bluuebunny/crossref_metadata_2025 huggingface dataset:
Linear Estimation of Aggregate Dynamic Discrete Demand for Durable Goods: Overcoming the Curse of Dimensionality
Authors: Chou Cheng , Derdenger Tim , Kumar Vineet
Published: September 2019

New estimation method for dynamic discrete choice models with aggregate data.
Revisiting Approximate Linear Programming: Constraint-Violation Learning with Applications to Inventory Control and Energy Storage
Authors: Lin Qihang , Nadarajah Selvaprabu , Soheili Negar
Published: September 2019

Approximate linear programs (ALPs) are well-known models for computing value function approximations (VFAs) of intractable Markov decision processes (MDPs). VFAs from ALPs have desirable theoretical properties, define an operating policy, and provide a lower bound on the optimal policy cost. However, solving ALPs near-optimally remains challenging, for example, when approximating MDPs with nonlinear cost functions and transition dynamics or when rich basis functions are required to obtain a good VFA. We address this tension between theory and solvability by proposing a convex saddle-point reformulation of an ALP that includes as primal and dual variables, respectively, a vector of basis function weights and a constraint violation density function over the state-action space. To solve this reformulation, we develop a proximal stochastic mirror descent (PSMD) method that learns regions of high ALP constraint violation via its dual update. We establish that PSMD returns a near-optimal ALP solution and a lower bound on the optimal policy cost in a finite number of iterations with high probability. We numerically compare PSMD with several benchmarks on inventory control and energy storage applications. We find that the PSMD lower bound is tighter than a perfect information bound. In contrast, the constraint-sampling approach to solve ALPs may not provide a lower bound, and applying row generation to tackle ALPs is not computationally viable. PSMD policies outperform problem-specific heuristics and are comparable or better than the policies obtained using constraint sampling. Overall, our ALP reformulation and solution approach broadens the applicability of approximate linear programming.

This paper was accepted by Yinyu Ye, optimization.
A Clustered Overflow Configuration of Inpatient Beds in Hospitals
Authors: Izady Navid , Mohamed Israa
Published: September 2019

Problem definition: The shortage of inpatient beds is a major cause of delays and cancellations in many hospitals. It may also lead to patients being admitted to inappropriate wards, resulting in a lower quality of care and a longer length of stay. Academic/practical relevance: Investment in additional beds is not always feasible. Instead, new and creative solutions for a more efficient use of existing resources must be sought. Methodology: We propose a new configuration of inpatient beds, which we call the clustered overflow configuration. In this configuration, patients who are denied admission to their primary wards as a result of beds being fully occupied are admitted to overflow wards, with each designated to serve overflows from a certain subset of specialties and providing the same quality of care as in primary wards. We propose two different formulations for partitioning and bed allocation in the proposed configuration: one minimizing the sum of average daily costs of turning patients away and nursing teams, and another minimizing the numbers turned away subject to nursing cost falling below a given threshold. We heuristically solve instances from both formulations. Results: Applying the models to real data shows that the configurations obtained from our models compare very well with the other configurations proposed in the literature, provided that patients’ willingness to wait is relatively short. Managerial implications: The proposed configuration provides the combined advantages of the dedicated configuration, wherein patients are only admitted to their primary wards, and the flexible configuration, in which all specialties share a single ward. On the other hand, it restricts the adverse impacts of pooling and minimizes cross-training costs through appropriate partitioning and bed allocation. As such, it serves as a viable alternative to existing inpatient configurations.
Caring for HIV-positive children: healthcare providers' pre-and post-disclosure experiences in Nairobi, Kenya
Authors: Makworo Drusilla , Odero Theresa
Published: September 2019

Background

The number of children living with HIV has increased worldwide, largely due to improvements in antiretroviral therapy. Most of these children are living in sub-Saharan Africa. The rate of disclosure to children of their HIV-positive status is low in low-resource countries compared to high-resource countries.

Aim

To explore health professionals' experiences of caring for HIV-positive children before and after their HIV-positive status was disclosed to them. The health professionals included nurses, counsellors, nutritionists, social workers, pharmacists and clinicians with at least 1 year of experience at the paediatric section of the comprehensive care centre.

Methods

Nine health professionals were interviewed.

Findings

Results revealed that there were more challenges before disclosure than after. The main challenge was communicating with the children. The children's main concerns before disclosures included the reason for treatment and its duration, and clinic follow-up.

