bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a retrospective process for analyzing results of a HMM based posture recognition system in a functionalized nursing bed
Authors: Demmer Julia , Kitzig Andreas , Naroska Edwin 
Published: September 2017

Abstract
In the area of care in general but especially in the care of elderly, there is a great interest in deriving patient parameters preparation free. For this purpose, a load cell functionalized nursing bed has been developed at Niederrhein University of Applied Science. The system allows analysis and recognition of the persons’ positions and actions in the bed. The Hidden Markov Toolkit (HTK) based posture recognition system was initially presented at the BMT 2015 by our research group. The initial system shows good results but to draw conclusions about the patient's condition, a minimum possible error rate should be achieved. For this purpose, a two-step retrospective analysis of the initial results was developed as an extension to improve the accuracy of the system.
In a first step, the results of the initial recognition are analysed and classified into correct or incorrect results. This is done by means of probability based distance measure. The distances are calculated by the Viterbi algorithm. Based on these distance measures, errors and so called ‘secure support points’ are determined in the recognition result and the associated parameters are extracted.
The second part of the extension deals with a retrospective recognition method to improve the error rate of the initial recognition step. Based on the determined support points, the errors are analysed again applying syntactic relation. To this end, a special parameter set to control the recognition system, the so-called ‘syntax’, is generated individually for each erroneous recognition result based on the preceding secure support point. The new parameterized recognition system is then used to improve the initial erroneous results by re-classification. Finally, the corrected recognition results are combined with the preliminary recognition result.
Inflow mapping method for numerical flow simulations of OCT-based patient-specific vessels using CFD
Authors: Wüstenhagen Carolin , Borowski Finja , Haude Michael , Neumann Franz-Josef , Grabow Niels , Schmitz Klaus-Peter , Stiehm Michael 
Published: September 2017

Abstract
Alteration of the flow characteristics in coronary vessels is correlated with coronary heart disease (CHD). In particular, wall shear stress (WSS) appears to be a hemody-namic key factor in the genesis of CHD. Since computational fluid dynamics (CFD) is a well-known method for the inves-tigation of WSS, it may be a valuable tool for the prediction of CHD. Latest imaging techniques, such as optical coher-ence tomography (OCT) in conjunction with angiography deliver precise 2D data sets of patient-specific vessel geome-try, which can be used for CFD analysis. Current CFD stud-ies utilize patient-specific geometries, but are lacking well defined physiologic inflow conditions.
In this study, we present an inflow mapping method for patient-specific arterial vessels, which is capable of consider-ing the influence of bifurcations located proximal of the OCT-data set. At first, the patient-specific vessel was recon-structed. For this purpose the OCT-based vessel cross sec-tions were arranged along an angiographic based vessel pathway. Secondly, we simulated the flow field in a generic bifurcation model by means of CFD. Thereafter the flow field of a side branch was extracted and transferred (mapped) to the inlet of the patient-specific vessel.
To evaluate the influence of the physiological inlet the WSS distribution of the same patient-specific vessel was calculated using an axial-symmetric inflow condition. Analy-sis of the simulation data yielded deviations of the WSS distribution in the proximal vessel segment. A bifurcation, located upstream of the relevant vessel segment strongly affects the flow in the OCT-based vessel reconstruction and has a strong influence on the results of the numerical analy-sis. Therefore, it is important to implement not only the pa-tient-specific geometry, but also an inlet boundary condition adapted to the upstream velocity distribution reflecting the actual proximal flow situation of the vessel.
Numerical design studies on a novel electrostimulative osteosynthesis system for the mandible
Authors: Raben Hendrikje , Schmidt Christian , Sridhar Karthik , Kämmerer Peer W. , van Rienen Ursula 
Published: September 2017

