bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of a Housing First intervention on primary care retention among homeless individuals with mental illness
Authors: Whisler Adam , Dosani Naheed , To Matthew J. , O’Brien Kristen , Young Samantha , Hwang Stephen W.
Published: February 2021

Background

Primary care retention, defined as ongoing periodic contact with a consistent primary care provider, is beneficial for people with serious chronic illnesses. This study examined the effect of a Housing First intervention on primary care retention among homeless individuals with mental illness.

Methods

Two hundred individuals enrolled in the Toronto site of the At Home Project and randomized to Housing First or Treatment As Usual were studied. Medical records were reviewed to determine if participants were retained in primary care, defined as having at least one visit with the same primary care provider in each of two consecutive six-month periods during the 12 month period preceding and following randomization.

Results

Medical records were obtained for 47 individuals randomized to Housing First and 40 individuals randomized to Treatment As Usual. During the one year period following randomization, the proportion of Housing First and Treatment As Usual participants retained in primary care was not significantly different (38.3% vs. 47.5%, p = 0.39). The change in primary care retention rates from the year preceding randomization to the year following randomization was +10.6% in the Housing First group and -5.0% in the Treatment As Usual group.

Conclusion

Among homeless individuals with mental illness, Housing First did not significantly affect primary care retention over the follow-up period. These findings suggest Housing First interventions may need to place greater emphasis on connecting clients with primary care providers.
Epidemiological characterization of symptomatic and asymptomatic COVID-19 cases and positivity in subsequent RT-PCR tests in the United Arab Emirates
Authors: Al-Rifai Rami H. , Acuna Juan , Al Hossany Farida Ismail , Aden Bashir , Al Memari Shamma Abdullah , Al Mazrouei Shereena Khamis , Ahmed Luai A.
Published: February 2021

The coronavirus disease 2019 (COVID-19) cases could be symptomatic or asymptomatic. We (1) characterized and analyzed data collected from the first cohort of reverse transcriptase polymerase chain reaction (RT-PCR)-confirmed COVID-19 cases reported in the Emirate of Abu Dhabi, United Arab Emirates, according to the symptomatic state, and (2) identified factors associated with the symptomatic state. The association between the symptomatic state and testing positive in three subsequent RT-PCR testing rounds was also quantified. Between February 28 and April 8, 2020, 1,249 cases were reported. Sociodemographic characteristics, working status, travel history, and chronic comorbidities of 791 cases were analyzed according to the symptomatic state (symptomatic or asymptomatic). After the first confirmatory test, the results of three subsequent tests were analyzed. The mean age of the 791 cases was 35.6 ± 12.7 years (range: 1–81). Nearly 57.0% of cases were symptomatic. The two most frequent symptoms were fever (58.0%) and cough (41.0%). Symptomatic cases (mean age 36.3 ± 12.6 years) were significantly older than asymptomatic cases (mean age 34.5 ± 12.7 years). Compared with nonworking populations, working in public places (adjusted odds ratio (aOR), 1.76, 95% confidence interval (95% CI): 1.11–2.80), healthcare settings (aOR, 2.09, 95% CI: 1.01–4.31), or in the aviation and tourism sectors (aOR, 2.24, 95% CI: 1.14–4.40) was independently associated with the symptomatic state. Reporting at least one chronic comorbidity was also associated with symptomatic cases (aOR, 1.76, 95% CI: 1.03–3.01). Compared with asymptomatic cases, symptomatic cases had a prolonged duration of viral shedding and consistent odds of ≥2 positive COVID-19 tests result out of the three subsequent testing rounds. A substantial proportion of the diagnosed COVID-19 cases in the Emirate of Abu Dhabi were asymptomatic. Quarantining asymptomatic cases, implementing prevention measures, and raising awareness among populations working in high-risk settings are warranted.
Older adults’ motivations to participate or not in epidemiological research. Qualitative inquiry on a study into dementia in Switzerland
Authors: Fiordelli Maddalena , Fadda Marta , Amati Rebecca , Albanese Emiliano
Published: February 2021

Introduction

High participation in epidemiological studies is crucial for both external and internal validity. Because response rates have declined in recent years, there is an increasing need to understand the drivers and the barriers to research participation. This study aims to uncover the motivations in favour and against participation of older adults to an epidemiological study on health and dementia.

Methods

Twenty-two older adults, who already took part to the preliminary phase of an epidemiological study in Switzerland, agreed to participate to semi-structured, face-to- face interviews. An experienced researcher carried out all interviews in a quiet place of choice of the interviewee either at their domicile or the university, between November 2019 and January 2020. The interviews were audio and video taped, transcribed verbatim, and thematically analysed by two independent researchers.

Results

We identified three main themes for the motivations in favour of participation (i.e. personal, related to the outcomes of research, and altruistic motivations), and we highlighted subthemes for each theme (e.g. personal motivations: curiosity; civic engagement; interest in the topic; trust in science; everyone counts; openness; play the game). Motivations against participation reflected the first two themes, while there was no counterpart for altruistic motivations.