Conclusions

Health professionals should be trained on the benefits of HIV disclosure to children, in order to allow for open and direct communication between healthcare providers, parents/carers and children.
Parapharyngeal abscess and vocal cord palsy caused by minor salivary gland sialadenitis: an atypical presentation treated using an endoscopic surgical approach
Authors: Kumar R , Thomas C , Darr A , Donnai M
Published: September 2019

Parapharyngeal infections carry a significant risk of extensive suppuration and airway compromise. We report the case of a patient presenting with a right paranasopharyngeal abscess, featuring atypical symptoms that made diagnosis particularly challenging. Complications included evidence of right vocal cord paralysis, likely secondary to involvement of the vagus nerve. Notably, this paralysis occurred in isolation, without involvement of cranial nerves IX or XI, which would be expected from jugular foramen encroachment. Imaging demonstrated the presence of a collection extending towards the skull base, which was drained using a transnasal endoscopic approach, avoiding the use of external incisions. Tissue biopsies from the abscess wall suggest that the underlying aetiology was minor salivary gland sialadenitis, which has not been previously reported in the literature.
Principles of embodied pedagogy: The role of the drama educator in transforming student understanding through a collaborative and embodied aesthetic practice
Authors: Bird Jane , Sinclair Christine
Published: September 2019

When undertaking teaching as an embodied pedagogy, the teacher understands the body as a site of risk and possibility as well as a site of knowing – of self, of others (empathy) and of the world. This article focuses on research undertaken by the authors in the International Centre for Classroom Research at the University of Melbourne into the pedagogical and creative learning practices associated with an embodied approach to teaching, and draws on a growing body of research undertaken by cognitive scientists investigating the role of the body in thinking, learning and problem-solving (Glenberg 2008), and by drama education researchers into the ways that embodiment can substantially enhance learning (Ewing 2010). The authors contend that researchers have focused principally on the processes and characteristics of embodied learning and have given less attention to the pedagogical practices employed by drama educators as facilitators of embodied learning. This article addresses this gap in the research by examining the role of the drama educator in facilitating the conditions for aesthetic embodied learning experiences in a classroom environment. The authors propose a set of principles of embodied pedagogies for implementation in and beyond the drama classroom.
Reviews
Authors: Inchley Maggie , Bartley Sarah , Massey-Chase Kate
Published: September 2019

Applied Theatre with Looked-After Children: Dramatising Social Care, Claire MacNeill (2018) Oxford: Peter Lang, ISBN: 9 7817 8707 0714, 287 pp., £40.00

Applied Theatre: Economies, Molly Mullen (ed.) (2018) London: Bloomsbury, ISBN: 9 7813 5000 1725, 280pp., US$76.99

Web of Performance: An Ensemble Workbook, Monica Prendergast and Will Weigler (eds) (2018) Victoria, BC: University of Victoria Press, ISBN: 9 7815 5058 6220, free e-book, https://dspace.library.uvic.ca//handle/1828/9426
Empatía en enfermería y el contexto de la relación enfermero-paciente: consideraciones críticas
Authors: Mufato Leandro Felipe , Gaíva Maria Aparecida Munhoz
Published: September 2019

La empatía se considera una habilidad para comprender al otro, fundamental en la relación enfermero-paciente. En la enfermería, Theresa Wiseman formuló conceptos propios sobre la empatía a partir de las características de la profesión. Sin embargo, después de más de diez años del concepto de empatía en enfermería formulado por la autora, tenemos que detenernos sobre el contexto actual de incidencia de este fenómeno: la relación enfermero-paciente. En este ensayo, observamos algunos factores que demuestran la importancia de la empatía entre enfermeros y pacientes, también, qué desafíos la profesión enfrenta para la promoción de su autonomía y que interfieren directamente en el modo como los enfermeros ocupan el espacio en la relación con sus pacientes y en el desarrollo de la empatía. El trabajo de enfermería en centros sanitarios, la división del trabajo con técnicos y la sumisión de la profesión a los modos de producción del cuidado hospitalario se presentan como aspectos que interfieren en la relación enfermero-paciente y en la empatía. Se concluye por la necesidad de retomada de acciones de cuidado individualizadas en la relación directa con los pacientes, de modo que el enfermero pueda ser visto como un recurso, como una fuente de cuidados por los pacientes.
Envelhecendo no campo: perfil de idosos residentes no meio rural
Authors: Mainardi Diana Cristina Buz , Leite Marinês Tambara , Hildebrandt Leila Mariza , Kirchner Rosane Maria
Published: September 2019

Objetivo: Descrever as características sociodemográficas e relacionadas à saúde de idosos residentes no meio rural de um município do Rio Grande do Sul/Brasil. Método: Estudo de abordagem quantitativa, descritivo-analítico, de inquérito domiciliar. Dados foram coletados por meio de entrevistas e analisados. Resultados: Participaram 290 idosos, prevalência do sexo feminino, idade entre 60 e 70 anos, casados. A maioria possui 3 a 4 filhos, coabita com uma a três pessoas, sabe ler e escrever. Ter alguma doença é referido por 87,2% dos idosos e 26,48% deles apresentam três ou mais doenças, com prevalência da hipertensão arterial. Na autopercepção da condição de saúde, 60,3% a consideram boa. Quando adoecem 38,6% dos idosos recorrem ao uso de chás, seguidos do hospital 34,5%. Conclusões: A contribuição deste estudo está no conhecimento das particularidades sociodemográficas e de saúde de idosos residentes em áreas rurais, podendo auxiliar na operacionalização de políticas públicas a este estrato populacional.
Reseña de Enfermería Mandálica, un modelo cultural de intervención en Atención Primaria, de Pedro M. Salas Iglesias
Authors: Cibanal Juan Luis
Published: September 2019

