TY  - JOUR
A1  - Frotscher, Ralf
A1  - Staat, Manfred
T1  - Stresses produced by different textile mesh implants in a tissue equivalent
JF  - BioNanoMaterials
N2  - Two single-incision mini-slings used for treating urinary incontinence in women are compared with respect to the stresses they produce in their surrounding tissue. In an earlier paper we experimentally observed that these implants produce considerably different stress distributions in a muscle tissue equivalent. Here we perform 2D finite element analyses to compare the shear stresses and normal stresses in the tissue equivalent for the two meshes and to investigate their failure behavior. The results clearly show that the Gynecare TVT fails for increasing loads in a zipper-like manner because it gradually debonds from the surrounding tissue. Contrary to that, the tissue at the ends of the DynaMesh-SIS direct may rupture but only at higher loads. The simulation results are in good agreement with the experimental observations thus the computational model helps to interpret the experimental results and provides a tool for qualitative evaluation of mesh implants.
Y1  - 2014
U6  - https://doi.org/10.1515/bnm-2014-0003
SN  - 2191-4672 (E-Journal); 2193-066X (E-Journal); 0011-8656 (Print); 1616-0177 (Print); 2193-0651 (Print)
VL  - 15
IS  - 1-2
SP  - 25
EP  - 30
PB  - De Gruyter
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Vu, Duc Khoi
A1  - Staat, Manfred
A1  - Tran, Ich Thinh
T1  - Analysis of pressure equipment by application of the primal-dual theory of shakedown
JF  - Communications in Numerical Methods in Engineering. 23 (2007), H. 3
Y1  - 2007
SN  - 1069-8299
SP  - 213
EP  - 225
ER  - 
TY  - JOUR
A1  - Staat, Manfred
A1  - Vu, Khoi Duc
T1  - Limit loads of circumferentially flawed pipes and cylindrical vessels under internal pressure
JF  - International Journal of Pressure Vessels and Piping. 83 (2006), H. 3
Y1  - 2006
SN  - 0308-0161
SP  - 188
EP  - 196
ER  - 
TY  - JOUR
A1  - Jung, Alexander
A1  - Staat, Manfred
T1  - Erratum to "Modeling and simulation of human induced pluripotent stem cell-derived cardiac tissue" [GAMM-Mitteilungen, (2019), 42, 4, 10.1002/gamm.201900002]
JF  - GAMM-Mitteilungen
Y1  - 2020
U6  - https://doi.org/10.1002/gamm.202000011
SN  - 1522-2608
N1  - Refers to: Modeling and simulation of human induced pluripotent stem cell-derived cardiac tissue. Alexander Jung, Manfred Staat.
Volume 42, Issue 4. GAMM-Mitteilungen, 2019. https://doi.org/10.1002/gamm.201900002
VL  - 43
IS  - 4
PB  - Wiley-VCH GmbH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Staat, Manfred
T1  - Shakedown and ratchetting under tension-torsion loadings: analysis and experiments
N2  - Structural design analyses are conducted with the aim of verifying the exclusion of ratchetting. To this end it is important to make a clear distinction between the shakedown range and the ratchetting range. The performed experiment comprised a hollow tension specimen which was subjected to alternating axial forces, superimposed with constant moments. First, a series of uniaxial tests has been carried out in order to calibrate a bounded kinematic hardening rule. The load parameters have been selected on the basis of previous shakedown analyses with the PERMAS code using a kinematic hardening material model. It is shown that this shakedown analysis gives reasonable agreement between the experimental and the numerical results. A linear and a nonlinear kinematic hardening model of two-surface plasticity are compared in material shakedown analysis.
KW  - Einspielen <Werkstoff>
KW  - Einspielen
KW  - Ratchetting
KW  - Zug-Druck Belastung
KW  - shakedown
KW  - ratchetting
KW  - tension–torsion loading
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Staat, Manfred
A1  - Vu, Duc-Khoi
T1  - Limit analysis of flaws in pressurized pipes and cylindrical vessels. Part I: Axial defects
JF  - Engineering Fracture Mechanics. 74 (2007), H. 3
Y1  - 2007
SN  - 0013-7944
SP  - 431
EP  - 450
ER  - 
TY  - JOUR
A1  - Vant, Christianne
A1  - Staat, Manfred
A1  - Baroud, Gamal
T1  - Percutaneous Vertebroplasty: A Review of Two Intraoperative Complications
JF  - Bioengineering in Cell and Tissue Research / Artmann, Gerhard M. ; Chien, Shu (Eds.)
Y1  - 2008
SN  - 978-3-540-75408-4
SP  - 527
EP  - 539
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Vu, Duc Khoi
A1  - Staat, Manfred
T1  - Shakedown analysis of structures made of materials with temperature-dependent yield stress
JF  - International Journal of Solids and Structures. 44 (2007), H. 13
Y1  - 2007
SN  - 0020-7683
SP  - 4524
EP  - 4540
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Carnelli, I.
A1  - Vasile, M.
T1  - Optimizing low-thrust gravity assist interplanetary trajectories using evolutionary neurocontrollers / I. Carnelli ; B. Dachwald ; M. Vasile
JF  - IEEE Congress on Evolutionary Computation, 2007 : CEC 2007 ; 25 - 28 September 2007, Singapore
Y1  - 2007
SN  - 978-1-424-41339-3
N1  - ISBN 10: 1-424-41339-7 ; IEEE Congress on Evolutionary Computation <2007, Singapore> ; 	Institute of Electrical and Electronics Engineers ; Nebent: CEC 2007 ; Parallel als Online-Ausg. erschienen
SP  - 965
EP  - 972
PB  - IEEE Service Center
CY  - Piscataway, NJ
ER  - 
TY  - JOUR
A1  - Doorschodt, B. M.
A1  - Schreinemachers, M. C. J. M.
A1  - Behbahani, Mehdi
A1  - Florquin, S.
A1  - Weis, J.
A1  - Staat, Manfred
A1  - Tolba, R. H.
T1  - Hypothermic machine perfusion of kidney grafts: which pressure is preferred
JF  - Annals of Biomedical Engineering. 39 (2011), H. 3
Y1  - 2011
SN  - 1573-9686
SP  - 1051
EP  - 1059
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Digel, Ilya
A1  - Zerlin, Kay
A1  - Temiz Artmann, Aysegül
A1  - Engels, S.
T1  - Protein dynamics in thermosensation
JF  - Regenerative medicine. 2 (2007), H. 5
Y1  - 2007
SN  - 1746-0751
N1  - Proceedings of the 3rd World Congress on Regenerative Medicine. October 18-20, 2007. Leipzig, Germany
SP  - 533
EP  - 533
ER  - 
TY  - JOUR
A1  - Bhattarai, Aroj
A1  - Staat, Manfred
T1  - Modelling of Soft Connective Tissues to Investigate Female Pelvic Floor Dysfunctions
JF  - Computational and Mathematical Methods in Medicine
N2  - After menopause, decreased levels of estrogen and progesterone remodel the collagen of the soft tissues thereby reducing their stiffness. Stress urinary incontinence is associated with involuntary urine leakage due to pathological movement of the pelvic organs resulting from lax suspension system, fasciae, and ligaments. This study compares the changes in the orientation and position of the female pelvic organs due to weakened fasciae, ligaments, and their combined laxity. A mixture theory weighted by respective volume fraction of elastin-collagen fibre compound (5%), adipose tissue (85%), and smooth muscle (5%) is adopted to characterize the mechanical behaviour of the fascia. The load carrying response (other than the functional response to the pelvic organs) of each fascia component, pelvic organs, muscles, and ligaments are assumed to be isotropic, hyperelastic, and incompressible. Finite element simulations are conducted during Valsalva manoeuvre with weakened tissues modelled by reduced tissue stiffness. A significant dislocation of the urethrovesical junction is observed due to weakness of the fascia (13.89 mm) compared to the ligaments (5.47 mm). The dynamics of the pelvic floor observed in this study during Valsalva manoeuvre is associated with urethral-bladder hypermobility, greater levator plate angulation, and positive Q-tip test which are observed in incontinent females.
Y1  - 2018
U6  - https://doi.org/10.1155/2018/9518076
SN  - 1748-6718
VL  - 2018
IS  - Article ID 9518076
SP  - 1
EP  - 16
PB  - Hindawi
CY  - New York, NY
ER  - 
TY  - JOUR
A1  - Colombo, Daniele
A1  - Drira, Slah
A1  - Frotscher, Ralf
A1  - Staat, Manfred
T1  - An element-based formulation for ES-FEM and FS-FEM models for implementation in standard solid mechanics finite element codes for 2D and 3D static analysis
JF  - International Journal for Numerical Methods in Engineering
N2  - Edge-based and face-based smoothed finite element methods (ES-FEM and FS-FEM, respectively) are modified versions of the finite element method allowing to achieve more accurate results and to reduce sensitivity to mesh distortion, at least for linear elements. These properties make the two methods very attractive. However, their implementation in a standard finite element code is nontrivial because it requires heavy and extensive modifications to the code architecture. In this article, we present an element-based formulation of ES-FEM and FS-FEM methods allowing to implement the two methods in a standard finite element code with no modifications to its architecture. Moreover, the element-based formulation permits to easily manage any type of element, especially in 3D models where, to the best of the authors' knowledge, only tetrahedral elements are used in FS-FEM applications found in the literature. Shape functions for non-simplex 3D elements are proposed in order to apply FS-FEM to any standard finite element.
KW  - distorted element
KW  - ES-FEM
KW  - FS-FEM
KW  - non-simplex S-FEM elements
KW  - S-FEM
Y1  - 2022
U6  - https://doi.org/10.1002/nme.7126
SN  - 1097-0207
VL  - 124
IS  - 2
SP  - 402
EP  - 433
PB  - Wiley
CY  - Chichester
ER  - 
TY  - JOUR
A1  - Savitskaya, I.S.
A1  - Kistaubayeva, A.S.
A1  - Ignatova, L.V.
A1  - Digel, Ilya
T1  - Antimicrobial and wound healing properties of a bacterial cellulose based material containing B. subtilis cells
JF  - Heliyon
Y1  - 2019
U6  - https://doi.org/10.1016/j.heliyon.2019.e02592
SN  - 2405-8440
VL  - 5
IS  - 10
SP  - Artikelnummer e02592
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - McDonald, Malcolm
A1  - McInnes, Colin R.
A1  - Mengali, Giovanni
T1  - Impact of Optical Degradation on Solar Sail Mission Performance
JF  - Journal of Spacecraft and Rockets. 44 (2007), H. 4
Y1  - 2007
SN  - 0022-4650
N1  - 2. ISSN: 1533-6794
SP  - 740
EP  - 749
ER  - 
TY  - JOUR
A1  - Nguyen, Nhu Huynh
A1  - Duong, Minh Tuan
A1  - Tran, Thanh Ngoc
A1  - Pham, Phu Tinh
A1  - Grottke, O.
A1  - Tolba, R.
A1  - Staat, Manfred
T1  - Influence of a freeze–thaw cycle on the stress–stretch curves of tissues of porcine abdominal organs
JF  - Journal of Biomechanics
N2  - The paper investigates both fresh porcine spleen and liver and the possible decomposition of these organs under a freeze–thaw cycle. The effect of tissue preservation condition is an important factor which should be taken into account for protracted biomechanical tests. In this work, tension tests were conducted for a large number of tissue specimens from twenty pigs divided into two groups of 10. Concretely, the first group was tested in fresh state; the other one was tested after a freeze-thaw cycle which simulates the conservation conditions before biomechanical experiments. A modified Fung model for isotropic behavior was adopted for the curve fitting of each kind of tissues. Experimental results show strong effects of the realistic freeze–thaw cycle on the capsule of elastin-rich spleen but negligible effects on the liver which virtually contains no elastin. This different behavior could be explained by the autolysis of elastin by elastolytic enzymes during the warmer period after thawing. Realistic biomechanical properties of elastin-rich organs can only be expected if really fresh tissue is tested. The observations are supported by tests of intestines.
KW  - Autolysis
KW  - Decomposition
KW  - Freeze–thaw process
KW  - Spleen
KW  - Liver
Y1  - 2012
U6  - https://doi.org/10.1016/j.jbiomech.2012.07.008
SN  - 1873-2380
VL  - 45
IS  - 14
SP  - 2382
EP  - 2386
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Staat, Manfred
A1  - Trenz, Eva
A1  - Lohmann, Philipp
A1  - Frotscher, Ralf
A1  - Klinge, Uwe
A1  - Tabaza, Ruth
A1  - Kirschner-Hermanns, Ruth
T1  - New measurements to compare soft tissue anchoring systems in pelvic floor surgery
JF  - Journal of Biomedical Materials Research Part B: Applied Biomaterials
N2  - Suburethral slings as well as different meshes are widely used treating stress urinary incontinence and prolaps in women. With the development of MiniSlings and special meshes using less alloplastic material anchorage systems become more important to keep devices in place and to put some tension especially on the MiniSlings. To date, there are many different systems of MiniSlings of different companies on the market which differ in the structure of the used meshes and anchors. A new objective measurement method to compare different properties of MiniSling systems (mesh and anchor) is presented in this article. Ballistic gelatine acts as soft tissue surrogate. Significant differences in parameters like pull-out strength of anchors or shrinkage of meshes under loading conditions have been determined. The form and size of the anchors as well as the structural stability of the meshes are decisive for a proper integration. The tested anchorings sytems showed markedly different mechanical function at their respective load bearing capacity. As the stable fixation of the device in tissue is a prerequisite for a permanet reinforcement, the proposed test system permits further optimisation of anchor and mesh devices to improve the success of the surgical treatment
Y1  - 2012
U6  - https://doi.org/10.1002/jbm.b.32654
SN  - 1552-4981
VL  - 100B
IS  - 4
SP  - 924
EP  - 933
PB  - Wiley
CY  - Hoboken, NJ
ER  - 
TY  - JOUR
A1  - Konstantinidis, Konstantinos
A1  - Flores Martinez, Claudio
A1  - Dachwald, Bernd
A1  - Ohndorf, Andreas
A1  - Dykta, Paul
A1  - Bowitz, Pascal
A1  - Rudolph, Martin
A1  - Digel, Ilya
A1  - Kowalski, Julia
A1  - Voigt, Konstantin
A1  - Förstner, Roger
T1  - A lander mission to probe subglacial water on Saturn's moon enceladus for life
JF  - Acta astronautica
Y1  - 2015
SN  - 1879-2030 (E-Journal); 0094-5765 (Print)
VL  - Vol. 106
SP  - 63
EP  - 89
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Novacek, V.
A1  - Tran, Thanh Ngoc
A1  - Klinge, U.
A1  - Tolba, R. H.
A1  - Staat, Manfred
A1  - Bronson, D. G.
A1  - Miesse, A. M.
A1  - Whiffen, J.
A1  - Turquier, F.
T1  - Finite element modelling of stapled colorectal end-to-end anastomosis : Advantages of variable height stapler design
JF  - Journal of Biomechanics
