Ein Billardroboter: Praktische Realisierung von ausgewählten Konzepten der Robotik

Die Arbeit beschreibt Konzipierung, Bau und Untersuchung eines Robotersystems, welches die grundlegenden Züge des Billardspiels beherrscht. Die Realisierung erfolgte in Form eines an die Charakteristika von mobilen Robotern angelehnten Fahrzeuges, welches sich auf einem Billardtisch bewegt und mit einer Art Queue Billardstöße ausführt. Alle Abläufe werden mit Hilfe einer über dem Tisch montierten Digitalkamera erfaßt und überwacht. Die Steuerung erfolgt durch einen Personalcomputer. Schwerpunkte der Arbeit bilden Probleme der Bilderkennung, Wegplanung und technischen Umsetzung. Die Lösung wurde mit Hilfe relativ einfacher technischer Mittel und geringem finanziellen Budget erstellt

Randomized, active-controlled, comparative phase 3 efficacy and safety equivalence trial of Ovaleap® (recombinant human follicle-stimulating hormone) in infertile women using assisted reproduction technology (ART)

Background: Pharmacokinetic studies with XM17 (Ovaleap®), a recombinant human follicle-stimulating hormone (r-hFSH, follitropin alfa), have demonstrated good safety and tolerability in healthy women whose endogenous FSH levels were down-regulated with a long agonist protocol. In these studies, Ovaleap® pharmacokinetics were dose-proportional and bioequivalent to the reference follitropin alfa product (Gonal-f®). The objective of the present study is to determine whether Ovaleap® is equivalent to Gonal-f® with respect to the number of oocytes retrieved in infertile but ovulatory women undergoing assisted reproductive technology (ART) therapy. Methods: This multinational, multicenter, randomized (1:1), active-controlled, assessor-blind, comparative study included infertile normally gonadotrophic women 18 to 37 years old with a body mass index of 18 to 29 kg/m2 and regular menstrual cycles of 21 to 35 days undergoing ART therapy. During a 5-day fixed-dose phase, women received 150 IU/day of Ovaleap® (n = 153) or Gonal-f® (n = 146), followed by an up to 15-day dose-adaptation phase during which doses could be adjusted every 3 to 5 days, up to a maximum of 450 IU/day. Ovaleap® was to be deemed equivalent to Gonal-f® if the two-sided 0.95 confidence interval (CI) for the difference in the number of oocytes retrieved fell within the equivalence range of ±3 oocytes. Results: Similar numbers of oocytes were retrieved in the 2 treatment groups. The mean ± SD number of oocytes retrieved was 12.2 ± 6.7 in the Ovaleap® group and 12.1 ± 6.7 in the Gonal-f® group (intent-to-treat [ITT] population). Regression analysis estimated a mean difference of 0.03 oocytes between the treatment groups (95 % CI: −0.76-0.82), which was well within the prespecified equivalence range of ±3 oocytes. Ovaleap® and Gonal-f® showed favorable and comparable safety profiles, with no unexpected safety findings. Conclusions: Ovaleap® has shown the same efficacy and safety as Gonal-f® for stimulation of follicular development in infertile women (up to 37 years of age) who are undergoing ART therapy. Trial Registration EudraCT: 2009-017674-20. Current controlled trials: ISRCTN74772901. Date of trial registration: 19 March 2010

Rapid Prototyping for In Vitro Knee Rig Investigations of Prosthetized Knee Biomechanics: Comparison with Cobalt-Chromium Alloy Implant Material

Retropatellar complications after total knee arthroplasty (TKA) such as anterior knee pain and subluxations might be related to altered patellofemoral biomechanics, in particular to trochlear design and femorotibial joint positioning. A method was developed to test femorotibial and patellofemoral joint modifications separately with 3D-rapid prototyped components for in vitro tests, but material differences may further influence results. This pilot study aims at validating the use of prostheses made of photopolymerized rapid prototype material (RPM) by measuring the sliding friction with a ring-on-disc setup as well as knee kinematics and retropatellar pressure on a knee rig. Cobalt-chromium alloy (standard prosthesis material, SPM) prostheses served as validation standard. Friction coefficients between these materials and polytetrafluoroethylene (PTFE) were additionally tested as this latter material is commonly used to protect pressure sensors in experiments. No statistical differences were found between friction coefficients of both materials to PTFE. UHMWPE shows higher friction coefficient at low axial loads for RPM, a difference that disappears at higher load. No measurable statistical differences were found in knee kinematics and retropatellar pressure distribution. This suggests that using polymer prototypes may be a valid alternative to original components for in vitro TKA studies and future investigations on knee biomechanics

Posterior cruciate ligament balancing in total knee arthroplasty: a numerical study with a dynamic force controlled knee model