Esta reseña describe las características la enfermería mandálica en el contexto de la enfermería de atención primaria.
Rosenthal's Disease (Hemophilia C or factor XI Deficiency) Revealed by Chronic Epistaxis: The First Observation in Sub-Saharan Africa.
Authors: PADARO Essohana , KUEVIAKOE Irenée MD , LAYIBO Yao , AGBETIAFA Kossi , MAGNANG Hèzouwè , MAWUSSI Koffi , VOVOR Ahoefa
Published: September 2019

Objective Rosenthal's disease (RD) is a rare constitutional hemorrhagic disorder defined by factor XI deficiency. It is clinically characterized by the presence of minimal haemorrhage. We report the first observation of RD in Togo. Observation Mrs. G. A., 45 years old with no particular pathological antecedents, was referred for anemia in a context of chronic epistaxis. It was a spontaneous anterior exteriorization epistaxis often of great abundance, rocking and which evolved episodically. The patient received several transfusions for anemia. The ear-nose-throat examination was normal and a sinus CT scan found only an inflammatory process of the right maxillary sinus. The blood count showed microcytic severe anemia (2,2g/dl). Hemostasis tests showed a prolonged aPTT (57,9 seconds). Clinical examination documented an anemic syndrome with dry skin. Iron deficiency was found. The hemostasis balance confirmed aPTT elongation. Coagulation factors activity showed normal VIII and IX level, but moderate decrease of factor XI (32%). The family survey was not possible (orphan patient). It is recommended the setting under fresh frozen plasma (FFP) in case of a new episode. Follow-up is in progress. Conclusion In the event of any hemorrhagic syndrome, the isolated elongation of the aPTT must lead to a systematic analysis of intrinsic pathway factors
Using a Medication Plan as a Quality Indicator: Feasibility and Satisfaction Results from an Observational Study
Authors: Blondon K. , Skalafouris C. , Simonet M. Louis , Piguet V.
Published: September 2019

Background
Medication adherence remains a challenge for patient management. Changes in the drug regimen after a hospital stay can lead to confusion or misunderstandings. We implemented a structured patient-centered interview during which a computer-generated individualized medication plan was discussed and provided to patients at discharge.

Objective
To explore whether a medication plan can be a quality indicator, in terms of its content (quality) and its implementation in the resident’s workflow (feasibility).

Methods
An observational mixed method study with interviews of 174 patients from general internal medicine wards at 1 week and 1 month after discharge, and of 91 physicians at baseline. We report the quality of the medication plan in terms of content and state of completion. We describe feasibility for residents to complete this plan, as well as patient and resident satisfaction with the plan.

Results
83% of participants received a medication plan. Physicians verified renal function (83%) to adapt doses but did not regularly assess for medication interactions (43%). Incomplete plans (61%), were due to blanks when physicians considered the information irrelevant for their patients. Error rate was <3%. Patients reported low use of their plan after discharge (64% found it useful after 1 week, whereas only 37% used it when taking their medication 1 week after discharge).

Conclusion
Although the plans were considered useful by both patients and physicians, their implementation could have been optimized by considering the overall process (creation to patient use). Mobile apps could help fill gaps in supporting patients for medication adherence.
CELLULAR AUTOMATA MODELING IN THE BUILT UP AREAS WITHIN URBAN DEVELOPMENT AT PONTIANAK, WEST BORNEO, INDONESIA
Authors: Nurhidayati Ely , Buchori Imam , Mussadun Mussadun
Published: September 2019

This research integrated the GIS-Cellular Automata model with the regression model to predict urban development in Pontianak within the built up area change phenomena approach. The research aimed to understand built-up land use development in Pontianak during 1990-2015 and to predict its regional development in 2033. The employed method were satellite the image interpretation approach, hybrid interpretation, and built up land development prediction using transition rules like driving factors and inhibiting factors of urban development. The driving ones are accessibility related to distances to CBD, to main roads, and to the existing built regional areas while the inhibiting ones are peatland and the protected areas. The result showed that the hybrid interpretation, between visual and digital interpretations from the landsat images, can be used to map the built up lands with 94.8% of sampling point’s precision. The non-built up areas in Pontianak during 1990-2015 were 83.52 Ha/year, and the modelling result predicts that non-built regional areas in Pontianak during 2015-2033 will be 80.51 Ha/year heading toward northern and central areas of Pontianak.
In simply connected cotangent bundles, exact Lagrangian cobordisms are h-cobordisms
Authors: Tanaka Hiro Lee
Published: September 2019

Let Q be a simply connected manifold. We show that every exact Lagrangian cobordism between compact, exact Lagrangians in T
*
Q is an h-cobordism. This is a corollary of the Abouzaid–Kragh Theorem.
Strategic Activism in an Uncertain World
Authors: van der Made Allard
Published: September 2019

