Localised conduction electrons in carbon nanotubes and related structures

Single localized polaron (quasiparticle) States are considered in structures relating to carbon nanotubes. The hamiltonian is derived in the tight-binding approximation first on a hexagonal lattice and later on a general carbon nanotube with specifiable chirality, and shares close links with the Davydov model of excitations of a one-dimensional molecular chain. First-order interactions of the lattice degrees of freedom with the electron on-site and exchange terms are included. The system equations are shown, under certain approximations, to share a close relationship with the nonlinear Schrödinger equation - an equation that is known to possess localised solutions. The ground state of system is investigated numerically and is found to depend crucially upon the strengths of the electron-phonon interactions

The effect of boundary constraints on finite element modelling of the human pelvis

The use of finite element analysis (FEA) to investigate the biomechanics of anatomical systems critically relies on the specification of physiologically representative boundary conditions. The biomechanics of the pelvis has been the specific focus of a number of FEA studies previously, but it is also a key aspect in other investigations of, for example, the hip joint or new design of hip prostheses. In those studies, the pelvis has been modelled in a number of ways with a variety of boundary conditions, ranging from a model of the whole pelvic girdle including soft tissue attachments to a model of an isolated hemi-pelvis. The current study constructed a series of FEA models of the same human pelvis to investigate the sensitivity of the predicted stress distributions to the type of boundary conditions applied, in particular to represent the sacro-iliac joint and pubic symphysis. Varying the method of modelling the sacro-iliac joint did not produce significant variations in the stress distribution, however changes to the modelling of the pubic symphysis were observed to have a greater effect on the results. Over-constraint of the symphysis prevented the bending of the pelvis about the greater sciatic notch, and underestimated high stresses within the ilium. However, permitting medio-lateral translation to mimic widening of the pelvis addressed this problem. These findings underline the importance of applying the appropriate boundary conditions to FEA models, and provide guidance on suitable methods of constraining the pelvis when, for example, scan data has not captured the full pelvic girdle. The results also suggest a valid method for performing hemi-pelvic modelling of cadaveric or archaeological remains which are either damaged or incomplete

The biomechanical function of periodontal ligament fibres in orthodontic tooth movement

Orthodontic tooth movement occurs as a result of resorption and formation of the alveolar bone due to an applied load, but the stimulus responsible for triggering orthodontic tooth movement remains the subject of debate. It has been suggested that the periodontal ligament (PDL) plays a key role. However, the mechanical function of the PDL in orthodontic tooth movement is not well understood as most mechanical models of the PDL to date have ignored the fibrous structure of the PDL. In this study we use finite element (FE) analysis to investigate the strains in the alveolar bone due to occlusal and orthodontic loads when PDL is modelled as a fibrous structure as compared to modelling PDL as a layer of solid material. The results show that the tension-only nature of the fibres essentially suspends the tooth in the tooth socket and their inclusion in FE models makes a significant difference to both the magnitude and distribution of strains produced in the surrounding bone. The results indicate that the PDL fibres have a very important role in load transfer between the teeth and alveolar bone and should be considered in FE studies investigating the biomechanics of orthodontic tooth movement. © 2014 McCormack et al

Implementing A Balanced Scorecard In A Not-For-Profit Organization

This paper examines the use of the Balanced Scorecard in a not-for-profit organization (Cattaraugus County ReHabilitation Center).  The ReHabilitation Center has begun using the Balanced Scorecard paradigm in its strategic planning process.  In this paper an overview is presented of the basic concepts of the Balanced Scorecard including the financial perspective, customer perspective, internal process perspective, and learning and growth perspective.  The history and services of the ReHabilitation Center are then summarized.  The application of the Balanced Scorecard approach to the ReHabilitation Center is discussed in detail.  Implications in using the Balanced Scorecard are discussed.  Finally, conclusions regarding the use of the Balanced Scorecard in a not-for-profit organization are presented

Implementing A Balanced Scorecard In A Not-For-Profit Organization

This paper examines the use of the Balanced Scorecard in a not-for-profit organization (Cattaraugus County ReHabilitation Center).  The ReHabilitation Center has begun using the Balanced Scorecard paradigm in its strategic planning process.  In this paper an overview is presented of the basic concepts of the Balanced Scorecard including the financial perspective, customer perspective, internal process perspective, and learning and growth perspective.  The history and services of the ReHabilitation Center are then summarized.  The application of the Balanced Scorecard approach to the ReHabilitation Center is discussed in detail.  Implications in using the Balanced Scorecard are discussed.  Finally, conclusions regarding the use of the Balanced Scorecard in a not-for-profit organization are presented

Masticatory biomechanics in the rabbit : a multi-body dynamics analysis

Acknowledgement We thank Sue Taft (University of Hull) for the µCT-scanning of the rabbit specimen used in this study. We also thank Raphaël Cornette, Jacques Bonnin, Laurent Dufresne, and l'Amicale des Chasseurs Trappistes (ACT) for providing permission and helping us capture the rabbits used for the in vivo bite force measurements at la Réserve Naturelle Nationale de St Quentin en Yvelines, France.Peer reviewedPublisher PD