N2  - The impact of surgical staplers on tissues has been studied mostly in an empirical manner. In this paper, finite element method was used to clarify the mechanics of tissue stapling and associated phenomena. Various stapling modalities and several designs of circular staplers were investigated to evaluate the impact of the device on tissues and mechanical performance of the end-to-end colorectal anastomosis. Numerical simulations demonstrated that a single row of staples is not adequate to resist leakage due to non-linear buckling and opening of the tissue layers between two adjacent staples. Compared to the single staple row configuration, significant increase in stress experienced by the tissue at the inner staple rows was observed in two and three rows designs. On the other hand, adding second and/or third staple row had no effect on strain in the tissue inside the staples. Variable height design with higher staples in outer rows significantly reduced the stresses and strains in outer rows when compared to the same configuration with flat cartridge.
KW  - Variable height stapler design
KW  - Anastomotic leakage
KW  - Finite element modelling
KW  - End-to-end colorectal anastomosis
KW  - Surgical staplers
Y1  - 2012
U6  - https://doi.org/10.1016/j.jbiomech.2012.07.021
SN  - 1873-2380
VL  - 45
IS  - 115
SP  - 2693
EP  - 2697
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Staat, Manfred
T1  - Direct finite element route for design-by-analysis of pressure components
N2  - In the new European standard for unfired pressure vessels, EN 13445-3, there are two approaches for carrying out a Design-by-Analysis that cover both the stress categorization method (Annex C) and the direct route method (Annex B) for a check against global plastic deformation and against progressive plastic deformation. This paper presents the direct route in the language of limit and shakedown analysis. This approach leads to an optimization problem. Its solution with Finite Element Analysis is demonstrated for mechanical and thermal actions. One observation from the examples is that the so-called 3f (3Sm) criterion fails to be a reliable check against progressive plastic deformation. Precise conditions are given, which greatly restrict the applicability of the 3f criterion.
KW  - Einspielen <Werkstoff>
KW  - Plastizität
KW  - Deformation
KW  - Analytischer Zulaessigkeitsnachweis
KW  - Einspiel-Analyse
KW  - fortschreitende plastische Deformation
KW  - alternierend Verformbarkeit
KW  - Einspiel-Kriterium
KW  - Design-by-analysis
KW  - Shakedown analysis
KW  - Progressive plastic deformation
KW  - Alternating plasticity
KW  - Shakedown criterion
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Staat, Manfred
A1  - Heitzer, M.
T1  - Probabilistic limit and shakedown problems
JF  - Numerical Methods for Limit and Shakedown Analysis. Deterministic and Probabilistic Approach. NIC Series Vol. 15 / Ed. by Staat, M; Heitzer, M.
Y1  - 2003
SN  - 3-00-010001-6
SP  - 217
EP  - 268
PB  - John von Neumann Institute for Computing (NIC)
CY  - Jülich
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Ulamec, Stephan
A1  - Postberg, Frank
A1  - Sohl, Frank
A1  - Vera, Jean-Pierre de
A1  - Christoph, Waldmann
A1  - Lorenz, Ralph D.
A1  - Hellard, Hugo
A1  - Biele, Jens
A1  - Rettberg, Petra
T1  - Key technologies and instrumentation for subsurface exploration of ocean worlds
JF  - Space Science Reviews
N2  - In this chapter, the key technologies and the instrumentation required for the subsurface exploration of ocean worlds are discussed. The focus is laid on Jupiter’s moon Europa and Saturn’s moon Enceladus because they have the highest potential for such missions in the near future. The exploration of their oceans requires landing on the surface, penetrating the thick ice shell with an ice-penetrating probe, and probably diving with an underwater vehicle through dozens of kilometers of water to the ocean floor, to have the chance to find life, if it exists. Technologically, such missions are extremely challenging. The required key technologies include power generation, communications, pressure resistance, radiation hardness, corrosion protection, navigation, miniaturization, autonomy, and sterilization and cleaning. Simpler mission concepts involve impactors and penetrators or – in the case of Enceladus – plume-fly-through missions.
Y1  - 2020
U6  - https://doi.org/10.1007/s11214-020-00707-5
SN  - 1572-9672
N1  - Corresponding author: Bernd Dachwald
VL  - 216
IS  - Art. 83
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Staat, Manfred
T1  - Some Achievements of the European Project LISA for FEM Based Limit and Shakedown Analysis
JF  - Computational mechanics : developments and applications, 2002 : presented at the 2002 ASME Pressure Vessels and Piping Conference, Vancouver, British Columbia, Canada, August 5 - 9. / Badie, N. [ed]
Y1  - 2002
SN  - 0791846520
N1  - Serie PVP ; vol. 441.
SP  - 177
EP  - 185
PB  - American Society of Mechanical Engineers
CY  - New York
ER  - 
TY  - JOUR
A1  - Staat, Manfred
A1  - Heitzer, M.
A1  - Reiners, H.
A1  - Schubert, F.
T1  - Shakedown and ratchetting under tension–torsion loadings: analysis and experiments
JF  - Nuclear Engineering and Design. 225 (2003), H. 1
Y1  - 2003
SN  - 0029-5493
SP  - 11
EP  - 26
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Wi, Bong
T1  - Solar Sail Kinetic Energy Impactor Trajectory Optimization for an Asteroid-Deflection Mission
JF  - Journal of Spacecraft and Rockets. 44 (2007), H. 4
Y1  - 2007
SN  - 0022-4650
N1  - 2. ISSN: 1533-6794
SP  - 755
EP  - 764
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
T1  - Minimum Transfer Times for Nonperfectly Reflecting Solar Sailcraft
JF  - Journal of Spacecraft and Rockets. 41 (2004), H. 4
Y1  - 2004
SN  - 0022-4650
N1  - 2. ISSN: 1533-6794
SP  - 693
EP  - 695
ER  - 
TY  - JOUR
A1  - Stadler, A.  M.
A1  - Digel, Ilya
A1  - Artmann, Gerhard
A1  - Embs, Jan P.
A1  - Zaccai, Joe
A1  - Büldt, Georg
T1  - Hemoglobin Dynamics in Red Blood Cells: Correlation to Body Temperature
JF  - Biophysical Journal. 95 (2008), H. 11
Y1  - 2008
SN  - 1542-0086
SP  - 5449
EP  - 5461
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
T1  - Optimization of Interplanetary Solar Sailcraft Trajectories Using Evolutionary Neurocontrol
JF  - Journal of guidance, control, and dynamics. 27 (2004), H. 1
Y1  - 2004
SN  - 0162-3192
N1  - 2. ISSN: 0162-3192. - 3. ISSN: 0731-5090
SP  - 66
EP  - 72
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Ohndorf, A.
A1  - Gill, E.
T1  - Optimization of low-thrust Earth-Moon transfers using evolutionary neurocontrol  / Ohndorf, A. ; Dachwald, B. ; Gill, E.
JF  - IEEE Congress on Evolutionary Computation, 2009. CEC '09.
Y1  - 2009
SN  - 978-1-4244-2958-5
SP  - 358
EP  - 364
ER  - 
TY  - JOUR
A1  - Tran, Thanh Ngoc
A1  - Kreißig, R.
A1  - Staat, Manfred
T1  - Probabilistic limit and shakedown analysis of thin plates and shells
JF  - Structural safety. 31 (2009), H. 1
Y1  - 2009
SN  - 0167-4730
SP  - 1
EP  - 18
PB  - -
ER  - 
TY  - JOUR
A1  - Scholz, Christina
A1  - Romagnoli, Daniele
A1  - Dachwald, Bernd
A1  - Theil, Stephan
T1  - Performance analysis of an attitude control system for solar sails using sliding masses
JF  - Advances in Space Research
Y1  - 2011
SN  - 0273-1177
VL  - 48
IS  - 11
SP  - 1822
EP  - 1835
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Leipold, M.
A1  - Fichtner, H.
A1  - Heber, B.
A1  - Groepper, P.
A1  - Lascar, S.
A1  - Burger, F.
A1  - Eiden, M.
A1  - Niederstadt, T.
A1  - Sickinger, C.
A1  - Herbeck, L.
A1  - Dachwald, Bernd
A1  - Seboldt, Wolfgang
T1  - Heliopause Explorer - A Sailcraft Mission to the Outer Boundaries of the Solar System
JF  - Acta Astronautica. 59 (2006), H. 8-11
Y1  - 2006
SN  - 0094-5765
N1  - International Conference on Low Cost Planetary Missions <5, 2003, Noordwijk> ; Selected Proceedings
SP  - 786
EP  - 796
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Turyshev, Slava G.
A1  - Dittus, H.
A1  - Shao, M. [u.a.]
T1  - Fundamental Physics with the Laser Astrometric Test Of Relativity / S.G. Turyshev ;  H. Dittus ; M. Shao ... B.Dachwald ...
JF  - Proceedings of the 39th ESLAB Symposium "Trends in Space Science and Cosmic Vision 2020" : 19 - 21 April 2005, ESTEC, Noordwijk, the Netherlands / European Space Agency. [Comp. by: F. Favata ...] . - (ESA SP ; 588)
Y1  - 2005
SN  - 9290928999
N1  - ISBN der CD-ROM-Ausg.: 9290928999 ; Symposium Trends in Space Science and Cosmic Vision 2020 <2005, Noordwijk> ; ESLAB symposium <39, 2005, Noordwijk> ; European Space Laboratory
SP  - 8
EP  - 11
PB  - ESA Publ. Div.
CY  - Noordwijk
ER  - 
TY  - JOUR
A1  - Dittus, H.
A1  - Turyshev, S. G.
A1  - Dachwald, Bernd
A1  - Blome, Hans-Joachim
T1  - A Mission to Explore the Pioneer Anomaly
JF  - Proceedings of the 39th ESLAB Symposium "Trends in Space Science and Cosmic Vision 2020" : 19 - 21 April 2005, ESTEC, Noordwijk, the Netherlands / European Space Agency. [Comp. by: F. Favata ...] . - (ESA SP ; 588)
Y1  - 2005
SN  - 9290928999
N1  - ISBN der CD-ROM-Ausg.: 9290928999 ; Symposium Trends in Space Science and Cosmic Vision 2020 <2005, Noordwijk> ; ESLAB symposium <39,2005, Noordwijk> ; European Space Laboratory ; Report Number: LA-UR-05-4907 ; The Pioneer Explorer Collaboration
SP  - 3
EP  - 10
PB  - ESA Publ. Div.
CY  - Noordwijk
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - MacDonald, Malcolm
A1  - McInnes, Colin R.
T1  - Heliocentric Solar Sail Orbit Transfers with Locally Optimal Control Laws / Malcolm Macdonald ; Colin McInnes ; Bernd Dachwald
JF  - Journal of Spacecraft and Rockets. 44 (2007), H. 1
Y1  - 2007
SN  - 0022-4650
SP  - 273
EP  - 276
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Seboldt, Wolfgang
T1  - Solar Sails for Near- and Medium-Term Scientific Deep Space Missions / W. Sebolt ; B. Dachwald
JF  - In-space propulsion : edited book of proceedings of the 10-IWCP, the 10th International Workshop on Combustion and Propulsion held in Lerici, La Spezia, Italy, 21-25 September 2003 / [ed.: Luigi T. DeLuca]
Y1  - 2005
N1  - Paper 31 ; International workshop on combustion and propulsion <10, 2003, Lerici>
PB  - SP Lab, Politecnico di Milano
CY  - Milano
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Carnelli, I.
A1  - Vasile, M.
T1  - Evolutionary Neurocontrol as a Novel Method for Low-Thrust Gravity Assist Trajectory Optimization / I. Carnelli ; B. Dachwald ; M. Vasile
JF  - Proceedings of the Twenty-Fifth International Symposium on Space Technology and Science (Selected papers) : Kanazawa, [June 4 through June 11, 2006, at Kanazawa-shi Kanko Kaikan in Kanazawa city] / [Japan Society for Aeronautical and Space Sciences. Kohtaro Matsumoto [ed.-in-chief]
Y1  - 2006
SN  - 4-99005-002-9
N1  - International Symposium on Space Technology and Science <25, 2006, Kanazawa> ; ISTS 2006-d-46
SP  - 569
EP  - 574
PB  - JSASS
CY  - Tokyo
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Carnelli, I.
A1  - Vasile, M.
T1  - Low-Thrust Gravity Assist Trajectory Optimization Using Evolutionary Neurocontrollers / I. Carnelli ; B. Dachwald ; M. Vasile ...
JF  - Astrodynamics 2005 : proceedings of the AAS/AIAA astrodynamics conference held August 7 - 11, 2005, South Lake Tahoe, California / ed. by Bobby G. Williams. - Pt. 3. - (Advances in the astronautical sciences ; 123,3)
Y1  - 2006
SN  - 0-87703-527-X
N1  - Astrodynamics Conference <2005, South Lake Tahoe, Calif.> ; American Astronautical Society ; Number: AAS-05-374
SP  - 1911
EP  - 1928
PB  - Univelt
CY  - San Diego, Calif.
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Leipold, M.
A1  - Fichtner, H.
T1  - Heliopause Explorer - A Sailcraft Mission to the Outer Boundaries of the Solar System / M. Leipold ; H. Fichtner ; B. Heber  ... B. Dachwald ...
JF  - Proceedings of the Fifth IAA International Conference on Low Cost Planetary Missions : 24 - 26 September 2003, ESTEC, Noordwijk, the Netherlands / [comp. by R. A. Harris]
Y1  - 2003
SN  - 92-9092-853-0
N1  - International Conference on Low Cost Planetary Missions <5, 2003, Noordwijk> ; International Academy of Astronautics ; European Space Research and Technology Centre
SP  - 367
EP  - 375
PB  - ESA
CY  - Noordwijk
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
T1  - Interplanetary Mission Analysis for Non-Perfectly Reflecting Solar Sailcraft Using Evolutionary Neurocontrol
JF  - Astrodynamics 2003 : proceedings of the AAS/AIAA Astrodynamics Conference held August 3 - 7, 2003, Big Sky, Montana / ed. by Jean de Lafontaine. - Pt. 2. - (Advances in the astronautical sciences ; 116,2)
Y1  - 2004
SN  - 0-87703-509-1
N1  - Astrodynamics Conference <2003, Big Sky, Mont.> ; American Institute of Aeronautics and Astronautics <Reston, Va.> ; AAS-03-579
SP  - 1247
EP  - 1262
PB  - Univelt
CY  - San Diego, Calif.
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Seboldt, Wolfgang
T1  - Optimization of Interplanetary Rendezvous Trajectories for Solar Sailcraft Using a Neurocontroller
JF  - A collection of technical papers / AIAA Astrodynamics Specialist Conference : Monterey, California, 5 - 8 August 2002. - Vol. 2
Y1  - 2002
SN  - 1-56347-549-9
N1  - Astrodynamics Specialist Conference <2002, Monterey, Calif.> American Institute of Aeronautics and Astronautics <Reston, Va.>  ; AIAA  paper number: AIAA-2002-4989
SP  - 1263
EP  - 1270
PB  - American Institute of Aeronautics and Astronautics
CY  - Reston, Va.
ER  - 
TY  - JOUR
A1  - Staat, Manfred
A1  - Tran, Thanh Ngoc
A1  - Kreißig, R.
T1  - Load bearing capacity of thin shell structures made of elastoplastic material by direct methods
JF  - Technische Mechanik. 28 (2008), H. 3-4
Y1  - 2008
SP  - 299
EP  - 309
ER  - 
TY  - JOUR
A1  - Tran, Thanh Ngoc
A1  - Pham, Phu Tinh
A1  - Vu, D. K.
A1  - Staat, Manfred
T1  - Reliability Analysis of Inelastic Shell Structures Under Variable Loads
JF  - Limit States of Materials and Structures : Direct Methods / Hrsg. Dieter Weichert; Hrsg. Alan Ponter
Y1  - 2009
SN  - 978-1-4020-9633-4
SP  - 135
EP  - 156
PB  - Springer Netherland
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Stadler, Andreas M.
A1  - Embs, Jan P.
A1  - Digel, Ilya
A1  - Artmann, Gerhard
A1  - Unruh, Tobias
A1  - Büldt, Georg
A1  - Zaccai, Guiseppe
T1  - Cytoplasmic water and hydration layer dynamics in human red blood cells
JF  - Journal of the American Chemical Society. 50 (2008), H. 130
Y1  - 2008
SN  - 1520-5126
SP  - 16852
EP  - 16853
ER  - 
TY  - JOUR
A1  - Horbach, Andreas
A1  - Staat, Manfred
A1  - Perez-Viana, Daniel
A1  - Simmen, Hans-Peter
A1  - Neuhaus, Valentin
A1  - Pape, Hans-Christoph
A1  - Prescher, Andreas
A1  - Ciritsis, Bernhard
T1  - Biomechanical in vitro examination of a standardized low-volume tubular femoroplasty
JF  - Clinical Biomechanics
N2  - Background
Osteoporosis is associated with the risk of fractures near the hip. Age and comorbidities increase the perioperative risk. Due to the ageing population, fracture of the proximal femur also proves to be a socio-economic problem. Preventive surgical measures have hardly been used so far.