We model private politics in the presence of two-sided incomplete information. An interest group (IG) threatens to inform consumers about a firm’s damaging technology should the firm not adopt a clean technology. The IG does not know how costly adopting the clean technology is and the firm does not know how much the IG cares about the damages. In equilibrium an IG who cares a lot signals its type to the firm and the firm is more inclined to adopt the clean technology if it receives such a signal. However, impasses can occur: the firm does not adopt the clean technology despite the fact that the IG has signaled that it cares a lot and threatens to inform a large fraction of the consumer population. The IG never informs all consumers: as soon as a certain fraction of the consumers is informed by the IG the firm reduces its price and thereby reveals to the remaining consumers that it is employing a damaging technology. The IG’s actions increase consumer well-being, but decrease total welfare unless the cost of adopting the clean technology is likely to be low. Yet, since the IG is inclined to target firms with this property, a regulator might want to delegate information provision to the IG.
Quadriceps mechanomyography reflects muscle fatigue during electrical stimulus-sustained standing in adults with spinal cord injury – a proof of concept
Authors: Ibitoye Morufu Olusola , Hamzaid Nur Azah , Abdul Wahab Ahmad Khairi , Hasnan Nazirah , Davis Glen M.
Published: September 2019

This study investigates whether mechanomyography (MMG) produced from contracting muscles as a measure of their performance could be a proxy of muscle fatigue during a sustained functional electrical stimulation (FES)-supported standing-to-failure task. Bilateral FES-evoked contractions of quadriceps and glutei muscles, of four adults with motor-complete spinal cord injury (SCI), were used to maintain upright stance using two different FES frequencies: high frequency (HF – 35 Hz) and low frequency (LF – 20 Hz). The time at 30° knee angle reduction was taken as the point of critical “fatigue failure”, while the generated MMG characteristics were used to track the pattern of force development during stance. Quadriceps fatigue, which was primarily responsible for the knee buckle, was characterized using MMG-root mean square (RMS) amplitude. A double exponential decay model fitted the MMG fatigue data with good accuracy [R2 = 0.85–0.99; root mean square error (RMSE) = 2.12–8.10] implying changes in the mechanical activity performance of the muscle’s motor units. Although the standing duration was generally longer for the LF strategy (31–246 s), except in one participant, when compared to the HF strategy, such differences were not significant (p > 0.05) but suggested a faster muscle fatigue onset during HF stimulation. As MMG could discriminate between different stimulation frequencies, we speculate that this signal can quantify muscle fatigue characteristics during prolonged FES applications.
Neighborhood Optimization for Therapy Decision Support
Authors: Gräßer Felix , Malberg Hagen , Zaunseder Sebastian
Published: September 2019

This work targets the development of a neighborhood-based Collaborative Filtering therapy recommender system for clinical decision support. The proposed algorithm estimates outcome of pharmaceutical therapy options in order to derive recommendations. Two approaches, namely a Relief-based algorithm and a metric learning approach are investigated. Both adapt similarity functions to the underlying data in order to determine the neighborhood incorporated into the filtering process. The implemented approaches are evaluated regarding the accuracy of the outcome estimations. The metric learning approach can outperform the Relief-based algorithms. It is, however, inferior regarding explainability of the generated recommendations.
Gait analysis for early Parkinson’s disease detection based on deep learning
Authors: Kondragunta Jyothsna , Wiede Christian , Hirtz Gangolf
Published: September 2019

Better handling of neurological or neurodegenerative disorders such as Parkinson’s Disease (PD) is only possible with an early identification of relevant symptoms. Although the entire disease can’t be treated but the effects of the disease can be delayed with proper care and treatment. Due to this fact, early identification of symptoms for the PD plays a key role. Recent studies state that gait abnormalities are clearly evident while performing dual cognitive tasks by people suffering with PD. Researches also proved that the early identification of the abnormal gaits leads to the identification of PD in advance. Novel technologies provide many options for the identification and analysis of human gait. These technologies can be broadly classified as wearable and non-wearable technologies. As PD is more prominent in elderly people, wearable sensors may hinder the natural persons movement and is considered out of scope of this paper. Non-wearable technologies especially Image Processing (IP) approaches captures data of the person’s gait through optic sensors Existing IP approaches which perform gait analysis is restricted with the parameters such as angle of view, background and occlusions due to objects or due to own body movements. Till date there exists no researcher in terms of analyzing gait through 3D pose estimation. As deep leaning has proven efficient in 2D pose estimation, we propose an 3D pose estimation along with proper dataset. This paper outlines the advantages and disadvantages of the state-of-the-art methods in application of gait analysis for early PD identification. Furthermore, the importance of extracting the gait parameters from 3D pose estimation using deep learning is outlined.
Combination of sensor-embedded and secure server-distributed artificial intelligence for healthcare applications
Authors: Gembaczka Pierre , Heidemann Burkhard , Bennertz Bernhard , Groeting Wolfgang , Norgall Thomas , Seidl Karsten
Published: September 2019

