Defects in superfluid3 He, high-Tc superconductors, QCD colour superfluids and cosmic vortons can possess (anti)ferromagnetic cores, and their generalisations. In each case there is a second order parameter whose value is zero in the bulk which does not vanish in the core. We examine the production of defects in the simplest 1+1 dimensional scalar theory in which a second order parameter can take non-zero values in a defect core. We study in detail the effects of core condensation on the defect production mechanism.
This work presents a novel miniature contact-aided compliant joint mechanism that can be integrated into millimeter-sized manual or robotic surgical instruments. The design aims to address the trade-off between notched-tube compliant joints' range of motion and stiffness, while also ensuring a compact form factor. The mechanism is constructed from a nitinol tube with asymmetric cutouts and is actuated in bending by a cable. The innovative feature of this design is the incorporation of a contact aid into the notched-tube topology, which acts to both increase the stiffness of the joint and change the shape that it undertakes during bending. Using finite element modeling (FEM) techniques, we present a sensitivity analysis investigating how the performance of this contact-aided compliant mechanism (CCM) is affected by its geometry, and derive a kinematics and statics model for the joint. The FEM simulations and the kinematic and static models are compared to experimental results. The design and modeling presented in this study can be used to develop new miniature dexterous instruments, with a particular emphasis on applications in minimally invasive neurosurgery.
ObjectiveThis paper reviews our experience of potassium titanyl phosphate (KTP) laser in transcanal totally endoscopic cholesteatoma surgery.MethodsA prospective cohort study was conducted in a tertiary referral centre, involving a consecutive series of children with cholesteatoma who underwent totally endoscopic cholesteatoma surgery with a KTP laser.ResultsThe patients’ mean age was 10.5 years (range, 1.8–18 years). A KTP laser was used in 70 of the 83 cases (84 per cent). The laser was not used in 13 ‘clean’ cases, in which disease was removed more easily. Residual disease was detected in five cases (6 per cent), of which the KTP laser had been used in four (5 per cent). No complications were associated with KTP laser use.ConclusionThe combination of KTP laser use with endoscopic visualisation is effective for minimising the risk of residual disease using a minimally invasive surgical approach. The thin, semi-flexible fibre carrier of the KTP laser is ideally suited to work alongside the endoscope within the narrow confines of the ear canal.
In addition to highlighting and quantifying some of the common TEES challenges, these findings provide valuable insight into the design requirements for developing improved surgical instrumentation and techniques.
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