Methods
10 pairs of human femora from fresh cadavers were divided into control and low-volume femoroplasty groups and subjected to a Hayes fall-loading fracture test. The results of the respective localization and classification of the fracture site, the Singh index determined by computed tomography (CT) examination and the parameters in terms of fracture force, work to fracture and stiffness were evaluated statistically and with the finite element method. In addition, a finite element parametric study with different position angles and variants of the tubular geometry of the femoroplasty was performed.

Findings
Compared to the control group, the work to fracture could be increased by 33.2%. The fracture force increased by 19.9%. The used technique and instrumentation proved to be standardized and reproducible with an average poly(methyl methacrylate) volume of 10.5 ml. The parametric study showed the best results for the selected angle and geometry.

Interpretation
The cadaver studies demonstrated the biomechanical efficacy of the low-volume tubular femoroplasty. The numerical calculations confirmed the optimal choice of positioning as well as the inner and outer diameter of the tube in this setting. The standardized minimally invasive technique with the instruments developed for it could be used in further comparative studies to confirm the measured biomechanical results.
Y1  - 2020
U6  - https://doi.org/10.1016/j.clinbiomech.2020.105104
VL  - 80
IS  - Art. 105104
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Bassam, Rasha
A1  - Artmann, Gerhard
A1  - Hescheler, Jürgen
A1  - Graef, T.
A1  - Temiz Artmann, Aysegül
A1  - Porst, Dariusz
A1  - Linder, Peter
A1  - Kayser, Peter
A1  - Arinkin, Vladimir
A1  - Gossmann, Matthias
A1  - Digel, Ilya
T1  - Alterations in human hemoglobin structure related to red blood cell storage
N2  - The importance of the availability of stored blood or blood cells, respectively, for urgent transfusion cannot be overestimated. Nowadays, blood storage becomes even more important since blood products are used for epidemiological studies, bio-technical research or banked for transfusion purposes. Thus blood samples must not only be processed, stored, and shipped to preserve their efficacy and safety, but also all parameters of storage must be recorded and reported for Quality Assurance. Therefore, blood banks and clinical research facilities are seeking more accurate, automated means for blood storage and blood processing.
KW  - Hämoglobin
KW  - Hämoglobinstruktur
KW  - Blutzellenlagerung
KW  - Hemoglobin structure
KW  - Red blood cell storage
Y1  - 2011
ER  - 
TY  - JOUR
A1  - Knox, Ronald
A1  - Bruggemann, Andrea
A1  - Gossmann, Matthias
A1  - Thomas, Ulrich
A1  - Horváth, András
A1  - Dragicevic, Elena
A1  - Stoelzle-Feix, Sonja
A1  - Fertig, Niels
A1  - Jung, Alexander
A1  - Raman, Aravind Hariharan
A1  - Staat, Manfred
A1  - Linder, Peter
T1  - Combining physiological relevance and throughput for in vitro cardiac contractility measurement
JF  - Biophysical Journal
N2  - Despite increasing acceptance of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in safety pharmacology, controversy remains about the physiological relevance of existing in vitro models for their mechanical testing. We hypothesize that existing signs of immaturity of the cell models result from an improper mechanical environment. We cultured hiPSC-CMs in a 96-well format on hyperelastic silicone membranes imitating their native mechanical environment, resulting in physiological responses to compound stimuli.We validated cell responses on the FLEXcyte 96, with a set of reference compounds covering a broad range of cellular targets, including ion channel modulators, adrenergic receptor modulators and kinase inhibitors. Acute (10 - 30 min) and chronic (up to 7 days) effects were investigated. Furthermore, the measurements were complemented with electromechanical models based on electrophysiological recordings of the used cell types.hiPSC-CMs were cultured on freely-swinging, ultra-thin and hyperelastic silicone membranes. The weight of the cell culture medium deflects the membranes downwards. Rhythmic contraction of the hiPSC-CMs resulted in dynamic deflection changes which were quantified by capacitive distance sensing. The cells were cultured for 7 days prior to compound addition. Acute measurements were conducted 10-30 minutes after compound addition in standard culture medium. For chronic treatment, compound-containing medium was replaced daily for up to 7 days. Electrophysiological properties of the employed cell types were recorded by automated patch-clamp (Patchliner) and the results were integrated into the electromechanical model of the system.Calcium channel agonist S Bay K8644 and beta-adrenergic stimulator isoproterenol induced significant positive inotropic responses without additional external stimulation. Kinase inhibitors displayed cardiotoxic effects on a functional level at low concentrations. The system-integrated analysis detected alterations in beating shape as well as frequency and arrhythmic events and we provide a quantitative measure of these.
Y1  - 2020
U6  - https://doi.org/10.1016/j.bpj.2019.11.3104
SN  - 0006-3495
N1  - Raman, Arayind Hariharan 
im Artikel unter dem Namen: Raman, Alexander H.
VL  - 118
IS  - Issue 3, Supplement 1
SP  - 570a
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Nguyen-Xuan, H.
A1  - Rabczuk, T.
A1  - Nguyen-Thoi, T.
A1  - Tran, Thanh Ngoc
A1  - Nguyen-Thanh, N.
T1  - Computation of limit and shakedown loads using a node-based smoothed finite element method
JF  - International Journal for Numerical Methods in Engineering
N2  - This paper presents a novel numerical procedure for computing limit and shakedown loads of structures using a node-based smoothed FEM in combination with a primal–dual algorithm. An associated primal–dual form based on the von Mises yield criterion is adopted. The primal-dual algorithm together with a Newton-like iteration are then used to solve this associated primal–dual form to determine simultaneously both approximate upper and quasi-lower bounds of the plastic collapse limit and the shakedown limit. The present formulation uses only linear approximations and its implementation into finite element programs is quite simple. Several numerical examples are given to show the reliability, accuracy, and generality of the present formulation compared with other available methods.
Y1  - 2011
U6  - https://doi.org/10.1002/nme.3317
SN  - 1097-0207
VL  - 90
IS  - 3
SP  - 287
EP  - 310
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Tran, Ngoc Trinh
A1  - Staat, Manfred
T1  - Direct plastic structural design under random strength and random load by chance constrained programming
JF  - European Journal of Mechanics - A/Solids
Y1  - 2021
U6  - https://doi.org/10.1016/j.euromechsol.2020.104106
SN  - 0997-7538
VL  - 85
IS  - Article 104106
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Bhattarai, Aroj
A1  - May, Charlotte Anabell
A1  - Staat, Manfred
A1  - Kowalczyk, Wojciech
A1  - Tran, Thanh Ngoc
T1  - Layer-specific damage modeling of porcine large intestine under biaxial tension
JF  - Bioengineering
N2  - The mechanical behavior of the large intestine beyond the ultimate stress has never been investigated. Stretching beyond the ultimate stress may drastically impair the tissue microstructure, which consequently weakens its healthy state functions of absorption, temporary storage, and transportation for defecation. Due to closely similar microstructure and function with humans, biaxial tensile experiments on the porcine large intestine have been performed in this study. In this paper, we report hyperelastic characterization of the large intestine based on experiments in 102 specimens. We also report the theoretical analysis of the experimental results, including an exponential damage evolution function. The fracture energies and the threshold stresses are set as damage material parameters for the longitudinal muscular, the circumferential muscular and the submucosal collagenous layers. A biaxial tensile simulation of a linear brick element has been performed to validate the applicability of the estimated material parameters. The model successfully simulates the biomechanical response of the large intestine under physiological and non-physiological loads.
KW  - biaxial tensile experiment
KW  - anisotropy
KW  - hyperelastic
KW  - constitutive modeling
KW  - damage
Y1  - 2022
U6  - https://doi.org/10.3390/bioengineering9100528
SN  - 2306-5354
N1  - Der Artikel gehört zum Sonderheft "Computational Biomechanics"
VL  - 9
IS  - 10, Early Access
SP  - 1
EP  - 17
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Kurulgan Demirci, Eylem
A1  - Linder, Peter
A1  - Demirci, Taylan
A1  - Trzewik, Jürgen
A1  - Digel, Ilya
A1  - Artmann, Gerhard
A1  - Temiz Artmann, Aysegül
T1  - Contractile tension of endothelial cells: An LPS based in-vitro sepsis model
JF  - IUBMB Life. 61 (2009), H. 3
Y1  - 2009
SN  - 1521-6543
N1  - Abstracts: Turkish Society of Molecular Medicine, Third International Congress of Molecular Medicine, May 5-8, 2009, Istanbul, Turkey
SP  - 307
EP  - 308
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Pham, Phu Tinh
A1  - Staat, Manfred
T1  - FEM-based shakedown analysis of hardening structures
JF  - Asia Pacific journal on computational engineering
N2  - This paper develops a new finite element method (FEM)-based upper bound algorithm for limit and shakedown analysis of hardening structures by a direct plasticity method. The hardening model is a simple two-surface model of plasticity with a fixed bounding surface. The initial yield surface can translate inside the bounding surface, and it is bounded by one of the two equivalent conditions: (1) it always stays inside the bounding surface or (2) its centre cannot move outside the back-stress surface. The algorithm gives an effective tool to analyze the problems with a very high number of degree of freedom. Our numerical results are very close to the analytical solutions and numerical solutions in literature.
Y1  - 2014
U6  - https://doi.org/10.1186/2196-1166-1-4
SN  - 2196-1166 (E-Journal)
IS  - 1
SP  - Article No. 4
PB  - SpringerOpen
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Albracht, Kirsten
A1  - Arampatzis, Adamantios
T1  - Exercise-induced changes in triceps surae tendon stiffness and muscle strength affect running economy in humans
JF  - European Journal of Applied Physiology
Y1  - 2013
U6  - https://doi.org/10.1007/s00421-012-2585-4
SN  - 1439-6327
VL  - 113
IS  - 6
SP  - 1605
EP  - 1615
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Arampatzis, Adamantios
A1  - Peper, Andreas
A1  - Bierbaum, Stefanie
A1  - Albracht, Kirsten
T1  - Plasticity of human Achilles tendon mechanical and morphological properties in response to cyclic strain
JF  - Journal of Biomechanics
N2  - The purpose of the current study in combination with our previous published data (Arampatzis et al., 2007) was to examine the effects of a controlled modulation of strain magnitude and strain frequency applied to the Achilles tendon on the plasticity of tendon mechanical and morphological properties. Eleven male adults (23.9±2.2 yr) participated in the study. The participants exercised one leg at low magnitude tendon strain (2.97±0.47%), and the other leg at high tendon strain magnitude (4.72±1.08%) of similar frequency (0.5 Hz, 1 s loading, 1 s relaxation) and exercise volume (integral of the plantar flexion moment over time) for 14 weeks, 4 days per week, 5 sets per session. The exercise volume was similar to the intervention of our earlier study (0.17 Hz frequency; 3 s loading, 3 s relaxation) allowing a direct comparison of the results. Before and after the intervention ankle joint moment has been measured by a dynamometer, tendon–aponeurosis elongation by ultrasound and cross-sectional area of the Achilles tendon by magnet resonance images (MRI). We found a decrease in strain at a given tendon force, an increase in tendon–aponeurosis stiffness and tendon elastic modulus of the Achilles tendon only in the leg exercised at high strain magnitude. The cross-sectional area (CSA) of the Achilles tendon did not show any statistically significant (P>0.05) differences to the pre-exercise values in both legs. The results indicate a superior improvement in tendon properties (stiffness, elastic modulus and CSA) at the low frequency (0.17 Hz) compared to the high strain frequency (0.5 Hz) protocol. These findings provide evidence that the strain magnitude applied to the Achilles tendon should exceed the value, which occurs during habitual activities to trigger adaptational effects and that higher tendon strain duration per contraction leads to superior tendon adaptational responses.
Y1  - 2010
U6  - https://doi.org/10.1016/j.jbiomech.2010.08.014
SN  - 0021-9290
VL  - 43
IS  - 16
SP  - 3073
EP  - 3079
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Aggeloussis, Nickos
A1  - Giannakou, Erasmia
A1  - Albracht, Kirsten
A1  - Arampatzis, Adamantios
T1  - Reproducibility of fascicle length and pennation angle of gastrocnemius medialis in human gait in vivo
JF  - Gait and Posture
N2  - The purpose of the current study was to examine the reproducibility of fascicle length and pennation angle of gastrocnemius medialis while human walking. To the best of our knowledge, this is the first study of the reproducibility of fascicle length and pennation angle of gastrocnemius medialis in vivo during human gait. Twelve males performed 10 gait trials on a treadmill, in 2 separate days. B-mode ultrasonography, with the ultrasound probe firmly adjusted in the transverse and frontal planes using a special cast, was used to measure the fascicle length and the pennation angle of the gastrocnemius medialis (GM). A Vicon 624 system with three cameras operating at 120 Hz was also used to record the ankle and knee joint angles. The results showed that measurements of fascicle length and pennation angle showed high reproducibility during the gait cycle, both within the same day and between different days. Moreover, the root mean square differences between the repeated waveforms of both variables were very small, compared with their ranges (fascicle length: RMS = ∼3 mm, range: 38–63 mm; pennation angle: RMS = ∼1.5°, range: 22–32°). However, their reproducibility was lower compared to the joint angles. It was found that representative data have to be derived by a wide number of gait trials (fascicle length ∼six trials, pennation angle more than 10 trials), to assure the reliability of the fascicle length and pennation angle in human gait.
Y1  - 2010
U6  - https://doi.org/10.1016/j.gaitpost.2009.08.249
SN  - 0966-6362
VL  - 31
IS  - 1
SP  - 73
EP  - 77
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Arampatzis, Adamantios
A1  - Karamanidis, Kiros
A1  - Mademli, Lida
A1  - Albracht, Kirsten
T1  - Plasticity of the human tendon to short and long-term mechanical loading
JF  - Exercise and Sport Sciences Reviews
Y1  - 2009
U6  - https://doi.org/10.1097/JES.0b013e31819c2e1d
SN  - 1538-3008
VL  - 37
IS  - 2
SP  - 66
EP  - 72
ER  - 
TY  - JOUR
A1  - Albanna, Walid
A1  - Lüke, Jan Niklas
A1  - Schubert, Gerrit Alexander
A1  - Dibué-Adjei, Maxine
A1  - Kotliar, Konstantin
A1  - Hescheler, Jürgen
A1  - Clusmann, Hans
A1  - Steiger, Hans-Jakob
A1  - Hänggi, Daniel
A1  - Kamp, Marcel A.
A1  - Schneider, Toni
A1  - Neumaier, Felix
T1  - Modulation of Ca v 2.3 channels by unconjugated bilirubin (UCB) – Candidate mechanism for UCB-induced neuromodulation and neurotoxicity
JF  - Molecular and Cellular Neuroscience
Y1  - 2019
U6  - https://doi.org/10.1016/j.mcn.2019.03.003
SN  - 1044-7431
VL  - 96
IS  - 4
SP  - 35
EP  - 46
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Quittmann, Oliver J.
A1  - Meskemper, Joshua
A1  - Albracht, Kirsten
A1  - Abel, Thomas
A1  - Foitschik, Tina
A1  - Strüder, Heiko K.
T1  - Normalising surface EMG of ten upper-extremity muscles in handcycling: Manual resistance vs. sport-specific MVICs
JF  - Journal of Electromyography and Kinesiology
N2  - Muscular activity in terms of surface electromyography (sEMG) is usually normalised to maximal voluntary isometric contractions (MVICs). This study aims to compare two different MVIC-modes in handcycling and examine the effect of moving average window-size. Twelve able-bodied male competitive triathletes performed ten MVICs against manual resistance and four sport-specific trials against fixed cranks. sEMG of ten muscles [M. trapezius (TD); M. pectoralis major (PM); M. deltoideus, Pars clavicularis (DA); M. deltoideus, Pars spinalis (DP); M. biceps brachii (BB); M. triceps brachii (TB); forearm flexors (FC); forearm extensors (EC); M. latissimus dorsi (LD) and M. rectus abdominis (RA)] was recorded and filtered using moving average window-sizes of 150, 200, 250 and 300 ms. Sport-specific MVICs were higher compared to manual resistance for TB, DA, DP and LD, whereas FC, TD, BB and RA demonstrated lower values. PM and EC demonstrated no significant difference between MVIC-modes. Moving average window-size had no effect on MVIC outcomes. MVIC-mode should be taken into account when normalised sEMG data are illustrated in handcycling. Sport-specific MVICs seem to be suitable for some muscles (TB, DA, DP and LD), but should be augmented by MVICs against manual/mechanical resistance for FC, TD, BB and RA.
Y1  - 2020
U6  - https://doi.org/10.1016/j.jelekin.2020.102402
SN  - 1050-6411
VL  - 51
IS  - Article 102402
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Kopp, Alexander
A1  - Schunck, Laura
A1  - Gosau, Martin
A1  - Smeets, Ralf
A1  - Burg, Simon
A1  - Fuest, Sandra
A1  - Kröger, Nadja
A1  - Zinser, Max
A1  - Krohn, Sebastian
A1  - Behbahani, Mehdi
A1  - Köpf, Marius
A1  - Lauts, Lisa
A1  - Rutkowski, Rico
T1  - Influence of the casting concentration on the mechanical and optical properties of Fa/CaCl2-derived silk fibroin membranes
JF  - International Journal of Molecular Sciences
N2  - In this study, we describe the manufacturing and characterization of silk fibroin membranes derived from the silkworm Bombyx mori. To date, the dissolution process used in this study has only been researched to a limited extent, although it entails various potential advantages, such as reduced expenses and the absence of toxic chemicals in comparison to other conventional techniques. Therefore, the aim of this study was to determine the influence of different fibroin concentrations on the process output and resulting membrane properties. Casted membranes were thus characterized with regard to their mechanical, structural and optical assets via tensile testing, SEM, light microscopy and spectrophotometry. Cytotoxicity was evaluated using BrdU, XTT, and LDH assays, followed by live–dead staining. The formic acid (FA) dissolution method was proven to be suitable for the manufacturing of transparent and mechanically stable membranes. The fibroin concentration affects both thickness and transparency of the membranes. The membranes did not exhibit any signs of cytotoxicity. When compared to other current scientific and technical benchmarks, the manufactured membranes displayed promising potential for various biomedical applications. Further research is nevertheless necessary to improve reproducible manufacturing, including a more uniform thickness, less impurity and physiological pH within the membranes.
Y1  - 2020
U6  - https://doi.org/10.3390/ijms21186704
SN  - 1422-0067
N1  - Special issue: Optimization of Biomaterials for Reconstructive and Regenerative Medicine
VL  - 21
IS  - 18 art. no. 6704
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Conzen, Catharina
A1  - Albanna, Walid
A1  - Weiss, Miriam
A1  - Kürten, David
A1  - Vilser, Walthard
A1  - Kotliar, Konstantin
A1  - Zäske, Charlotte
A1  - Clusmann, Hans
A1  - Schubert, Gerrit Alexander
T1  - Vasoconstriction and Impairment of Neurovascular Coupling after Subarachnoid Hemorrhage: a Descriptive Analysis of Retinal Changes
JF  - Translational Stroke Research
N2  - Impaired cerebral autoregulation and neurovascular coupling (NVC) contribute to delayed cerebral ischemia after subarachnoid hemorrhage (SAH). Retinal vessel analysis (RVA) allows non-invasive assessment of vessel dimension and NVC hereby demonstrating a predictive value in the context of various neurovascular diseases. Using RVA as a translational approach, we aimed to assess the retinal vessels in patients with SAH. RVA was performed prospectively in 24 patients with acute SAH (group A: day 5–14), in 11 patients 3 months after ictus (group B: day 90 ± 35), and in 35 age-matched healthy controls (group C). Data was acquired using a Retinal Vessel Analyzer (Imedos Systems UG, Jena) for examination of retinal vessel dimension and NVC using flicker-light excitation. Diameter of retinal vessels—central retinal arteriolar and venular equivalent—was significantly reduced in the acute phase (p < 0.001) with gradual improvement in group B (p < 0.05). Arterial NVC of group A was significantly impaired with diminished dilatation (p < 0.001) and reduced area under the curve (p < 0.01) when compared to group C. Group B showed persistent prolonged latency of arterial dilation (p < 0.05). Venous NVC was significantly delayed after SAH compared to group C (A p < 0.001; B p < 0.05). To our knowledge, this is the first clinical study to document retinal vasoconstriction and impairment of NVC in patients with SAH. Using non-invasive RVA as a translational approach, characteristic patterns of compromise were detected for the arterial and venous compartment of the neurovascular unit in a time-dependent fashion. Recruitment will continue to facilitate a correlation analysis with clinical course and outcome.
Y1  - 2018
U6  - https://doi.org/10.1007/s12975-017-0585-8
SN  - 1868-601X
IS  - 9
SP  - 284
EP  - 293
PB  - Springer Nature
CY  - Cham
ER  - 
TY  - JOUR
A1  - Arampatzis, Adamantios
A1  - Karamanidis, Kiros
A1  - Albracht, Kirsten
T1  - Adaptational responses of the human Achilles tendon by modulation of the applied cyclic strain magnitude
JF  - Journal of Experimental Biology
Y1  - 2007
U6  - https://doi.org/10.1242/jeb.003814
SN  - 0022-0949
VL  - 210
IS  - 15
SP  - 2743
EP  - 2753
ER  - 
TY  - JOUR
A1  - Albracht, Kirsten
A1  - Arampatzis, Adamantios
T1  - Influence of the mechanical properties of the muscle-tendon unit on force generation in runners with different running economy
JF  - Biological Cybernetics
Y1  - 2006
U6  - https://doi.org/10.1007/s00422-006-0070-z
SN  - 1432-0770
VL  - 95
IS  - 1
SP  - 87
EP  - 96
ER  - 
TY  - JOUR
A1  - Heinke, Lars N.
A1  - Knicker, Axel J.
A1  - Albracht, Kirsten
T1  - Evaluation of passively induced shoulder stretch reflex using an isokinetic dynamometer in male overhead athletes
JF  - Isokinetics and Exercise Science
N2  - BACKGROUND: Muscle stretch reflexes are widely considered to beneficially influence joint stability and power generation in the lower limbs. While in the upper limbs and especially in the muscles surrounding the shoulder joint such evidence is lacking. OBJECTIVE: To quantify the electromyographical response in the muscles crossing the shoulder of specifically trained overhead athletes to an anterior perturbation force. METHODS: Twenty healthy male participants performed six sets of different external shoulder rotation stretches on an isokinetic dynamometer over a range of amplitudes and muscle pre-activation moment levels. All stretches were applied with a dynamometer acceleration of 10,000∘/s2 and a velocity of 150∘/s. Electromyographical response was measured via sEMG. RESULTS: Consistent reflexes were not observed in all experimental conditions. The reflex latencies revealed a significant muscle main effect (F (2,228) = 99.31, p< 0.001; η2= 0.466; f= 0.934) and a pre-activation main effect (F (1,228) = 142.21, p< 0.001; η2= 0.384; f= 1.418). The stretch reflex amplitude yielded a significant pre-activation main effect (F (1,222) = 470.373, p< 0.001; η2= 0.679; f= 1.454). CONCLUSION: Short latency muscle reflexes showed a tendency to an anterior to posterior muscle recruitment whereby the main internal rotator muscles of the shoulder revealed the most consistent results.
Y1  - 2018
U6  - https://doi.org/10.3233/IES-184111
SN  - 1878-5913
VL  - 26
IS  - 4
SP  - 265
EP  - 274
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Quittmann, Oliver J.
A1  - Abel, Thomas
A1  - Albracht, Kirsten
A1  - Meskemper, Joshua
A1  - Foitschik, Tina
A1  - Strüder, Heiko K.
T1  - Biomechanics of handcycling propulsion in a 30-min continuous load test at lactate threshold: Kinetics, kinematics, and muscular activity in able-bodied participants
JF  - European Journal of Applied Physiology
N2  - Purpose
This study aims to investigate the biomechanics of handcycling during a continuous load trial (CLT) to assess the mechanisms underlying fatigue in upper body exercise.

Methods
Twelve able-bodied triathletes performed a 30-min CLT at a power output corresponding to lactate threshold in a racing recumbent handcycle mounted on a stationary ergometer. During the CLT, ratings of perceived exertion (RPE), tangential crank kinetics, 3D joint kinematics, and muscular activity of ten muscles of the upper extremity and trunk were examined using motion capturing and surface electromyography.

Results
During the CLT, spontaneously chosen cadence and RPE increased, whereas crank torque decreased. Rotational work was higher during the pull phase. Peripheral RPE was higher compared to central RPE. Joint range of motion decreased for elbow-flexion and radial-duction. Integrated EMG (iEMG) increased in the forearm flexors, forearm extensors, and M. deltoideus (Pars spinalis). An earlier onset of activation was found for M. deltoideus (Pars clavicularis), M. pectoralis major, M. rectus abdominis, M. biceps brachii, and the forearm flexors.

