, which defines the morphology of the QRS complex of the ECG to a large degree. While it cannot be imaged in-vivo, it plays an important role for personalizing computer simulations of cardiac electrophysiology. Here, we present a new method to automatically model and customize the Purkinje system based on the measured electrocardiogram (ECG) of a patient. A graphbased algorithm was developed to generate Purkinje systems based on the parameters fibre density, minimal distance from the atrium, conduction velocity, and position and timing of excitation sources mimicking the bundle branches. Based on the resulting stimulation profile, the activation times of the ventricles were calculated using the fast marching approach. Predescribed action potentials and a finite element lead field matrix were employed to obtain surface ECG signals. The root mean square error (RMSE) between the simulated and measured QRS complexes of the ECGs was used as cost function to perform optimization of the Purkinje parameters. One complete evaluation from Purkinje tree generation to the simulated ECG could be computed in about 10 seconds on a standard desktop computer. The measured ECG of the patient used to build the anatomical model was matched via parallel simplex optimization with a remaining RMSE of 4.05 mV in about 16 hours. The approach presented here allows to tailor the structure of the Purkinje system through the measured ECG in a patient-specific way. The computationally efficient implementation facilitates global optimization.
Simulation and Dynamic Optimization of an Industrial Naphtha Thermal Cracking Furnace Based on Time Variant Feeding Policy
Authors: Abbasali S.M. Zaker , Farsi M. , Rahimpour M.R. 
Published: September 2017

Abstract
The main goal of this research is modeling and simulation of ethylene production through naphtha thermal cracking in a coil furnace reactor. The naphtha cracking and decoking processes are modeled based on the mass, energy and momentum balance equations considering a detail kinetic model at pseudo-dynamic condition. To develop a reliable and applicable model, a detail thermal model is considered to predict tube skin temperature. To prove accuracy of developed model and considered assumptions, the simulation results are compared with the plant data. In addition, the results of coke burning in the decoking cycle by mixture of air and steam are presented. It is appeared that ethylene production decreases during the process run time gradually. The simulation results proved that increasing feed temperature, feed pressure and combustion chamber temperature during the process run time is a practical solution to maintain production capacity at an acceptable level. Finally, the optimal operating condition of thermal cracking process is calculated during the process run time based on the time variant feeding policy to achieve maximum ethylene production capacity. It is appeared that applying optimal condition on the system could increase ethylene production capacity from 15.31 ton.h‒1 to 15.49 ton.h‒1.
A New Approach Towards Life Prediction of Case Hardened Bearing Steels Subjected to Rolling Contact Fatigue
Authors: Bhattacharyya Abir , Londhe Nikhil , Arakere Nagaraj , Subhash Ghatu 
Published: September 2017

Abstract
The failure of a bearing-raceway assembly is governed by the spatial distribution of subsurface stresses at the vicinity of a bearing-raceway contact and the evolution of these stresses during rolling contact fatigue (RCF) loading. In this paper, we propose an experimental methodology that allows one to accurately measure the location and magnitude of the cyclically evolving elastoplastic von Mises stresses in terms of microhardness numbers. An M50NiL steel rod is subjected to RCF by three silicon nitride (Si3N4) balls for over several hundred million cycles at 5.5 GPa contact stress level. Microindentation hardness measurements within the subsurface RCF-affected regions of the rod revealed significant material hardening. A mechanistic methodology to construct a stress-life (S-N) diagram for RCF loading is proposed. S-N diagrams are constructed based on maximum von Mises stress amplitude and volume average von Mises stress amplitude. The effects of elastic modulus and yield strength gradient on stress fields are also considered in this analysis. Comparison of S-N diagrams based on both stress amplitudes indicates that the maximum von Mises stress amplitude overpredicts the fatigue strength of material in S-N diagrams. The experimental results obtained by following this methodology can help construct material hardening models for RCF, which may lead to an improved estimate of bearing fatigue life.
Extended Synaptotagmin Localizes to Presynaptic ER and Promotes Neurotransmission and Synaptic Growth inDrosophila
Authors: Kikuma Koto , Li Xiling , Kim Daniel , Sutter David , Dickman Dion K 
Published: September 2017

AbstractIn highly polarized neurons, an extensive endoplasmic reticulum (ER) network extends to distal dendrites and axons. Several human diseases result from...The endoplasmic reticulum (ER) is an extensive organelle in neurons with important roles at synapses including the regulation of cytosolic Ca2+, neurotransmission, lipid metabolism, and membrane trafficking. Despite intriguing evidence for these crucial functions, how the presynaptic ER influences synaptic physiology remains enigmatic. To gain insight into this question, we have generated and characterized mutations in the single extended synaptotagmin (Esyt) ortholog in Drosophila melanogaster. Esyts are evolutionarily conserved ER proteins with Ca2+-sensing domains that have recently been shown to orchestrate membrane tethering and lipid exchange between the ER and plasma membrane. We first demonstrate that Esyt localizes to presynaptic ER structures at the neuromuscular junction. Next, we show that synaptic growth, structure, and homeostatic plasticity are surprisingly unperturbed at synapses lacking Esyt expression. However, neurotransmission is reduced in Esyt mutants, consistent with a presynaptic role in promoting neurotransmitter release. Finally, neuronal overexpression of Esyt enhances synaptic growth and the sustainment of the vesicle pool during intense activity, suggesting that increased Esyt levels may modulate the membrane trafficking and/or resting Ca2+ pathways that control synapse extension. Thus, we identify Esyt as a presynaptic ER protein that can promote neurotransmission and synaptic growth, revealing the first in vivo neuronal functions of this conserved gene family.
Entrevista con Ralph Lee Woodward Jr.
Authors: Arguedas Zamora Aharon 
Published: September 2017

En esta entrevista se intentará presentar las opiniones de un reconocido intelectual, maestro de generaciones. En ella se extiende sobre aspectos significativos de su vida, su formación profesional y el origen de su interés por la historia hispanoamericana. Woodward refiere, entre otras cosas, cómo se convirtió en historiador y de qué manera aumento su pasión por el desarrollo de la disciplina; además presenta las razones que lo llevaron a dedicar gran parte de su vida al estudio de Centroamérica.