Conclusions

Our thematic analysis revealed that older adults hold specular motivations in favour and against participation to research. Studying jointly motivations in favour and against provides information for recruitment strategies and to overcome barriers to participation, respectively. Participatory action research can inform the design and conduction of and should precede epidemiological studies in older adults, and can potentially contribute to attain high response rates.
Sustainable actions – through events in Brasilia’s perspective
Authors: Souza Iara Oliveira de
Published: February 2021

This paper aims to determine the sustainable actions in the events held in Brasilia, Federal District, as well as to verify the perception of future operating events area of sustainable actions and identify the challenges and benefits that these actions can generate for the events and the community. To achieve the objectives, we used methodology, besides the bibliographic qualitative and quantitative approach research, as well as data collection through two questionnaires to students of the course of Technology in Events and producers that work with sustainability in events. The results showed the understanding of future events managers about the meaning of sustainable actions and showed the possibilities of sustainable actions that they can use in future events. In addition, it identified the social, economic, and environmental importance of the viability of sustainable practices in the events.Â
The complexity of the term sexual tourism: approach to the project to prevent sexual exploitation of children and adolescents
Authors: Paes Elissélia Keila Ramos Leão , Moesch Marutschka Martini , Santos Alessandra Santos dos
Published: February 2021

In large part, attempts to understand tourism produce inadequate typologies that, in the desire to operationalize the phenomenon, hinder the clarity of the concept and encourage the ill-use of tourist destinations. It is in this way, in the context of globalization that sexual exploitation by tourism arises, associated with the exploitation of under ages in situations of social vulnerability, configure a complex approach to the term sexual tourism. In that framework, this article was elaborated with the objective to analyze the theoretical discussion of the term sexual tourism portrayed in the training courses for multipliers of the Project for the Prevention of the Sexual Exploitation of Children and Adolescents in Tourism of the Ministry of Tourism, in partnership with the Center of Excellence in Tourism of the University of Brasília in the light of the complexity of tourism through the participating subjects - the multipliers. The study adopted the research action and the dialectic method to investigate the level of understanding of the acquired knowledge from these trained actors in the different Brazilian regions, after the institutional training received in the years 2016 to 2017, with the perspective of pointing out possible ways to approach new content that allows the rereading of what may be sex tourism, fundamental to the most responsible practices of tourism professionals.
Media Permainan Kotak dan Kartu Misterius (KOKAMI) untuk Meningkatkan Keaktifan Siswa Kelas VII dalam Pembelajaran Bahasa Arab
Authors: Umi Khotijah  , Nisa Syuhda
Published: February 2021

The activeness of students in the process of teaching and learning activities needs attention so that the learning process can produce maximum results. Seeing the inactivity of class VII students of MTs Taruna al-Qur'an Yogyakarta in the Arabic language learning process initiated researchers to conduct experimental research on the use of the mysterious box and card games (KOKAMI) in the Arabic learning process which aims to determine differences in student activity between experimental groups with the control group after the application of KOKAMI media. This type of research is quasi-experimental research (Quasi-Experimental) using a quantitative approach. The research subjects consisted of class VIIA students as the experimental class and class VIIB students as the control class. The data were obtained based on the results of observations, interviews and questionnaires which were then analyzed quantitatively descriptively using paired sample t-test and independent sample t-test with the help of SPSS16. The results showed that Arabic learning activity increased after the implementation of KOKAMI media. Based on the independent sample t-test, it was obtained a post-experimental value of 0.017 <0.05 and a post-control value of 0.017 <0.05, it can be concluded that there was a significant difference between the students' Arabic learning activeness in the experimental class and the control class.

Abstrak: Keaktifan siswa dalam proses kegiatan belajar mengajar perlu mendapat perhatian agar proses pembelajaran dapat membuahkan hasil yang maksimal. Melihat kurang aktifnya siswa kelas VII MTs Taruna al-Qur’an Yogyakarta dalam proses pembelajaran bahasa Arab menginisiasi peneliti dalam melakukan penelitian eksperimen penggunaan media permainan kotak dan kartu misterius (KOKAMI) dalam proses pembelajaran bahasa Arab yang bertujuan untuk mengetahui perbedaan keaktifan siswa antara kelompok eksperimen dengan kelompok kontrol setelah diterapkannya media KOKAMI. Jenis penelitian ini merupakan penelitian eksperimen semu (Quasi Experimental) dengan menggunakan pendekatan kuantitatif. Subyek penelitian terdiri dari siswa kelas VIIA sebagai kelas eksperimen dan siswa kelas VIIB sebagai kelas kontrol. Data diperoleh berdasarkan pada hasil observasi, wawancara dan kuesioner yang kemudian dianalisis secara kuntitatif deskriptif menggunakan uji paired sample t-test dan independent sample t-test dengan bantuan SPSS16. Hasil penelitian menunjukkan bahwa keaktifan belajar bahasa Arab meningkat setelah diterapkannya media KOKAMI. Berdasarkan uji independent sample t-test diperoleh nilai post-eksperimen sebesar 0,017<0,05 dan nilai post-kontrol 0,017<0,05, maka dapat disimpulkan terdapat perbedaan yang signifikan antara keaktifan belajar bahasa Arab siswa kelas eksperimen dengan kelas kontrol.
The Brunn--Minkowski inequality and a Minkowski problem for 𝒜-harmonic Green's function
Authors: Akman Murat , Lewis John , Saari Olli , Vogel Andrew
Published: February 2021