Conclusion
Fatigue-related alterations seem to apply analogously in handcycling and cycling. The most distal muscles are responsible for force transmission on the cranks and might thus suffer most from neuromuscular fatigue. The findings indicate that peripheral fatigue (at similar lactate values) is higher in handcycling compared to leg cycling, at least for inexperienced participants. An increase in cadence might delay peripheral fatigue by a reduced vascular occlusion. We assume that the gap between peripheral and central fatigue can be reduced by sport-specific endurance training.
Y1  - 2020
U6  - https://doi.org/10.1007/s00421-020-04373-x
SN  - 1439-6327
IS  - 120
SP  - 1403
EP  - 1415
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Attar, Mandana Hossein Zadeh
A1  - Merk, Hans F.
A1  - Kotliar, Konstantin
A1  - Wurpts, Gerda
A1  - Röseler, Stefani
A1  - Moll-Slodowy, Silke
A1  - Plange, Johann
A1  - Baron, Jens Malte
A1  - Balakirski, Galina
T1  - The CD63 basophil activation test as a diagnostic tool for assessing autoimmunity in patients with chronic spontaneous urticaria
JF  - European Journal of Dermatology
Y1  - 2019
U6  - https://doi.org/10.1684/ejd.2019.3680
VL  - 29
IS  - 6
SP  - 614
EP  - 618
ER  - 
TY  - JOUR
A1  - Mandekar, Swati
A1  - Holland, Abigail
A1  - Thielen, Moritz
A1  - Behbahani, Mehdi
A1  - Melnykowycz, Mark
T1  - Advancing towards Ubiquitous EEG, Correlation of In-Ear EEG with Forehead EEG
JF  - Sensors
N2  - Wearable EEG has gained popularity in recent years driven by promising uses outside of clinics and research. The ubiquitous application of continuous EEG requires unobtrusive form-factors that are easily acceptable by the end-users. In this progression, wearable EEG systems have been moving from full scalp to forehead and recently to the ear. The aim of this study is to demonstrate that emerging ear-EEG provides similar impedance and signal properties as established forehead EEG. EEG data using eyes-open and closed alpha paradigm were acquired from ten healthy subjects using generic earpieces fitted with three custom-made electrodes and a forehead electrode (at Fpx) after impedance analysis. Inter-subject variability in in-ear electrode impedance ranged from 20 kΩ to 25 kΩ at 10 Hz. Signal quality was comparable with an SNR of 6 for in-ear and 8 for forehead electrodes. Alpha attenuation was significant during the eyes-open condition in all in-ear electrodes, and it followed the structure of power spectral density plots of forehead electrodes, with the Pearson correlation coefficient of 0.92 between in-ear locations ELE (Left Ear Superior) and ERE (Right Ear Superior) and forehead locations, Fp1 and Fp2, respectively. The results indicate that in-ear EEG is an unobtrusive alternative in terms of impedance, signal properties and information content to established forehead EEG.
KW  - in-ear EEG
KW  - correlation
KW  - forehead EEG
KW  - impedance spectroscopy
KW  - biopotential electrodes
Y1  - 2022
U6  - https://doi.org/10.3390/s22041568
SN  - 1424-8220
VL  - 22
IS  - 4
SP  - 1
EP  - 19
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Niedermeyer, Angela
A1  - Zhou, Bei
A1  - Dursun, Gözde
A1  - Temiz Artmann, Aysegül
A1  - Markert, Bernd
T1  - An examination of tissue engineered scaffolds in a bioreactor
JF  - Proceedings in Applied Mathematics and Mechanics PAMM
N2  - Replacement tissues, designed to fill in articular cartilage defects, should exhibit the same properties as the native material. The aim of this study is to foster the understanding of, firstly, the mechanical behavior of the material itself and, secondly, the influence of cultivation parameters on cell seeded implants as well as on cell migration into acellular implants. In this study, acellular cartilage replacement material is theoretically, numerically and experimentally investigated regarding its viscoelastic properties, where a phenomenological model for practical applications is developed. Furthermore, remodeling and cell migration are investigated.
Y1  - 2016
U6  - https://doi.org/10.1002/pamm.201610038
SN  - 1617-7061
N1  - Joint Annual Meeting of DMV and GAMM 2016, 87th Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM) and Deutsche Mathematiker-Vereinigung (DMV), Braunschweig, DE, Mar 7-11, 2016
VL  - 16
IS  - 1
SP  - 99
EP  - 100
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Tran, Linda
A1  - Mottaghy, K.
A1  - Arlt-Körfer, Sabine
A1  - Waluga, Christian
A1  - Behbahani, Mehdi
T1  - An experimental study of shear-dependent human platelet adhesion and underlying protein-binding mechanisms in a cylindrical Couette system
JF  - Biomedizinische Technik
Y1  - 2017
U6  - https://doi.org/10.1515/bmt-2015-0034
SN  - 0013-5585
VL  - 62
IS  - 4
SP  - 383
EP  - 392
PB  - De Gruyter
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Albanna, Walid
A1  - Lueke, Jan Niklas
A1  - Sjapic, Volha
A1  - Kotliar, Konstantin
A1  - Hescheler, Jürgen
A1  - Clusmann, Hans
A1  - Sjapic, Sergej
A1  - Alpdogan, Serdan
A1  - Schneider, Toni
A1  - Schubert, Gerrit Alexander
A1  - Neumaier, Felix
T1  - Electroretinographic Assessment of Inner Retinal Signaling in the Isolated and Superfused Murine Retina
JF  - Current Eye Research
Y1  - 2017
U6  - https://doi.org/10.1080/02713683.2017.1339807
SN  - 1460-2202
IS  - Article in press
SP  - 1
EP  - 9
PB  - Taylor & Francis
CY  - London
ER  - 
TY  - JOUR
A1  - Kotliar, Konstantin
A1  - Hauser, Christine
A1  - Ortner, Marion
A1  - Muggenthaler, Claudia
A1  - Diehl-Schmid, Janine
A1  - Angermann, Susanne
A1  - Hapfelmeier, Alexander
A1  - Schmaderer, Christoph
A1  - Grimmer, Timo
T1  - Altered neurovascular coupling as measured by optical imaging: a biomarker for Alzheimer’s disease
JF  - Scientific Reports
Y1  - 2017
U6  - https://doi.org/10.1038/s41598-017-13349-5
SN  - 2045-2322
N1  - Article 12906
VL  - 7
IS  - 1
SP  - 1
EP  - 11
PB  - Springer Nature
CY  - Cham
ER  - 
TY  - JOUR
A1  - Werkhausen, Amelie
A1  - Albracht, Kirsten
A1  - Cronin, Neil J.
A1  - Meier, Rahel
A1  - Mojsen-Moeller, Jens
A1  - Seynnes, Olivier R.
T1  - Modulation of muscle-tendon interaction in the human triceps surae during an energy dissipation task
JF  - Journal of Experimental Biology
Y1  - 2017
U6  - https://doi.org/10.1242/jeb.164111
SN  - 0022-0949
VL  - 220
IS  - 22
SP  - 4141
EP  - 4149
ER  - 
TY  - JOUR
A1  - Lapitan, Denis G.
A1  - Rogatkin, Dmitrii A.
A1  - Persheyev, Sydulla K.
A1  - Kotliar, Konstantin
T1  - False spectra formation in the differential two-channel scheme of the laser Doppler flowmeter
JF  - Biomedizinische Technik
N2  - Noise in the differential two-channel scheme of a classic laser Doppler flowmetry (LDF) instrument was studied. Formation of false spectral components in the output signal due to beating of electrical signals in the differential amplifier was found out. The improved block-diagram of the flowmeter was developed allowing to reduce the noise.
Y1  - 2018
U6  - https://doi.org/10.1515/bmt-2017-0060
SN  - 0013-5585
VL  - 63
IS  - 4
SP  - 439
EP  - 444
PB  - De Gruyter
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Albanna, Walid
A1  - Kotliar, Konstantin
A1  - Lüke, Jan Niklas
A1  - Alpdogan, Serdar
A1  - Conzen, Catharina
A1  - Lindauer, Ute
A1  - Clusmann, Hans
A1  - Hescheler, Jürgen
A1  - Vilser, Walthard
A1  - Schneider, Toni
A1  - Schubert, Gerrit Alexander
T1  - Non-invasive evaluation of neurovascular coupling in the murine retina by dynamic retinal vessel analysis
JF  - Plos one
N2  - Background
Impairment of neurovascular coupling (NVC) was recently reported in the context of subarachnoid hemorrhage and may correlate with disease severity and outcome. However, previous techniques to evaluate NVC required invasive procedures. Retinal vessels may represent an alternative option for non-invasive assessment of NVC.

Methods
A prototype of an adapted retinal vessel analyzer was used to assess retinal vessel diameter in mice. Dynamic vessel analysis (DVA) included an application of monochromatic flicker light impulses in predefined frequencies for evaluating NVC. All retinae were harvested after DVA and electroretinograms were performed.

Results
A total of 104 retinal scans were conducted in 21 male mice (90 scans). Quantitative arterial recordings were feasible only in a minority of animals, showing an emphasized reaction to flicker light impulses (8 mice; 14 scans). A characteristic venous response to flicker light, however, could observed in the majority of animals. Repeated measurements resulted in a significant decrease of baseline venous diameter (7 mice; 7 scans, p < 0.05). Ex-vivo electroretinograms, performed after in-vivo DVA, demonstrated a significant reduction of transretinal signaling in animals with repeated DVA (n = 6, p < 0.001).

Conclusions
To the best of our knowledge, this is the first non-invasive study assessing murine retinal vessel response to flicker light with characteristic changes in NVC. The imaging system can be used for basic research and enables the investigation of retinal vessel dimension and function in control mice and genetically modified animals.
Y1  - 2018
U6  - https://doi.org/10.1371/journal.pone.0204689
VL  - 13
IS  - 10
PB  - PLOS
CY  - San Francisco
ER  - 
TY  - JOUR
A1  - Balakirski, Galina
A1  - Kotliar, Konstantin
A1  - Pauly, Karolin J.
A1  - Krings, Laura K.
A1  - Rübben, Albert
A1  - Baron, Jens M.
A1  - Schmitt, Laurenz
T1  - Surgical Site Infections After Dermatologic Surgery in Immunocompromised Patients: A Single-Center Experience
JF  - Dermatologic Surgery
N2  - BACKGROUND 
Immunosuppression is often considered as an indication for antibiotic prophylaxis to prevent surgical site infections (SSI) while performing skin surgery. However, the data on the risk of developing SSI after dermatologic surgery in immunosuppressed patients are limited.

PATIENTS AND METHODS 
All patients of the Department of Dermatology and Allergology at the University Hospital of RWTH Aachen in Aachen, Germany, who underwent hospitalization for a dermatologic surgery between June 2016 and January 2017 (6 months), were followed up after surgery until completion of the wound healing process. The follow-up addressed the occurrence of SSI and the need for systemic antibiotics after the operative procedure. Immunocompromised patients were compared with immunocompetent patients. The investigation was conducted as a retrospective analysis of patient records.

RESULTS 
The authors performed 284 dermatologic surgeries in 177 patients. Nineteen percent (54/284) of the skin surgery was performed on immunocompromised patients. The most common indications for surgical treatment were nonmelanoma skin cancer and malignant melanomas. Surgical site infections occurred in 6.7% (19/284) of the cases. In 95% (18/19), systemic antibiotic treatment was needed. Twenty-one percent of all SSI (4/19) were seen in immunosuppressed patients.

CONCLUSION 
According to the authors' data, immunosuppression does not represent a significant risk factor for SSI after dermatologic surgery. However, larger prospective studies are needed to make specific recommendations on the use of antibiotic prophylaxis while performing skin surgery in these patients.

The available data on complications after dermatologic surgery have improved over the past years. Particularly, additional risk factors have been identified for surgical site infections (SSI). Purulent surgical sites, older age, involvement of head, neck, and acral regions, and also the involvement of less experienced surgeons have been reported to increase the risk of the SSI after dermatologic surgeries.1 In general, the incidence of SSI after skin surgery is considered to be low.1,2 However, antibiotics in dermatologic surgeries, especially in the perioperative setting, seem to be overused,3,4 particularly regarding developing antibiotic resistances and side effects.

Immunosuppression has been recommended to be taken into consideration as an additional indication for antibiotic prophylaxis to prevent SSI after skin surgery in special cases.5,6 However, these recommendations do not specify the exact dermatologic surgeries, and were not specifically developed for dermatologic surgery patients and treatments, but adopted from other surgical fields.6 According to the survey conducted on American College of Mohs Surgery members in 2012, 13% to 29% of the surgeons administered antibiotic prophylaxis to immunocompromised patients to prevent SSI while performing dermatologic surgery on noninfected skin,3 although this was not recommended by Journal of the American Academy of Dermatology Advisory Statement. Indeed, the data on the risk of developing SSI after dermatologic surgery in immunosuppressed patients are limited. However, it is possible that due to the insufficient evidence on the risk of SSI occurrence in this patient group, dermatologic surgeons tend to overuse perioperative antibiotic prophylaxis.