The application of artificial intelligence (AI) in the areas of health, care and social participation offers great opportunities but also involves great challenges. Extensive regulatory, ethical and data-security related requirements exist for data recording, storage and processing of respective personalized and patient-related data. “Artificial Intelligence as a Service” (AIaaS) is pushed for consumer applications by global players, which implies data storage on external database server. However, the available solutions do not meet the requirements. Moreover, small and medium-sized enterprises (SMEs) in the field of healthcare fear the loss of data sovereignty and information outflow. In this paper, we propose a secure and resource-efficient approach by embedding AI directly close to the sensor in combination with secure and distributed data processing on local server or certified “Trusted Data Center”. For this purpose, we have developed the Artificial Intelligence for Embedded Systems (AIfES) platform-independent machine learning library in C programming language. It contains a fully configurable deep artificial neural network with feedforward structure. The library can be run directly on a microcontroller and even allows to train the neural network. Possible healthcare applications include direct (pre-) processing of sensor data, sensor calibration, pattern recognition and classification.
Surface EMG-based Surgical Instrument Classification for Dynamic Activity Recognition in Surgical Workflows
Authors: Bieck Richard , Fuchs Reinhard , Neumuth Thomas
Published: September 2019

We introduce a wearable-based recognition system for the classification of natural hand gestures during dynamic activities with surgical instruments. An armbandbased circular setup of eight EMG-sensors was used to superficially measure the muscle activation signals over the broadest cross-section of the lower arm. Instrument-specific surface EMG (sEMG) data acquisition was performed for 5 distinct instruments. In a first proof-of-concept study, EMG data were analyzed for unique signal courses and features, and in a subsequent classification, both decision tree (DTR) and shallow artificial neural network (ANN) classifiers were trained. For DTR, an ensemble bagging approach reached precision and recall rates of 0.847 and 0.854, respectively. The ANN network architecture was configured to mimic the ensemble-like structure of the DTR and achieved 0.952 and 0.953 precision and recall rates, respectively. In a subsequent multi-user study, classification achieved 70 % precision. Main errors potentially arise for instruments with similar gripping style and performed actions, interindividual variations in the acquisition procedure as well as muscle tone and activation magnitude. Compared to hand-mounted sensor systems, the lower arm setup does not alter the haptic experience or the instrument gripping, which is critical, especially in an intraoperative environment. Currently, drawbacks of the fixed consumer product setup are the limited data sampling rate and the denial of frequency features into the processing pipeline.
Modification of joint prosthesis surfaces by ultrashort pulse laser treatment for improved joint lubrication
Authors: Drescher Philipp , Oldorf Paul , Dreier Tim , Peters Rigo , Seitz Hermann
Published: September 2019

Endoprostheses such as hip replacements are subject to wear. Lubrication of the joint interface plays a key role in the wear process, but the mechanisms of lubrication is challenging to understand. The main issue is the three-body abrasion which leads to a shorter life cycle. In order to improve the life cycle, the surfaces of the articulating components can be modified, for example by pulsed femtosecond-laser microstructuring. By microstructuring of the implant surface, the viscosity of the synovial fluid between the joint can be increased due to the non-Newtonian properties of the synovia. This leads to better lubrication and therefore lower particle abrasion. The objective of this study was to evaluate the impact of different microstructures on the viscosity of a joint fluid substitute. Various microstructures were investigated in a modified rheometer setup featuring a decreased gap size. As a test fluid, a synovial fluid substitute was used. The results show that an increase in the viscosity of the synovial fluid substitute can be achieved by microstructuring. An increase of viscosity of up to 20 % compared to the unstructured reference was observed with ring-structures with a diameter of 100 μm and a depth of 20 μm.
Influence of ECG Lead Reduction Techniques for Extracellular Potassium and Calcium Concentration Estimation
Authors: Hernández Mesa María , Pilia Nicolas , Dössel Olaf , Loewe Axel
Published: September 2019