In this article we study two classical problems in convex geometry associated to

𝒜

{\mathcal{A}}

-harmonic PDEs, quasi-linear elliptic PDEs whose structure is modelled on the p-Laplace equation. Let p be fixed with

2
≤
n
≤
p
<
∞

{2\leq n\leq p<\infty}

. For a convex compact set E in

ℝ
n

{\mathbb{R}^{n}}

, we define and then prove the existence and uniqueness of the so-called

𝒜

{\mathcal{A}}

-harmonic Green’s function for the complement of E with pole at infinity. We then define a quantity

C
𝒜

⁢

(
E
)

{\mathrm{C}_{\mathcal{A}}(E)}

which can be seen as the behavior of this function near infinity.
In the first part of this article, we prove that

C
𝒜

⁢

(
⋅
)

{\mathrm{C}_{\mathcal{A}}(\,\cdot\,)}

satisfies the following Brunn–Minkowski-type inequality:

[

C
𝒜

⁢

(

λ
⁢

E
1

+

(

1
-
λ

)

⁢

E
2

)

]

1

p
-
n

≥

λ
⁢

[

C
𝒜

⁢

(

E
1

)

]

1

p
-
n

+

(

1
-
λ

)

⁢

[

C
𝒜

⁢

(

E
2

)

]

1

p
-
n

[\mathrm{C}_{\mathcal{A}}(\lambda E_{1}+(1-\lambda)E_{2})]^{\frac{1}{p-n}}\geq%
\lambda[\mathrm{C}_{\mathcal{A}}(E_{1})]^{\frac{1}{p-n}}+(1-\lambda)[\mathrm{C%
}_{\mathcal{A}}(E_{2})]^{\frac{1}{p-n}}

when

n
<
p
<
∞

{n<p<\infty}

,

0
≤
λ
≤
1

{0\leq\lambda\leq 1}

, and

E
1

,

E
2

{E_{1},E_{2}}

are nonempty convex compact sets in

ℝ
n

{\mathbb{R}^{n}}

. While

p
=
n

{p=n}

then

C
𝒜

⁢

(

λ
⁢

E
1

+

(

1
-
λ

)

⁢

E
2

)

≥

λ
⁢

C
𝒜

⁢

(

E
1

)

+

(

1
-
λ

)

⁢

C
𝒜

⁢

(

E
2

)

,

\mathrm{C}_{\mathcal{A}}(\lambda E_{1}+(1-\lambda)E_{2})\geq\lambda\mathrm{C}_%
{\mathcal{A}}(E_{1})+(1-\lambda)\mathrm{C}_{\mathcal{A}}(E_{2}),

where

0
≤
λ
≤
1

{0\leq\lambda\leq 1}

and

E
1

,

E
2

{E_{1},E_{2}}

are convex compact sets in

ℝ
n

{\mathbb{R}^{n}}

containing at least two points.
Moreover, if equality holds in the either of the above inequalities for some

E
1

{E_{1}}

and

E
2

{E_{2}}

, then under certain
regularity and structural assumptions on

𝒜

{\mathcal{A}}

we show that these two sets are homothetic.
The classical Minkowski problem asks for necessary and sufficient conditions on a non-negative
Borel measure on the unit sphere

𝕊

n
-
1

{\mathbb{S}^{n-1}}

to be the surface area
measure of a convex compact set in

ℝ
n

{\mathbb{R}^{n}}

under the Gauss mapping for the boundary of this convex set.
In the second part of this article we study a Minkowski-type problem for a measure
associated to the

𝒜

{\mathcal{A}}

-harmonic Green’s function for the complement of
a convex compact set E when

n
≤
p
<
∞

{n\leq p<\infty}

. If

μ
E

{\mu_{E}}

denotes this measure,
then we show that necessary and sufficient conditions for existence under this setting are
exactly the same conditions as in the classical Minkowski problem. Using the Brunn–Minkowski
inequality result from the first part, we also show that this problem has a unique solution up to translation.
Impact of artificial airway resistances on regional ventilation distribution during airway closure
Authors: März Melanie , Howe Sarah , Laufer Bernhard , Moeller Knut , Krueger-Ziolek Sabine
Published: February 2021

