All atomic force microscope (AFM) images suffer from distortions, which are principally produced by the interaction between the measured sample and the AFM tip. If the three-dimensional shape of the tip is known, the distorted image can be processed and the original surface form `restored', typically by deconvolution approaches. This restored image gives a better representation of the real 3D surface of the measured sample than the original distorted image. In this paper, we propose a method for estimating the three-dimensional shape of the AFM tip by measuring a micro-cylinder with a-priori known dimensions. The estimated tip shape is then used to restore subsequent AFM images, when measured with the same tip, under similar measurement conditions. Significantly, the impulse response of the AFM can be deduced using this method. The suitability of this novel approach for restoring AFM images has been confirmed using both computer simulation and also with real experimental AFM images. The proposed method is compared with standard restoration techniques and is shown to provide superior performance to such approaches.

An investigation into orientation preferences shown by actin fibres within ex-situ actin as imaged by Atomic Force Microscopy (AFM) is described. Actin is a primary cytoskeletal component and is believed to play a vital role in cell structure. Actin structure images measured by AFM were analysed using automated pre-processing steps. These steps were identical for the production of an initial binary image, which was then processed by both Hough transformation and thinning. Results obtained question the validity of using the Hough transform approach, as bias could not easily be eliminated, and hence the Hough transform method was deemed to be unsuitable for this application and instead the thinning technique was used to identify and locate actin orientation within the AFM images. The results show that polymerised ex-situ actin fibres appears to display a bimodal distribution of orientation, with a 90 degree separation, with a significant co-efficient of bimodality of 0.656.

The programming of the interrupt handling mechanisms, process switching primitives, scheduling mechanism, and synchronization primitives of an operating system for a multiprocessor require both efficient code in order to support the needs of high- performance or real-time applications and careful organization to facilitate maintenance. Although many advantages have been claimed for object-oriented class hierarchical languages and their corresponding design methodologies, the application of these techniques to the design of the primitives within an operating system has not been widely demonstrated. To investigate the role of class hierarchical design in systems programming, the authors have constructed the Choices multiprocessor operating system architecture the C++ programming language. During the implementation, it was found that many operating system design concerns can be represented advantageously using a class hierarchical approach, including: the separation of mechanism and policy; the organization of an operating system into layers, each of which represents an abstract machine; and the notions of process and exception management. In this paper, we discuss an implementation of the low-level primitives of this system and outline the strategy by which we developed our solution.