Chronic kidney disease (CKD) affects 13% of the worldwide population and end stage patients often receive haemodialysis treatment to control the electrolyte concentrations. The cardiovascular death rate increases by 10% - 30% in dialysis patients than in general population. To analyse possible links between electrolyte concentration variation and cardiovascular diseases, a continuous non-invasive monitoring tool enabling the estimation of potassium and calcium concentration from features of the ECG is desired. Although the ECG was shown capable of being used for this purpose, the method still needs improvement. In this study, we examine the influence of lead reduction techniques on the estimation results of serum calcium and potassium concentrations.We used simulated 12 lead ECG signals obtained using an adapted Himeno et al. model. Aiming at a precise estimation of the electrolyte concentrations, we compared the estimation based on standard ECG leads with the estimation using linearly transformed fusion signals. The transformed signals were extracted from two lead reduction techniques: principle component analysis (PCA) and maximum amplitude transformation (Max- Amp). Five features describing the electrolyte changes were calculated from the signals. To reconstruct the ionic concentrations, we applied a first and a third order polynomial regression connecting the calculated features and concentration values. Furthermore, we added 30 dB white Gaussian noise to the ECGs to imitate clinically measured signals. For the noisefree case, the smallest estimation error was achieved with a specific single lead from the standard 12 lead ECG. For example, for a first order polynomial regression, the error was 0.0003±0.0767 mmol/l (mean±standard deviation) for potassium and -0.0036±0.1710 mmol/l for calcium (Wilson lead V1). For the noisy case, the PCA signal showed the best estimation performance with an error of -0.003±0.2005 mmol/l for potassium and -0.0002±0.2040 mmol/l for calcium (both first order fit). Our results show that PCA as ECG lead reduction technique is more robust against noise than MaxAmp and standard ECG leads for ionic concentration reconstruction.
Parameter sensitivity analysis on a mathematical model of reepithelialization
Authors: Dawn Parente Jacquelyn , Möller Knut , Kannan Bala Amala , Hensler Sabine , Kuhlbach Claudia , Mueller Margareta M.
Published: September 2019

Reepithelialization is the single requirement to define a wound as healed when the barrier function of the skin is restored. An existing reepithelialization mathematical model (RM) simulates wound healing in vitro. This work performs a parameter sensitivity analysis on an existing RM to see how robust the model is for changing wound healing rates for application to chronic wounds (inhibition) and wound healing therapies (activation). The existing RM balances the optimal distance between cells and basal membrane segments (BMs) according to the calculation of intercellular pressure and adhesion force. The RM mimics cell behavior and their interaction by passive migration, which is the displacement of cells from its initial position. First, this work reproduces the RM. The initial case recreates the interaction of a cell with its surrounding cells, while the second case recreates the interaction of the cell with its nearest BMs. These two cases were implemented in MATLAB to estimate optimal distance, intercellular pressure, an adhesive force between cells and the BMs. The analysis computes movement vectors and new positions of each cell at different time steps. Parameter sensitivity analysis was then conducted on the adhesion coefficient, where the original value in the RM was unknown. The results obtained at the assumed original parameter values are similar to the existing RM. As a result of the parameter sensitivity analysis, increasing the adhesion coefficient increases cell movement. High basal adhesion causes passive movement of cells, which in the simulation results is seen as a cellular movement towards wound closure. The existing RM is robust to changing adhesion coefficient values which change the rate of the advancing reepithelialization front. Future work includes fitting adhesion coefficient parameter values to an in vitro wounded tissue visualized by live dyes in treatment therapy experiments.
The effect of dipole housing and feeding wires in physical phantoms for EEG
Authors: Machts René , Hunold Alexander , Haueisen Jens
Published: September 2019

Current dipoles are well established models in the localization of neuronal activity to electroencephalography (EEG) data. In physical phantoms, current dipoles can be used as signal sources. Current dipoles are often powered by constant current sources connected via twisted pair wires mostly consisting of copper. The poles are typically formed by platinum wires. These wires as well as the dipole housing might disturb the electric potential distributions in physical phantom measurements. We aimed to quantify this distortion by comparing simulation setups with and without the wires and the housing. The electric potential distributions were simulated using finite element method (FEM). We chose a homogenous volume conductor surrounding the dipoles, which was 100 times larger than the size of the dipoles. We calculated the difference of the electric potential at the surface of the volume conductor between the simulations with and without the connecting wires and the housing. Comparing simulations neglecting all connecting wires and the housing rod to simulations considering them, the electric potential at the surface of the volume conductor differed on average by 2.85 %. Both platinum and twisted pair copper wires had a smaller effect on the electric potentials with a maximum average change of 6.38 ppm. Consequently, source localization of measurements in physical head phantoms should consider these rods in the forward model.
Evaluation of machine learning methods for seizure prediction in epilepsy
Authors: Eberlein Matthias , Müller Jens , Yang Hongliu , Walz Simon , Schreiber Janina , Tetzlaff Ronald , Creutz Susanne , Uckermann Ortrud , Leonhardt Georg
Published: September 2019

Epilepsy affects about 50 million people worldwide of which one third is refractory to medication. An automated and reliable system that warns of impending seizures would greatly improve patient’s quality of life by overcoming the uncertainty and helplessness due to the unpredicted events. Here we present new seizure prediction results including a performance comparison of different methods. The analysis is based on a new set of intracranial EEG data that has been recorded in our working group during presurgical evaluation. We applied two different methods for seizure prediction and evaluated their performance pseudoprospectively. The comparison of this evaluation with common statistical evaluation reveals possible reasons for overly optimistic estimations of the performance of seizure forecasting systems.
Medical robotics simulation framework for application-specific optimal kinematics
Authors: Böttger Sven , Çallar Tolga-Can , Schweikard Achim , Rückert Elmar
Published: September 2019