Electrical impedance tomography (EIT), a noninvasive and radiation-free imaging technique can be used in pulmonary function monitoring for determining regional ventilation distribution within the lung. Gold standard in pulmonary function monitoring is spirometry/body plethysmography, a method using forced breathing maneuvers to obtain global lung function parameters. However, this method is heavily dependent on the cooperation of the patients. Within this observational study, a method under normal breathing was tested with 5 healthy volunteers, which provides regional information about ventilation distribution. The occlusion method Rocc, a method for determining airway resistance, was used to create a short-term airway closure. Regional ventilation during the airway closure was examined with EIT. Simultaneously four different artificial airway resistances were used to simulate airway obstructions. Results show that EIT in combination with the ROcc method is suitable for the detection of regional differences in ventilation during airway closure for all four artificial airway resistances. Although the sum of relative impedances at the end of the shutter maneuver are smaller (nearly -0.100 AU) for the airway resistances Ø 12.5 mm, Ø 10.5 mm and Ø 9.5 mm than for the smallest one with Ø 30.0 mm (~ -0.070 AU), the changes in impedance from the start to the end of the shutter maneuver differs only slightly between the four artificial airway resistances. All impedance changes are in the range of 0.100 to 0.130 AU. The combination of EIT and the ROcc method provides not only global parameters such as airway resistance under normal breathing conditions, but also results of regional ventilation, which could enable the identification of areas affected by airway obstructions. However, the obtained results indicate that EIT might be a useful tool in the diagnosis and follow-up of obstructive lung diseases.
A Deep-Learning Approach to Detect Fiducials in Planar X-Ray Images for Undistortion of Conventional C-Arm Images
Authors: Alvarez-Gomez Julio , Arne Spieß , Hubert Roth , Jürgen Wahrburg
Published: February 2021

In some applications such as 2D-3D registration, undistorted images are required to achieve optimal results. These types of images can be obtained from a distortion-free C-arm (flat-panel detector) or by undistorting the images given from a conventional C-arm (analogue image intensifier.) Undistorting images require a plate with fiducials connected to the C-arm detector. Detecting fiducials is affected by differences in the image contrast due to elements in the background. Therefore, the results vary from image to image and could require manual tuning of parameters. We propose a deep-learning approach for detecting undistortion-platefiducials in X-ray images to overcome the drawbacks previously stated. With an undistortion plate, we took 1120 XRays using a C-arm in different poses. Every X-ray is afterward cut into 60 sub-images. We used these sub-images for training a convolutional neural network (CNN). Comparing the CNN and a traditional image processing method based on the Hough Circle algorithm, we found that the detected fiducials using the traditional method give a similar fiducial positioning error. Nevertheless, the fiducial detection rate goes from 89.7% using the traditional method to 100% with the developed CNN. The results show that the detection rate and precision of our deep-learning approach guarantee the undistortion of conventional C-Arm images.
Automated Cephalometric Landmark Localization using a Coupled Shape Model
Authors: Wirtz Andreas , Lam Julian , Wesarg Stefan
Published: February 2021

Cephalometric analysis is an important method in orthodontics for the diagnosis and treatment of patients. It is performed manually in clinical practice, therefore automation of this time consuming task would be of great assistance. In order to provide dentists with such tools, a robust and accurate identification of the necessary landmarks is required. However, poor image quality of lateral cephalograms like low contrast or noise make this task difficult. In this paper, an approach for automatic landmark localization is presented and used to find 19 landmarks in lateral cephalometric images. An initial predicting of the individual landmark locations is done by using a 2-D coupled shape model to utilize the spatial relation between landmarks and other anatomical structures. These predictions are refined with a Hough Forest to determine the final landmark location. The approach achieves competitive performance with a successful detection rate of 70.24% on 250 images for the clinically relevant 2mm accuracy range.
Transfer activities for cardiovascular, ophthalmologic and otolaryngologic medical device innovations
Authors: Grabow Niels , Senz Volkmar , Schmitz Klaus-Peter
Published: February 2021

The consortium RESPONSE is a cooperation of partners from science and industry within the BMBFProgram “Twenty20 - Partnership for Innovation”, 2014- 2021. Current efforts are being made towards the transfer of new products, technologies and processes in the field of medical devices. Here, RESPONSE is focusing on novel concepts of implantable medical devices for cardiovascular, ophthalmologic and otolaryngologic application. Platform technology approaches, such as drug delivery systems for responsive functionalized implants or smart implant technologies, are being used to enable new applications.
Wearable Pressure Sensing for Vojta Therapy Guidance
Authors: Steffen Büchner , Christian Gibas , Rainer Brück , Nina Nemcová , Wolfram Müller , Katrin Schürholz
Published: February 2021

The authors propose a glove with pressure sensitive fingertips and muscle tension detection of the thumb to aid in the physiotherapy of infants, children and adults according to Vojta. The therapy has to be carried out at home by the parents of children with cerebral palsy, or other movement disturbances up to 4 times per day. Often, parents struggle to carry out the practices because of insecurities regarding the therapy’s proper application. The presented glove is tailored towards the specific needs of Vojta therapy, e.g. flexibility and small sensor size, and can help parents gather objective data on their therapy application at home. It has been tested in multiple therapy sessions on adult probands and seems to be a suitable tool to support parents and therapists in training alike. Additionally, the results of the accompanied therapy sessions provide arguments against what the critics have often cited about the painfulness of the therapy.
Sensitivity analysis of a computer model of neonatal oxygen transport
Authors: Huttova Veronika , Rafl Jakub , Bachman Thomas E. , Kudrna Petr , Rozanek Martin , Möller Knut
Published: February 2021

