INTERNAL LOAD ESTIMATION FOR CLINICAL PROGNOSIS

Introduction: In therapy and rehabilitation it is important to know the ranges of the expected loads in the human body resulting from different movements. Because of the difficulty of measuring experimental dynamic loads (hip loads, Bergmann, Taylor), the loads created under these dynamic conditions are estimated by theoretical models and computer simulation. The method will be presented considering a squat jump. Methods: A squat jump performed with both legs, maximum strength and without counter-movement was modeled by a two-dimensional multi-body system with four segments. The movement-generating muscles were implemented taking into account the muscle insertions and paths, as well as Hill’s force-velocity-relation. The data were extracted from MR images and the literature. The muscles were excited by Hatze’s stimulation model. To obtain maximal jump height, the muscles were excited coordinately by optimization algorithms. Results: In the case of a vertical jump, the loads reached maximum values of 4250 N, 4750 N and 4800 N in hip, knee and ankle joints, respectively. The mean values of the hip, knee and ankle joint loads were 3100 N, 3650 N and 2600 N, respectively. Comparing the calculated values with those of Bassey et al. (1997), who measured the hip load during a fast jump, a good agreement of the load values was found. Conclusion: With this vertical jump it was proved that an estimation of joint loads is possible. A multitude of movements can be examined with this model in order to compile data for a joint load database which can be used for clinical prognosis. References: Bassey, E.J., Littlewood, J.J., Taylor, S.J.G. (1997). Relations Between Compressive Axial Forces in an Instrumented Massive Femoral Implant, Ground Reaction Forces, and Integrated Electromyographs From Vastus Lateralis During Various Ostogenic Exercies. J. Biomechanics 30, 213-223. Bergmann, G., Graichen, F., Rohlmann, A. (1993). Hip Joint Loading During Walking and Running, Measured in Two Patients. J. Biomechanics 26, 969-990

Improved detection of pulmonary nodules on energy-subtracted chest radiographs with a commercial computer-aided diagnosis software: comparison with human observers

Objective: To retrospectively analyze the performance of a commercial computer-aided diagnosis (CAD) software in the detection of pulmonary nodules in original and energy-subtracted (ES) chest radiographs. Methods: Original and ES chest radiographs of 58 patients with 105 pulmonary nodules measuring 5-30mm and images of 25 control subjects with no nodules were randomized. Five blinded readers evaluated firstly the original postero-anterior images alone and then together with the subtracted radiographs. In a second phase, original and ES images were analyzed by a commercial CAD program. CT was used as reference standard. CAD results were compared to the readers' findings. True-positive (TP) and false-positive (FP) findings with CAD on subtracted and non-subtracted images were compared. Results: Depending on the reader's experience, CAD detected between 11 and 21 nodules missed by readers. Human observers found three to 16 lesions missed by the CAD software. CAD used with ES images produced significantly fewer FPs than with non-subtracted images: 1.75 and 2.14 FPs per image, respectively (p = 0.029). The difference for the TP nodules was not significant (40 nodules on ES images and 34 lesions in non-subtracted radiographs, p = 0.142). Conclusion: CAD can improve lesion detection both on energy subtracted and non-subtracted chest images, especially for less experienced readers. The CAD program marked less FPs on energy-subtracted images than on original chest radiograph

3D Printed Carbon Fiber Electric Mountain Bike Frame

3D printing of carbon fiber composites has been a developing technology for about 5 years, and in this time, Arevo Labs has established itself as a leader in the field. Our team joined forces with Arevo, who sponsored our project as we showcased their new, innovative carbon fiber manufacturing process. To do so, we focused on the conceptual design, analysis, assembly, and material testing of an electric mountain-bike frame printed with Arevo’s continuous carbon fiber printing technology. Our bike consists of the main frame and a chain stay subsystem, which connects the rear wheel to the rest of the frame and interfaces with a suspension system. Understanding how the capabilities of the printer, the properties of the materials, and the typical loading scenarios experienced by mountain bikes all worked together was paramount in analysis, simulation, and design optimization and iteration. Thus, the focus of this project is to design a mountain bike capable of withstanding typical loading patterns with a high level of safety. Further, the team aimed to optimize a bike frame which used the minimal amount of material necessary to reduce weight and cost for the user

Single-exposure dual-energy subtraction chest radiography: Detection of pulmonary nodules and masses in clinical practice

The purpose of this retrospective study was to evaluate the impact of energy subtraction (ES) chest radiography on the detection of pulmonary nodules and masses in daily routine. Seventy-seven patients and 25 healthy subjects were examined with a single exposure digital radiography system. Five blinded readers evaluated first the non-subtracted PA and lateral chest radiographs alone and then together with the subtracted PA soft tissue images. The size, location and number of lung nodules or masses were registered with the confidence level. CT was used as standard of reference. For the 200 total lesions, a sensitivity of 33.5-52.5% was found at non-subtracted and a sensitivity of 43.5-58.5% at energy-subtracted radiography, corresponding to a significant improvement in four of five readers (p < 0.05). However, in three of five readers the rate of false positives was higher with ES. With ES, sensitivity, but not the area under the alternative free-response receiver operating characteristics (AFROC) curve, showed a good correlation with reader experience (R = 0.90, p = 0.026). In four of five readers, the diagnostic confidence improved with ES (p = 0.0036). We conclude that single-exposure digital ES chest radiography improves detection of most pulmonary nodules and masses, but identification of nodules <1cm and false-positive findings remain a proble

Thoraxbildgebung bei COVID-19

Die Bildgebung bei COVID-19 war zu Beginn der Pandemie sehr kontroversen Diskussionen unterworfen. Ist sie für Diagnose und therapeutische Entscheidungen überhaupt notwendig und wenn ja, bei wem? Wann und wie sollte sie durchgeführt werden? Verschiedene nationale und internationale Fachgesellschaften sowie die WHO haben Konsensuspapere oder Leitlinien zur Indikationsstellung und Befundung erstellt. Anhand des WHO-Guides sollen einige dieser Empfehlungen reflektiert und mit eigenen Erfahrungen kommentiert werden

Towards a self-consistent modelling of pulsar magnetospheres

The numerical modelling of the general case of an obligue rotator is a very complicated time-dependent three-dimensional problem and in its full extent probably outside the capacity of present-day computers. A considerable simplification occurs if one can assume that the essential effects may be understood by modelling the magnetosphere of an aligned rotator (where the rotation axis is parallel to the magnetic axis of the neutron star). This assumption is only reasonable for small obliguenses, since by this approach all electromagnetic wave effects are not taken into account. An advantage, however, is that unipolar induction, which should be responsible for populsting the magnetosphere with charged particles pulled out from the neutron star surface via field emission, can be studied purity