To make specific recommendations on the use of antibiotic prophylaxis in immunosuppressed patients in the field of skin surgery, more information about the incidence of SSI after dermatologic surgery in these patients is needed. The aim of this study was to fill this data gap by investigating whether there is an increased risk of SSI after skin surgery in immunocompromised patients compared with immunocompetent patients.
Y1  - 2018
U6  - https://doi.org/10.1097/DSS.0000000000001615
IS  - 44 (12)
SP  - 1525
EP  - 1536
PB  - Wolters Kluwer
ER  - 
TY  - JOUR
A1  - Rittweger, Jörn
A1  - Albracht, Kirsten
A1  - Flück, Martin
A1  - Ruoss, Severin
A1  - Brocca, Lorenza
A1  - Longa, Emanuela
A1  - Moriggi, Manuela
A1  - Seynnes, Olivier
A1  - Di Giulio, Irene
A1  - Tenori, Leonardo
A1  - Vignoli, Alessia
A1  - Capri, Miriam
A1  - Gelfi, Cecilia
A1  - Luchinat, Claudio
A1  - Franceschi, Claudio
A1  - Bottinelli, Roberto
A1  - Cerretelli, Paolo
A1  - Narici, Marco
T1  - Sarcolab pilot study into skeletal muscle’s adaptation to longterm spaceflight
JF  - npj Microgravity
Y1  - 2018
U6  - https://doi.org/10.1038/s41526-018-0052-1
SN  - 2373-8065
VL  - 4
IS  - 1
SP  - 1
EP  - 9
PB  - Nature Portfolio
ER  - 
TY  - JOUR
A1  - Werkhausen, Amelie
A1  - Cronin, Neil J.
A1  - Albracht, Kirsten
A1  - Bojsen-Møller, Jens
A1  - Seynnes, Olivier R.
T1  - Distinct muscle-tendon interaction during running at different speeds and in different loading conditions
JF  - Journal of Applied Physiology
Y1  - 2019
U6  - https://doi.org/10.1152/japplphysiol.00710.2018
SN  - 1522-1601
VL  - 127
IS  - 1
SP  - 246
EP  - 253
ER  - 
TY  - JOUR
A1  - Capri, Miriam
A1  - Morsiani, Cristina
A1  - Santoro, Aurelia
A1  - Moriggi, Manuela
A1  - Conte, Maria
A1  - Martucci, Morena
A1  - Bellavista, Elena
A1  - Fabbri, Cristina
A1  - Giampieri, Enrico
A1  - Albracht, Kirsten
A1  - Flück, Martin
A1  - Ruoss, Severin
A1  - Brocca, Lorenza
A1  - Canepari, Monica
A1  - Longa, Emanuela
A1  - Giulio, Irene Di
A1  - Bottinelli, Roberto
A1  - Cerretelli, Paolo
A1  - Salvioli, Stefano
A1  - Gelfi, Cecilia
A1  - Franceschi, Claudio
A1  - Narici, Marco
A1  - Rittweger, Jörn
T1  - Recovery from 6-month spaceflight at the International Space Station: muscle-related stress into a proinflammatory setting
JF  - The FASEB journal : official publication of the Federation of American Societies for Experimental Biology
Y1  - 2019
U6  - https://doi.org/10.1096/fj.201801625R
VL  - 33
IS  - 4
SP  - 5168
EP  - 5180
ER  - 
TY  - JOUR
A1  - Quittmann, Oliver J.
A1  - Abel, Thomas
A1  - Albracht, Kirsten
A1  - Strüder, Heiko K.
T1  - Reliability of muscular activation patterns and their alterations during incremental handcycling in able-bodied participants
JF  - Sports Biomechanics
Y1  - 2019
U6  - https://doi.org/10.1080/14763141.2019.1593496
SN  - 1752-6116
IS  - Article in press
PB  - Taylor & Francis
CY  - London
ER  - 
TY  - JOUR
A1  - Kopp, Alexander
A1  - Schmeets, Ralf
A1  - Gosau, Martin
A1  - Friedrich, Reinhard E.
A1  - Fuest, Sandra
A1  - Behbahani, Mehdi
A1  - Barbeck, Mike
A1  - Rutkowski, Rico
A1  - Burg, Simon
A1  - Kluwe, Lan
A1  - Henningsen, Anders
T1  - Production and Characterization of Porous Fibroin Scaffolds for Regenerative Medical Application
JF  - In Vivo
Y1  - 2019
U6  - https://doi.org/10.21873/invivo.11536
SN  - 1791-7549
VL  - 33
IS  - 3
SP  - 757
EP  - 762
ER  - 
TY  - JOUR
A1  - Kodomskoi, Leonid
A1  - Kotliar, Konstantin
A1  - Schröder, Andreas
A1  - Weiss, Michael
A1  - Hille, Konrad
T1  - Suture-Probe Canaloplasty as an Alternative to Canaloplasty using the iTrack™ Microcatheter
JF  - Journal of Glaucoma
Y1  - 2019
U6  - https://doi.org/10.1097/IJG.0000000000001321
SN  - 1057-0829
IS  - Epub ahead of print
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  - 
TY  - JOUR
A1  - Heinke, Lars N.
A1  - Knicker, Axel J.
A1  - Albracht, Kirsten
T1  - Increased shoulder muscle stretch reflex elicitability in supine subject posture
JF  - Isokinetics and Exercise Science
N2  - BACKGROUND: Muscle stretch reflexes are widely used to examine neural muscle function. The knowledge of reflex response in muscles crossing the shoulder is limited. OBJECTIVE: To quantify reflex modulation according to various subject postures and different procedures of muscle pre-activation steering. METHODS: Thirteen healthy male participants performed two sets of external shoulder rotation stretches in various positions and with different procedures of muscle pre-activation steering on an isokinetic dynamometer over a range of two different pre-activation levels. All stretches were applied with a dynamometer acceleration of 104∘/s2 and a velocity of 150∘/s. Electromyographical response was measured via sEMG. RESULTS: Consistent reflexive response was observed in all tested muscles in all experimental conditions. The reflex elicitation rate revealed a significant muscle main effect (F (5,288) = 2.358, ρ= 0.040; η2= 0.039; f= 0.637) and a significant test condition main effect (F (1,288) = 5.884, ρ= 0.016; η2= 0.020; f= 0.143). Reflex latency revealed a significant muscle pre-activation level main effect (F (1,274) = 5.008, ρ= 0.026; η2= 0.018; f= 0.469). CONCLUSION: Muscular reflexive response was more consistent in the primary internal rotators of the shoulder. Supine posture in combination with visual feedback of muscle pre-activation level enhanced the reflex elicitation rate.
Y1  - 2020
U6  - https://doi.org/10.3233/IES-192219
SN  - 1878-5913
VL  - 28
IS  - 2
SP  - 139
EP  - 146
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Müller, Wolfram
A1  - Jung, Alexander
A1  - Ahammer, Helmut
T1  - Advantages and problems of nonlinear methods applied to analyze physiological time signals: human balance control as an example
JF  - Scientific Reports
Y1  - 2017
SN  - 2045-2322
U6  - https://doi.org/10.1038/s41598-017-02665-5
VL  - 7
IS  - Article number 2464
SP  - 1
EP  - 11
PB  - Springer Nature
CY  - Cham
ER  - 
TY  - JOUR
A1  - Heinke, Lars N.
A1  - Knicker, Axel J.
A1  - Albracht, Kirsten
T1  - Test-retest reliability of the internal shoulder rotator muscles' stretch reflex in healthy men
JF  - Journal of Electromyography and Kinesiology
N2  - Until now the reproducibility of the short latency stretch reflex of the internal rotator muscles of the glenohumeral joint has not been identified. Twenty-three healthy male participants performed three sets of external shoulder rotation stretches with various pre-activation levels on two different dates of measurement to assess test-retest reliability. All stretches were applied with a dynamometer acceleration of 104°/s2 and a velocity of 150°/s. Electromyographical response was measured via surface EMG. Reflex latencies showed a pre-activation effect (ƞ2 = 0,355). ICC ranged from 0,735 to 0,909 indicating an overall “good” relative reliability. SRD 95% lay between ±7,0 to ±12,3 ms.. The reflex gain showed overall poor test-retest reproducibility. The chosen methodological approach presented a suitable test protocol for shoulder muscles stretch reflex latency evaluation. A proof-of-concept study to validate the presented methodical approach in shoulder involvement including subjects with clinically relevant conditions is recommended.
KW  - stretch reflex
KW  - shoulder
KW  - test-retest reliability
KW  - intraclass correlation coefficient
KW  - standard error of measurement
Y1  - 2021
U6  - https://doi.org/10.1016/j.jelekin.2021.102611
SN  - 1050-6411
VL  - 62
IS  - Article 102611
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Zange, Jochen
A1  - Schopen, Kathrin
A1  - Albracht, Kirsten
A1  - Gerlach, Darius A.
A1  - Frings-Meuthen, Petra
A1  - Maffiuletti, Nicola A.
A1  - Bloch, Wilhelm
A1  - Rittweger, Jörn
T1  - Using the Hephaistos orthotic device to study countermeasure effectiveness of neuromuscular electrical stimulation and dietary lupin protein supplementation, a randomised controlled trial
JF  - Plos one
Y1  - 2017
U6  - https://doi.org/10.1371/journal.pone.0171562
VL  - 12
IS  - 2
ER  - 
TY  - JOUR
A1  - Waldvogel, Janice
A1  - Ritzmann, Ramona
A1  - Freyler, Kathrin
A1  - Helm, Michael
A1  - Monti, Elena
A1  - Albracht, Kirsten
A1  - Stäudle, Benjamin
A1  - Gollhofer, Albert
A1  - Narici, Marco
T1  - The Anticipation of Gravity in Human Ballistic Movement
JF  - Frontiers in Physiology
N2  - Stretch-shortening type actions are characterized by lengthening of the pre-activated muscle-tendon unit (MTU) in the eccentric phase immediately followed by muscle shortening. Under 1 g, pre-activity before and muscle activity after ground contact, scale muscle stiffness, which is crucial for the recoil properties of the MTU in the subsequent push-off. This study aimed to examine the neuro-mechanical coupling of the stretch-shortening cycle in response to gravity levels ranging from 0.1 to 2 g. During parabolic flights, 17 subjects performed drop jumps while electromyography (EMG) of the lower limb muscles was combined with ultrasound images of the gastrocnemius medialis, 2D kinematics and kinetics to depict changes in energy management and performance. Neuro-mechanical coupling in 1 g was characterized by high magnitudes of pre-activity and eccentric muscle activity allowing an isometric muscle behavior during ground contact. EMG during pre-activity and the concentric phase systematically increased from 0.1 to 1 g. Below 1 g the EMG in the eccentric phase was diminished, leading to muscle lengthening and reduced MTU stretches. Kinetic energy at take-off and performance were decreased compared to 1 g. Above 1 g, reduced EMG in the eccentric phase was accompanied by large MTU and muscle stretch, increased joint flexion amplitudes, energy loss and reduced performance. The energy outcome function established by linear mixed model reveals that the central nervous system regulates the extensor muscles phase- and load-specifically. In conclusion, neuro-mechanical coupling appears to be optimized in 1 g. Below 1 g, the energy outcome is compromised by reduced muscle stiffness. Above 1 g, loading progressively induces muscle lengthening, thus facilitating energy dissipation.
Y1  - 2021
U6  - https://doi.org/10.3389/fphys.2021.614060
SN  - 1664-042X
PB  - Frontiers
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Morat, Mareike
A1  - Faude, Oliver
A1  - Hanssen, Henner
A1  - Ludyga, Sebastian
A1  - Zacher, Jonas
A1  - Eibl, Angi
A1  - Albracht, Kirsten
A1  - Donath, Lars
T1  - Agility Training to Integratively Promote Neuromuscular, Cognitive, Cardiovascular and Psychosocial Function in Healthy Older Adults: A Study Protocol of a One-Year Randomized-Controlled Trial
JF  - International Journal of Environmental Research and Public Health
N2  - Exercise training effectively mitigates aging-induced health and fitness impairments. Traditional training recommendations for the elderly focus separately on relevant physiological fitness domains, such as balance, flexibility, strength and endurance. Thus, a more holistic and functional training framework is needed. The proposed agility training concept integratively tackles spatial orientation, stop and go, balance and strength. The presented protocol aims at introducing a two-armed, one-year randomized controlled trial, evaluating the effects of this concept on neuromuscular, cardiovascular, cognitive and psychosocial health outcomes in healthy older adults. Eighty-five participants were enrolled in this ongoing trial. Seventy-nine participants completed baseline testing and were block-randomized to the agility training group or the inactive control group. All participants undergo pre- and post-testing with interim assessment after six months. The intervention group currently receives supervised, group-based agility training twice a week over one year, with progressively demanding perceptual, cognitive and physical exercises. Knee extension strength, reactive balance, dual task gait speed and the Agility Challenge for the Elderly (ACE) serve as primary endpoints and neuromuscular, cognitive, cardiovascular, and psychosocial meassures serve as surrogate secondary outcomes. Our protocol promotes a comprehensive exercise training concept for older adults, that might facilitate stakeholders in health and exercise to stimulate relevant health outcomes without relying on excessively time-consuming physical activity recommendations.
KW  - agility
KW  - prevention
KW  - healthy aging
KW  - community dwelling
KW  - psychosocial
Y1  - 2020
U6  - https://doi.org/10.3390/ijerph17061853
SN  - 1660-4601
VL  - 17
IS  - 6
SP  - 1
EP  - 14
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Malinowski, Daniel
A1  - Fournier, Yvan
A1  - Horbach, Andreas
A1  - Frick, Michael
A1  - Magliani, Mirko
A1  - Kalverkamp, Sebastian
A1  - Hildinger, Martin
A1  - Spillner, Jan
A1  - Behbahani, Mehdi
A1  - Hima, Flutura
T1  - Computational fluid dynamics analysis of endoluminal aortic perfusion
JF  - Perfusion
N2  - Introduction: In peripheral percutaneous (VA) extracorporeal membrane oxygenation (ECMO) procedures the femoral arteries perfusion route has inherent disadvantages regarding poor upper body perfusion due to watershed. With the advent of new long flexible cannulas an advancement of the tip up to the ascending aorta has become feasible. To investigate the impact of such long endoluminal cannulas on upper body perfusion, a Computational Fluid Dynamics (CFD) study was performed considering different support levels and three cannula positions.

Methods: An idealized literature-based- and a real patient proximal aortic geometry including an endoluminal cannula were constructed. The blood flow was considered continuous. Oxygen saturation was set to 80% for the blood coming from the heart and to 100% for the blood leaving the cannula. 50% and 90% venoarterial support levels from the total blood flow rate of 6 l/min were investigated for three different positions of the cannula in the aortic arch. 

Results: For both geometries, the placement of the cannula in the ascending aorta led to a superior oxygenation of all aortic blood vessels except for the left coronary artery. Cannula placements at the aortic arch and descending aorta could support supra-aortic arteries, but not the coronary arteries. All positions were able to support all branches with saturated blood at 90% flow volume.

