TY - JOUR
AB - AbstractObjectiveConcerns about short‐ and long‐term consequences of repetitive heading contributed to heading restrictions in youth football in some countries. This prospective longitudinal cohort study aims to describe heading exposure in children's and youth football over two seasons using standardized video analysis.MethodsAll matches and training sessions of a male Under‐11 (n = 29), Under‐15 (n = 28), Under‐19 (n = 38), and female Under‐17 (n = 39) team were videotaped during the seasons 2019–2020 and 2020–2021. Heading frequencies and characteristics were analyzed. Individual heading exposure is presented as average incidence rates (IR) per 1000 match/training hours.ResultsIn 275 matches and 673 training sessions, 22 921 headers were observed. Heading IR per player in matches was 1256 (Under‐11 m), 1608 (Under‐15 m), 1050 (Under‐17 f), and 1966 (Under‐19 m). In training sessions, IR per player was 739 (Under‐11 m), 2206 (Under‐15 m), 1661 (Under‐17 f), and 1419 (Under‐19 m). Five Under‐15 males headed the ball five to eight times per training on average. Most headers were performed without heading duels. Flight distance was predominantly 5–20 m (54%) in matches and <5 m (65%) in training. While head impact location most frequently was at frontal areas, one‐third of all headers in Under‐11 in matches hit temporal, parietal, and occipital parts of the head.ConclusionHeading incidence was low in the youngest age group, whereas (predominantly five) Under‐15 males showed very high heading exposures in training. In assessment and regulation of heading burden, training sessions and individual heading behavior should specifically be addressed. Recommendations for heading the ball in practice should account for individual and age‐related differences.
AU - Reeschke, Rebecca
AU - Haase, Franziska Katharina
AU - Dautzenberg, Lena
AU - Krutsch, Werner
AU - Reinsberger, Claus
ID - 46818
IS - 9
JF - Scandinavian Journal of Medicine & Science in Sports
KW - Physical Therapy
KW - Sports Therapy and Rehabilitation
KW - Orthopedics and Sports Medicine
SN - 0905-7188
TI - Training matters: Heading incidence and characteristics in children's and youth football (soccer) players
VL - 33
ER -
TY - BOOK
AU - Rossel, Moritz Sebastian
AU - Meschut, Gerson
ID - 46812
TI - Methodenentwicklung zur verbesserten Prognosegüte beim Clinchen mit beweglicher Matrize in der numerischen Fügeprozesssimulation
VL - 598
ER -
TY - JOUR
AU - Höper, Lukas
AU - Schulte, Carsten
ID - 46186
IS - 4
JF - MNU journal
SN - 0025-5866
TI - Paradigmenwechsel vom klassischen zum datengetriebenen Problemlösen im Informatikunterricht
VL - 76
ER -
TY - JOUR
AU - Pfister, Daniel
AU - Jackson, Robin C
AU - Güldenpenning, Iris
AU - Williams, A Mark
ID - 46736
JF - Human Movement Science
TI - Timing a fake punch: Inhibitory effects in a boxing-specific spatial attention task
VL - 89
ER -
TY - CONF
AU - Blömer, Johannes
AU - Bobolz, Jan
AU - Bröcher, Henrik
ID - 35014
TI - On the impossibility of surviving (iterated) deletion of weakly dominated strategies in rational MPC
ER -
TY - CONF
AU - Blömer, Johannes
AU - Bobolz, Jan
AU - Porzenheim, Laurens Alexander
ID - 43458
TI - A Generic Construction of an Anonymous Reputation System and Instantiations from Lattices
ER -
TY - CHAP
AU - Schroeter-Wittke, Harald
AU - Junkermann, Ilse
ID - 46856
T2 - Ich lobe meinen Gott, der aus der Tiefe mich holt. Hymnologische Kommentare zu den Liedern im Ergänzungsheft zum Evangelischen Gesangbuch. Jan Janssen zum 60. Geburtstag. HEG 3/Ergänzungsheft, Göttingen 2023
TI - Stern über Bethlehem (EG.E 1)
ER -
TY - CHAP
AU - Schroeter-Wittke, Harald
ID - 46857
T2 - Ich lobe meinen Gott, der aus der Tiefe mich holt. Hymnologische Kommentare zu den Liedern im Ergänzungsheft zum Evangelischen Gesangbuch. Jan Janssen zum 60. Geburtstag. HEG 3/Ergänzungsheft, Göttingen 2023
TI - Wir haben Gottes Spuren festgestellt (EG.E 20)
ER -
TY - JOUR
AB - In this work, the influence of the filler–matrix adhesion on the tensile properties of laser-sintered parts built with Polyamide 613 filled with glass beads was investigated. For this purpose, dry blends of glass beads with and without organosilane coupling agents and polyamide powder were prepared and processed into tensile specimens on an EOS P396 laser sintering system. The samples were tested both in the dry state and after an accelerated conditioning in a climate chamber. Furthermore, finite element method (FEM) simulations were performed to model the extreme cases of optimum adhesion and no adhesion. By correlating the tensile tests with the simulation results and by analyzing the fracture surfaces, it was shown that the filler–matrix adhesion is sufficient in the dry state but is strongly degraded by conditioning. Even the presence of various organosilane thin films could not prevent a strong deterioration of the filler–matrix adhesion and the associated deterioration of the mechanical properties. Since a comparison with an injection-molded sample of the same polymer filler combination shows identical behavior after conditioning, it is assumed that this problem is not limited to additively manufactured parts.
AU - Kletetzka, Ivo
AU - Kosanke, Maren
AU - Meinderink, Dennis
AU - Neßlinger, Vanessa
AU - Grundmeier, Guido
AU - Schmid, Hans-Joachim
ID - 46815
JF - Progress in Additive Manufacturing
KW - Industrial and Manufacturing Engineering
SN - 2363-9512
TI - Influence of the filler–matrix adhesion and the effects of conditioning on tensile properties of laser-sintered parts built with polyamide–glass bead dry blends
ER -
TY - GEN
AB - Abstract
In this work, the influence of the filler matrix adhesion on the tensile properties of laser-sintered parts built with Polyamide 613 filled with glass beads was investigated. For this purpose, dry blends of glass beads with and without organosilane coupling agents and polyamide powder were prepared and processed into tensile specimens on an EOS P396. The samples were tested both in the dry state and after an accelerated conditioning in a climate chamber. Furthermore, FEM simulations were performed to model the limiting cases of optimum adhesion and no adhesion. By correlating the tensile tests with the simulation results and by analyzing the fracture surfaces, it was shown that the filler matrix adhesion is sufficient in the dry state but is strongly degraded by conditioning. Even the presence of various organosilane thin films could not prevent a strong deterioration of the filler-matrix adhesion and the associated deterioration of the mechanical properties. Since a comparison with an injection molded sample of the same polymer filler combination shows identical behavior after conditioning, it is assumed that this problem is not limited to additively manufactured parts.
AU - Kletetzka, Ivo
AU - Kosanke, Maren
AU - Meinderink, Dennis
AU - Neßlinger, Vanessa
AU - Grundmeier, Guido
AU - Schmid, Hans-Joachim
ID - 43049
TI - Influence of the filler matrix adhesion and the effects of conditioning on tensile properties of laser sintered parts built with polyamide glass bead dry blends
ER -