Abstract
Fractures or other major bone defects in the mandible are commonly treated by mounting a reconstruction plate at the fracture site. To avoid complications due to loosening of the implant or the fixation screws, electrical stimulation presents a possibility to accelerate bone healing. The aim of this study was to investigate different combinations of activated electrodes and plate designs regarding their feasibility for electrostimulation of the mandibular bone. The electric field distribution for multiple implant designs was computed using the finite element method. The results suggest that the electrode insulation renders a crucial parameter, which influences substantially the stimulation impact and its power consumption.
Numerical flow simulation methods and additive manufacturing methods for the development of a flow optimised design of a novel point-of-care diagnostic device
Authors: Dethloff Manuel , Seitz Hermann , Dangers Marc 
Published: September 2017

Abstract
For the development of a novel, user-friendly and low cost point-of-care diagnostic device for the detection of disease specific biomarker a flow optimised design of the test system has to be investigated. The resulting test system is characterised by a reduced execution period, a reduction of execution steps and an integrated waste management. Based on previous results, the current study focused on the design implementation of the fluidic requirements, e. g. tightness, inside the test device. With the help of fluid flow simulations (CFD – computational fluid dynamics) the flow behaviour inside the test device was analysed for different designs and arrangements. Prototypes generated from additive manufacturing technologies (PolyJet modeling) are used for validating the simulation results and further experimental tests.
Investigation of Bauschinger effect in thermo-plastic polymers for biodegradable stents
Authors: Schümann Kerstin , Sahmel Olga , Martin Heiner , Schmitz Klaus-Peter , Grabow Niels 
Published: September 2017

Abstract
The Bauschinger effect is a phenomenon metals show as a result of plastic deformation. After a primary plastic deformation the yield strength in the opposite loading direction decreases. The aim of this study is to investigate if there is a phenomenon similar to Bauschinger effect in thermoplastic polymers for stent application that would influence the mechanical properties of these biodegradable implants. Combined uniaxial tensile with subsequent compression tests as well as conventional compression tests without prior tensile loading were performed using biodegradable polymers for stent application (PLLA and a PLLA based blend). Comparing the results of compression tests with prior tensile loading to the compression-only tests a decrease in compressive strength can be observed for both of the tested materials. The conclusion of the performed experiments is that there is a phenomenon similar to Bauschinger effect not only in metallic materials but also in the examined thermoplastic polymers. The observed reduction of compressive strength as a consequence of prior tensile loading can influence the mechanical behaviour, e.g. the radial strength, of polymeric stents after sustaining a complex load history due to crimping and expansion.
Patient-related QA for helical TomoTherapy with Delta4: analysis of the results
Authors: Salz Henning , Howitz Simon , Brachwitz Tim , Wiezorek Tilo 
Published: September 2017

Abstract
The biplanar diode arrays Delta4PT and Delta4+ has been used in our hospital since the introduction of the TomoTherapy in 2013 to ensure a good agreement between the calculated and the measured dose distributions in patient-related QA with helical TomoTherapy. The aim of this presentation is to evaluate the quality of the measurement procedure with the Delta4 phantoms Delta4PT and (since January 2016) Delta4+. This includes the influence of a cross calibration with a treatment plan with low modulation.
Two analyses were performed: (i) All treatment plans in a period of three months (n=86) were not only calculated and measured with Delta4PT or Delta4+ but also with an ionization chamber (Exradin A1SL) in the homogeneous “cheese phantom”. (ii) All data measured from January 2016 to April 2017 (Delta4+, n=132) were analyzed regarding median dose deviation, Gamma analysis and others.
The comparison with chamber measurements shows that all measurements with Delta4 and almost all with the ionization chambers (79 of 86) yield a deviation of measured vs. planned dose in the PTV of less than 2.5%, but with a lower variation of the Delta4 measurements. However, a strong correlation between both was not observed.
The separate analysis of the measurements with the newer Delta4+ (since January 2016) shows a mean dose deviation in the PTVs of only 0.14% with a standard deviation (S.D.) of 0.69%. Before every measurement a cross calibration has been performed. Without this cross calibration, the deviation would be 0.96% with an increased standard deviation of 0.93%.
It is concluded that the Delta4 systems are well suited for patient-related QA for helical TomoTherapy treatment plans. The comparison with chamber measurements shows a plausible accordance between both systems whereas the variation of single measurements is quite different.
With the help of a daily cross calibration the variability of the Delta4 results is further decreased and the results show higher accuracy and reliability. According to our experience, a daily cross calibration is mandatory for a reliable patient-related QA.
Analysis of resolution properties for three generations of MV imagers in radiation therapy using the modulation transfer function
Authors: Loot Katharina , Waletzko Oliver , Rohn Ralf , Spaan Bernhard , Block Andreas 
Published: September 2017