Background: Adequate soft tissue balancing is a key factor for a successful result after total knee arthroplasty (TKA). Posterior cruciate ligament (PCL) is the primary restraint to posterior translation of the tibia after cruciate retaining TKA and is also responsible for the amount of joint compression. However, it is complex to quantify the amount of ligament release with its effects on load bearing and kinematics in TKA and limited both in vivo and in vitro. The goal of this study was to create a dynamic and deformable finite element model of a full leg and analyze a stepwise release of the PCL regarding knee kinematics, pressure distribution and ligament stresses. Methods: A dynamic finite element model was developed in Ansys V14.0 based on boundary conditions of an existing knee rig. A cruciate retraining knee prosthesis was virtually implanted. Ligament and muscle structures were simulated with modified spring elements. Linear elastic materials were defined for femoral component, inlay and patella cartilage. A restart algorithm was developed and implemented into the finite element simulation to hold the ground reaction force constant by adapting quadriceps force. After simulating the unreleased PCL model, two models were developed and calculated with the same boundary conditions with a 50% and 75% release of the PCL stiffness. Results: From the beginning of the simulation to approximately 35 degrees of flexion, tibia moves posterior related to the femur and with higher flexion anteriorly. Anterior translation of the tibia ranged from 5.8 mm for unreleased PCL to 3.7 mm for 75% PCL release (4.9 mm 50% release). A decrease of maximum von Mises equivalent stress on the inlay was given with PCL release, especially in higher flexion angles from 11.1 MPa for unreleased PCL to 8.9 MPa for 50% release of the PCL and 7.8 MPa for 75% release. Conclusions: Our study showed that dynamic FEM is an effective method for simulation of PCL balancing in knee arthroplasty. A tight PCL led in silico to more anterior tibia translation, a higher collateral ligament and inlay stress, while retropatellar pressure remained unchanged. Surgeons may take these results in vivo into account

Calculation of the elastic properties of prosthetic knee components with an iterative finite element-based modal analysis: quantitative comparison of different measuring techniques.

With the aging but still active population, research on total joint replacements relies increasingly on numerical methods, such as finite element analysis, to improve wear resistance of components. However, the validity of finite element models largely depends on the accuracy of their material behavior and geometrical representation. In particular, material properties are often based on manufacturer data or literature reports, but can alternatively be estimated by matching experimental measurements and structural predictions through modal analyses and identification of eigenfrequencies. The aim of the present study was to compare the accuracy of common setups used for estimating the eigenfrequencies of typical components often used in prosthetized joints. Eigenfrequencies of cobalt-chrome and ultra-high-molecular weight polyethylene components were therefore measured with four different setups, and used in modal analyses of corresponding finite element models for an iterative adjustment of their material properties. Results show that for the low-damped cobalt chromium endoprosthesis components, all common measuring setups provided accurate measurements. In the case of high-damped structures, measurements were only possible with setups including a continuously excitation system such as electrodynamic shakers. This study demonstrates that the iterative back-calculation of eigenfrequencies can be a reliable method to estimate the elastic properties for finite element models

Safety and efficacy of Ovaleap® (recombinant human follicle-stimulating hormone) for up to 3 cycles in infertile women using assisted reproductive technology: a phase 3 open-label follow-up to Main Study

Background: Ovaleap® (follitropin alfa), a recombinant human follicle-stimulating hormone intended for use in controlled ovarian stimulation in women undergoing assisted reproductive technologies (ART), showed therapeutic equivalence to Gonal-f® in a multinational, multicenter, randomized, controlled, assessor-blind phase 3 Main Study. The current study examined safety, including immunogenicity, and efficacy of Ovaleap® in an open-label, uncontrolled, follow-up treatment period of up to 2 additional treatment cycles in patients who did not become pregnant in the phase 3 Main Study. Methods: Patients with negative biochemical or clinical pregnancy in the phase 3 Main Study, regardless of treatment group (ie, Ovaleap® or Gonal-f®), were eligible to participate. Patients received Ovaleap® (Merckle Biotec GmbH, Ulm, Germany) for up to 2 additional cycles, administered using a reusable semi-automated pen device. The primary objective was the assessment of safety, including adverse events (AEs), ovarian hyperstimulation syndrome (OHSS), and anti-drug antibodies. Tolerability, patient satisfaction with the Ovaleap® pen device, and efficacy outcomes (as evaluated in the Main Study) were also assessed. Results: One hundred forty-seven patients were included in cycle 2, and 61 patients were included in cycle 3. In cycles 2 and 3, 10.9% (16/147) and 6.6% (4/61) of patients experienced treatment-emergent AEs (TEAEs), respectively. Three serious TEAEs (ie, appendicitis, OHSS, and borderline ovarian tumor) were reported and successfully resolved. The OHSS TEAE was the only OHSS reported in the study (0.7% [1/147]). Positive findings on anti-drug antibody assays in 6 serum samples did not show neutralizing activity or clinical relevance in biochemical pregnancy rate. No hypersensitivity reaction occurred. Most patients reported “very good”/“good” local tolerability. All patients were “very confident”/“confident” about dose accuracy and correctness of the injection. They all found use of the pen “very convenient”/“convenient” and were all “very satisfied”/“satisfied” with the pen device. Efficacy outcomes were consistent with the phase 3 Main Study. Conclusions: These findings further support the safety, including immunogenicity, and efficacy of Ovaleap® for stimulation of follicular development in infertile women undergoing ART. The findings support continued use of Ovaleap® for multiple cycles or a switch to Ovaleap® if pregnancy is initially not achieved with Gonal-f®. Trial registration: EudraCT number: 2009-017674-20. Current controlled trials register number: ISRCTN74772901