Computer models of neonatal oxygenation could serve as a tool for a comprehensive comparison of closed-loop automated oxygen control systems. The behaviour of such models depends, besides the input data of the inspired fraction of oxygen and the premature infant's breath pattern, on internal parameters of the model. The aim of this study was to perform a sensitivity analysis of a computer model of neonatal oxygen transport to clarify the influence of its internal physiological parameters on the output signal of peripheral oxygen saturation (SpO2). We performed a multi-parameter sensitivity analysis using Monte Carlo simulations for randomly generated values of eight internal parameters. The influence on the model output SpO2 signal was evaluated using five characteristics of the output signal. The relations between the parameters and the output characteristics were displayed using scatter plots and analysed by linear correlation, standardized regression, and partial correlation. The main result of the study is that in our model the oxygen consumption in the tissue and the cardiac output have the greatest influence on the SpO2 drop and minimal SpO2 value during simulated desaturation. The rate of development of desaturation and its duration are most affected by the diffusion resistance of the alveolar-capillary membrane. The results of the sensitivity analysis will help to optimize the performance of the computer model of neonatal oxygen transport.
A rule-based expert system for real-time feedback-control in deep brain stimulation
Authors: Bremm Rene Peter , Koch Klaus Peter , Krüger Rejko , Hertel Frank , Gonçalves Jorge
Published: February 2021

Programming in deep brain stimulation (DBS) is often a labour-intensive process. Although automatic closed-loop stimulation has recently been receiving considerable attention, it is still far from clinical settings. Testing in-loop stimulation in a clinical setting is extremely challenging due to manual programming and the lack of synchronisation between stimulation and monitoring devices. In this work, we present a simple rulebased expert system to test feedback-controlled DBS in a clinical setting. The new application operates in closed-loop with the physician as acting person and real-time feedback from an accelerometer. Patients with movement disorders such as in essential tremor announce an individually acceptable level of tremor as a boundary condition for control. As a proof-of-concept, the expert system provides continuous recommendations of stimulation parameters and guides the physician to increase or decrease DBS amplitude by capturing tremor acceleration power on the patients’ forearms. The introduced application considers the technical and practical aspects in a clinical setting. Data obtained from test subjects provide insight into tremor dynamics. We demonstrate the clinical applicability of the rule-based control system for future research focusing on tremor dynamics and inloop stimulation. Finally, a telemetry streaming system could provide the interface for the application of automatic tremor control without the physician as acting person.
Efficient Body Registration Using Single-View Range Imaging and Generic Shape Templates
Authors: Çallar Tolga-Can , Rueckert Elmar , Böttger Sven
Published: February 2021

Computer-aided medical systems, e.g. in the fields of medical robotics or image-based assistance, are continuously investigated to overcome human limitations concerning perception, memory or dexterity. A common requirement of such systems is the availability of a digital model describing the patient’s position and morphology during a procedure. Operational complexity and technical limitations of established 3D imaging methods leave clinical settings in need of a method for the fast acquisition of a three-dimensional body surface representation. For this purpose, we propose an unsupervised and efficient body registration pipeline based on the markerless elastic registration and completion of single-view stereo range images of the body surface with statistical parametric body shape templates. Initial results show a promising representative quality of the models generated through the registration process with submillimetric fitting accuracy and realistic surface morphology, indicating the general feasibility of our approach as an instant body registration method for automated medical and biometric applications.
Cross-sectional analysis of tubular polymer semi-finished products using ultrasound in comparison with other measuring methods
Authors: Sahmel Olga , Siewert Stefan , Schmidt Wolfram , Schmitz Klaus-Peter , Grabow Niels
Published: February 2021

In the sector of biomedical engineering and implant technology, high-precision geometry is often decisive for successful end product functionalization. Especially in the production of tubular polymer semi-finished products, e.g. for stent fabrication, it is important to assure the desired parameters, such as inner and outer diameter and wall thickness. Within the current study we analyzed semifinished products for manufacturing of polymeric stents using three different methods. Biodegradable poly-L-lactide (PLLA) tubes were examined by means of micro computed tomography, ultrasonic scanning and scanning electron microscopy. The final evaluation presents clear advantages of the ultrasonic measuring method for the measurement of outer and inner diameter and wall thickness.
Investigations of flow alteration of commissural misalignment of TAVR using Particle Image Velocimetry
Authors: Borowski Finja , Oldenburg Jan , Pfensig Sylvia , Kaule Sebastian , Siewert Stefan , Schmitz Klaus-Peter , Stiehm Michael
Published: February 2021