Abstract
Imaging in radiation therapy has become an important part of clinical routine. In order to evaluate and compare the image quality of verification images from different imaging modalities, one needs objective criteria like the modulation transfer function (MTF). The aim of our study was to compare the resolution properties of three generations of electronic portal imaging devices (EPIDs), namely one fluoroscopic-optical system and two different flat-panel imaging systems.
Impact of 4D CT for treatment planning of moving targets: a computer-based biological evaluation
Authors: Helf Eike , Waletzko Oliver , Mehrens Christian , Rohn Ralf , Block Andreas 
Published: September 2017

Abstract
This study deals with comparison of conventional and 4D CT (GE Lightspeed) planning on the tumour control probability (TCP), using the TCP model of the AAPM-Report Task Group 166. In the first step a VMAT treatment plan was calculated (Varian Eclipse 13.7) on basis of conventional CT data. This treatment plan was transferred to the complete 4D CT, which represents the tumour volume in motion. Due to the increased volume and the resulting decrease of tumour coverage the TCP went down from 97,6% to 91,2%. After adding an internal target volume (ITV, ICRU 62) to the conventional CT according to our clinical protocols (1,0 cm cc and 0,3 cm axial plane) the TCP increased to 98,0% when applying the conventional plan to the 4D CT. This finding demonstrates the need of 4D CT for moving tumours in chest and abdomen region.
Average IPs with increasing width have been created to evaluate the impact on the TCP and the non-malignant tissue. Our observations had shown that heart, lung and spinal cord radiation exposure did not correlate to chosen respiration segment. This could be explained by the extremely slight ratio of the planning target volume and the irradiated normal tissue.
This procedure enables us to evaluate the efficacy of treatment plans. Furthermore, optimizing trials like the influence of respiration-gated RT, setting individual margins and fitting planning objectives and parameters are still under investigation.
Development of sonosensitive Poly-(L)-lactic acid nanoparticles
Authors: Hiltl Pia-Theresa , Fink Michael , Rupitsch Stefan J. , Lee Geoffrey , Ermert Helmut 
Published: September 2017

Abstract
Due to serious side effects of traditional chemotherapeutic treatment, novel treatment techniques like targeted drug delivery, which allows a reduction of the overall dosage of drugs, are investigated. It is worth mentioning that at the same time, precise drug delivery offers an increased dosage of chemotherapeutic drugs in the tumorous area employing the EPR effect. Therefore, vehicles smaller than 400 nm can be used to pass the poorly aligned endothelial cells of tumour vessels passively through their fenestrations. In a subsequent step, the chemotherapeutic drugs need to be released. One possibility is an ultrasound-based release via inertial cavitation. Thereby, it is desirable to restrict the drug release to a narrow range. Thus, the cavitation inducing ultrasound wave has to be focused to that region of interest. Ultrasound frequencies of more than 500 kHz enable sufficient focusing, however, inertial cavitation occurs primarily at much lower frequencies. In order to afford inertial cavitation at 500 kHz, either bigger particles in the range of micrometres are needed as cavitation nucleus, which is not possible due to the EPR effect or high acoustic pressure is needed to generate inertial cavitation. Nevertheless, this high pressure is inappropriate for clinical applications due to thermal and mechanical effects on biological tissue.
We have produced Poly-(L)-lactic acid (PLLA) nanoparticles by a solvent evaporation technique that serve as nucleus for inertial cavitation at moderate acoustic pressure of 800 kPa and at high frequencies of 800 kHz after the particles have been freeze-dried. In this contribution, we characterize the designed particles and present the production process. Moreover, we show that these particles enable inertial cavitation at an acoustic pressure and at acoustic frequencies which are commonly used in clinical ultrasound units. We also show that other particles with the same size at the same acoustic parameters do not induce cavitation activity.
Distance-dependent adhesion of vascular cells on biofunctionalized nanostructures
Authors: Biela Sarah , Striegl Britta , Frey Kerstin , Spatz Joachim P. , Kemkemer Ralf 
Published: September 2017