Conclusions: In accordance with clinical observations CFD analysis reveals, that retrograde advancement of a long endoluminal cannula can considerably improve the oxygenation of the upper body and lead to oxygen saturation distributions similar to those of a central cannulation.
KW  - computational fluid dynamics analysis
KW  - simulation
KW  - endoluminal
KW  - aortic perfusion
KW  - extracorporeal membrane oxygenation
Y1  - 2022
U6  - https://doi.org/10.1177/02676591221099809
SN  - 1477-111X
VL  - 0
IS  - 0
SP  - 1
EP  - 8
PB  - Sage
CY  - London
ER  - 
TY  - JOUR
A1  - Chloé, Radermacher
A1  - Malyaran, Hanna
A1  - Craveiro, Rogerio Bastos
A1  - Peglow, Sarah
A1  - Behbahani, Mehdi
A1  - Pufe, Thomas
A1  - Wolf, Michael
A1  - Neuss, Sabine
T1  - Mechanical loading on cementoblasts: a mini review
JF  - Osteologie
N2  - Orthodontic treatments are concomitant with mechanical forces and thereby cause teeth movements. The applied forces are transmitted to the tooth root and the periodontal ligaments which is compressed on one side and tensed up on the other side. Indeed, strong forces can lead to tooth root resorption and the crown-to-tooth ratio is reduced with the potential for significant clinical impact. The cementum, which covers the tooth root, is a thin mineralized tissue of the periodontium that connects the periodontal ligament with the tooth and is build up by cementoblasts. The impact of tension and compression on these cells is investigated in several in vivo and in vitro studies demonstrating differences in protein expression and signaling pathways. In summary, osteogenic marker changes indicate that cyclic tensile forces support whereas static tension inhibits cementogenesis. Furthermore, cementogenesis experiences the same protein expression changes in static conditions as static tension, but cyclic compression leads to the exact opposite of cyclic tension. Consistent with marker expression changes, the singaling pathways of Wnt/ß-catenin and RANKL/OPG show that tissue compression leads to cementum degradation and tension forces to cementogenesis. However, the cementum, and in particular its cementoblasts, remain a research area which should be explored in more detail to understand the underlying mechanism of bone resorption and remodeling after orthodontic treatments.
KW  - Cementoblast
KW  - Compression
KW  - Tension
KW  - Mechanotransduction
KW  - Forces
Y1  - 2022
U6  - https://doi.org/10.1055/a-1826-0777
SN  - 1019-1291
VL  - 31
IS  - 2
SP  - 111
EP  - 118
PB  - Thieme
CY  - Stuttgart
ER  - 
TY  - JOUR
A1  - Waldvogel, Janice
A1  - Freyler, Kathrin
A1  - Helm, Michael
A1  - Monti, Elena
A1  - Stäudle, Benjamin
A1  - Gollhofer, Albert
A1  - Narici, Marco V.
A1  - Ritzmann, Ramona
A1  - Albracht, Kirsten
T1  - Changes in gravity affect neuromuscular control, biomechanics, and muscle-tendon mechanics in energy storage and dissipation tasks
JF  - Journal of Applied Physiology
N2  - This study evaluates neuromechanical control and muscle-tendon interaction during energy storage and dissipation tasks in hypergravity. During parabolic flights, while 17 subjects performed drop jumps (DJs) and drop landings (DLs), electromyography (EMG) of the lower limb muscles was combined with in vivo fascicle dynamics of the gastrocnemius medialis, two-dimensional (2D) kinematics, and kinetics to measure and analyze changes in energy management. Comparisons were made between movement modalities executed in hypergravity (1.8 G) and gravity on ground (1 G). In 1.8 G, ankle dorsiflexion, knee joint flexion, and vertical center of mass (COM) displacement are lower in DJs than in DLs; within each movement modality, joint flexion amplitudes and COM displacement demonstrate higher values in 1.8 G than in 1 G. Concomitantly, negative peak ankle joint power, vertical ground reaction forces, and leg stiffness are similar between both movement modalities (1.8 G). In DJs, EMG activity in 1.8 G is lower during the COM deceleration phase than in 1 G, thus impairing quasi-isometric fascicle behavior. In DLs, EMG activity before and during the COM deceleration phase is higher, and fascicles are stretched less in 1.8 G than in 1 G. Compared with the situation in 1 G, highly task-specific neuromuscular activity is diminished in 1.8 G, resulting in fascicle lengthening in both movement modalities. Specifically, in DJs, a high magnitude of neuromuscular activity is impaired, resulting in altered energy storage. In contrast, in DLs, linear stiffening of the system due to higher neuromuscular activity combined with lower fascicle stretch enhances the buffering function of the tendon, and thus the capacity to safely dissipate energy.
KW  - electromyography
KW  - locomotion
KW  - overload
KW  - stretch-shortening cycle
KW  - ultrasound
Y1  - 2023
U6  - https://doi.org/10.1152/japplphysiol.00279.2022
SN  - 1522-1601 (Onlineausgabe)
SN  - 8750-7587 (Druckausgabe)
VL  - 134
IS  - 1
SP  - 190
EP  - 202
PB  - American Physiological Society
CY  - Bethesda, Md.
ER  - 
TY  - JOUR
A1  - Heieis, Jule
A1  - Böcker, Jonas
A1  - D'Angelo, Olfa
A1  - Mittag, Uwe
A1  - Albracht, Kirsten
A1  - Schönau, Eckhard
A1  - Meyer, Andreas
A1  - Voigtmann, Thomas
A1  - Rittweger, Jörn
T1  - Curvature of gastrocnemius muscle fascicles as function of muscle–tendon complex length and contraction in humans
JF  - Physiological Reports
N2  - It has been shown that muscle fascicle curvature increases with increasing contraction level and decreasing muscle–tendon complex length. The analyses were done with limited examination windows concerning contraction level, muscle–tendon complex length, and/or intramuscular position of ultrasound imaging. With this study we aimed to investigate the correlation between fascicle arching and contraction, muscle–tendon complex length and their associated architectural parameters in gastrocnemius muscles to develop hypotheses concerning the fundamental mechanism of fascicle curving. Twelve participants were tested in five different positions (90°/105°*, 90°/90°*, 135°/90°*, 170°/90°*, and 170°/75°*; *knee/ankle angle). They performed isometric contractions at four different contraction levels (5%, 25%, 50%, and 75% of maximum voluntary contraction) in each position. Panoramic ultrasound images of gastrocnemius muscles were collected at rest and during constant contraction. Aponeuroses and fascicles were tracked in all ultrasound images and the parameters fascicle curvature, muscle–tendon complex strain, contraction level, pennation angle, fascicle length, fascicle strain, intramuscular position, sex and age group were analyzed by linear mixed effect models. Mean fascicle curvature of the medial gastrocnemius increased with contraction level (+5 m−1 from 0% to 100%; p = 0.006). Muscle–tendon complex length had no significant impact on mean fascicle curvature. Mean pennation angle (2.2 m−1 per 10°; p < 0.001), inverse mean fascicle length (20 m−1 per cm−1; p = 0.003), and mean fascicle strain (−0.07 m−1 per +10%; p = 0.004) correlated with mean fascicle curvature. Evidence has also been found for intermuscular, intramuscular, and sex-specific intramuscular differences of fascicle curving. Pennation angle and the inverse fascicle length show the highest predictive capacities for fascicle curving. Due to the strong correlations between pennation angle and fascicle curvature and the intramuscular pattern of curving we suggest for future studies to examine correlations between fascicle curvature and intramuscular fluid pressure.
KW  - biomechanics
KW  - connective tissue
KW  - physiology
KW  - ultrasound
Y1  - 2023
U6  - https://doi.org/10.14814/phy2.15739
SN  - 2051-817X
VL  - 11
IS  - 11
SP  - e15739, Seite 1-11
PB  - Wiley
ER  - 
TY  - JOUR
A1  - Werkhausen, Amelie
A1  - Cronin, Neil J.
A1  - Albracht, Kirsten
A1  - Paulsen, Gøran
A1  - Larsen, Askild V.
A1  - Bojsen-Møller, Jens
A1  - Seynnes, Olivier R.
T1  - Training-induced increase in Achilles tendon stiffness affects tendon strain pattern during running
JF  - PeerJ
N2  - Background
During the stance phase of running, the elasticity of the Achilles tendon enables the utilisation of elastic energy and allows beneficial contractile conditions for the triceps surae muscles. However, the effect of changes in tendon mechanical properties induced by chronic loading is still poorly understood. We tested the hypothesis that a training-induced increase in Achilles tendon stiffness would result in reduced tendon strain during the stance phase of running, which would reduce fascicle strains in the triceps surae muscles, particularly in the mono-articular soleus.
Methods 
Eleven subjects were assigned to a training group performing isometric singleleg plantarflexion contractions three times per week for ten weeks, and another ten subjects formed a control group. Before and after the training period, Achilles tendon stiffness was estimated, and muscle-tendon mechanics were assessed during running at preferred speed using ultrasonography, kinematics and kinetics.
Results 
Achilles tendon stiffness increased by 18% (P <0:01) in the training group, but the associated reduction in strain seen during isometric contractions was not statistically significant. Tendon elongation during the stance phase of running was similar after training, but tendon recoil was reduced by 30% (P <0:01), while estimated tendon force remained unchanged. Neither gastrocnemius medialis nor soleus fascicle shortening during stance was affected by training.
Discussion 
These results show that a training-induced increase in Achilles tendon
stiffness altered tendon behaviour during running. Despite training-induced changes in tendon mechanical properties and recoil behaviour, the data suggest that fascicle shortening patterns were preserved for the running speed that we examined. The asymmetrical changes in tendon strain patterns supports the notion that simple inseries models do not fully explain the mechanical output of the muscle-tendon unit during a complex task like running.
KW  - Achilles tendon
KW  - Stiffness
KW  - Running
KW  - Tendon properties
KW  - Architectural gear ratio
Y1  - 2019
U6  - https://doi.org/10.7717/peerj.6764
SN  - 21678359
PB  - Peer
CY  - London
ER  - 
TY  - JOUR
A1  - Quittmann, Oliver J.
A1  - Abel, Thomas
A1  - Albracht, Kirsten
A1  - Strüder, Heiko K.
T1  - Biomechanics of all-out handcycling exercise: kinetics, kinematics and muscular activity of a 15-s sprint test in able-bodied participants
JF  - Sports Biomechanics
N2  - This study aims to quantify the kinematics, kinetics and muscular activity of all-out handcycling exercise and examine their alterations during the course of a 15-s sprint test. Twelve able-bodied competitive triathletes performed a 15-s all-out sprint test in a recumbent racing handcycle that was attached to an ergometer. During the sprint test, tangential crank kinetics, 3D joint kinematics and muscular activity of 10 muscles of the upper extremity and trunk were examined using a power metre, motion capturing and surface electromyography (sEMG), respectively. Parameters were compared between revolution one (R1), revolution two (R2), the average of revolution 3 to 13 (R3) and the average of the remaining revolutions (R4). Shoulder abduction and internal-rotation increased, whereas maximal shoulder retroversion decreased during the sprint. Except for the wrist angles, angular velocity increased for every joint of the upper extremity. Several muscles demonstrated an increase in muscular activation, an earlier onset of muscular activation in crank cycle and an increased range of activation. During the course of a 15-s all-out sprint test in handcycling, the shoulder muscles and the muscles associated to the push phase demonstrate indications for short-duration fatigue. These findings are helpful to prevent injuries and improve performance in all-out handcycling.
KW  - Handbike
KW  - sEMG
KW  - Paralympic sport
KW  - performance testing
KW  - high-intensity exercise
Y1  - 2022
U6  - https://doi.org/10.1080/14763141.2020.1745266
SN  - 1752-6116 (Onlineausgabe)
SN  - 1476-3141 (Druckausgabe)
VL  - 21
IS  - 10
SP  - 1200
EP  - 1223
PB  - Taylor & Francis
CY  - London
ER  - 
TY  - JOUR
A1  - Richter, Charlotte
A1  - Braunstein, Björn
A1  - Stäudle, Benjamin
A1  - Attias, Julia
A1  - Süss, Alexander
A1  - Weber, Tobias
A1  - Mileva, Katya N.
A1  - Rittweger, Jörn
A1  - Green, David A.
A1  - Albracht, Kirsten
T1  - Gastrocnemius medialis contractile behavior during running differs between simulated Lunar and Martian gravities
JF  - Scientific reports
N2  - The international partnership of space agencies has agreed to proceed forward to the Moon sustainably. Activities on the Lunar surface (0.16 g) will allow crewmembers to advance the exploration skills needed when expanding human presence to Mars (0.38 g). Whilst data from actual hypogravity activities are limited to the Apollo missions, simulation studies have indicated that ground reaction forces, mechanical work, muscle activation, and joint angles decrease with declining gravity level. However, these alterations in locomotion biomechanics do not necessarily scale to the gravity level, the reduction in gastrocnemius medialis activation even appears to level off around 0.2 g, while muscle activation pattern remains similar. Thus, it is difficult to predict whether gastrocnemius medialis contractile behavior during running on Moon will basically be the same as on Mars. Therefore, this study investigated lower limb joint kinematics and gastrocnemius medialis behavior during running at 1 g, simulated Martian gravity, and simulated Lunar gravity on the vertical treadmill facility. The results indicate that hypogravity-induced alterations in joint kinematics and contractile behavior still persist between simulated running on the Moon and Mars. This contrasts with the concept of a ceiling effect and should be carefully considered when evaluating exercise prescriptions and the transferability of locomotion practiced in Lunar gravity to Martian gravity.