Due to the raising number of TAVR implantations (transcatheter aortic valve replacement), tests for durability and prevention of associated diseases are becoming increasingly important. Not only the anatomy but also the positioning of the TAVR is decisive for its clinical performance. A misalignment in the circumferential direction can influence the flow in the sinus and thus inhibit the blood supply of the coronary arteries and influence the thrombosis potential. Therefore, the modification of the flow field is investigated in this study. For the characterization of the flow fields the measuring method of digital particle image velocimetry is used. A hydraulic circulation model is used to generate physiological flow and pressure conditions. Additionally, an aortic root model with Sinus Valsalvae, which represents the implantation environment, was developed. A prototype of a TAVR was implanted aligned to the commissure lines of the native valve leaflets on the one hand, and misaligned by 60 degree to the commissure of the native valves on the other hand. By determining the velocity vector fields, it could be shown that implantation of the TAVR with a commissureal misalignment influences the flow around the leaflets. A comparison of the flow fields shows that different recirculation areas occur. This is also indicated by a comparison of the mean velocities in the sinus and the observed shear rates. The influence of the altered flow field on the thrombosis and hemolysis potential should be investigated in future studies.
Degradable dual co-electrospun polyester based nonwovens for guided tissue regeneration
Authors: Oschatz Stefan , Reske Thomas , Schmitz Klaus-Peter , Illner Sabine , Markhoff Jana , Eickner Thomas , Grabow Niels
Published: February 2021

In this study, initial experiments are presented regarding the suitability of polyester based nonwoven composite materials for guided tissue regeneration based on degradation. The in vitro degradation of poly(lactic-coglycolic acid)/polydioxanone and polycaprolactone/ polydioxanone mats has been performed under accelerated condition in alkaline glycine buffer at 50 °C for 21 days. The degradation of the materials has been characterized regarding total mass loss and macroscopic morphological changes, as well as determination of the molecular weight degradation via GPC experiments.
Immobilizing hydrolytic active Papain on biodegradable PLLA for biofilm inhibition in cardiovascular applications
Authors: Teske Michael , Kießlich Tina , Fischer Julia , Bahl Hubert , Wulf Katharina , Eickner Thomas , Grabow Niels , Illner Sabine
Published: February 2021

The use of biomaterials in medicine is becoming increasingly important. One of the main concerns is the foreign body associated infection caused by direct microbial contamination or clinical infections. The bacterial biofilm formation on biomaterials depends on their surface properties. Therefore, several anti-adhesive surface modifications were developed. Nevertheless, the demand for antimicrobial agents that prevent bacterial colonisation is still largely unmet. The immobilization of active antimicrobial agents, such as antibacterial peptides or enzymes, offers a potential approach to achieve long-lasting effectiveness. In this investigation, the hydrolytic enzyme papain with its published antibacterial activity was covalently immobilized on the well-established biodegradable biomaterial poly-L-lactic acid (PLLA). For the characterization of the enzymes on the PLLA surfaces, the protein content and enzyme activity were determined. A biofilm assay was performed to test the effect of the papain-modified PLLA samples on the biofilm-forming bacterial strain Clostridioides difficile, one of the most frequently occurring human nosocomial pathogens. The investigated hydrolytic enzyme papain could be immobilized by coupling via the crosslinker EDC to the PLLA surface. Detection was performed by determination of the amount of protein and the reduced biofilm growth after 24 h and 72 h compared to the reference.
PEGDA drug delivery scaffolds prepared with UV curing process
Authors: Rekowska Natalia , Konasch Jan , Riess Alexander , Mau Robert , Eickner Thomas , Seitz Hermann , Grabow Niels , Teske Michael
Published: February 2021

Individually tailored drug delivery systems (DDSs) are considered one of the most promising therapeutic tools for the creation of safe and effective treatments. DDSs as a novel approach should be beneficial in curing systemic as well as local ailments, where a high topical concentration of the drug and a reduction of side effects are desirable. It could also be favorable for patients requiring customized treatments, showing atypical profiles of drug metabolism. Development of particular drug delivery devices require the selection of a suitable scaffold material, which should exhibit proper mechanical and biological properties, but also enable adjustment of the drug release according to a specific need. Thus, it is extremely important to expand the knowledge concerning potential DDS components. Poly(ethylene glycol) diacrylate (PEGDA) according to its properties can be easily used as a DDS resin and shaped into a desired structure with the employment of techniques based on photopolymerization, including some novel 3D printing techniques. As a continuation of our previous works, in this paper drug release studies from conventionally prepared PEGDA scaffolds are presented. We have shown that in PEGDA materials, the release profile of the low molecular weight model drug acetylsalicylic acid can be altered by water content. PEGDA as a delivery material should be further investigated to specify its potential as a comonomer and a matrix for pharmaceutical agents.
Recognition of tenogenic differentiation using convolutional neural network
Authors: Dursun Gözde , Balkrishna Tandale Saurabh , Eschweiler Jörg , Tohidnezhad Mersedeh , Markert Bernd , Stoffel Marcus
Published: February 2021

Methodologies to assess stem cell differentiation in the culturing state are needed for regenerative medicine and tissue engineering techniques. In recent years, convolutional neural networks (CNNs), a class of deep neural networks, have made impressive advancements in image-based classification, recognition and detection tasks. CNNs have been introduced as a non-invasive cell characterization method by learning features directly from image data of unlabeled cells. Furthermore, this approach serves as a rapid and inexpensive methodology with high performance compared to traditional techniques that require complex laboratory procedures including antibody staining and gene expression analysis. Here, we studied the potential of the CNNs approach to recognize stem cell differentiation based on cell morphology utilizing phasecontrast microscopy images.We have examined the differentiation potential of bone marrow mesenchymal stem cells (BMSCs) into tenocytes, with the treatment of bone morphogenetic protein-12 (BMP-12). After treatment, the phase-contrast images of cells were obtained directly from cell culture flasks to train CNN and the differentiated phenotype of stem cells was characterized by immunostaining. CNN was able to classify the cells into three groups including non-stem cells (chondrocytes), stem cells (BMSCs) and differentiated stem cells (tenocytes) based on their morphology with 92.2 % accuracy. The presented study revealed that CNN performed faster and non-invasive cell classification task compared to traditional methodologies.
Smart 4D-printed implants and instruments
Authors: Wild Michael de , Dany Sebastian , John Christoph , Schuler Felix
Published: February 2021