Abstract
Cell-cell and cell-extracellular matrix (ECM) adhesion regulates fundamental cellular functions and is crucial for cell-material contact. Adhesion is influenced by many factors like affinity and specificity of the receptor-ligand interaction or overall ligand concentration and density. To investigate molecular details of cell-ECM and cadherins (cell-cell) interaction in vascular cells functional nanostructured surfaces were used Ligand-functionalized gold nanoparticles (AuNPs) with 6-8 nm diameter, are precisely immobilized on a surface and separated by non-adhesive regions so that individual integrins or cadherins can specifically interact with the ligands on the AuNPs. Using 40 nm and 90 nm distances between the AuNPs and functionalized either with peptide motifs of the extracellular matrix (RGD or REDV) or vascular endothelial-cadherins (VEC), the influence of distance and ligand specificity on spreading and adhesion of endothelial cells (ECs) and smooth muscle cells (SMCs) was investigated. We demonstrate that RGD-dependent adhesion of vascular cells is similar to other cell types and that the distance dependence for integrin binding to ECM-peptides is also valid for the REDV motif. VEC-ligands decrease adhesion significantly on the tested ligand distances. These results may be helpful for future improvements in vascular tissue engineering and for development of implant surfaces.
Rheological analysis of hybrid hydrogels during polymerization processes
Authors: Illner Sabine , Sahmel Olga , Siewert Stefan , Eickner Thomas , Grabow Niels 
Published: September 2017

Abstract
Development of new implant coatings with temperature-controlled drug release to treat infections after device implantation can be triggered by highly elastic hydrogels with adequate stability and adhesive strength in the swollen state. By using an ionic liquid (IL [ViPrIm]+[Br]−) as additive to N-isopropylacrylamide (NIPAAm) unique effects on volumetric changes and mechanical properties as well as thermoresponsive drug release of the obtained hybrid hydrogels were observed. In this context, rheological measurements allow the monitoring of gelation processes as well as chemical, mechanical, and thermal treatments and effects of additives. Hybrid hydrogels of pNIPAAm and poly (ionic liquid) (PIL) were prepared by radical emulsion polymerization with N,N′-methylenebis(acrylamide) as 3D crosslinking agent. By varying monomer, initiator and crosslinker amounts the multi-compound system during polymerization was monitored by oscillatory time sweep experiments. The time dependence of the storage modulus (G′) and the loss modulus (G″) was measured, whereby the intersection of G′ and G″ indicates the sol-gel transition. Viscoelastic behavior and complex viscosity of crosslinked and non-crosslinked hydrogels were obtained. Within material characterization rheology can be used to determine process capability and optimal working conditions. For biomedical applications complete hydrogelation inter-connecting all compounds can be received providing the possibility to process mechanically stable, swellable implant coatings or wound closures.
Marker for the pre-clinical development of bone substitute materials
Authors: de Wild Michael , Zimmermann Simon , Obrecht Marcel , Dard Michel 
Published: September 2017