Most kinematic structures in robot architectures for medical tasks are not optimal. Further, the workspace and payloads are often oversized which results in high product prices that are not suitable for a clinical technology transfer. To investigate optimal kinematic structures and configurations, we have developed an adaptive simulation framework with an associated workflow for requirement analyses, modelling and simulation of specific robot kinematics. The framework is used to build simple and cost effective medical robot designs and was evaluated in a tool manipulation task where medical instruments had to be positioned precisely and oriented on the patient's body. The model quality is measured based on the maximum workspace coverage according to a configurable scoring metric. The metric generalizes among different human body shapes that are based on anthropometric data from UMTRI Human Shape. This dexterity measure is used to analyze different kinematic structures in simulations using the open source simulation tool V-REP. Therefor we developed simulation and visualization procedures for medical tasks based on a patchwork of size-variant anatomical target regions that can be configured and selectively activated in a motion planning controller. In our evaluations we compared the dexterity scores of a commercial lightweight robot arm with 7 joints to optimized kinematic structures with 6, 7 and 8 joints. Compared to the commercial hardware, we achieved improvements of 59% when using an optimized 6- dimensional robot arm, 64% with the 7-dimensional arm and 96% with an 8-dimensional robot arm. Our results show that simpler robot designs can outperform the typically used commercial robot arms in medical applications where the maximum workspace coverage is essential. Our framework provides the basis for a fully automatic optimization tool of the robot parameters that can be applied to a large variety of problems.
Investigation of a non-invasive venous blood flow measurement device
Authors: Stewart Kent , Dangelmaier Simon , Pott Peter , Anders Jens
Published: September 2019

Venous blood circulation can be restricted due to various conditions commonly indicating a related medical condition. However, current non-invasive methods for determining venous blood flow are limited to be either very inaccurate or expensive. Alternatively, a method to measure sap flow non-invasively in trees is through thermal mass measurement principles. This paper investigates applying the thermal mass flow measurement principle to determine venous blood flow. A simplified finite element model (FEM) and simulation are created to determine the operating behavior and expected response of a thermal mass flow meter with venous blood flow under the skin. An initial prototype of a thermal mass venous blood flow meter is designed using a Peltier-element and RTD thermistors. Initial tests were done on N = 8 subjects identifying the presence of blood flow and, testing the devices basic functionality and performance. The simplified FEM model of venous blood flow proved the thermal mass blood flow device is feasible, and determined the initial characteristics of the first prototype. The initial prototype proved to be functional detecting rises in temperature downstream of +1.4 K (0.8 - 1.8 inter- quartile range) when the blood flow was released (t = 90 s after release), compared to when blood was not flowing. The initial prototype proved to be able to detect the presence of blood flow in all subjects. However, further work is required to increase the differences in temperature values or gradient measured for a change in flow rate so the actual flow rate can be determined.
Impact of lung volume changes on perfusion estimates derived by Electrical Impedance Tomography
Authors: Krueger-Ziolek Sabine , Gong Bo , Laufer Bernhard , Moeller Knut
Published: September 2019

Electrical Impedance Tomography (EIT), an imaging technique which operates non-invasively and without radiation exposure, provides information about ventilation- and cardiac-synchronous (pulsatile) changes in the lung. It is well known, that perfusion within the thorax is influenced by lung volume or intrathoracic pressure. In this observational study, it shall be investigated if this phenomenon can be monitored by EIT. Therefore, the impact of the amount of air within the lung on the pulsatile EIT signal was evaluated by carrying out EIT measurements with a spontaneously breathing lung healthy subject holding the breath at three different inspiratory and three various expiratory volume levels during normal tidal breathing. For EIT data analysis, a region of interest was defined by including lung tissue and excluding the heart region. The EIT data revealed, that the shape and the amplitude of the pulsatile EIT signal (evaluated per heartbeat) during the phases of breath holding were dependent on the enclosed lung volume. For lung volumes > 4 L, the amplitude of the pulsatile EIT signal increased with rising inspiratory level and the shape remained almost unchanged. For lung volumes < 4 L, a change in shape was visible but the amplitude remained more or less the same with decreasing expiratory level. Since the results of this observational study show that the pulsatile EIT signal is influenced by the lung volume, it might be used in future to draw conclusions of cardiacpulmonary interactions or intrathoracic pressure states, benefitting the treatment of intensive care patients.
Modeling and Analysis of a Visual Feedback System to Support Efficient Object Grasping of an EMG-Controlled Prosthetic Hand
Authors: Kara Tolgay , Soliman Masri Ahmad
Published: September 2019