Selective laser melting (SLM) was used to manufacture smart programmed structures with customized properties made of biocompatible NiTi shape-memory alloy. A series of helixes was produced with systematically varied SLM process parameters Laser Exposure Time and Laser Power in order to specifically change the thermo-mechanical material properties of the 3D-structures. This innovation opens up the possibility to adjust the NiTi phase transformation temperature during the manufacturing process. This controllable property determines which of the two crystallographic phases martensite or austenite is present at a certain operating temperature and allows the mechanical properties to be adjusted: martensitic devices are soft and pseudo-plastic due to the shape-memory effect, whereas austenitic structures are pseudo-elastic. In a further step, the SLM process parameters were locally varied within 4Dprinted twin-helixes. As a result, the phases, respectively the mechanical properties of a single component were adjusted at different locations. The ratio of elastic to plastic deformation and the spring constant of the helix can be locally controlled. This allows, for example, the spatio-temporal programming of 3D-printed surgical instruments or implants that are stimuliresponsive.
Measurement of respiratory rate with inertial measurement units
Authors: Beck Simon , Laufer Bernhard , Krueger-Ziolek Sabine , Moeller Knut
Published: February 2021

Demographic changes and increasing air pollution entail that monitoring of respiratory parameters is in the focus of research. In this study, two customary inertial measurement units (IMUs) are used to measure the breathing rate by using quaternions. One IMU was located ventral, and one was located dorsal on the thorax with a belt. The relative angle between the quaternion of each IMU was calculated and compared to the respiratory frequency obtained by a spirometer, which was used as a reference. A frequency analysis of both signals showed that the obtained respiratory rates vary slightly (less than 0.2/min) between the two systems. The introduced belt can analyse the respiratory rate and can be used for surveillance tasks in clinical settings.
Raman Spectroscopy to Characterize Bladder Tissue for Multidimensional Diagnostics of Cancer in Urology
Authors: Krafft C. , Guo S. , Bocklitz T. , Popp J. , Bronsert P. , Miernik A.
Published: February 2021

Fiber optic Raman spectroscopy offers labelfree identification of cancer in the bladder under in vivo conditions. However, state-of-the-art Raman technology does not enable to scan the entire bladder wall. Our multidimensional approach within the project Uro-MDD combines panoramic 3D-image reconstruction of white light cystoscopy and fluorescence lifetime imaging to define regions of interest for Raman-assisted diagnostics. First Raman results are presented from human control and cancer bladder specimens that demonstrated how to obtain specific molecular information. Such Raman images can be used in a clinical setting to determine cancer margins and the resection status. Fiber probes are under development to translate the technique to in vivo screening.
Simulating a Ground Truth for Transit Time Analysis of Indicator Dilution Curves
Authors: Reiß Michael , Naber Ady , Nahm Werner
Published: February 2021

Transit times of a bolus through an organ can provide valuable information for researchers, technicians and clinicians. Therefore, an indicator is injected and the temporal propagation is monitored at two distinct locations. The transit time extracted from two indicator dilution curves can be used to calculate for example blood flow and thus provide the surgeon with important diagnostic information. However, the performance of methods to determine the transit time Δt cannot be assessed quantitatively due to the lack of a sufficient and trustworthy ground truth derived from in vivo measurements. Therefore, we propose a method to obtain an in silico generated dataset of differently subsampled indicator dilution curves with a ground truth of the transit time. This method allows variations on shape, sampling rate and noise while being accurate and easily configurable. COMSOL Multiphysics is used to simulate a laminar flow through a pipe containing blood analogue. The indicator is modelled as a rectangular function of concentration in a segment of the pipe. Afterwards, a flow is applied and the rectangular function will be diluted. Shape varying dilution curves are obtained by discrete-time measurement of the average dye concentration over different cross-sectional areas of the pipe. One dataset is obtained by duplicating one curve followed by subsampling, delaying and applying noise. Multiple indicator dilution curves were simulated, which are qualitatively matching in vivo measurements. The curves temporal resolution, delay and noise level can be chosen according to the requirements of the field of research. Various datasets, each containing two corresponding dilution curves with an existing ground truth transit time, are now available. With additional knowledge or assumptions regarding the detection-specific transfer function, realistic signal characteristics can be simulated. The accuracy of methods for the assessment of Δt can now be quantitatively compared and their sensitivity to noise evaluated.
Measurement of the retinal irradiation exposure during diaphanoscopic illumination
Authors: Sieber Nicole , Kölbl Phillip , Lingenfelder Christian , Stucke-Straub Kathrin , Kupferschmid Sebastian , Hessling Martin
Published: February 2021