Abstract
Thin mechanically stable Ti-cages have been developed for the in-vivo application as X-ray and histology markers for the optimized evaluation of pre-clinical performance of bone graft materials. A metallic frame defines the region of interest during histological investigations and supports the identification of the defect site. This standardization of the procedure enhances the quality of pre-clinical experiments. Different models of thin metallic frameworks were designed and produced out of titanium by additive manufacturing (Selective Laser Melting). The productibility, the mechanical stability, the handling and suitability of several frame geometries were tested during surgery in artificial and in ex-vivo bone before a series of cages was preclinically investigated in the female Göttingen minipigs model. With our novel approach, a flexible process was established that can be adapted to the requirements of any specific animal model and bone graft testing.
Signal and energy transmission for implanted systems
Authors: Müller Carsten , Audí Josep M. Cardona , Ruff Roman , Hoffmann Klaus-Peter 
Published: September 2017

Abstract
Aspects and approaches for the design of systems for simultaneous signal and energy transmission for medical implants are presented. The main focus is on the consideration of the mutual influence on both transmission lines. To minimize the influence of capacitive as well as inductive paths, that affect the transmission, reducing the number of components is discussed. In order to increase the degree of miniaturization and reliability, the realization of certain functionalities is based on the so-called parasitics of electrical components. An implementation example is presented.
An evaluation study of vital parameter determination with RGB cameras in the field of ambient assisted living
Authors: Wiede Christian , Richter Julia , Hirtz Gangolf 
Published: September 2017

Abstract
The remote determination of vital parameters can contribute to the field of ambient assisted living (AAL) to face the challenges of a steadily ageing society. In this study, we examined the possibility to remotely measure the four vital parameters heart rate, respiration rate, oxygen saturation and blood pressure in AAL environments. For this, we evaluated the state of the art, implementations and concepts. While, the determination of heart and respiration rate is ready for usage, further attention has to be paid to the determination of oxygen saturation and blood pressure.
Data-driven analysis of interactions between people with dementia and a tablet device
Authors: Doneit Wolfgang , Lohse Jana , Glesing Kristina , Simon Clarissa , Fischer Monika , Depner Anamaria , Kruse Andreas , Franz Ingo , Schultz Tanja , Putze Felix , Schulze Timo , Engels Marc Aurel , Gaerte Philipp , Bothe Dietmar , Ziegler Christof , Maucher Irene , Ricken Michael , Dimitrov Todor , Herzig Joachim , Bernardin Keni , Gehrig Tobias , Mikut Ralf 
Published: September 2017

Abstract
In the project I-CARE a technical system for tablet devices is developed that captures the personal needs and skills of people with dementia. The system provides activation content such as music videos, biographical photographs and quizzes on various topics of interest to people with dementia, their families and professional caregivers. To adapt the system, the activation content is adjusted to the daily condition of individual users. For this purpose, emotions are automatically detected through facial expressions, motion, and voice. The daily interactions of the users with the tablet devices are documented in log files which can be merged into an event list. In this paper, we propose an advanced format for event lists and a data analysis strategy. A transformation scheme is developed in order to obtain datasets with features and time series for popular methods of data mining. The proposed methods are applied to analysing the interactions of people with dementia with the I-CARE tablet device. We show how the new format of event lists and the innovative transformation scheme can be used to compress the stored data, to identify groups of users, and to model changes of user behaviour. As the I-CARE user studies are still ongoing, simulated benchmark log files are applied to illustrate the data mining strategy. We discuss possible solutions to challenges that appear in the context of I-CARE and that are relevant to a broad range of applications.
Fast care – real-time sensor data analysis framework for intelligent assistance systems
Authors: Hein Albert , Grützmacher Florian , Haubelt Christian , Kirste Thomas 
Published: September 2017

Abstract
Main target of fast care is the development of a real-time capable sensor data analysis framework for intelligent assistive systems in the field of Ambient Assisted Living, eHealth, Tele Rehabilitation, and Tele Care. The aim is to provide a medically valid integrated situation model based on a distributed, ad-hoc connected, energy-efficient sensor infrastructure suitable for daily use. The integrated situation model combining physiological, cognitive, and kinematic information about the patient is grounded on the intelligent fusion of heterogeneous sensor data on different levels. The model can serve as a tool for quickly identifying risk and hazards as well as enable medical assistance systems to autonomously intervene in real-time and actively give telemedical feedback.