Millions of people around the world have lost their upper limbs mainly due to accidents and wars. Recently in the Middle East, the demand for prosthetic limbs has increased dramatically due to ongoing wars in the region. Commercially available prosthetic limbs are expensive while the most economical method available for controlling prosthetic limbs is the Electromyography (EMG). Researchers on EMG-controlled prosthetic limbs are facing several challenges, which include efficiency problems in terms of functionality especially in prosthetic hands. A major issue that needs to be solved is the fact that currently available low-cost EMG-controlled prosthetic hands cannot enable the user to grasp various types of objects in various shapes, and cannot provide the efficient use of the object by deciding the necessary hand gesture. In this paper, a computer vision-based mechanism is proposed with the purpose of detecting and recognizing objects and applying optimal hand gesture through visual feedback. The objects are classified into groups and the optimal hand gesture to grasp and use the targeted object that is most efficient for the user is implemented. A simulation model of the human hand kinematics is developed for simulation tests to reveal the efficacy of the proposed method. 80 different types of objects are detected, recognized, and classified for simulation tests, which can be realized by using two electrodes supplying the input to perform the action. Simulation results reveal the performance of proposed EMG-controlled prosthetic hand in maintaining optimal hand gestures in computer environment. Results are promising to help disabled people handle and use objects more efficiently without higher costs.
Using Deep Correlation Features to define the Meta Style of Cell Images for Classification
Authors: Grützmacher Simon , Kemkemer Ralf , Curio Cristóbal
Published: September 2019

Digital light microscopy techniques are among the most widely used methods in cell biology and medical research. Despite that, the automated classification of objects such as cells or specific parts of tissues in images is difficult. We present an approach to classify confluent cell layers in microscopy images by learned deep correlation features using deep neural networks. These deep correlation features are generated through the use of gram-based correlation features and are input to a neural network for learning the correlation between them. In this work we wanted to prove if a representation of cell data based on this is suitable for its classification as has been done for artworks with respect to their artistic period. The method generates images that contain recognizable characteristics of a specific cell type, for example, the average size and the ordered pattern.
3d print of heart rhythm model with cryoballoon catheter ablation of pulmonary vein
Authors: Wehsener Sandra , Heinke Matthias , Müssig Robin , Hörth Johannes , Junk Stefan , Schrock Steffen
Published: September 2019

The visualization of heart rhythm disturbance and atrial fibrillation therapy allows the optimization of new cardiac catheter ablations. With the simulation software CST (Computer Simulation Technology, Darmstadt) electromagnetic and thermal simulations can be carried out to analyze and optimize different heart rhythm disturbance and cardiac catheters for pulmonary vein isolation. Another form of visualization is provided by haptic, three-dimensional print models. These models can be produced using an additive manufacturing method, such as a 3d printer. The aim of the study was to produce a 3d print of the Offenburg heart rhythm model with a representation of an atrial fibrillation ablation procedure to improve the visualization of simulation of cardiac catheter ablation. The basis of 3d printing was the Offenburg heart rhythm model and the associated simulation of cryoablation of the pulmonary vein. The thermal simulation shows the pulmonary vein isolation of the left inferior pulmonary vein with the cryoballoon catheter Arctic Front AdvanceTM from Medtronic. After running through the simulation, the thermal propagation during the procedure was shown in the form of different colors. The three-dimensional print models were constructed on the base of the described simulation in a CAD program. Four different 3d printers are available for this purpose in a rapid prototyping laboratory at the University of Applied Science Offenburg. Two different printing processes were used and a final print model with additional representation of the esophagus and internal esophagus catheter was also prepared for printing. With the help of the thermal simulation results and the subsequent evaluation, it was possible to draw a conclusion about the propagation of the cold emanating from the catheter in the myocardium and the surrounding tissue. It was measured that just 3 mm from the balloon surface into the myocardium the temperature dropped to 25 °C. The simulation model was printed using two 3d printing methods. Both methods, as well as the different printing materials offer different advantages and disadvantages. All relevant parts, especially the balloon catheter and the conduction, are realistically represented. Only the thermal propagation in the form of different colors is not shown on this model. Three-dimensional heart rhythm models as well as virtual simulations allow very clear visualization of complex cardiac rhythm therapy and atrial fibrillation treatment methods. The printed models can be used for optimization and demonstration of cryoballoon catheter ablation in patients with atrial fibrillation.
Assessment of 4D Ultrasound Systems for Image-guided Radiation Therapy – Image Quality, Framerates and CT Artifacts
Authors: Ipsen Svenja , Bruder Ralf , García-Vázquez Verónica , Schweikard Achim , Ernst Floris
Published: September 2019

4D ultrasound (4D US) is gaining relevance as a tracking method in radiation therapy (RT) with modern matrix array probes offering new possibilities for real-time target detection. However, for clinical implementation of USguided RT, image quality, volumetric framerate and artifacts caused by the probe’s presence during planning and / or setup computed tomography (CT) must be quantified. We compared three diagnostic 4D US systems with matrix array probes using a commercial wire phantom to measure spatial resolution as well as a calibration and a torso phantom to assess different image quality metrics. CT artifacts were quantified in the torso phantom by calculating the total variation and percentage of affected voxels between a reference CT scan and CT scans with probes in place. We found that state-of-the-art 4D US systems with small probes can fit inside the CT bore and cause fewer metal artifacts than larger probes. US image quality varies between systems and is task-dependent. Volume sizes and framerates are much higher than the commercial guidance solution for US-guided RT, warranting further investigation regarding clinical performance for image guidance.