We theoretically investigate the optical functionality of a semiconducting quantum ring manipulated by two electrostatic lateral gates used to induce a double quantum well along the ring. The well parameters and corresponding interlevel spacings, which lie in the THz range, are highly sensitive to the gate voltages. Our analysis shows that selection rules for interlevel dipole transitions, caused by linearly polarized excitations, depend on the polarization vector angle with respect to the gates. In striking difference from the conventional symmetric double well potential, the ring geometry permits polarization-dependent transitions between the ground and second excited states, allowing the use of this structure in a three-level lasing scheme.
Presentation of research at orthopaedic conferences is an important component for surgical evidence-based practice. However, there remains uncertainty as to how many conference abstracts proceed to achieve full-text publication (FTP) for wider dissemination. This study aimed to determine the abstract-to-publication rate (APR) of research presented in the largest hip and knee orthopaedic meetings in the UK, and to identify predictive factors which influence the APR. All published abstracts (n=744) from the 2006, 2008, 2009 and 2010 British Hip Society (BHS) and the 2007, 2009, 2010 and 2011 British Association for Surgery of the Knee (BASK) annual conference meetings were examined by four researchers independently. To determine whether abstracts had been published in full-text form, Google Scholar, Medline and EMBASE evidence databases were used to verify FTP status. Variables including sample size, statistical significance, grade of the first author, research affiliated institution and research design were extracted and analysed to identify whether these were associated with FTP. 176 out of 744 abstracts achieved FTP status (APR: 23.7%). Factors associated with FTP status included statistically significant results (P<0.01) and research design (P=0.02). Factors not associated included sample size, grade of the first author and research affiliated institution (P>0.05). APRs of the assessed BHS and BASK annual conference presentations are low in comparison to other scientific meetings. Encouragement should be provided to clinicians and academics to submit their work for publication to address this short fall, thereby enhancing the potential for full-text research publications to inform evidence-based orthopaedics.
We outline a range of proposals on using quantum rings and nanohelices for terahertz device implementations. We show that an Aharonov-Bohm quantum ring system and a double-gated quantum ring system both permit control over the polarization properties of the associated terahertz radiation. In addition, we review the superlattice properties of a mathematically similar system, that of a nanohelix in external electric fields, which reveals negative differential conductance.
We theoretically investigate the problem of an electron confined to a nanohelix between two parallel gates modelled as charged wires. The double-gated nanohelix system is a binary superlattice with properties highly sensitive to the gate voltages. In particular, the band structure exhibits energy band crossings for certain combinations of gate voltages, which could lead to quasi-relativistic Dirac-like phenomena. Our analysis for optical transitions induced by linearly and circularly polarized light suggests that a double-gated nanohelix can be used for versatile optoelectronic applications.
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