Increase in the Tibial Slope Reduces Wear after Medial Unicompartmental Fixed-Bearing Arthroplasty of the Knee

Introduction. Unicompartmental arthroplasty of the knee in patients with isolated medial osteoarthritis gives good results, but survival is inferior to that of total knee prosthesis. Knees may fail because positioning of the prosthesis has been suboptimal. The aim of this study was to investigate the influence of the tibial slope on the rate of wear of amedial fixed-bearing unicompartmental knee arthroplasty. Materials and Methods. We simulated wear on a medial fixed-bearing unicompartmental knee prosthesis (Univation) in vitro with a customised, four-station, and servohydraulic knee wear simulator, which exactly reproduced the walking cycle (International Organisation for Standardisation (ISO) 14243-1: 2002(E)). The medial prostheses were inserted with 3 different posterior tibial slopes: 0 degrees, 4 degrees, and 8 degrees (n = 3 in each group). Results. The wear rate decreased significantly between 0 degrees and 4 degrees slope from 10.4 (SD 0.62) mg/million cycles to 3.22 (SD 1.71) mg/million cycles. Increasing the tibial slope to 8 degrees did not significantly change the wear rate. Discussion. As an increase in the tibial slope reduced the wear rate in a fixed-bearing prosthesis, a higher tibial slope should be recommended. However, other factors that are influenced by the tibial slope (e.g.,the tension of the ligament) must also be considered

Increase in the Tibial Slope Reduces Wear after Medial Unicompartmental Fixed-Bearing Arthroplasty of the Knee

Introduction. Unicompartmental arthroplasty of the knee in patients with isolated medial osteoarthritis gives good results, but survival is inferior to that of total knee prosthesis. Knees may fail because positioning of the prosthesis has been suboptimal. The aim of this study was to investigate the influence of the tibial slope on the rate of wear of amedial fixed-bearing unicompartmental knee arthroplasty. Materials and Methods. We simulated wear on a medial fixed-bearing unicompartmental knee prosthesis (Univation) in vitro with a customised, four-station, and servohydraulic knee wear simulator, which exactly reproduced the walking cycle (International Organisation for Standardisation (ISO) 14243-1: 2002(E)). The medial prostheses were inserted with 3 different posterior tibial slopes: 0 degrees, 4 degrees, and 8 degrees (n = 3 in each group). Results. The wear rate decreased significantly between 0 degrees and 4 degrees slope from 10.4 (SD 0.62) mg/million cycles to 3.22 (SD 1.71) mg/million cycles. Increasing the tibial slope to 8 degrees did not significantly change the wear rate. Discussion. As an increase in the tibial slope reduced the wear rate in a fixed-bearing prosthesis, a higher tibial slope should be recommended. However, other factors that are influenced by the tibial slope (e.g.,the tension of the ligament) must also be considered

The new Felsenkeller 5 MV underground accelerator

The field of nuclear astrophysics is devoted to the study of the creation of the chemical elements. By nature, it is deeply intertwined with the physics of the Sun. The nuclear reactions of the proton-proton cycle of hydrogen burning, including the 3He({\alpha},{\gamma})7Be reaction, provide the necessary nuclear energy to prevent the gravitational collapse of the Sun and give rise to the by now well-studied pp, 7Be, and 8B solar neutrinos. The not yet measured flux of 13N, 15O, and 17F neutrinos from the carbon-nitrogen-oxygen cycle is affected in rate by the 14N(p,{\gamma})15O reaction and in emission profile by the 12C(p,{\gamma})13N reaction. The nucleosynthetic output of the subsequent phase in stellar evolution, helium burning, is controlled by the 12C({\alpha},{\gamma})16O reaction. In order to properly interpret the existing and upcoming solar neutrino data, precise nuclear physics information is needed. For nuclear reactions between light, stable nuclei, the best available technique are experiments with small ion accelerators in underground, low-background settings. The pioneering work in this regard has been done by the LUNA collaboration at Gran Sasso/Italy, using a 0.4 MV accelerator. The present contribution reports on a higher-energy, 5.0 MV, underground accelerator in the Felsenkeller underground site in Dresden/Germany. Results from {\gamma}-ray, neutron, and muon background measurements in the Felsenkeller underground site in Dresden, Germany, show that the background conditions are satisfactory for nuclear astrophysics purposes. The accelerator is in the commissioning phase and will provide intense, up to 50{\mu}A, beams of 1H+, 4He+ , and 12C+ ions, enabling research on astrophysically relevant nuclear reactions with unprecedented sensitivity.Comment: Submitted to the Proceedings of the 5th International Solar Neutrino Conference, Dresden/Germany, 11-14 June 2018, to appear on World Scientific -- updated version (Figure 2 and relevant discussion updated, co-author A. Domula added