KW  - Bone quality and biomechanics
KW  - Environmental impact
KW  - Skeletal muscle
KW  - Tendons
KW  - Ultrasound
Y1  - 2021
U6  - https://doi.org/10.1038/s41598-021-00527-9
SN  - 2045-2322
N1  - Corresponding author: Charlotte Richter
VL  - 11
IS  - Article number: 22555
PB  - Springer Nature
CY  - London
ER  - 
TY  - JOUR
A1  - Werkhausen, Amelie
A1  - Willwacher, Steffen
A1  - Albracht, Kirsten
T1  - Medial gastrocnemius muscle fascicles shorten throughout stance during sprint acceleration
JF  - Scandinavian Journal of Medicine & Science in Sports
N2  - The compliant nature of distal limb muscle-tendon units is traditionally considered suboptimal in explosive movements when positive joint work is required. However, during accelerative running, ankle joint net mechanical work is positive. Therefore, this study aims to investigate how plantar flexor muscle-tendon behavior is modulated during fast accelerations. Eleven female sprinters performed maximum sprint accelerations from starting blocks, while gastrocnemius muscle fascicle lengths were estimated using ultrasonography. We combined motion analysis and ground reaction force measurements to assess lower limb joint kinematics and kinetics, and to estimate gastrocnemius muscle-tendon unit length during the first two acceleration steps. Outcome variables were resampled to the stance phase and averaged across three to five trials. Relevant scalars were extracted and analyzed using one-sample and two-sample t-tests, and vector trajectories were compared using statistical parametric mapping. We found that an uncoupling of muscle fascicle behavior from muscle-tendon unit behavior is effectively used to produce net positive mechanical work at the joint during maximum sprint acceleration. Muscle fascicles shortened throughout the first and second steps, while shortening occurred earlier during the first step, where negative joint work was lower compared with the second step. Elastic strain energy may be stored during dorsiflexion after touchdown since fascicles did not lengthen at the same time to dissipate energy. Thus, net positive work generation is accommodated by the reuse of elastic strain energy along with positive gastrocnemius fascicle work. Our results show a mechanism of how muscles with high in-series compliance can contribute to net positive joint work.
KW  - locomotion
KW  - muscle mechanics
KW  - running
KW  - sprint start
KW  - ultrasonography
Y1  - 2021
U6  - https://doi.org/10.1111/sms.13956
SN  - 0905-7188 (Druckausgabe)
SN  - 1600-0838 (Onlineausgabe)
VL  - 31
IS  - 7
SP  - 1471
EP  - 1480
PB  - Wiley-Blackwell
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Monti, Elena
A1  - Waldvogel, Janice
A1  - Ritzmann, Ramona
A1  - Freyler, Kathrin
A1  - Albracht, Kirsten
A1  - Helm, Michael
A1  - De Cesare, Niccolò
A1  - Pavan, Piero
A1  - Reggiani, Carlo
A1  - Gollhofer, Albert
A1  - Narici, Marco Vincenzo
T1  - Muscle in variable gravity: “I do not know where I am, but I know what to do”
JF  - Frontiers in Physiology
N2  - Performing tasks, such as running and jumping, requires activation of the agonist and antagonist muscles before (motor unit pre-activation) and during movement performance (Santello and Mcdonagh, 1998). A well-timed and regulated muscle activation elicits a stretch-shortening cycle (SSC) response, naturally occurring in bouncing movements (Ishikawa and Komi, 2004; Taube et al., 2012). By definition, the SSC describes the stretching of a pre-activated muscle-tendon complex immediately followed by a muscle shortening in the concentric push-off phase (Komi, 1984).
Given the importance of SSC actions for human movement, it is not surprising that many studies investigated the biomechanics of this phenomenon; in particular, drop jumps (DJs) represent a good paradigm to study muscle fascicle and tendon behavior in ballistic movements involving the SSC.
Within a DJ, three main phases [pre-activation, braking, and push-off (PO; Komi, 2000)] have been recognized and extensively studied in common and challenging conditions, such as changes in load, falling height, or simulated hypo-gravity (Avela et al., 1994; Arampatzis et al., 2001; Fukashiro et al., 2005; Ishikawa et al., 2005; Sousa et al., 2007; Ritzmann et al., 2016; Helm et al., 2020).
These studies show that the timing and amount of triceps-surae muscle-tendon unit pre-activation in DJs are differentially regulated based on the load applied to the muscle, being optimal in normal “Earth” gravity conditions (Avela et al., 1994), but decreased in simulated hypo-gravity, hyper-gravity (Avela et al., 1994; Ritzmann et al., 2016), or unknown conditions (i.e., unknown falling heights; Helm et al., 2020). Some authors indicated that, when falling from heights different from the optimal one [defined as the drop height giving a maximum DJ performance indicated as peak ground reaction force (GRF) or jump high], electromyographic (EMG) activity of the plantar flexors increases from lower than optimal to higher than optimal heights (Ishikawa and Komi, 2004; Sousa et al., 2007).
These findings highlight the ability of the central nervous system to regulate the timing and amount of pre-activation according to different jumping conditions, thus regulating muscle fascicle length, tendon and joint stiffness as well as position, in order to safely land on the ground and quickly re-bounce.
Similarly, to pre-activation, also in the braking phase, the plantar flexors are differentially regulated. In optimal height (i.e., load) jumping conditions, gastrocnemius medialis (GM) fascicles shorten at early ground contact (possibly due to the intervention of the stretch reflex; Gollhofer et al., 1992) and behave quasi-isometrically in the late braking phase, enabling tendon elongation, and storage of elastic energy (Gollhofer et al., 1992; Fukashiro et al., 2005; Sousa et al., 2007). When increasing the falling height (augmenting the impact GRF), the quasi-isometric behavior of fascicles disappears, and fast fascicle lengthening occurs (Ishikawa et al., 2005; Sousa et al., 2007).
In the third and last PO phase, fascicles shorten and the tendon releases the elastic energy previously stored. Bobbert et al. (1987) reported no influence of jumping height on the work done and on the net vertical impulse assessed during PO; this observation suggests that, despite an optimal DJ performance might be achieved only in specific conditions (falling heights, loads), the central nervous system seems to be able to regulate muscle behavior in order to effectively perform the required task also in challenging situations.
Although the regulation of triceps-surae muscle-tendon unit in DJs has been extensively investigated, very few studies focused on sarcomeres behavior during the performance of this SSC movement (Kurokawa et al., 2003; Fukashiro et al., 2005, 2006). Sarcomeres represent muscle contractile units and are known to express different amounts of force depending on their length (Gordon et al., 1966; Walker and Schrodt, 1974); thus, understanding the time course of their responses during DJs is fundamental to gain further insights into muscle force-generating capacity. In vivo measurement of sarcomere length in humans has been so far been performed only in static positions and under highly controlled experimental conditions (Llewellyn et al., 2008; Sanchez et al., 2015). Instead, human sarcomere length estimation (achieved by dividing GM measured fascicle length for a fixed sarcomere number) in dynamic contractions provided an indirect measure of sarcomere operating range during squat jump, countermovement jump, and DJ (Fukashiro et al., 2005, 2006; Kurokawa et al., 2003). The results of these studies showed that sarcomeres operate in the ascending limb of their length-tension (L-T) relationship in all types of jumps, and particularly so in DJ.
However, most of the available observations on sarcomere and muscle fascicle behavior were made in condition of constant gravity. Thus, in order to understand how sarcomere and muscle fascicle length are regulated in variable gravity conditions, we performed experiments in a parabolic flight, involving variable gravity levels, ranging from about zero-g to about double the Earth’s gravity (1 g; Waldvogel et al., 2021).
Specifically, the aims of the present study were as follows:
1. To investigate the ability of the neuromuscular system in regulating fascicle length in response to conditions of variable gravity.
2. To estimate sarcomere operative length in the different DJ phases, in order to calculate its theoretical force production and its possible modulation in conditions of variable gravity.
We hypothesized that muscle fascicles would be differentially regulated in different gravity conditions compared to 1 g, particularly in anticipation of landing and re-bouncing in unknown gravity levels. In addition, we hypothesized that sarcomeres would operate in the upper part of the ascending limb of their L-T relationship, possibly lengthening during the braking phase (especially in hyper-gravity) while operating quasi-isometrically in 1 g.
KW  - parabolic flight
KW  - drop jump
KW  - hypo-gravity
KW  - hyper-gravity
KW  - sarcomere operating length
Y1  - 2021
U6  - https://doi.org/10.3389/fphys.2021.714655
SN  - 1664-042X
VL  - 12
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Werkhausen, Amelie
A1  - Albracht, Kirsten
A1  - Cronin, Neil J
A1  - Paulsen, Gøran
A1  - Bojsen-Møller, Jens
A1  - Seynnes, Olivier R
T1  - Effect of training-induced changes in achilles tendon stiffness on muscle-tendon behavior during landing
JF  - Frontiers in physiology
N2  - During rapid deceleration of the body, tendons buffer part of the elongation of the muscle-tendon unit (MTU), enabling safe energy dissipation via eccentric muscle contraction. Yet, the influence of changes in tendon stiffness within the physiological range upon these lengthening contractions is unknown. This study aimed to examine the effect of training-induced stiffening of the Achilles tendon on triceps surae muscle-tendon behavior during a landing task. Twenty-one male subjects were assigned to either a 10-week resistance-training program consisting of single-leg isometric plantarflexion (n = 11) or to a non-training control group (n = 10). Before and after the training period, plantarflexion force, peak Achilles tendon strain and stiffness were measured during isometric contractions, using a combination of dynamometry, ultrasound and kinematics data. Additionally, testing included a step-landing task, during which joint mechanics and lengths of gastrocnemius and soleus fascicles, Achilles tendon, and MTU were determined using synchronized ultrasound, kinematics and kinetics data collection. After training, plantarflexion strength and Achilles tendon stiffness increased (15 and 18%, respectively), and tendon strain during landing remained similar. Likewise, lengthening and negative work produced by the gastrocnemius MTU did not change detectably. However, in the training group, gastrocnemius fascicle length was offset (8%) to a longer length at touch down and, surprisingly, fascicle lengthening and velocity were reduced by 27 and 21%, respectively. These changes were not observed for soleus fascicles when accounting for variation in task execution between tests. These results indicate that a training-induced increase in tendon stiffness does not noticeably affect the buffering action of the tendon when the MTU is rapidly stretched. Reductions in gastrocnemius fascicle lengthening and lengthening velocity during landing occurred independently from tendon strain. Future studies are required to provide insight into the mechanisms underpinning these observations and their influence on energy dissipation.
KW  - achilles tendon
KW  - energy absorption
KW  - energy dissipation
KW  - mechanical buffer
KW  - stiffness
Y1  - 2018
U6  - https://doi.org/10.3389/fphys.2018.00794
SN  - 1664-042X
IS  - 9
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Angermann, Susanne
A1  - Günthner, Roman
A1  - Hanssen, Henner
A1  - Lorenz, Georg
A1  - Braunisch, Matthias C.
A1  - Steubl, Dominik
A1  - Matschkal, Julia
A1  - Kemmner, Stephan
A1  - Hausinger, Renate
A1  - Block, Zenonas
A1  - Haller, Bernhard
A1  - Heemann, Uwe
A1  - Kotliar, Konstantin
A1  - Grimmer, Timo
A1  - Schmaderer, Christoph
T1  - Cognitive impairment and microvascular function in end-stage renal disease
JF  - International Journal of Methods in Psychiatric Research (MPR)
N2  - Objective
Hemodialysis patients show an approximately threefold higher prevalence of cognitive impairment compared to the age-matched general population. Impaired microcirculatory function is one of the assumed causes. Dynamic retinal vessel analysis is a quantitative method for measuring neurovascular coupling and microvascular endothelial function. We hypothesize that cognitive impairment is associated with altered microcirculation of retinal vessels.

