Validation of a Paper-and-Pencil Test Instrument Measuring Biology Teachers’ Pedagogical Content Knowledge by Using Think-Aloud Interviews

The topic of ‘teacher professionalism’ is one of the most crucial ones in quality education research. It has a potential to generate results that could inform and hence enhance the practice in classrooms. Thus, research in this field needs reliable instruments to measure the professional knowledge of our teachers to be able to generate reliable results for our research problems. Not many instruments have been developed with regard to this topic. At the same time, an adequate validation of the instrument developed is often missing (Schilling & Hill, 2007). Hence, in a bigger project ProwiN (German acronym for professional knowledge of science teachers), test instruments for measuring science teachers’ pedagogical, pedagogical content and content knowledge (PK, PCK, and CK) were developed for the subjects biology, chemistry and physics. The present study tested the validity of some of these items which were used to measure the pedagogical content knowledge (PCK) of biology teachers. These items focused on measuring teachers’ professional knowledge by analyzing 1) teachers’ knowledge about student understanding (or lack of understanding) of several topics in biology and 2) knowledge about instructional strategies like the use of models or experiments. The content validity of these instruments was examined by think-aloud interviews with American and German Biology teachers (N=11). This study shows a high content validity for these items. Furthermore, this paper demonstrates the scope for adapting the conceptual framework of these items to measure biology teachers’ PCK in other countries

Measurement of global mechanical properties of human thorax: Costal cartilage

Surgical resection of chest wall tumours may lead to a loss of ribcage stability and requires reconstruction to allow for physical thorax functioning. When titanium implants are used especially for larger, lateral defects, they tend to break. Implant failures are mainly due to specific mechanical requirements for chest-wall reconstruction which must mimic the physiological properties and which are not yet met by available implants. In order to develop new implants, the mechanical characteristics of ribs, joints and cartilages are investigated. Rib loading is highly dependent on the global thorax kinematics, making implant development substantially challenging. Costal cartilage contributes vastly to the entire thorax load-deformation behaviour, and also to rib loading patterns. Computational models of the thoracic cage require mechanical properties on the global stiffness, to simulate rib kinematics and evaluate stresses in the ribs and costal cartilage. In this study the mechanical stiffness of human costal cartilage is assessed with bending, torsion and tensile tests. The elastic moduli for the bending in four major directions ranged from 2.2 to 60.8 MPa, shear moduli ranged from 5.7 to 24.7 MPa for torsion, and tensile elastic moduli ranging from 5.6 to 29.6 MPa. This article provides mechanical properties for costal cartilage. The results of these measurements are used for the development of a whole thorax finite element model to investigate ribcage biomechanics and subsequently to design improved rib implants.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Measuring the global mechanical properties of the human thorax: Costo-vertebral articulation

Biomechanical simulation of the human thorax, e.g. for 3D-printed rib implant optimisation, requires an accurate knowledge of the associated articulation and tissue stiffness. The present study is focusing on determining the stiffness of the costo-vertebral articulations.Specimens of rib segments including the adjacent thoracic vertebrae and ligaments were obtained from two human post-mortem bodies at four different rib levels. The rib samples were loaded with a tensile force in the local longitudinal, sagittal and transverse direction and the resulting displacement was continuously measured. The moment–angle response of the rib articulations was also determined by applying a load at the rib end in the cranial – caudal direction and measuring the resulting displacement.The torsional load response of the costo-vertebral articulations at an applied moment between −0.1 Nm and 0.1 Nm corresponded to a median range of motion of 13.2° (6.4° to 20.9°). An almost uniform stiffness was measured in all tensile loading directions. The median displacement at the defined force of 28 N was 1.41 mm in the longitudinal, 1.55 mm in the sagittal, and 1.08 mm in the transverse direction.The measured moment–angle response of the costo-vertebral articulation is in line with the data from literature. On the contrary, larger displacements in longitudinal, sagittal and transverse directions were measured compared to the values found in literature.info:eu-repo/semantics/publishe