49 research outputs found
Buckling mediated by mobile localized elastic excitations
Experiments reveal that structural transitions in thin sheets are mediated by
the passage of transient and stable mobile localized elastic excitations. These
``crumples'' or ``d-cones'' nucleate, propagate, interact, annihilate, and
escape. Much of the dynamics occurs on millisecond time scales. Nucleation
sites correspond to regions where generators of the ideal unstretched surface
converge. Additional stable intermediate states illustrate two forms of
quasistatic inter-crumple interaction through ridges or valleys. These
interactions create pairs from which extended patterns may be constructed in
larger specimens. The onset of localized transient deformation with increasing
sheet size is correlated with a characteristic stable crumple size, whose
measured scaling with thickness is consistent with prior theory and experiment
for localized elastic features in thin sheets. We offer a new theoretical
justification of this scaling.Comment: contains link to video
Sagittal joint spaces of the temporomandibular joint: Systematic review and meta-analysis
Introduction: The joint space measurements of the temporomandibular joint have been used to determine the condyle position variation. Therefore, the aim of this study is to perform a systematic review and meta-analysis on the
coronal joint spaces measurements of the temporomandibular joint.
Materials and Methods: An electronic database search was performed with the terms âcondylar positionâ; âjoint
spaceâANDâTMJâ. Inclusionary criteria included: tomographic 3D imaging of the TMJ, presentation of at least
two joint space measurements on the coronal plane. Exclusionary criteria were: mandibular fractures, animal studies, surgery, presence of genetic or chronic diseases, case reports, opinion or debate articles or unpublished material. The risk of bias of each study was judged as high, moderate or low according to the âCochrane risk of bias
toolâ. The values used in the meta-analysis were the medial, superior and lateral joint space measurements and their
differences between the right and left joint.
Results: From the initial search 2706 articles were retrieved. After excluding the duplicates and all the studies that
did not match the eligibility criteria 4 articles classified for final review. All the retrieved articles were judged as low
level of evidence. All of the reviewed studies were included in the meta-analysis concluding that the mean coronal
joint space values were: medial joint space 2.94 mm, superior 2.55 mm and lateral 2.16 mm.
Conclusions: the analysis also showed high levels of heterogeneity. Right and left comparison did not show statistically significant differences
Multilevel analysis of hepatitis A infection in children and adolescents: a household survey in the Northeast and Central-west regions of Brazil
Background The objectives were to estimate the prevalence of hepatitis A among children and adolescents from the Northeast and Midwest regions and the Federal District of Brazil and to identify individual-, household- and area-levels factors associated with hepatitis A infection