Methods
152 chronic hemodialysis patients underwent cognitive testing using the Montreal Cognitive Assessment. Retinal microcirculation was assessed by Dynamic Retinal Vessel Analysis, which carries out an examination recording retinal vessels' reaction to a flicker light stimulus under standardized conditions.

Results
In unadjusted as well as in adjusted linear regression analyses a significant association between the visuospatial executive function domain score of the Montreal Cognitive Assessment and the maximum arteriolar dilation as response of retinal arterioles to the flicker light stimulation was obtained.

Conclusion
This is the first study determining retinal microvascular function as surrogate for cerebral microvascular function and cognition in hemodialysis patients. The relationship between impairment in executive function and reduced arteriolar reaction to flicker light stimulation supports the involvement of cerebral small vessel disease as contributing factor for the development of cognitive impairment in this patient population and might be a target for noninvasive disease monitoring and therapeutic intervention.
KW  - cerebral small vessel disease
KW  - cognitive impairment
KW  - dialysis
KW  - retinal vessels
Y1  - 2022
U6  - https://doi.org/10.1002/mpr.1909
SN  - 1049-8931 (Print)
SN  - 1557-0657 (Online)
VL  - 31
IS  - 2
SP  - 1
EP  - 10
PB  - Wiley
ER  - 
TY  - JOUR
A1  - Kotliar, Konstantin
A1  - Ortner, Marion
A1  - Conradi, Anna
A1  - Hacker, Patricia
A1  - Hauser, Christine
A1  - Günthner, Roman
A1  - Moser, Michaela
A1  - Muggenthaler, Claudia
A1  - Diehl-Schmid, Janine
A1  - Priller, Josef
A1  - Schmaderer, Christoph
A1  - Grimmer, Timo
T1  - Altered retinal cerebral vessel oscillation frequencies in Alzheimer's disease compatible with impaired amyloid clearance
JF  - Neurobiology of Aging
N2  - Retinal vessels are similar to cerebral vessels in their structure and function. Moderately low oscillation frequencies of around 0.1 Hz have been reported as the driving force for paravascular drainage in gray matter in mice and are known as the frequencies of lymphatic vessels in humans. We aimed to elucidate whether retinal vessel oscillations are altered in Alzheimer's disease (AD) at the stage of dementia or mild cognitive impairment (MCI). Seventeen patients with mild-to-moderate dementia due to AD (ADD); 23 patients with MCI due to AD, and 18 cognitively healthy controls (HC) were examined using Dynamic Retinal Vessel Analyzer. Oscillatory temporal changes of retinal vessel diameters were evaluated using mathematical signal analysis. Especially at moderately low frequencies around 0.1 Hz, arterial oscillations in ADD and MCI significantly prevailed over HC oscillations and correlated with disease severity. The pronounced retinal arterial vasomotion at moderately low frequencies in the ADD and MCI groups would be compatible with the view of a compensatory upregulation of paravascular drainage in AD and strengthen the amyloid clearance hypothesis.
KW  - Alzheimer's disease
KW  - Retinal vessel analysis
KW  - Vasomotions
KW  - Pulsations
KW  - Mild cognitive impairment
Y1  - 2022
U6  - https://doi.org/10.1016/j.neurobiolaging.2022.08.012
SN  - 0197-4580
VL  - 120
SP  - 117
EP  - 127
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Neumaier, Felix
A1  - Weiss, Miriam
A1  - Veldeman, Michael
A1  - Kotliar, Konstantin
A1  - Wiesmann, Martin
A1  - Schulze-Steinen, Henna
A1  - Höllig, Anke
A1  - Clusmann, Hans
A1  - Schubert, Gerrit Alexander
A1  - Albanna, Walid
T1  - Changes in endogenous daytime melatonin levels after aneurysmal subarachnoid hemorrhage – preliminary findings from an observational cohort study
JF  - Clinical Neurology and Neurosurgery
N2  - Aneurysmal subarachnoid hemorrhage (aSAH) is associated with early and delayed brain injury due to several underlying and interrelated processes, which include inflammation, oxidative stress, endothelial, and neuronal apoptosis. Treatment with melatonin, a cytoprotective neurohormone with anti-inflammatory, anti-oxidant and anti-apoptotic effects, has been shown to attenuate early brain injury (EBI) and to prevent delayed cerebral vasospasm in experimental aSAH models. Less is known about the role of endogenous melatonin for aSAH outcome and how its production is altered by the pathophysiological cascades initiated during EBI. In the present observational study, we analyzed changes in melatonin levels during the first three weeks after aSAH.
KW  - constructive alignment
KW  - examination
KW  - long-term retention
KW  - multimodal
KW  - practical learning
Y1  - 2021
U6  - https://doi.org/10.1016/j.clineuro.2021.106870
SN  - 0303-8467
VL  - 208
IS  - Article No.: 106870
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Alnemer, Momin Sami Mohammad
A1  - Kotliar, Konstantin
A1  - Neuhaus, Valentin
A1  - Pape, Hans-Christoph
A1  - Ciritsis, Bernhard D.
T1  - Cost-effectiveness analysis of surgical proximal femur fracture prevention in elderly: a Markov cohort simulation model
JF  - Cost Effectiveness and Resource Allocation
N2  - Background
Hip fractures are a common and costly health problem, resulting in significant morbidity and mortality, as well as high costs for healthcare systems, especially for the elderly. Implementing surgical preventive strategies has the potential to improve the quality of life and reduce the burden on healthcare resources, particularly in the long term. However, there are currently limited guidelines for standardizing hip fracture prophylaxis practices.

Methods
This study used a cost-effectiveness analysis with a finite-state Markov model and cohort simulation to evaluate the primary and secondary surgical prevention of hip fractures in the elderly. Patients aged 60 to 90 years were simulated in two different models (A and B) to assess prevention at different levels. Model A assumed prophylaxis was performed during the fracture operation on the contralateral side, while Model B included individuals with high fracture risk factors. Costs were obtained from the Centers for Medicare & Medicaid Services, and transition probabilities and health state utilities were derived from available literature. The baseline assumption was a 10% reduction in fracture risk after prophylaxis. A sensitivity analysis was also conducted to assess the reliability and variability of the results.

Results
With a 10% fracture risk reduction, model A costs between $8,850 and $46,940 per quality-adjusted life-year ($/QALY). Additionally, it proved most cost-effective in the age range between 61 and 81 years. The sensitivity analysis established that a reduction of ≥ 2.8% is needed for prophylaxis to be definitely cost-effective. The cost-effectiveness at the secondary prevention level was most sensitive to the cost of the contralateral side’s prophylaxis, the patient’s age, and fracture treatment cost. For high-risk patients with no fracture history, the cost-effectiveness of a preventive strategy depends on their risk profile. In the baseline analysis, the incremental cost-effectiveness ratio at the primary prevention level varied between $11,000/QALY and $74,000/QALY, which is below the defined willingness to pay threshold.

Conclusion
Due to the high cost of hip fracture treatment and its increased morbidity, surgical prophylaxis strategies have demonstrated that they can significantly relieve the healthcare system. Various key assumptions facilitated the modeling, allowing for adequate room for uncertainty. Further research is needed to evaluate health-state-associated risks.
KW  - Hip fractures
KW  - Prevention
KW  - Geriatric
KW  - Cost-effectiveness
KW  - Prophylaxis
Y1  - 2023
U6  - https://doi.org/10.1186/s12962-023-00482-4
SN  - 1478-7547
N1  - Corresponding author: Momin S. Alnemer
IS  - 21, Article number: 77
PB  - Springer Nature
ER  -