For the visualisation of the intraocular space it is essential to illuminate the inside of the eye. One illumination approach is diaphanoscopy, in which the light of an extraocular source is transmitted through the tissue layers of the eyewall. The transmission properties of these tissues and their irradiation load depend on applied diaphanoscope contact pressure. However, excessive illumination can lead to irreversible photochemical and thermal damage to the retina. In diaphanoscopic illumination, the retina is particularly at risk due to its proximity to the light source. Therefore, the photochemical and thermal retinal hazards, resulting from direct transmitted light through the eyewall, are determined for different applied pressures of the diaphanoscope on the eye (15, 65 and 115 kPa). The study is performed on porcine eyes with different pigmentation. So, the difference in intraocular irradiance, photochemical and thermal hazards, as well as the maximal exposure time is also examined for different pigmentations. For less pigmented eyes the irradiance inside the eye, the photochemical and the thermal hazard are higher than for higher pigmented eyes. The values also become significantly higher for increasing applied pressure with the diaphanoscope but do not exceed given limits in the standard DIN EN ISO 15004-2: 2014.
Developing an Intuitive and Feasible Setup for In-room Control During MRI-guided Interventions
Authors: Reich C. Martin , Unger Michael , Melzer Leon , Jochimsen Thies , Sattler Bernhard , Sabri Osama , Melzer Andreas
Published: February 2021

Magnetic resonance image (MRI)-guidance for minimally invasive interventions instead of CT-guidance is a promising technique to reduce radiation exposure for both patients and clinicians. Technical challenges have to be managed in order to meet safety regulations while enabling inroom system control and communication. Using nonproprietary software and hardware, several gradations for a setup for interventional MRI were elaborated. Eventually, a quickly and easily installable setup was established for technical support during MRI-guided interventions in the PET/MRI suite at the Department of Nuclear Medicine at University Hospital Leipzig. It is adaptable for most MRI suites.
Automatic Detection and Classification of Cough Events Based on Deep Learning
Authors: Hossein Tabatabaei Seyed Amir , Augustinov Gabriela , Gross Volker , Sohrabi Keywan , Fischer Patrick , Koehler Ulrich
Published: February 2021

In this paper, a deep learning approach for classification of cough sound segments is presented. The architecture of the network is based on a pre-trained network and the spectrogram images of three recording channels have been extracted for the sake of training the network. The classification accuracy based on three recording channels is 92% for a binary classification model and the network converges fast. Two classification models based on binary and multi-class problems are proposed. Relevant classification parameters including the Receiver Operating Characteristic (ROC) curve are reported.
Standardization of in vitro testing for cardiovascular implants in the era of European Medical Device Regulation
Authors: Schmidt Wolfram , Brandt-Wunderlich Christoph , Stiehm Michael , Kaule Sebastian , Siewert Stefan , Bock Andrea , Schmitz Klaus-Peter , Kurzhals Anja , Grabow Niels
Published: February 2021

In case of cardiovascular implants classified as class III medical products there is a specific responsibility for manufacturers as well as regulatory authorities to follow international standards to guarantee for safety and efficacy. Fast developments of science and technology as well as novel clinical findings create permanent needs to match the standardization. Therefore, a set of international standards is analyzed with respect to their use for particular coronary drug-eluting stents and artificial heart valves. It was found that standards (ISO, ASTM) exist for general requirements on passive implants, but also specifically relate to arterial stents, stent grafts, bioresorbable and drug-eluting stents, as well as artificial heart valves. New work items address new methods for characterization of coating integrity, particulate matter and simulated use testing. European Medical Device Regulation (MDR) requires technical expertise and capacity at Notified Bodies supported by independent test laboratories. Generally, the interest in standardization from industry, test laboratories and authorities is high, but more input from medical experts would further improve the value of standardization and its relevance for safe and even more effective implants.
Automatic Detection of Pediatric Craniofacial Deformities using Convolutional Neural Networks
Authors: Sonja Wattendorf , Amir Hossein Tabatabaei Seyed , Patrick Fischer , Hans-Peter Hans-Peter , Wilbrand Martina , Wilbrand Jan-Falco , Keywan Sohrabi
Published: February 2021

The geometric shape of our skull is very important, not only from an esthetic perspective, but also from medical viewpoint. However, the lack of designated medical experts and wrong positioning is leading to an increasing number of abnormal head shapes in newborns and infants. To make screening and therapy monitoring for these abnormal shapes easier, we develop a mobile application to automatically detect and quantify such shapes. By making use of modern machine learning technologies like deep learning and transfer learning, we have developed a convolutional neural network for semantic segmentation of bird’s-eye view images of child heads. Using this approach, we have been able to achieve a segmentation accuracy of approximately 99 %, while having sensitivity and specificity of above 98 %. Given these promising results, we will use this basis to calculate medical parameters to quantify the skull shape. In addition, we will integrate the proposed model into a mobile application for further validation and usage in a real-world scenario.